The amount of low-temperature heat generated in industrial processes is high, but recycling is limited due to low grade and low recycling efficiency, which is one of the reasons for low energy efficiency. It implies that there is a great potential for low-temperature heat recovery and utilization. This article provided a detailed review of recent advances in the development of low-temperature thermal upgrades, power generation, refrigeration, and thermal energy storage. The detailed description will be given from the aspects of system structure improvement, work medium improvement, and thermodynamic and economic performance evaluation. It also pointed out the development bottlenecks and future development trends of various technologies. The low-temperature heat combined utilization technology can recover waste heat in an all-round and effective manner, and has great development prospects.

Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion. Although, several debatable issues including feedstock availability and price, fuel and food competition, changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel. However, non-crop feedstocks could be a promising alternative. In this article, waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation. The important factors such as the quantity of waste cooking oil produced, crude oil and vegetable oil import expenses, high-speed diesel imports, waste management issues and environmental hazards are considered. Moreover, process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted. The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66USD·L^-1. We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.

Graphene oxide (GO) is one typical two-dimension structured and oxygenated planar molecular material. Researchers across multiple disciplines have paid enormous attention to it due to the unique physiochemical properties. However, models used to describe the structure of GO are still in dispute and ongoing to update. And currently, synthesis methods for mass production are seemingly abundant but in fact, dominated by a few core methodologies. To update with the state-of-art opinions and progresses, herein we present a mini critical review regarding the synthesis of GO as well as its models and simulations of structure. Also, we discuss the perspectives.

The co-firing of coal and biomass in oxy-fuel fluidized beds is one of the most promising technologies for capturing CO₂. This technology has attracted wide attention from academia and industry in recent years as a negative emission method to capture CO₂ produced by carbon contained in biomass. In the past decades, many studies have been carried out regarding experiments and numerical simulations under oxy-fuel combustion conditions. This paper firstly briefly discusses the techno-economic viability of the biomass and coal co-firing with oxycombustion and then presents a review of recent advancements involving experimental research and computational fluid dynamics (CFD) simulations in this field. Experimental studies on mechanism research, such as thermogravimetric analysis and tube furnace experiments, and fluidized bed experiments based on oxy-fuel fluidized beds with different sizes as well as the main findings, are summarized as a part of this review. It has been recognized that CFD is a useful approach for understanding the behaviors of the co-firing of coal and biomass in oxyfuel fluidized beds. We summarize a recent survey of published CFD research on oxy-fuel fluidized bed combustion, which categorized into Eulerian and Lagrangian methods. Finally, we discuss the challenges and interests for future research.

Five different internals were designed, and their effects on phase holdup and backmixing were investigated in a gas-liquid concurrent upflow reactor where the spherical alumina packing particles of three diameters (3.0, 4.5 and 6.0 mm) were slightly expanded under the conditions of varied superficial gas velocities (6.77×10^-2-3.61×10^-1 m·s^-1) and superficial liquid velocities (9.47×10^-4-2.17×10^-3 m·s^-1). The experimental results show that the gas holdup increases with the superficial gas velocity and particle size, opposite to the variational trend of liquid holdup. When an internal component is installed amid the upflow reactor, a higher gas holdup, a less liquid holdup and a larger Peclet number characterizing the weaker backmixing are obtained compared to those in the bed without internals under the same operating conditions. Additionally, the minimal backmixing is observed in the reactor equipped with the internals with a novel multi-step design. Finally, empirical correlations were proposed for estimating gas holdup, liquid holdup and Peclet number with the relative deviations within 11%, 12% and 25%, respectively.

The non-uniformity of gas-liquid mixture is a critical issue which leads to the heat transfer deterioration of spiralwound heat exchangers (SWHEs). Two-phase mass flow rate and the content of gas are important parameters as well as structural parameters which have prominent influences on flow distribution uniformity of SWHE shell side. In order to investigate the influences of these parameters, an experimental test system was built using water and air as mediums and a novel distributor named "tubes distributor" was designed. The effects of mass flow rate and the content of gas on two-phase distribution performance were analyzed, where the mass flow rate ranged from 28.4 to 171.9 kg·h^-1 and the content of gas changed from 0.2 to 0.8, respectively. The results showed that the mixture mass flow rate considerably influenced the liquid distribution than that of gas phase and the larger mass flow rate exhibited the better distribution uniformity of two-phase flow. It was also found that the tubes distributor had the better two-phase uniformity when the content of gas was around 0.4. Tube diameter played an important role in the distribution of gas phase and slit width was more significant for the uniformity of liquid phase.

Particle descent velocities in an annular stripper were measured by a laser Doppler velocimetry (LDV) system. In the radial direction, particle descent velocity was relatively constant in the mid-region of the stripper and increased towards the walls on both sides, exhibiting an anti-U-shaped distribution. Particle descent velocity in the radial mid-region increased with the increase of superficial gas velocity, and the maximum in the outer wall region increased significantly with the increase of solid mass flux. Superficial stripping gas velocity had stronger effect on particle velocity distributions near the stripper gas distributor, and such effect weakened with the increase of the distance from the distributor. Local particle velocity and its radial profiles could be adjusted by changing the superficial stripping gas velocity. Empirical formulas were established to describe the relationships between the local particle velocity and cross-sectional averaged velocity based on the effects of operating conditions and measuring positions. The result showed that the predicted data was in good agreement with the experimental value.

Computational fluid dynamics (CFD) and experimental analyses of some of the basic characteristics of air sparging in a tall stirred vessel equipped with a three-stage impeller are presented. The impeller was assembled from a radial ABT impeller as the lower, a turbine 6PBT45 as the middle and an axial Scaba-type 3SHP1 impeller as the upper. All the impellers were of the same diameter, i.e., 225 mm, while the vessel diameter was 450 mm. The impeller's rotational speed was 178 r·min^-1. The aeration regime was established with an air volumetric flow rate of 28.3 m³·h^-1. To the best of our knowledge, this study is the first to consider the very high gassing rate by means of CFD in a tank stirred by three-stage axial/radial impellers.
The numerical simulation was performed using the ANSYS Fluent (R17.2, 2016) code for solving the governing equations of fluid dynamics in single- and multi-phase systems. While discussing the bubble size distribution, a discrete population balance model (PBM) was used. Adopting CFD, the stirring power and the total void fraction (the total gas holdup) were calculated. The results were in good agreement with the measured values using a laboratory experimental device.

In this study, the effects of geometrical and physical factors on light particles dispersion in stirred tank were investigated by agitation characteristic curve. The experiments and CFD simulations with discrete phase model (DPM) and volume of fluid model (VOF) were conducted in this paper. Five factors, which include four geometrical factors (submergence, impeller-to-tank ratio, number of impeller blades and baffling mode) and a physical factor (liquid viscosity) were considered. For each factor, the power consumption curve and agitation characteristic curve were drawn to compare the power consumption and mixing results in the stirred tank. Characteristics of the agitation characteristic curves were compared with the previous published literatures and theories. It is found that the agitation characteristic curves reflect the tendency of power consumption and particles distribution well in stirred tank. The good agreement indicates the applicability of the agitation characteristic curves for the study of light particles distribution in stirred tank.

A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object, whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics (CFD) method. Based on the Eulerian-Eulerian method and modified Brucato drag model, the just-suspension speed of impeller was predicted, and the simulation results were in good agreement with the experimental data. The quality of solid suspension under different rotation modes was also compared, and the results showed the coaxial mixer operating under co-rotation mode could get the best performance, and a larger anchor speed was beneficial to solid suspension by enhancing the turbulent intensity at the bottom. Compared with the anchor, the inner Rushton turbine played a dominant role in solid suspension due to its high rotational speed, whereas an extremely high inner impeller speed would make the uniformity of solid distributions become worse. Additionally, the effects of solid phase properties were also investigated, the results revealed that the higher the overall solid volume fraction and the smaller the Shields number, the worse the performance of solid suspension, meanwhile the solid suspension was more susceptible to solid density compared with particle diameter within the same Shields number gradient.

Passive micromixers are preferred over active mixers for many microfluidic applications due to their relative ease in integration into complex systems and operational flexibility. They also incur very low cost of manufacturing. However, the degree of mixing is comparatively low in passive mixers than active mixers due to the absence of disturbance in the flow by external forces and the inherent laminar nature of microchannel flows. Various designs of complex channel structures and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive mixers. But the studies on mixing enhancement with simple planar geometries of passive mixers have been few and limited. The present work aims to investigate the possibility of mixing enhancement by employing simple planar type designs, such as T-mixer and T-T mixer with cylindrical elements placed in the mixing channel. The mixing performance has been evaluated in the Reynolds number range of 6 to 700. Numerical results have shown that T-T mixer with cylindrical elements performed significantly well and obtained very good mixing quality over basic T-mixer for the entire range of Reynolds number (6 to 700). The device has also shown better mixing as compared to basic T-T mixer and T-mixer with cylindrical elements. A larger pair of vortices formed in the stagnation area due to the presence of a cylindrical element in the junction. Cylindrical elements downstream caused significant enhancement in mixing due to splitting and recombining action. The size of the cylindrical element in the T-T mixer has been optimized to obtain better mixing performance of the device. Remarkable improvement in mixing quality by T-T mixer with cylindrical elements has been obtained at the expense of small rise in pressure drop as compared to other passive designs considered in this study. Therefore, the current design of T-T mixer with cylindrical elements can act as an effective and simple passive mixing device for various micromixing applications.

This paper concerns the characteristics of heat and mass transfer in upper convected Maxwell fluid flow over a linear stretching sheet with solar radiation, viscous desperation and temperature based viscosity. After boundary layer approximation, the governing equations are achieved (namely Maxwell, upper convected material derivative, thermal and concentration diffusions). By using the self-similarity transformations the governing PDEs are converted into nonlinear ODEs and solved by RK-4 method in combination with Newton Raphson (shooting technique). The effects of developed parameters on velocity, temperature, concentration, fraction factor, heat and mass diffusions are exemplified through graphs and tabular form and are deliberated in detail. Numerical values of fraction factor, heat and mass transfer rates with several parameters are computed and examined. It is noticed that the temperature is more impactable for higher values of radiative heat transport, thermal conductivity and viscous dissipation. The comparison data for some limiting case are acquired and are originated to be in good agreement with previously published articles.

The three-dimensional (3D) model of cigarette was accurately constructed through reverse engineering as the research object of numerical simulation. The combustion process of cigarette was studied with computational fluid dynamics (CFD). Standard Laminar models with species transport approach were applied, and numerical simulation of the cigarette was analyzed with semi-implicit method for pressure-velocity coupling. The results showed that the model could predict velocity of cigarette smoke, the distributions of temperature and pressure at different times. In order to verify the correctness of model, it was found that the relationship between the velocity of smoke and pressure according to Darcy's law on z position (x=4 mm, y=0, 0 mm ≤ z ≤ 50.61 mm).

In order to develop high performance composite membranes for alcohol permselective pervaporation (PV), poly (dimethylsiloxane)/ZIF-8 (PDMS/ZIF-8) coated polymeric hollow fiber membranes were studied in this research. First, PDMS was used for the active layer, and Torlon®, PVDF, Ultem®, and Matrimid® with different porosity were used as support layer for fabrication of hollow fiber composite membranes. The performance of the membranes varied with different hollow fiber substrates was investigated. Pure gas permeance of the hollow fiber was tested to investigate the pore size of all fibers. The effect of support layer on the mass transfer in hydrophobic PV composite membrane was investigated. The results show that proper porosity and pore diameter of the support are demanded to minimize the Knudsen effect. Based on the result, ZIF-8 was introduced to prepare more selective separation layer, in order to improve the PV performance. The PDMS/ZIF-8/Torlon® membrane had a separation factor of 8.9 and a total flux of 847 g·m^-2·h^-1. This hollow fiber PDMS/ZIF-8/Torlon® composite membrane has a great potential in the industrial application.

Volatile organic compounds (VOCs) are difficult to be eliminated safely and effectively because of their large concentration fluctuations. Thus, maintaining a stable concentration of VOCs is a significant study. In this research, H₂O, Tween-80,[Emim]BF₄,[Emim]PF₆, and[Hnmp]HSO₄ were applied to absorb and desorb simulated VOCs. The ionic liquid[Emim]BF₄ demonstrated the best performance and was thus selected for further experiments. As the ionic liquid acted as a buffer, the toluene concentration with a fluctuation of 2000-20000 mg·m^-3 was stabilized at 6000-12000 mg·m^-3. Heating distillation (90℃) was highly efficient to recover[Emim]BF₄ from toluene. The regenerated[Emim]BF₄ could retain its initial absorption capacity even after multiple cycles. Moreover,[Emim]BF₄ had the same buffer function on various aromatic hydrocarbons.

In this work, an air-blast atomizing column was used to study the CO₂ capture performance with aqueous MEA (mono-ethanol-amine) and NaOH solutions. The effects of gas flow rate, the liquid to gas ratio (L/G), the CO₂ concentration on the CO₂ removal efficiency (η) and the volumetric overall mass transfer coefficient (K_Ga_v) were investigated. The air-blast atomizing column was also compared with the pressure spray tower on the studies of the CO₂ capture performance. For the aqueous MEA and NaOH solutions, the experimental results show that the η decreases with increasing gas flow rate and CO₂ concentration while it increases with increasing L/G. The effects on K_Ga_v are more complicated than those for η. When the CO₂ concentration is low (3 vol%), K_Ga_v increases with increasing gas flow rate while decreases with increasing L/G. However, when the CO₂ concentration is high (9.5 vol%), as the gas flow rate and L/G increases, K_Ga_v increases first and then decreases. The aqueous MEA solution achieves higher η and K_Ga_v than the aqueous NaOH solution. The air-blast atomizing column shows a good performance on CO₂ capture.

SAPO-34 zeolite membranes show high efficiency for CO₂/CH₄ separation but suffer from the reduction of separation performance when exposed to humid atmosphere. In this work, n-dodecyltrimethoxysilane (DTMS) was used to modify the hollow fibers supported SAPO-34 membranes to increase the external surface hydrophobicity and thus sustain their performance under moisture environment. The modified membranes were fully characterized. Their separation performance was extensively investigated in both dry and wet gaseous systems and compared with the un-modified ones. The un-modified SAPO-34 membrane exhibited a high separation selectivity of 160 and CO₂ permeance of 1.18×10^-6 mol·m^-2·s^-1·Pa^-1 for separation of dry CO₂/CH₄ at 298 K. However, its separation selectivity declined to 0.9 and the CO₂ permeance was only about 1.7×10^-8 mol·m^-2·s^-1·Pa^-1 for wet CO₂/CH₄ at same temperature. High temperature (e.g. 353 K) could reduce the effect of moisture to improve SAPO-34 separation selectivity, but further increasing temperature (e.g. 373 K) led to decrease in CO₂/CH₄ separation selectivity. A significant decrease of selectivity was observed at higher pressure drop. The modified SAPO-34 membrane showed decreased CO₂ permeance but increased separation selectivity for dry CO₂/CH₄ gas mixture, and super performance for wet CO₂/CH₄ gas mixture due to the improved hydrophobicity of membrane surface. A separation selectivity of 65 and CO₂ permeance of 4.73×10^-8 mol·m^-2·s^-1·Pa^-1 for wet CO₂/CH₄ mixture can be observed at 353 K with a pressure drop of 0.4 MPa. Furthermore, the modified membrane exhibited stable separation performance during the 120-hour test for wet CO₂/CH₄ mixture at 353 K. The hydrophobic modification paves a way for SAPO-34 membranes in real applications.

The supercritical carbon dioxide extraction was applied to obtain essential oil from Pogostemon cablin in this work. Effect of extraction parameters including temperature, pressure, extraction time and particle size on extraction yield was investigated, and the response surface methodology with a Box-Behnken Design was used to achieve the optimized extraction conditions. The maximum yield of essential oil was 2.4356% under the conditions of extraction temperature 47℃, pressure 24.5 MPa and extraction time 119 min. Moreover, based on the Brunauer-Emmett-Teller theory of adsorption, a mathematical modeling was performed to correlate the measured data. The model shows a function relationship between extraction yield and time by a simple equation with three significantly adjustable parameters. These model parameters have been optimized through simulated annealing algorithm. The predicted data from the mathematical model show a good agreement with the experimental data of the different extraction parameters.

In this work, in order to obtain deep clean gas oil, a novel organic-inorganic hybrid (n-C₄H₉)₄N)₇H₅Si₂W₁₈Cd₄O₆₈@β-cyclodextrin (abbreviated as TBA-SiWCd@β-CD) composite was synthesized by supporting quaternary ammonium salt of sandwich-type polysilicotungstate on β-cyclodextrin (TBA-SiWCd@β-CD) as an efficient catalyst for oxidative desulfurization (ODS) of gas oil. The successful composition of the materials explained by the formation of host-guest inclusion complex, which confirmed through FTIR, UV-vis, XRD, SEM, and EDX characterization analyses. Experimental results revealed that the levels of sulfur content and mercaptan compounds of gas oil lowered with 97% removal efficiency. Compared with the ODS treatment of gas oil, the TBA-SiWCd@β-CD composite showed an outstanding catalytic performance for the oxidation of dibenzothiophene (DBT) in the prepared model fuel. The main factors that influence the desulfurization efficiency and the kinetic study of the ODS process were investigated. The prepared heterogeneous catalyst was found to give remarkable reusability for five runs without a discernible decrease in its activity. This study suggested the potential application of the TBA-SiWCd@β-CD catalyst for removal of hazardous sulfur compounds from gas oil fuel.

Particle concentration significantly affected the gasification of petcoke particles according to our previous studies. In this work, gasification characteristics and morphological evolution of single petcoke particle were investigated using a high temperature stage microscope experimental setup. The results showed that the reaction temperature significantly affected the reactivity of petcoke in the temperature range of 1200-1300℃. While the promoting effect on gasification reactivity decreased with further increasing the reaction temperature, the SEM analysis demonstrated the pore development during the gasification process, which attributed to the increase of reaction rate with conversion. The Raman analysis, HRTEM and SEM-EDX analysis showed that the heterogeneous graphitization of petcoke and non-uniform distribution of catalytic elements in petcoke attributed to the development of surface pores with limited depth. The gasification mechanism of petcoke particle can be briefly described as the reaction rate mainly contributed from the fast-reaction area. Besides, the pore development in fast-reaction area also enlarged the surface area of petcoke particle.

A novel template-free oxalate route was applied to synthesize different mesoporous manganese oxides (amorphous manganese oxide (AMO), Mn₅O₈, Mn₃O₄, MnO₂) in the narrow temperature range from 350℃ to 400℃ by controlling the calcination conditions, which were employed as the efficient catalysts for the oxidative coupling of alcohols with amines to imines. The chemical and structural properties of the manganese oxides were characterized by the methods of thermogravimetry analysis and heat flow (TG-DSC), X-ray diffraction (XRD), nitrogen sorption, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR), and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The structures of different manganese oxides were confirmed by characterization. The M-350 (AMO) presented the maximum surface area, amorphous nature, the lowest reduction temperature, the higher (Mn³⁺ + Mn⁴⁺)/Mn²⁺ ratio, and the higher adsorbed oxygen species compared to other samples. Among the catalysts, M-350 showed the best catalytic performance using air as an oxidant, and the conversion of benzyl alcohol (BA) and the selectivity of N-benzylideneaniline (NBA) reached as high as 100% and 97.1% respectively at the lower reaction temperature (80℃) for 1 h. M-350 had also the highest TOF value (0.0100 mmol·mg^-1·h^-1) compared to the other manganese oxide catalysts. The catalyst was reusable and gave 95.8% conversion after 5 reuse tests, the XRD pattern of the reactivated M-350 did not show any obvious change. Lattice oxygen mobility and (Mn³⁺ + Mn⁴⁺)/Mn²⁺ ratio were found to play the important roles in the catalytic activity of aerobic reactions.

The chitosan was found to possess an excellent catalytic performance in n-butyraldehyde selfcondensation to 2E2H. Under suitable conditions, the conversion of n-butyraldehyde, the yield and selectivity of 2E2H separately attained 96.0%, 86.0% and 89.6%. The chitosan catalyst could be recovered and used for 5 times without a significant deactivation after being treated with ammonium hydroxide. In order to elucidate the reaction mechanism, the adsorption and desorption of n-butyraldehyde on the surface of chitosan were studied using in situ FT-IR spectroscopy analysis. The result showed that n-butyraldehyde interacts with-NH₂ group of chitosan to form an intermediate species with an enamine structure. Then the reaction process of n-butyraldehyde self-condensation was monitored by React-IR technique and it was found that n-butyraldehyde self-condensation to 2-ethyl-3-hydroxyhexanal followed by a dehydration reaction to 2-ethyl-2-hexenal. On this basis, chitosan-catalyzed n-butyraldehyde self-condensation reaction mechanism was speculated and its reaction kinetics was investigated. The self-condensation reaction follows auto-catalytic reaction characteristics and then the corresponding kinetic model was established.

To prepare polymer supported ionic liquids (PSILs) as effective catalysts for esterification, the free radical suspension copolymerization of vinylbenzyl chloride (VBC, monomer), styrene (St, monomer) and divinylbenzene (DVB, crosslinker) with the addition of n-heptane (porogen) was carried out for the fabrication of the porous polymer (PVD) microsphere as support, followed by the immobilization of sulfonic acid-functionalized ionic liquids by the successive treatment of benzimidazole (BIm), 1,3-propane sultone and sulfuric acid (H₂SO₄) or trifluoromethanesulfonic acid (CF₃SO₃H). The effects of the compositions of DVB and n-heptane on the internal structure of the polymer supports were investigated, and it was found that the support with 40 wt% DVB and 60 wt% n-heptane (with relative to the monomer) could endow the final PSILs with the relatively optimal catalytic performance. The preliminary experiment in the batch reactor indicated that PSILs herein exhibited higher catalytic activities than commercial Amberlyst 46 resin for the esterification of propanoic acid (PROAc) with n-propanol (PROOH). Consequently, the optimal PSILs catalyst, PVD-[Bim-SO₃H]HSO₄, was selected for further study in the batch reactive distillation column because of low cost and its ease of preparation. The yield of propyl ropionate (PROPRO) could reach up to 97.78% at the optimized conditions of PROOH/PROAc molar ratio (2:1) and catalyst dosage (2.0 wt%). The investigation of the reaction kinetic manifested that the calculated results of second order pseudo-homogeneous kinetic model were in good agreement with experimental values. The pre-exponential factor and activation energy were 4.12×10⁷ L·mol^-1·min^-1 and 60.57 kJ·mol^-1, respectively. It is worth noting that the PSILs catalyst could be simply recovered and reused with relatively satisfactory decrease in the catalytic activity, which made it an environmental friendly and promising catalyst in the industrial application.

The catalytic effects of four industrial wastes, namely, the soap residue (SR), brine sludge (BS), calcium carbide residue (CCR), and white lime mud (WLM), on coal thermal ignition were investigated. The acidity of palmitate anion associated with Na⁺ in SR was lower than that of chloride anion combined with Na⁺ in BS, which resulted in an improved the combustion of SR. The acidity of OH^- anion combined with Ca²⁺ in CCR was lower than that of CO₃^2- anion combined with Ca²⁺ in WLM, resulting in CCR exhibiting a better catalytic effect on coal ignition. The alkaline metal Na had lower initial ionisation energy than the alkaline earth metal Ca. Therefore, the Na-rich SR exhibited higher catalytic activity on coal ignition than Ca-rich CCR. The ignition temperature of coal with 0.5% SR decreased from 544 to 503℃.

This paper analyses the oxidation of ferrous iron via chemical and biological means in a class of Sequential Batch Reactors (SBR-type). For this, a kinetic model for the study of iron oxidation system is proposed, followed by a parametric sensitivity analysis and a bifurcation analysis, which allow selecting the most influential kinetic parameters in order to ensure a suitable prediction capacity of the mathematical structure. The system consists of two SBR bioreactors, the first being used to produce hydrogen peroxide (H₂O₂) that is fed to a second reactor where the iron oxidation is carried out by chemical-biological processes. Model predictions were compared with experimental data for the production of H₂O₂ and for ferrous iron oxidation, finding suitable correlation coefficients (r²> 0.98) for each state variable. The bifurcation analysis showed the trajectories of the main variables, such as, biomass, H₂O₂ and ferrous iron, under the change of the most influential kinetic parameters. This analysis demonstrates the usefulness of the constructed model to predict the kinetic behaviour of the SBR-type process.

Continuous biodiesel production from a waste pig-roasting lard, methanol and KOH was carried out in a reciprocating plate reactor (RPR) using a factorial design containing three process factors, namely methanol/lard molar ratio, catalyst loading, and normalized height of the reactor. The main goals were to optimize the influential process factors with respect to biodiesel purity using the response surface methodology and to model the kinetics of the transesterification reaction in order to describe the change of triacylglycerols (TAG) and fatty acid methyl esters (FAME) concentrations along the RPR height. The first-order rate law was proved for both the reaction and the mass transfer. The model of the changing reaction mechanism and mass transfer of TAG was also applicable. Both kinetic models agreed with the experimental concentrations of TAG and FAME determined along the RPR height.

A large amount of information is frequently encountered when characterizing the sample model in chemical process. A fault diagnosis method based on dynamic modeling of feature engineering is proposed to effectively remove the nonlinear correlation redundancy of chemical process in this paper. From the whole process point of view, the method makes use of the characteristic of mutual information to select the optimal variable subset. It extracts the correlation among variables in the whitening process without limiting to only linear correlations. Further, PCA (Principal Component Analysis) dimension reduction is used to extract feature subset before fault diagnosis. The application results of the TE (Tennessee Eastman) simulation process show that the dynamic modeling process of MIFE (Mutual Information Feature Engineering) can accurately extract the nonlinear correlation relationship among process variables and can effectively reduce the dimension of feature detection in process monitoring.

The inlet temperature of the Vacuum Gas Oil (VGO) hydrotreating reactor of a refinery is analyzed with the integration of multiple series reactors and hydrogen network considered. The effect of the inlet temperature (T₁) on hydrogen sinks/sources and the product output is analyzed systematically based on the simulation of the series reactors, including VGO hydrotreating reactor, hydrocracking reactor, fluid catalytic cracking reactor and visbreaking reactor. The general relation between the Hydrogen Utility Adjustment (HUA) and multiple pairs of varying sinks and sources is deduced, and correlations between varying streams and T₁ are linearly fitted. Based on this, the quantitative equation between HUA and T₁ is derived, and corresponding diagram is constructed. The T₁ corresponding the minimum hydrogen consumption is identified to be 345℃.

This paper presents the equilibrium desorption isotherms and the isosteric heat of sorption of a mixture containing mechanically dewatered fermentation residue (obtained from a blend of chicken, swine and cattle manure) used in biogas plants and corn spoiled silage in a ratio of 2:1. The moisture desorption isotherms of the fermentation residue were determined at 32℃, 40℃ and 80℃ and in the relative humidity range of 0.057/1 using static gravimetric method. Mathematical equations were used to analyze the desorption data of Modified Henderson, Modified Halsey, Modified Oswin, Modified Chung-Pfost and Modified GAB models. The constants of the model equations were calculated by non-linear regression analysis. The Modified Henderson model fitted to the desorption isotherm data well. Using the proposed function, the final moisture content of the material can be determined as long as it can be dried in infinite time with the drying gas in the given conditions. The isosteric heat of desorption was calculated by using the Modified Henderson model in the studied temperature range based on the Clausius-Clapeyron equation. The isosteric heat varied between 46 kJ·mol^-1 and 67 kJ·mol^-1 at moisture levels 1.91 < X_e < 4.05 kg_H2O·kg_dP^-1 for the material.

The solubility of ammonium dihydrogen phosphate (MAP) in the water-methanol system is essential for antisolvent crystallization studies. To investigate the effect of methanol on the solubility of MAP in water, the solubility of MAP in the water-methanol system was determined by dynamic method and static equilibrium method at temperatures ranging from 293.2 to 343.2 K at atmospheric pressure. Results showed that the solubility of MAP increased with the increase of temperature and the increase of water mole fraction in the water-methanol system. The experimental solubility data were correlated with the modified Apelblat equation, the combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) model and the Jouyban-Acree model. The calculated results based on these three models were in very good agreement with the experimental data with the average relative deviations of 0.65%, 0.97%, and 5.38%, respectively. Simultaneously, the thermodynamic properties of the MAP dissolution process in the water-methanol system, including Gibbs energy change, enthalpy, and entropy were obtained by the Van't Hoff equation, which can be used to assess the crystallization process.

In the present study, we propose a novel electrode material of β-nickel hydroxide covering nickel/aluminum layered double hydroxides via a facile complexation-precipitation method. The as-obtained materials with 3-dimensional nanostructures are further utilized as highly capable electrode material in nickel-metal hydride batteries. The electrochemical test results demonstrated the β-nickel hydroxide covering nickel/aluminum-layered double hydroxides with 28% of β-nickel hydroxide provided a superior specific capacity value of 452 mA·h·g^-1 in a current density of 5 A·g^-1 using 6 M KOH as electrolyte as compared with other materials. In addition, the optimized sample displays an outstanding cyclic stability along with a huge specific capacity value of 320 mAh·g^-1, and very small decay rate of 3.3% at 50 A·g^-1 after 3000 cycles of charge/discharge test. These indicate that the newly designed material with nanostructures not only provides an efficient contact interface between electrolyte and active species and facilitates the transport of electrons and ions, but also protects the 3-dimensional nickel/aluminum layered double hydroxides, achieving a high specific capacity, fast redox reaction and excellent long-term cyclic stability. Therefore, the β-nickel hydroxide covering nickel/aluminum layered double hydroxides with superior electrochemical performance is predictable to be a gifted electrode material in nickel-metal hydride batteries.

Hollow B-SiO₂@TiO₂ composites were prepared by the wet chemical deposition method starting from TiCl₄ and hollow B-SiO₂ microspheres. TiO₂ layers composed of anatase TiO₂ nanoparticles were coated on the surfaces of the hollow B-SiO₂ microspheres probably through the formation of Ti-O-Si and Ti-O-B bonds. A great number of-OH groups were also present at the TiO₂ coating layers. The presence of Ti-O-Si bonds and Ti-O-B bonds resulted in the formation of defects in the TiO₂ coating layers, which decreased the band gap of the TiO₂ coating layers to ca. 3.0 eV and endowed the TiO₂ coating layers with visible light absorption performance. The buoyancy hollow B-SiO₂@TiO₂ composites exhibited high photocatalytic activities for the degradation of ammonia-nitrogen and green algae. The conversion of ammonia-nitrogen reached 65% when the degradation of ammonia-nitrogen (43 mg·L^-1 at pH value of 8) was catalyzed by the B-SiO₂@TiO₂(100:10) composite under the simulated solar light irradiation at 35℃ for 660 min. The green algae (5 mg·L^-1) were almost completely degraded over the B-SiO@TiO₂(100:20) photocatalyst under the visible light irradiation at 35℃ for 510 min.

The adsorption of Cr(VI) from soil onto lignin-based weakly acidic cation exchange resin (LBR) has been investigated. Lignin is a three-dimensional amorphous polymer composed of methoxylated phenylpropane units. The unique structure and chemical properties render the lignin suitable for the remediation of hexavalent chromium in the soil. Soil column leaching experiments were conducted to optimize the adsorption conditions. The effects of contact time, pH, adsorbent dosage and temperature on the adsorption of Cr(VI) onto the LBR have been investigated. Experiment data were then correlated with Freundlich and Langmuir isotherms. The Langmuir isotherm model fits the experimental data better than the Freundlich isotherm. It was found that the LBR has a high adsorption capability for Cr(VI) (3.95 mg·g^-1) with a removal rate of 91.9%. Thus, LBR can serve as a good absorbent for the reduction of the concentration of Cr(VI) in soil.

In this study, aiming at optimization of a novel continuous biodiesel production system was developed by combining technologies based on microwaves and magnetic fields. Factors affecting microwave-assisted biodiesel (alkyl esters) production reaction were analyzed in this investigation. Studied factors included magnetic field intensity (0, 0.225 and 0.450 T), microwave power (400, 821, and 1181 W), percentages of KOH and NaOH catalysts at constant concentrations of 1 wt% (0, 50% and 100%), and percentages of ethanol and methanol at a constant molar ratio of 6:1 (0, 50% and 100%). Response Surface Methodology (RSM) was used to optimize the reaction conditions. RSM-based analysis indicated that, all independent parameters had significant effects on the reaction efficiency. Results of the investigations reveal that the largest effects on the conversion efficiency were due to type of alcohol and magnetic field intensity. The optimized conditions were found to be a magnetic field intensity of 0.331 T, a microwave power of 677.77 W, catalyst percentages of 30.35% and 69.65% for KOH and NaOH, respectively, and alcohol percentages of 80.47% and 19.53% for methanol and ethanol, respectively. Under the optimal conditions, yield of the reaction was 96.2%.

A hollow-fiber-supported stable Au/FAU catalytic membrane was successfully synthesized through a polydopamine coating modification-removal strategy and used as a flow-through catalytic membrane reactor for preferential oxidation of CO. Small Au nanoparticles can be efficiently isolated by dopamine and the dopamine-derived carbon shells. The interactions between Au nanoparticles and zeolite layer support are enhanced during annealing at high temperature under an inert atmosphere. A zeolite membrane supported Au nanoparticle catalyst was obtained after the removal of carbon shells, which showed high catalytic activity and stability for the removal of CO from hydrogen.

A composite-liquid absorbent (CLA), NaClO/KMnO₄, for simultaneous desulfurization and denitrification (SDD) was studied in a homemade bubbling reactor. The experimental results showed that the CLA configured by sodium hypochlorite (NaClO) and potassium permanganate (KMnO₄) had a very good synergistic effect on SDD. The effects of NaClO concentration (C_Na), KMnO₄ concentration (C_K), gas space velocity (V_g), initial pH value, and temperature of the absorption liquid (T_s) on efficiencies of the SDD were investigated. Under the optimal reaction conditions, the best removal efficiencies were 100% for sulfur dioxide (SO₂) and above 94% for nitric oxide (NO). The ion chromatography and titration were used to analyze the changes of both the ion species and concentrations in the liquid before and after the reaction. According to the experiment results and related literature, the reaction mechanism of the SDD based on the CLA was proposed.

A general and versatile strategy to prepare melamine-formaldehyde (MF) microcapsules encapsulating oil-based fragrances by combining solvent evaporation and in situ polymerization was proposed in this work. The oil-based fragrance was pre-encapsulated by an inner polyacrylate membrane via solvent evaporation, followed by in situ polymerization of MF precondensates as an outer shell. The polyacrylate membrane is used as an intermediate bridging layer to stabilize the oil-based fragrance, and to provide driving forces for in situ polymerization of MF precondensates through electrostatic attractions between carboxyl groups and ammonium ions. It was demonstrated that MF microcapsules containing clove oil were prepared successfully. The amount and the composition of the intermediate polyacrylate bridging layer were critical. Smooth and sphere-shaped MF-clove oil microcapsules were prepared when the weight ratio of polyacrylate to clove oil was over 60 wt% and the concentration of acrylic acid (AA) increased to 10 wt% in polyacrylate. In addition, MF microcapsules containing sunflower oil and hexyl salicylate were prepared by using this method. The work suggests that this new approach can be potentially used to encapsulate various core materials, tuning the shell properties of microcapsules such as thickness, mechanical strength and release properties.

A nitrogen and sulfur co-doped carbon has been synthesized employing egg white as a sustainable protein-rich precursor. According to CHNS elemental analysis, N, S and O heteroatoms accounted for mass fractions of 3.66%, 2.28% and 19.29% respectively, and the types of surface functionalities were further characterized by FT-IR and XPS measurements. Although the carbon possessed a smaller surface area (815 m²·g^-1) compared to a commercial activated carbon (1100 m²·g^-1), its adsorption capacity towards Co²⁺ reached 320.3 mg·g^-1, which was over 8 times higher compared to the limited 34.0 mg·g^-1 over the activate carbon. Furthermore, the carbon was found to be an efficient adsorbent towards a series of metal ions including VO²⁺, Cr³⁺, Ni²⁺, Cu²⁺ and Cd²⁺. Combined with its environmental merits, the protein derived carbon may be a promising candidate for heavy metal pollution control.

Organic compounds are widely used in both industry and daily life, and composite bilayer films with organic compound-triggered bending properties are promising for applications of transducers, soft robotics, and so on. Here, a universal and straightforward strategy to generate composite bilayer films with organic compoundtriggered bending properties is demonstrated. The composite bilayer films with organic compound-triggered bending properties are designed with bilayer structures, in which one layer is a porous polymeric membrane with appropriate solubility parameter that matches the value of organic solvents in order to produce prominent affinity to the solvent molecules, and the other layer is reduced graphene oxide membrane stacked on the porous polymeric membrane as an inert layer for restraining the swelling of the polymeric membrane on one side. Guided by matching the solubility parameters between solvent and polymer, a significant bending curvature of 27.3 cm^-1 is obtained in acetone vapor. The results in this study will provide valuable guidance for designing and developing functional composite materials with significant organic compound-triggered bending properties.

Novel environment friendly inorganic nano green pigments, Ni_1-xCu_xAl₂O₄ (x=0, 0.02, 0.04, 0.06, 0.08, 0.1) were successfully synthesised by simple, cost effective sol-gel method using citric acid as a gelling agent. Synthesised nano pigments were characterised by powder XRD, FT-IR, UV-DRS, SEM-EDX and TEM. Distribution of elements such as Ni, Cu, Al and O for the pigment Ni_0.98Cu_0.02Al₂O₄ was authenticated by elemental mapping analysis. The colour parameters were studied using CIE-LAB parameters. It is evident from the DRS measurement that the band gap energy of NiAl₂O₄ (3.11 eV) has been massively diminished to 2.63 eV when x=0.02, unexpectedly changed the colour of the pigment from cyan to green. Whilst x=0.1 the pigment colour has turned into grey and the corresponding band gap condensed into 2.17 eV. Effect of mineralisers like NaF, CaF₂, NH₄H₂PO₄ and Li₂CO₃ on the colour of Ni_0.98Cu_0.02Al₂O₄ was investigated.

In 2018, the petroleum and chemical industries of China achieved steady economic growth. The main business income of the entire industry was 12.4 trillion CNY, an increase of 13.6% over the previous year. The total profit was 83.93 billion CNY, an increase of 32.1% over the previous year. The total national oil and gas production reached 334 million tons of oil equivalent, increasing by 2.4% year-on-year. Among the total production, crude oil production was 189 million tons, decreased 1.2%, and natural gas production was 161.02 billion cubic meters, increased 7.5% year on year. Imported crude oil production was 462 million tons, an increase of 10.1% over the last year. Imported gas production was 125.72 billion cubic meters, increased 31.9%. The annual processing capacity of crude oil was 604 million tons, up by 6.8%. The refined oil production was 360 million tons, up by 3.6%. The industry structure was optimized for production growth in 2018, the transformation and upgrading of enterprises and products structure adjustment were sped up, energy efficiency was improved, and overall industrial benefit was rebounded. At present, the economic operation of the industry is still not very stable, and downward pressure is still great, mainly being reflected in the overcapacity of some industries, high cost operation of enterprises, increased tax burden, and weak investment. With the slow recovery of the global economy and the key support of high-quality development through technological innovation, it is expected that the petroleum and chemical industry of China will achieve the general objective of steady growth in 2019.