Polyoxymethylene dimethyl ethers are recognized as the prospective diesel additive to decrease the pollutant emission from the light-duty vehicles, which can be polymerize form the monomer of dimethoxymethane (DMM). The industrial synthesis of DMM is mainly involved two-step process: methanol is oxidized to form the formaldehyde in fixed bed reactor and then reacted with the generated formaldehyde through acetalization in continuous stirred-tank reactor. Due to huge energy consumption, this typical synthesis route of DMM needs to be upgraded and more green routes should be determined. In this review, four state-of-the-art one-step direct synthetic routes, including two upgrading routes (methanol direct oxidation and direct dehydrogenation) and two green routes (methanol diethyl ether direct oxidation and carbon oxides direct hydrogenation), have been summarized and compared. Combination with the reaction mechanism and catalytic performance on the different catalysts, the challenges and opportunities for every synthetic route are proposed. The relationships between catalyst structure and property in different synthesis strategy are also investigated and then the suggestions of the design of catalyst are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and synthesis technology to realize their commercial applications in the near future.

In this study, biochar (BC) derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride (g-C₃N₄) to synthesize the BC/g-C₃N₄ composite for the degradation of the tetracycline (TC) antibiotic under visible light irradiation. The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C₃N₄ composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83% in 100?min irradiation. The improvement of photocatalytic activity is mainly attributed to the following two points: (i) the strong bonding with π-π stacking between BC and g-C₃N₄ make the photogenerated electrons of light-excited g-C₃N₄ transfer to BC, quickly and improve the separation efficiency of carriers; (ii) the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites. This study provides a sustainable, economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.

Converting polyethylene terephthalate (PET) wastes to its monomer and valuable chemicals via eco-friendly chemical method is still a challenge task. Previously, phase transfer catalysts used for alkaline hydrolysis were soluble in reaction media and hardly separated after reaction. Here, we reported several pH-responsive catalysts combined alkyl quaternary ammonium units with heteropolyacid anion for achieving stepwise product/catalyst separation and catalyst recycling. The properties of homogeneous/heterogeneous transfer behavior allow catalyst to be easily separated from reaction media by adjusting of pH value. Among them, [C₁₆H₃₃N(CH₃)₃]₃PW₁₂O₄₀ (abbreviated as [CTA]₃PW) exhibits the highest activity and the most suitable pH responsive values. Such a pH triggered switchable catalytic system not only shows good performance for depolymerization of pure PET, but also some real PET wastes such as coloured trays and PE/PET complex films could be completely degraded into terephthalic acid. Additionally, the reaction kinetics and activation energy of PET alkaline hydrolysis also studied with and without pH-responsive [CTA]₃PW.

Efficient and low-cost recycling of spent lithium iron phosphate (LiFePO₄, LFP) batteries has become an inevitable trend. In this study, an integrated closed-loop recycling strategy including isomorphic substitution leaching and solvent extraction process for spent LFP was proposed. An inexpensive FeCl₃ was used as leaching agent to directly substitute Fe²⁺ from LFP. 99% of Li can be rapidly leached in just 30 min, accompanied by 98% of FePO₄ precipitated in lixivium. The tri-n-butyl phosphate (TBP)-sulfonated kerosene (SK) system was applied to extract Li from lixivium through a twelve-stage countercurrent process containing synchronous extraction and stepwise stripping of Li⁺ and Fe³⁺. 80.81% of Li can be selectively enriched in stripping liquor containing 3.059 mol·L^-1 of Li⁺ under optimal conditions. And the Fe stripping liquor was recovered for LFP re-leaching, of which, Fe²⁺ was oxidized to Fe³⁺ by appropriate H₂O₂. Raffinate and lixivium were concentrated and entered into extraction process to accomplished close-loop recycling process. Overall, the results suggest that more than 99% of Li was recovered. FeCl₃ holding in solution was directly regenerated without any pollutant emission. The sustainable mothed would be an alternative candidate for total element recycling of spent LFP batteries with industrial potential.

Enzyme-polymer conjugates are complex molecules with great practical significance. This work was designed to develop a novel enzyme-polymer conjugate by covalently coupling a zwitterionic polymer with side dimethyl chains (pID) to Candida rugosa lipase (CRL) via the reaction between the anhydrides of polymer chains with the amino groups of the enzyme. The resulting two CRL-pID conjugates with different pID grafting densities were investigated in term of the catalytic activity, stability and structural changes. In comparison with native CRL, both the CRL conjugates displayed 2.2 times higher activity than the native enzyme, and showed an increase in the maximum reaction rate (V_max) and a decrease in the Michaelis constant (K_m), thus resulting in about three-fold increases in the catalytic efficiency (k_cat/K_m). These are mainly attributed to the activation of lipase by the hydrophobic alky side chains. Moreover, the thermostability and pH tolerance of the lipase conjugates were significantly enhanced due to the stabilizing effect of the zwitterion moieties. For instance, a five-fold increase of the enzyme half-life at 50℃ for the high-pID conjugated CRL was observed. Spectroscopic studies reveal that the pID conjugation protected the enzyme in the changes in its microenvironment and conformation, well correlating with enhanced activity and stability of lipase conjugates. The findings indicate that enzyme conjugation to the zwitterionic polymer is promising for improving enzyme performance and deserves further development.

Investigations were conducted to purify crude Li₂CO₃ via direct carbonation with CO₂ at atmospheric pressure and pyrolysis with both water bath heating method and microwave heating method. The reaction kinetics of LiHCO₃ pyrolysis was studied and the effect of different operating conditions including initial concentration of LiHCO₃ solution, pyrolysis temperature and stirring speed on the purity of Li₂CO₃ was investigated to obtain the optimal operating conditions. Results showed that the effect law is similar in the two pyrolysis processes. The purity of the Li₂CO₃ increases firstly and then decreases with the increase of the initial concentration of LiHCO₃ solution and the stirring speed, while the purity of Li₂CO₃ first decreases and then increases with the increase of pyrolysis temperature. The product yield increases with the increase of initial concentration of LiHCO₃ solution and pyrolysis temperature and is essentially unaffected by the stirring speed. Under the optimal operating conditions, the purity of Li₂CO₃ can reach up to 99.86% and 99.81% in water bath heating and microwave heating process, respectively. In addition, the pyrolysis rate of microwave assisted pyrolysis is 6 times that of water bath heating process, indicating that the microwave heating technology can significantly improve pyrolysis efficiency and reduce energy consumption.

To improve performance of membrane electrode assembly (MEA) at large current density region, efficient mass transfer at the cathode is desired, for which a feasible strategy is to lower catalyst layer thickness by constructing high loading Pt-alloy catalysts on carbon. But the high loading may induce unwanted particle aggregation. In this work, H-PtNi/C with 33% (mass) Pt loading on carbon and monodisperse distribution of 3.55?nm PtNi nanoparticles, was prepared by a bimodal-pore route. In electrocatalytic oxygen reduction reaction (ORR), H-PtNi/C displays an activity inferior to the low Pt loading catalyst L-PtNi/C (13.3% (mass)) in the half-cell. While in H₂-O₂ MEA, H-PtNi/C delivers the peak power density of 1.51?W·cm^?2 and the mass transfer limiting current density of 4.4?A·cm^?2, being 21% and 16% higher than those of L-PtNi/C (1.25?W·cm^?2, 3.8?A·cm^?2) respectively, which can be ascribed to enhanced mass transfer brought by the thinner catalyst layer in the former. In addition, the same method can be used to prepare PtFe alloy catalyst with a high-Pt loading of 36% (mass). This work may lead to a range of catalyst materials for the large current density applications, such as fuel cell vehicles.

Water pollution regarding dyes and heavy metal ions is crucial facing the world. How to effectively separate these contaminants from water has been a key issue. Graphene oxide (GO) promises the green-water world as a long-lasting spotlight adsorbent material and therefore, harnessing GO has been the research hotspot for over a decade. The state of GO as well as its surface functional groups plays an important role in adsorption. And the way of preparation and structural modification matters to the performance of GO. In this review, the significance of the state of existence of stock GO and surface functional groups is explored in terms of preparation, structural modification, and adsorption. Besides, various adsorbates for GO adsorption are also involved, the discussion of which is rarely established elsewhere.

Sodium-contained compounds are promising sintering additives for the low-temperature preparation of reaction bonded SiC membranes. Although sodium-based sintering additives in various original states were attempted, their effects on microstructure and surface properties have rarely been studied. In this work, three types of sodium-based additives, including solid-state NaA zeolite residue (NaA) and liquid-state dodecylbenzene sulfonate (SDBS) and water glass (WG), were separately adopted to prepare SiC membranes, and the microstructure, surface characteristics and filtration performance of these SiC membranes were comparatively studied. Results showed that the SiC membranes prepared with liquid-state SDBS and WG (S-SDBS and S-WG) showed lower open porosity yet higher bending strength compared to those prepared with solid-state NaA (S-NaA). The observed differences in bending strength were further interpreted by analyzing the reaction process of each sintering additive and the composition of the bonding phase in the reaction bonded SiC membranes. Meanwhile, the microstructural differentiation was correlated to the original state of the additives. In addition, their surface characteristics and filtration performance for oil-in-water emulsion were examined and correlated to the membrane microstructure. The S-NaA samples showed higher hydrophilicity, lower surface roughness (1.80 μm) and higher rejection ratio (99.99%) in O/W emulsion separation than those of S-WG and S-SDBS. This can be attributed to the smaller mean pore size and higher open porosity, resulting from the originally solid-state NaA additives. Therefore, this work revealed the comprehensive effects of original state of sintering additives on the prepared SiC membranes, which could be helpful for the application-oriented fabrication by choosing additives in suitable state.

To improve the ability of diglycolamide extractants for the extraction of Sr(II) from high-level waste liquid, N,N,N',N'-tetracyclohexyldiglycolamide (TCHDGA) was proposed and studied to extract Sr(II) from nitrate media. TCHDGA was prepared and characterized by ¹H nuclear magnetic resonance spectroscopy (NMR), ¹³C NMR, and fourier transform infrared spectroscopy (FT-IR). Various factors affecting extraction were studied systematically. In just 20 s, the extraction rate can reach approximately 98.2%. The extraction capacity of cyclohexyl-substituted extractant TCHDGA is tens of times higher than that with linear or branched chain alkyl. The chemical structure of the complex has been demonstrated to be [Sr 3TCHDGA]·(NO₃)₂, based on FT-IR, X-ray photoelectron spectroscopy (XPS), and crystal structure analysis. The crystal belongs to the monoclinic system, space group P21, and a strontium ion coordinates with nine oxygen atoms, all of which contribute from TCHDGA. The stripping rate can reach over 99% when using distilled water or 0.50 mol·L^-1 oxalic acid as stripping agents.

The pyrolysis process of Shendong coal (SD) was first studied by combining the characteristics of thermal gravimetric (TG), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and Gray-King assay (G-K). The results show that the order of coke yields is G-K (76.35% (mass))>TG (73.11% (mass))>Py (70.03% (mass)). G-K coke yield caused by condensation reaction and secondary reaction accounts for 3.08% (mass) and 3.24% (mass), respectively. Compared with slow pyrolysis, fast pyrolysis has stronger fracture ability to coal molecules and can obtain more O-compounds, mono-ring aromatics and aliphatics. Especially, the content of phenolics increases significantly from 15.49% to 35.17%, but the content of multi-ring aromatics decreases from 23.13% to 2.36%. By comparing the compositions of Py primary tar and G-K final tar, it is found that secondary reactions occurred during G-K pyrolysis process include the cleavage of alkane and esters, condensation of mono-ring aromatics with low carbon alkene, ring opening, isomerization of tri-ring aromatics, hydrogenation of aromatics and acids.

The continuous use of chemical dyes in various industries, and their discharge into industrial effluents, results in severe problems to human life and water pollution. Laccases have the ability to decolorize dyes and toxic chemicals in industrial effluents as green biocatalysts. Their possible industrial applications have been limited by poor reusability, low stability, and loss of free laccase action. In this research, laccase was immobilized on zeolitic imidazolate framework coated multi-walled carbon nanotubes (Laccase@ZIF-8@MWCNTs) via metal affinity adsorption to develop an easy separable and stable enzyme. The optimum reaction conditions for immobilized laccase are at a pH of 3.0 and a temperature of 60?℃. The immobilized laccase was enhanced in storage and thermal stability. The results indicated that Laccase@ZIF-8@MWCNTs still maintained 68% of its original activity after 10 times of repeated use. Most importantly, the biocatalytic system was applied for decolorization of different dyes (20?mg·L^?1) without a mediator, and up to 97.4% for Eriochrome black T and 95.6% Acid red 88 was achieved in 25 min. Biocatalysts with these properties may be used in a variety of environmental and industrial applications.

The emerging one-dimensional wire-shaped supercapacitors (SCs) with structural advantages of low mass/volume structural advantages hold great interests in wearable electronic engineering. Although graphene fiber (GF) has full of vigor and tremendous potentiality as promising linear electrodefor wire-shaped SCs, simultaneously achieving its facile fabrication process and satisfactory electrochemical performance still remains challenging to date. Herein, two novel types of graphene hybrid fibers, namely ferroferric oxide dots (FODs)@GF and N-doped carbon polyhedrons (NCPs)@GF, have been proposed via a simple and efficient chemical reduction-induced fabrication. Synergistically coupling the electroactive units (FODs and NCPs) with conductive graphene nanosheets endows the fiber-shaped architecture with boosted electrochemical activity, high flexibility and structural integrity. The resultant FODs@GF and NCPs@GF hybrid fibers as linear electrodes both exhibit excellent electrochemical behaviors, including large volumetric specific capacitance, good rate capability, as well as favorable electrochemical kinetics in ionic liquid electrolyte. Based on such two linear electrodes and ionogel electrolyte, a high-performance wire-shaped SC is effectively assembled with ultrahigh volumetric energy density (26.9 mW·h·cm^-3), volumetric power density (4900 mW·cm^-3) and strong durability over 10,000 cycles under straight/bending states. Furthermore, the assembled wire-shaped SC with excellent flexibility and weavability acts as efficient energy storage device for the application in wearable electronics.

Rotating packed bed (RPB) is one of the most effective gas–liquid mass transfer enhancement reactors, its effective specific mass transfer area (a_e) is critical to understand the mass transfer process. By using the NaOH–CO₂ chemical absorption method, the a_e values of three RPB reactors with different rotor sizes were measured under different operation conditions. The results showed that the high gravity factor and liquid flow rate were major affecting factors, while the gas flow rate exhibited minor influence. The radius of packing is the dominant equipment factor to affect a_e value. The results indicated that the contact area depends on the dispersion of the liquid phase, thus the centrifugal force of rotating packed bed greatly influenced the a_e value. Moreover, the measured a_e/a_p (effective specific mass transfer area/specific surface area of packing) values were fitted with dimensionless correlation formulas. The unified correlation formula with dimensionless bed size parameter can well predict the experimental data and the prediction errors were within 15%.

An integrated vacuum pressure swing adsorption (VPSA) and Rectisol process is proposed for CO₂ capture from underground coal gasification (UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly designed to pre-separate and capture 74.57% CO₂ with a CO₂ purity of 98.35% from UCG syngas (CH₄/CO/CO₂/H₂/N₂ = 30.77%/6.15%/44.10%/18.46%/0.52%, mole fraction, from Shaar Lake Mine Field, Xinjiang Province, China) with a feed pressure of 3.5 MPa. Subsequently, the Rectisol process is constructed to furtherly remove and capture the residual CO₂ remained in light product gas from the VPSA process using cryogenic methanol (233.15 K, 100% (mass)) as absorbent. A final purified gas with CO₂ concentration lower than 3% and a regenerated CO₂ product with CO₂ purity higher than 95% were achieved by using the Rectisol process. Comparisons indicate that the energy consumption is deceased from 2.143 MJ·kg^–1 of the single Rectisol process to 1.008 MJ·kg^–1 of the integrated VPSA & Rectisol process, which demonstrated that the deployed VPSA was an energy conservation process for CO₂ capture from UCG syngas. Additionally, the high-value gas (e.g., CH₄) loss can be decreased and the effects of key operating parameters on the process performances were detailed.

The present work suggested the use of waste oil palm frond as an alternative precursor for nitrogen-doped carbon quantum dots (NCQDs) and proposed a straightforward in-situ hydrothermal method for the preparation of NCQDs/TiO₂ nanocomposites. The elemental composition, morphological, structural and optical characteristics of NCQDs/TiO₂ nanocomposites have been comprehensively investigated. The successful grafting of NCQDs on TiO₂ matrix was confirmed by the formation of TiOC bond and the electronic coupling between the π-states of NCQDs and the conduction band of TiO₂. For the first time, the oil palm frond-derived NCQDs/TiO₂ was adopted in the photodegradation of methylene blue (MB) under visible-light irradiation. As a result, the photocatalytic efficiency of NCQDs/TiO₂ nanocomposites (86.16%) was 2.85 times higher than its counterpart TiO₂ (30.18%). The enhanced performance of nanocomposites was attributed to the pivotal roles of NCQDs serving as electron mediator and visible-light harvester. Besides, the optimal NCQDs loading was determined at 4 ml while the removal efficiency of NCQDs/TiO₂-4 was the highest at a catalyst dosage of 1 g·L^-1 under alkaline condition. This research work is important as it proposed a new insight to the preparation of biomass-based NCQDs/TiO₂ using a facile synthetic method, which offers a green and sustainable water remediation technology.

In this study, different sizes of microcapsules with alginate and bentonite as natural macromolecular materials were prepared to investigate the release property of Pseudomonas putida Rs-198. The characteristics of three microcapsules were evaluated by SEM, FTIR, TG-DSC, XRD and wall thickness. The sizes of three microcapsules (MA, MB, and MC) were 1270.50, 831.79 and 42.52?μm, respectively. First, the encapsulation efficiency of three MA, MB, and MC microcapsules were 82.20%, 90.41%, and 85.84%, respectively. Second, the contact angles of MA and MB samples were similar, while smaller microcapsules MC have higher contact angle (85.05°), indicating poor hydrophilia and decreasing the swelling degrees. Third, the release cumulant of Rs-198 and macromolecule BSA linear stage was fitted to self-established mathematic model. Results show that the microcapsule size had a considerably positive effect on release detail. The large microcapsule possessed strong leak-tightness for Rs-198 as a slow-release microbial agent. Furthermore, the porosity of microcapsules determined their swelling and release and may affect bacterial growth and survival. In conclusion, the Rs-198 microcapsule with different sizes will be pertinently selected based on the characteristics of agricultural production requirements.

The ultra-deep desulfurization of oil needs to be solved urgently due to various problems, including environmental pollution and environmental protection requirements. Oxidative desulfurization (ODS) was considered to be the most promising technology. The facile synthesis of highly efficient and stable HPW-based heterogeneous catalysts for oxidative desulfurization is still a challenging task. In this paper, pentamethylene hexamine (PEHA) and phosphotungstic acid (HPW) were combined by a simple one-step method to prepare a heterogeneous catalyst of PEHA-HPW for the production of ultra-deep desulfurization fuel oil. The composite material exhibited excellent catalytic activity and high recyclability, which could reach a 100% dibenzothiophene (DBT) removal rate in 30 min and be recycled at least 5 times. Experiments and DFT simulations were used to better examine the ODS mechanism of PEHA-HPW. It was proved that the rich amino groups on the surface of PEHA-HPW play a crucial role. This work provides a simple and feasible way for the manufacture of efficient HPW-based catalysts.

The concept of “carbon neutrality” poses a huge challenge for chemical engineering and brings great opportunities for boosting the development of novel technologies to realize carbon offsetting and reduce carbon emissions. Developing high-efficient, low-cost, energy-efficient and eco-friendly microfluidic-based microchemical engineering is of great significance. Such kind of “green microfluidics” can reduce carbon emissions from the source of raw materials and facilitate controllable and intensified microchemical engineering processes, which represents the new power for the transformation and upgrading of chemical engineering industry. Here, a brief review of green microfluidics for achieving carbon neutral microchemical engineering is presented, with specific discussions about the characteristics and feasibility of applying green microfluidics in realizing carbon neutrality. Development of green microfluidic systems are categorized and reviewed, including the construction of microfluidic devices by bio-based substrate materials and by low carbon fabrication methods, and the use of more biocompatible and non-destructive fluidic systems such as aqueous two-phase systems (ATPSs). Moreover, low carbon applications benefit from green microfluidics are summarized, ranging from separation and purification of biomolecules, high-throughput screening of chemicals and drugs, rapid and cost-effective detections, to synthesis of fine chemicals and novel materials. Finally, challenges and perspectives for further advancing green microfluidics in microchemical engineering for carbon neutrality are proposed and discussed.

Catalytic pyrolysis of digestate to produce aromatic hydrocarbons can be combined with anaerobic fermentation to effectively transform and utilize all biomass components, which can achieve the meaningful purpose of transforming waste into high-value products. This study explored whether catalytic pyrolysis of digestate is feasible to prepare aromatic hydrocarbons by analyzing the thermogravimetric characteristics, pyrolysis characteristics, and catalytic pyrolysis characteristics of digestate. For digestate pyrolysis, an increase in temperature was found to elevate the CO, CH₄, and monocyclic aromatic hydrocarbon (benzene, toluene, and xylene; BTX) content, whereas it decreased the contents of phenols, acids, aldehydes, and other oxygenates. Furthermore, the catalytic pyrolysis process effectively inhibited the acids, phenols, and furans in the liquid, whereas the yield of BTX increased from 25.45% to 45.99%, and the selectivity of xylene was also increased from 10.32% to 28.72% after adding ZSM-5. ZSM-5 also inhibited the production of nitrogenous compounds.