Abstract: Composite materials are attracting considerable interest in water treatment due to their specific properties. Given these properties and the need to remove dyes from water, this work aims to develop an innovative composite material based on local clay (abundant and inexpensive), TiO₂ and CuO for wastewater treatment application. Although much work has been devoted to the design of clay-based composites, to our knowledge, no study has explored the use of Boula-Ibib clay decorated with TiO₂ and CuO to adsorb tartrazine (TTRZ) in aqueous solution. The CuO-TiO₂-clay composite was synthesized by incorporating TiO₂ and CuO on the clay surface using the sol-gel method. The crystalline properties, morphology and specific surface area of the composite were examined by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and the Brunauer-Emmett-Teller method respectively. As results, the specific surface area of 85.23 m²·g^-1 was obtained for the CuO-TiO₂-clay which is higher than that of the raw clay (53.84 m²·g^-1). The results of adsorption studies showed a TTRZ uptake capacity of 16.08 mg·g^-1 after 30 min, with a concentration of 50 mg·L^-1, at pH 6.4 with the optimal composite mass of 0.01 g. Kinetic and isothermal studies showed that adsorption obeyed the pseudo-second-order model and the Radke-Prausnitz isotherm. Thermodynamic studies revealed that the adsorption of TTRZ by the composite is an exothermic, non-spontaneous process that leads to a reduction of disorder in the system. It was established that CuO-TiO₂-clay could be effectively reused over four cycles without damage of its structure which represent an economic advantage.

Key words: Adsorption, Clay, Composite, Kinetic, Synthesis, Tartrazine

摘要： Composite materials are attracting considerable interest in water treatment due to their specific properties. Given these properties and the need to remove dyes from water, this work aims to develop an innovative composite material based on local clay (abundant and inexpensive), TiO₂ and CuO for wastewater treatment application. Although much work has been devoted to the design of clay-based composites, to our knowledge, no study has explored the use of Boula-Ibib clay decorated with TiO₂ and CuO to adsorb tartrazine (TTRZ) in aqueous solution. The CuO-TiO₂-clay composite was synthesized by incorporating TiO₂ and CuO on the clay surface using the sol-gel method. The crystalline properties, morphology and specific surface area of the composite were examined by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and the Brunauer-Emmett-Teller method respectively. As results, the specific surface area of 85.23 m²·g^-1 was obtained for the CuO-TiO₂-clay which is higher than that of the raw clay (53.84 m²·g^-1). The results of adsorption studies showed a TTRZ uptake capacity of 16.08 mg·g^-1 after 30 min, with a concentration of 50 mg·L^-1, at pH 6.4 with the optimal composite mass of 0.01 g. Kinetic and isothermal studies showed that adsorption obeyed the pseudo-second-order model and the Radke-Prausnitz isotherm. Thermodynamic studies revealed that the adsorption of TTRZ by the composite is an exothermic, non-spontaneous process that leads to a reduction of disorder in the system. It was established that CuO-TiO₂-clay could be effectively reused over four cycles without damage of its structure which represent an economic advantage.

关键词: Adsorption, Clay, Composite, Kinetic, Synthesis, Tartrazine