Sono-synthesis of cellulose-TiO₂ nanocomposite adsorbent for fast cleaning of anionic dyes containing wastewater

This work was devoted to synthesizing a composite of cellulose-TiO2 by the in-situ process using the sol-gel method and applied on representatives of acid dyes to determine the functionality regarding the adsorption of dyes from aqueous solution. The composite particle adsorbed 100% dyes within 3 min of the direct application. XRD, FTIR, SEM, and Zeta potential tests were conducted to investigate the effect of crystal, molecular structure, surface morphology, and surface charges on the absorption speed of cellulose-TiO2 composite particles. The experimental results revealed that the cellulose was partially hydrolyzed by concentrated hydrochloric acid and left some positive charge on the surface of cellulose during the synthesis of the composite structure. The test results demonstrated that nano TiO2 with a thin layer of cellulose covered the surface of undegraded cellulose particles. The structural changes in the composite made them beneficial to fast dye adsorption. The effect of initial dye concentration, composite dosage, and temperatures were also investigated to find the optimum condition for dye adsorption. The optimum condition was found at the initial concentration of 400 mg/l, dosage of 0.10 g, and temperature of 25 degrees C. The removal efficiency and maximum adsorption capacity at this condition were 100% and 40 mg/g, respectively. The adsorption data suggested that the data was well fitted with a pseudosecond-order model for adsorption kinetics and Langmuir model for adsorption isotherm. Thermodynamic analysis revealed that the adsorption process was physisorption, spontaneous, random, and endothermic. Overall, in this work, the developed cellulose-TiO2 nanocomposite might be an economical and efficient adsorbent to remove dyes from wastewater.