Kinetic and isotherm studies on adsorption of toxic pollutants using porous ZnO@SiO2 monolith
M. Sharmaa, S. Hazrab and S. Basua
aSchool of Chemistry and Biochemistry, Thapar University, Patiala 147004, India
bSaha Institute of Nuclear Physics, Kolkata 700064, India

Removal of toxic effluents (like dyes and pesticides) by cost-effective and user-friendly method is needed to provide sustaining the environment for civilization. Here, low-cost mesoporous silica monolith (SiO2) and silica supported metal-oxide (ZnO@SiO2) monolith were synthesized to reduce the solemn impact of toxic effluents. Batch experiments were performed to remove Alizarin (AZ), Paradol (PD), Acid blue-113 (AB) and Rhodamine-B (RD) from aqueous solution via synthesized monoliths. The influence of various parameters (like pH, contact time, temperature and adsorbate concentration) has been optimized. The maximum adsorption capacity of ZnO@SiO2 monolith is 625, 500, 714 and 555 mg/g for AZ, RD, AB, and PD respectively. The adsorption for AZ, PD, AB, and RD is spontaneous and exothermic. The adsorption process can be well described by the pseudo-second-order kinetic model (high regression coefficients) and the Freundlich isotherm model (R2 = 0.97-0.99).