Fabrication of ethylenediaminetetraacetic modified porous silica composite from rice husk for enhancing the remove of Pb2+ from aqueous solution

Abstract

Rice husk (RH) is well known as a by-product of rice production, and a large amount of RH is discharged in Southeast Asian countries yearly. Therefore, converting rice husks into valuable materials is challenging for governments. In this study, porous silica (PS) fabricated from RH was modified by ethylenediaminetetraacetic (EDTA) with binder polyvinyl alcohol (PVA) to enhance adsorption performance. The PS was an amorphous and porous material, its average particle size was about 10–20 nm, showing a pore size of about 2–5 nm. The N2 adsorption/desorption isotherm results showed that PS possessed a large specific surface of 544.5 m2/g and a high pore volume of 1.94 cm3/g. These were slightly mitigated to 496.8 m2/g and 1.44 cm3/g, respectively, for the EDTA modified porous silica composite (PS-EDTA), but it could improve the adsorption of Pb2+. The PS-EDTA 1.0 M sample had the highest adsorption performance among as-prepared samples. At optimal reaction conditions, PS-EDTA showed an adsorption efficiency of 99.98 % and a qmax of 84.70 mg/g determined by batch reaction and the Langmuir model. Besides, the kinetics, thermodynamics, and adsorption mechanism of Pb2+ on PS-EDTA were investigated.