Waste glass: An excellent adsorbent for crystal violet dye, Pb2+ and Cd2+ heavy metals ions decontamination from wastewater

Abstract

The suitability of waste glass as an eco-friendly adsorbent for the removal of crystal violet (CV) dye, Pb2+ and Cd2+ heavy metal ions in waste water samples was investigated in batch mode. Waste glass sample was pulverized and characterized by SEM/EDX, XRD, BET and FTIR. Effects of variation in temperature, pH, contact time and recyclability of the adsorbent were studied. FTIR spectra revealed major peaks around 491.53 and 3444.12 cm-1 corresponding to the bending vibrations of Si-O-Si and -OH groups respectively. SEM/EDX analysis showed a dense, coarse, porous morphology with predominantly silica component. The effective surface area and size of the adsorbent were 557.912 m2/g and 2.099 nm respectively. Increase in temperature, dosage, contact time resulted in increase in adsorption efficiency. Optimum adsorption efficiency of 94%, 97.5% and 89.1% was attained for Pb2+ , Cd2+ ions and CV dye respectively at 70?C. Adsorption process followed more accurately pseudo-first order model and isotherm fitted perfectly into Freundlich model indicating a multilayer adsorption mechanism for CV dye and the heavy metals. 89.87% reduction in Chemical Oxygen Demand (COD) level of wastewater was reported upon treatment with waste glass adsorbent affirming its efficiency for dye and heavy metal pollutants removal.