Synthesis and characterization of novel β-CD-Xanthate and its application in the treatment of heavy metal containing wastewater and lignin enriched paper industry wastewater

Abstract

ABSTRACT Three grades of β-cyclodextrin xanthates (β-CDXs) have been synthesized by the reaction of β-cyclodextrin (β-CD) with CS2 in alkaline medium (NaOH), through xanthation process. The synthesized β-CDXs has been characterized by UV-visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Proton Nuclear Magnetic Resonance (1HNMR) spectroscopy, Thermogravimetric (TG) analysis, Differential Scanning Calorimetry (DSC) analysis, scanning electron microscopy (SEM) analysis and point of zero charge (ΔpHPZC) analysis. Further, β-CDXs and raw β-CD has been used for the heavy metals removal (Cu2+ and Ni2+) and also used for the treatment of lignin enriched paper industry wastewater (LEPIW). The maximum % removal by β-CDX3 for Cu2+ ion at optimum dosage of 2 g/L, optimum pH of 6.5, temperature of 45°C, initial concentration of 1000 mg/L and at contact time of 80 min was 95.8%. For Ni2+ ion the maximum % removal by β-CDX3 at optimum dosage of 2.5 g/L, optimum pH of 5.8, initial concentration of 1000 mg/L, temperature of 55°C and contact time of 100 min was 94.1%. While LEPIW treatment efficacy of 86% has been observed with β-CDX3. The calculated data fitted well in Langmuir isotherm model confirming that the adsorption of Cu2+ & Ni2+ ions onto the β-CDXs adsorbent is monolayer. The rate of adsorption of heavy metals (Cu2+ and Ni2+) on the β-CDXs adsorbent has been controlled by Pseudo second order kinetic model indicating the chemisorption process. The optimal adsorption capacity of β-CDX3 has been found to be 534.75 mg/g for Cu2+ and 423.72 mg/g for Ni2+ ions, respectively.