A biotechnological approach of Pb(II) sequestration from synthetic wastewater using floral wastes

Abstract

This research is aimed at investigating the removal of lead from synthetic wastewater using floral wastes through biosorption. Lead reduction from synthetic wastewater using three distinct flower wastes—Tagetes erecta, Polianthes tuberosa, and Crossandra infundibuliformis, was investigated in this study. A batch experiment was conducted to assess and optimize different parameters—pH, bio-dosage, retention time, and initial lead ion concentration. Experimental data were examined by Langmuir, Freundlich, and Temkin isotherm models and pseudo-first-order and pseudo-second-order kinetic models. Biomass characteristics were analyzed by Fourier-transform infrared (FTIR) and field emission scanning electron microscopy (FESEM). Results showed that maximum absorption of lead using floral wastes (1% w/v) with an initial lead ion concentration of 750 mg L−1 for 6 h of retention time at pH 6 with an agitation speed of 150 rpm was 98.63%, 95.42%, and 93.69% by T. erecta, P. tuberosa, and C. infundibuliformis. Freundlich isotherm showed multilayer sorption on the heterogeneous surface of biosorbents. Biosorption of Pb(II) followed a pseudo-first-order kinetic model instead of pseudo-second-order kinetic model. FTIR revealed significant modification in the functional group that followed the metal chelation process. FESEM analyses showed changes in surface morphology in all the biosorbents. The desorption experiment revealed the reusability potential of these floral waste biosorbents. The toxicity of untreated and treated lead stock solution was verified by the phytotoxic assessment using Vigna radiata seeds. Elevated growth of V. radiata was observed in treated lead synthetic wastewater using T. erecta floral waste biosorbent and tap water (control).