Development of Biochar-Based Magnetic Nanocomposites for Efficient Removal of Heavy Metals from Industrial Wastewater

Abstract

The discharge of industrial wastewater with heavy metal ions causes major threats to both environment and human beings. The efficient and sustainable process for detoxifying such effluents is needed. In this context, Fe3O4-doped and amine functionalized magnetic biochar-based nanocomposite adsorbents for the removal of Pb (II), Cd (II), Cu (II), and Cr (VI) ions from wastewater are studied in this research work. Biochar was synthesized by using lignocellulosic biomass and magnetically treated as well as chemically functionalized to improve its adsorptive performance and recyclability. Physicochemical analysis and batch adsorption studies were carried out for adsorbent evaluation in terms of surface characteristics, adsorptive efficiency, adsorption kinetics, equilibrium and regenerability. Removal efficiencies for the respective metal ions were found to be 98.6%, 96.4%, 92.8% and 89.5%. There was excellent correlation between the pseudo-second order kinetic model and the adsorption process where determination coefficients ranged from 0.995 to 0.998. Langmuir isotherm models resulted in maximum adsorption capacity of 201.4, 190.8, 124.5, and 158.7 mg/g for Pb (II), Cd (II), Cu (II), and Cr (VI) metals respectively. Surface complexation, electrostatic attraction, ion exchange, and precipitation were responsible for the adsorption process. The use of magnet to separate the adsorbent enabled the recycling and reuse of the adsorbent. It can be concluded that functionalized magnetic biochar is an effective material for metal removal despite the need for further investigation.