Removal of cadmium ions via the magnetic biochar synthesised from sugarcane bagasse: Factors affecting yield and adsorption capability.

Abstract

The sugarcane bagasse (SCB) was a precursor in synthesising magnetic biochar using a modified single-stage electric muffle furnace to remove Cd2+ ions in industrial wastewater. Nickel (II) oxide (NiO2) was added to boost the efficiency of yield and the removal of heavy metals. The magnetic biochar (MBN3) was optimally synthesised at 500 °C for 30 min with an IR of 0.4 to evaluate its performance in adsorption capability. Analyses of Field Emission Scanning Electronic Microscopy indicated that pores in the magnetic biochar enlarged after the impregnation and decomposition with an average diameter of 3.2 nm (MBN3) and surface area of 63.5 m2g-1. The highest removal for Cd2+ onto MBN3 was 87.6%, reaching pH 6.0 and an agitation speed of 125 rpm for 60 min. The maximum adsorption capacity (qm) for the adsorption of Cd2+ onto MBN3 was 47.9 mgg-1. The adsorbent followed the pseudo-second-order kinetic model and the Langmuir-Freundlich isotherm model with R2 = 0.9853 (Langmuir) and R2 = 0.9538 (Freundlich), suggesting that the surface of MBN3 might be heterogeneous with different classes of active sites, heavy metals were adsorbed on some classes of active sites only, rather than on all active sites