Preparation of Rice Husk Biochar-Based Magnetic Nanocomposite for Effective Removal of Crystal Violet

Recently, magnetic biochars have attracted much attention and exhibited potential for dye removal from industrial wastewater. This work presents a cost-effective magnetic biochar (MBC) nanocomposite prepared from rice husk and iron oxide nanoparticles (IONPs), which was tested for removal of crystal violet (CV) from aqueous solution. Morphology and structure of rice husk biochar, IONPs, and MBC were characterized by transmission electron microscopy and x-ray diffraction, and the magnetic property was investigated with a vibrating sample magnetometer. The adsorption capacity of MBC was evaluated through CV removal with experimental parameters including pH solution, adsorbent dosage, and CV concentrations at room temperature. The adsorption kinetics of MBC for CV was also analysed using pseudo-first-order, and pseudo-second-order models. Results showed that rice husk biochar-based magnetic nanocomposite has been successfully prepared. The TEM image showed that many IONPs of 10–14 nm in diameter located inside the biochar network. Experimental results indicated that the adsorption efficiency of MBC rapidly reached 99.02% for CV removal within 15 min. The adsorption capacity of MBC for CV was found at 185.6 mg/g from aqueous solution with pH 6.0, contact time of 120 min at room temperature. This study illustrated the high adsorption capacity of rice husk-based MBC for CV compared to other MBCs and showed also that it is a potential cost-effective material for removal of other organic dyes from industrial wastewater.