Recent research has explored the potential of rice husk biochar as a low-cost adsorbent for the removal of contaminants from aqueous solutions, including aldrin, mercury (Hg2+), lead (Pb2+), and cadmium (Cd2+). Experimentation involved adding varying doses of biochar to wastewater with different contamination levels, agitating the mixture for 60 min, and filtering the solutions for analysis. The experiment revealed impressive removal efficiencies: 100% for aldrin, 99.92% – 99.99% for Hg2+, 95.90% – 99.52% for Pb2+, and 88.60% – 99.46% for Cd2+. In binary and quaternary mixtures, Hg2+ showed higher removal efficiency than Pb2+ and Cd2+, with the exception of aldrin. The adsorption order was identified as aldrin > Hg2+ > Pb2+ > Cd2+. The Freundlich adsorption isotherm best described heavy metals in the mono and quaternary component adsorption, while the Langmuir adsorption isotherm was a better fit for the binary component. Consequently, the study highlights rice husk biochar as an efficient, sustainable, and environmentally friendly option for wastewater treatment.
