Efficient removal of Lambda-cyhalothrin from simulated water using Co-composted-biochar: A modern day substituent of...

Lambda-cyhalothrin, a type II pyrethroid, is widely employed as an outdoor and indoor insect repellent due to its target specificity and moderate toxicity. However, its extensive use elevated its residual concentration to significant detectable levels in waterbodies, making it an immediate problem. Furthermore, as a lipophile, its accumulation in multicellular organisms has resulted in irreversible acute and chronic effects on numerous physiochemical and biological activities. Thus, to address its removal as a pollutant from waterbodies, bio-adsorbents are considered a cost-effective and environmentally sound cleanup method. Modern day bio-adsorbents like co-composted-biochar, because of their potential adsorption capability rather than the conventional ones, may become a commonly used remediation tool. Therefore, this study aims at producing co-composted-biochar (COMBI) by combining kitchen-derived putrescible waste and biochar to effectively remove Lambda-cyhalothrin (LC) from spiked up water. It has been further analysed for its physico-chemical characteristics using instrumentation such as BET, SEM-EDS and FTIR. The results showed that biochar and COMBI had a much greater surface area (2.174 m²/g-1.718 m²/g) and pore diameters (3.648 nm-3.628 nm) than the compost sample. Simultaneously, the response surface methodology (RSM) was employed to optimise the removal efficiency of COMBI against LC. A Box-Behnken Design (BBD) was developed with an experimental layout to perform tests for determining the effects of four basic parameters i.e. pH, contact time (minute), adsorbate concentration (g/l) and adsorbent dose (g) on (%) removal of LC. It was noted that variation among removal efficiencies for the experimental runs ranges between 94.8% and 99.9%, within the majority attaining an efficiency of greater than 95%. During the experiments, the ideal conditions were found to be as pH 2 in a contact time of 140 min and a dose of adsorbent 0.01 g. Thus, COMBI could be a promising and potential candidate for the elimination of LC.