Kinetic study of lead (Pb²⁺) removal from battery manufacturing wastewater using bagasse biochar as biosorbent

Agricultural waste of bagasse was employed for investigating its lead (Pb²⁺) removal potential from wastewater of battery manufacturing industry. To optimize maximum removal efficacy of the bagasse, it was thermally modified in the form of biochar. Adsorption kinetics and mechanism including various parameters (contact time, dose and pH) were studied employing biochar prepared from bagasse waste. The optimum adsorption occurred at pH 5 with 140 min. of contact time utilizing 5 g of adsorbent dosage at room temperature (25 ± 3 °C). The maximum removal efficiency was recorded as 12.741 mg g⁻¹ with 75.376% of removal at optimum pH 5 as compared to the initial concentration in the effluent. The result illustrated the most suitable fit was for Langmuir isotherm with monolayer and homogenous adsorption of Pb²⁺. The kinetics involved in the process was observed to be pseudo-second-order, which indicates chemisorption as a major phenomenon involved in the process. The characterization of the adsorbent biochar was done by SEM, EDX and FTIR analysis that provided details about ultrastructural and functionality of organic moiety present to have porous and rough surface, favoring the adsorption process. The functional groups identified by the FTIR analysis demonstrated involvement of carboxyl groups in Pb²⁺ binding. Postadsorption elution of metal-loaded bagasse was executed by 0.1 M HNO₃ with about 90% of regeneration.