A comparative study of raw and sulfuric acid-activated areca-fungal biochar for effective Pb (II) adsorption

The current study explores the potential of mixed adsorbents from Penicillium oxalicum and Areca palm leaves for Pb(II) removal from aqueous solutions. Concentrated sulphuric acid treatment was used to enhance the biochar’s porosity, surface area, and functional groups. Characterization studies for Raw Penicillium Palm Leaves Biochar (RPPLB) and Activated Penicillium Palm Leaves Biochar (APPLB) revealed the enhanced surface morphology with significant number of folds, functional groups, enhanced thermal stability and crystalline structure of APPLB relative to RPPLB. In optimization studies, APPLB achieved higher than 90 % Pb(II) removal at pH 5.0, 3.2 g/L, and 90 min, while RPPLB required 8 g/L and 100 min under the same conditions. Modelling studies showed that APPLB followed Redlich-Peterson isotherm (R² = 0.9805) and pseudo-second-order kinetics (R² = 0.9874), indicating combined heterogeneous and multilayer chemisorption. RPPLB fit the Langmuir isotherm (R² = 0.9722) and pseudo-first-order model (R² = 0.9489), indicating monolayer physisorption. Thermodynamic studies revealed exothermic and spontaneous nature of the adsorption process. The current study demonstrates the enhanced performance of chemically activated mixed adsorbents highlighting the potential of cost-effective, sustainable biochar derived from fungal and agro-waste biomass for heavy metal wastewater treatment. • Mixed Penicillium oxalicum -palm/Arcea leaves biomass was used for Pb(II) Removal studies. • The adsorption capability of Penicillium oxalicum -palm/ Arcea le aves biomass is enhanced by sulfuric acid treatment. • The best fit to the adsorption data was Redlich-Peterson and pseudo-second-order kinetics. • By sulfuric acid modification, the maximum Pb(II) ion adsorption of 182.2 mg/g was recorded. • The spontaneous and exothermic nature was confirmed by thermodynamic investigations.