Modelling and optimization of cadmium adsorption using dead Pseudomonas biomass isolates from brassware effluents using Box-Behnken Design and Artificial Neural Networks

This study investigates the potential of indigenous dead Pseudomonas biomass isolated from brassware workshop effluents as a potential adsorbent for cadmium elimination from effluents, addressing the dual challenge of metallic pollution and industrial waste management. The optimization of cadmium adsorption capacity by dead Pseudomonas biomass has been accomplished through a Box-Behnken Design integrated with Response Surface Methodology and Artificial Neural Networks. Optimal parameters identified (temperature 45°C, pH 9, biosorbent dose 2 g. L⁻¹, contact duration 75 min) enabled achievement of a maximum removal efficiency of 99.69 %. The dead Pseudomonas biomass was characterized using X-ray diffraction, iodine index determination, scanning electron microscopy, zeta potential analysis, X-ray fluorescence spectroscopy, Brunauer-Emmett-Teller surface analysis, and Fourier-transform infrared spectroscopy. The favorable mesoporous structure (specific surface 16.69 m². g⁻¹, pore volume 0.02294 cm³.g⁻¹, average pore diameter 5.50 nm) for metallic ion diffusion has been confirmed. Adsorption equilibrium analysis indicates that the Langmuir model best represents the process, with a maximum adsorption capacity of 52.34 mg. g⁻¹ consistent with monolayer adsorption on homogeneous sites. Kinetic study validates the pseudo-second-order model as the best fit, suggesting chemisorption as the rate-limiting step. Thermodynamic parameters confirm the spontaneous and endothermic nature of biosorption. Overall, this work demonstrates a circular economy approach by valorizing industrial effluents into efficient biosorbents, simultaneously addressing pollution control and waste management challenges in the metal finishing industry.