Innovative optimization for enhancing Pb2+ biosorption from aqueous solutions using Bacillus subtilis

Introduction: Toxic heavy metal pollution has been considered a major ecosystem pollution source. Unceasing or rare performance of Pb²⁺ to the surrounding environment causes damage to the kidney, nervous, and liver systems. Microbial remediation has acquired prominence in recent decades due to its high efficiency, environment-friendliness, and cost-effectiveness.

Methods: The lead biosorption by Bacillus subtilis was optimized by two successive paradigms, namely, a definitive screening design (DSD) and an artificial neural network (ANN), to maximize the sorption process.

Results: Five physicochemical variables showed a significant influence (p < 0.05) on the Pb²⁺ biosorption with optimal levels of pH 6.1, temperature 30°C, glucose 1.5%, yeast extract 1.7%, and MgSO₄.7H₂O 0.2, resulting in a 96.12% removal rate. The Pb²⁺ biosorption mechanism using B. subtilis biomass was investigated by performing several analyses before and after Pb²⁺ biosorption. The maximum Pb²⁺ biosorption capacity of B. subtilis was 61.8 mg/g at a 0.3 g biosorbent dose, pH 6.0, temperature 30°C, and contact time 60 min. Langmuir’s isotherm and pseudo-second-order model with R² of 0.991 and 0.999 were suitable for the biosorption data, predicting a monolayer adsorption and chemisorption mechanism, respectively.

Discussion: The outcome of the present research seems to be a first attempt to apply intelligence paradigms in the optimization of low-cost Pb²⁺ biosorption using B. subtilis biomass, justifying their promising application for enhancing the removal efficiency of heavy metal ions using biosorbents from contaminated aqueous systems.