Abstract Wastewater from the lead–acid battery industry poses serious environmental risks due to its low pH and heavy metals. Lead causes neurotoxic effects, organ damage, and thus requires treatment. Among removal methods, adsorption is a promising alternative due to its high effectiveness and low cost. In this study, eggshell waste was valorized as an adsorbent within alginate beads for lead uptake. Acid soaking and calcination were applied as preliminary treatments for the eggshell. The alginate–eggshell beads were characterized using SEM and FTIR analysis. In the first set of experiments, the effects of eggshell particle size, alginate-to-eggshell ratio, initial pH, and metal concentration on lead removal and desorption were evaluated. In the second phase, battery wastewater was treated in a column. The composite beads exhibited a highly rough surface that enhances the accessible surface area for binding, along with an appropriate size range for continuous operation. Alginate–eggshell beads (with < 100 μm particles at a 1:1 ratio) achieved 98% removal efficiency at pH 6, representing the optimum conditions. Pb 2+ adsorption followed the pseudo-first-order kinetic model and the Langmuir isotherm, with a maximum adsorption capacity of 218.3 mg/g. The beads allowed cost-effective reuse through simple acid regeneration. Although other pollutants (e.g., competing metals) in battery wastewater reduced the Pb 2+ adsorption capacity, continuous treatment at a flow rate of 3 mL/min resulted in 87.5% Pb 2+ removal, with the effluent concentration well below regulatory limits. Thus, alginate–eggshell beads are a cost-effective and efficient material for wastewater treatment, particularly in systems with low Pb 2+ concentrations. Graphical Abstract
Olğaç et al. (Mon,) studied this question.