Parametric optimization of Cu(II) removal process by a metakaolin-based geopolymer: Batch and continuous process design

Abstract

In the comprehensive research, the uptake of Cu(II) ions from contaminated water was explored using metakaolin-based geopolymer (MKG). The effects of contact time, adsorbent amount, initial pH, temperature, stirring speed, flow rate, column diameter, and adsorbate volume on the Cu(II) removal yield of MKG in the batch and column treatment systems were examined by employing Box-Behnken Design (BBD) approach. Cu(II) ions uptake was achieved at the optimum batch conditions of agitation speed: 160 rpm, temperature: ∼20 °C, initial pH: 5.3, contact time: 50 min, adsorbent amount: 0.04 g, with 95.02% removal yield. ANOVA results indicated that pH and adsorbent dosage were the most efficient Cu(II) adsorption parameters in the batch system. The PSO kinetic model could better describe the time-dependent data. Equilibrium adsorption data of Cu(II) showed a good adaptation with Langmuir isotherm with the maximum monolayer adsorption capacity of 1.36 × 10−3 mol g−1 (86.6 mg g−1). Breakthrough capacity at the exhausted point was computed as 42.2 mg g–1. The interaction mechanism between MKG and Cu(II) ions was tried to examine via zeta potential analysis, SEM/EDX, IR, XRD, and BET techniques. All the results have proven that MKG is a recoverable, cost-effective, and environment-friendly adsorbent for the removal of Cu(II) ions from aqueous solutions.