Statistical optimization, soft computing prediction, mechanistic and empirical evaluation for fundamental appraisal of copper, lead and malachite green adsorption

Abstract

This paper describes an efficient and low cost material for treatment of Cu2+, Pb2+ and malachite green from aquatic environments. Aerated Autoclave Concrete (AAC) was used as a low cost bed and modified by chitosan to synthesize of AAC?CH composite. Then, it was analyzed by the Energy Dispersive X-ray spectroscopy (EDX), X-Ray Fluorescence (XRF), Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared spectrophotometry (FT-IR) analysis. The key factors influencing on the removal percentage among each run including, sample's pH, amounts of adsorbent and contact time were optimized by the Central Composite Design in Response Surface Methodology (CCD-RSM). Based on the obtained results, the optimum conditions for the removal of both Cu2+ and Pb2+ are pH 5.8, amounts of adsorbent: 14 mg and 58 min contact time. Also, for MG, its maximum removal percentage obtained at pH 9.7, 13 mg adsorbent and 55 min removal time. In addition, the variations of adsorptive behaviors were scrutinized by Adaptive Network-based Fuzzy Inference System (ANFIS) based on Sugeno model with focusing on removal percentage predictions. Also, to evaluate the adsorption mechanism, Dubinin?Radushkevich (D-R), Langmuir, Temkin, Freundlich (two parameter equations) and Sips, Khan and Toth isotherms (Three parameter equations) were appraised and the outcomes demonstrate that the adsorptive reaction of Pb2+, Cu2+ and MG governed by the Freundlich isotherm with the maximum adsorption capacities of 78.12, 56.82 and 833.33 mg g?1, correspondingly. Likewise, outputs of the D-R and Temkin isotherms show that the physiosorption process is the main interaction of analytes with AAC?CH composite. The consequences of the kinetic modeling illustrated that the adsorptive reaction of Cu2+, Pb2+ and MG followed by the pseudo second order adsorption kinetic. The geometry kinetic computing depicted that the adsorption/desorption rates don't have any interfering during reaction process. The advantages such as high efficiency, low cost, reusability and green aspect, make AAC?CH composite as a high performance adsorbent for decontamination of Pb2+, Cu2+ and MG from water resources.