Optimization of activation of Kutigi clay for adsorption of copper (II) ion using response surface methodology

Abstract

This research paper presented the optimization of activation Kutigi clay for the adsorption of Cu²⁺ from aqueous solution using response surface methodology. The Kutigi clay sample was activated with H₂SO₄ by varying acid concentrations, activation temperature and activation time. X-ray fluorescence (XRF) analysis was carried out before activation in order to know the chemical composition of the clay sample. Response surface methodology was adopted to optimize the activation conditions, with percentage removal of Cu²⁺set as the response. Fourier-transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) surface area analyses were conducted on the clay sample before and after the activation procedure. A total of twenty experimental runs were carried out and the optimal clay activation conditions obtained was 2.5 M acid concentration at 50^oC and 75 minutes contact time using Cu²⁺ percentage removal as the response. At the optimum conditions, a BET surface area of 170.80 m²/g of the activated micro porous adsorbent gives good adsorption capacity of 238.095 mg Cu²⁺/g adsorbent. The effects of contact time, initial Cu²⁺ concentration, adsorbent dosage and pH on the activated Kutigi clay adsorption capacity also examined. Freundlich isotherm and pseudo-second-order models best described adsorption of Cu²⁺ onto the activated Kutigi clay when compared to Langmuir isotherm and pseudo-first order model respectively.