Removal of NO\(_3\)\(^-\), PO\(_4\)\(^{-3}\), Cu\(^{2+}\), Pb\(^{2+}\) and Cd\(^{2+}\) (Adsorbates) onto Mukurweini’s Kaolinite and Alkali Modified Kaolinite: Effect of Adsorbent Dosage and Intrinsic Factors

Abstract

Access to clean and safe water for domestic and industrial use remains a major challenge for developing countries in the Third World. The study aims to investigate the effect of adsorbent dosage, contact time, initial concentration, Temperature and pH on the percentage removal of NO3-, PO4-3, Cu2+, Pb2+ and Cd2+ (adsorbates) onto Mukurweini’s kaolinite and alkali-modified Kaolinite. The available fresh water resources are distributed unevenly across the country, with the available sources affected by heavy pollution from sources such as raw sewage, domestic and industrial waste, agricultural waste, and emerging pollutants such as plastic, which contribute significantly to the limited accessibility of clean water in Kenya. These studies examined the potential application of clay-derived zeolites derived from clay material (kaolinite) obtained from Mukurweini in Nyeri County to remediate water contaminated with agricultural waste. To achieve optimum removal of pollutants in wastewater, batch adsorption studies were carried out to determine the optimum operating conditions, i.e., contact time, pH, and calcination temperature. The batch adsorption study was carried out, and the sample solutions were analysed alongside standard solutions using an AA-6300 SHIMADZU Atomic Absorption Spectrophotometer. The optimum calcination temperature was determined at t = 550–900 °C, equilibrium contact time of 30 minutes, pH = 7, and temperature t = 25 °C. At these optimum conditions, the overall percentage removal of NO3-, PO4-3, Cu2+, Pb2+ and Cd2+ (adsorbates) was calculated at 99.2% for solutions of concentration c = 100 ppm for all ions. The results show that the pH of the solution uniquely affected the adsorption capacities of the five adsorbed substances. From the adsorption study, the percentage removal increased as the adsorbent dosage increased. 30 minutes of contact time was required to reach equilibrium. At a 100 ppm concentration of the adsorbate, the percentage removal remained at 99.2%.