Removal of Cu(II) from aqueous solutions using modified sewage sludge ash

The study aims to determine Cu(II) adsorption from wastewater in the laboratory condition using modified sewage sludge ash as adsorbent which was obtained from a thermal drying and incineration facility. This procedure was completed with an inexpensive pollutant material which has high metal-binding capacity and is available in abundant amounts. During experiments, the effects of particle size, pH, stirring speed, initial ion concentration, adsorbent dosage and temperature were investigated. Adsorption equilibrium was obtained in 10 min. Maximum Cu(II) removal was calculated as 83.63% with 20 mg L−1 initial Cu(II) ion concentration and 5 g L−1 adsorbent dosage. Kolmogorov–Smirnov normality test was performed to test the conformity of the data obtained as a result of the study to variance analysis, and it was determined that the data were distributed normally (p > 0.05). Levene test was performed for homogeneity test, and it was determined that the data were distributed homogeneously (p > 0.05). Langmuir was determined as the most suitable isotherm model for Cu(II) adsorption. Adsorption kinetics abided by the pseudo-second-order model. Based on kinetic studies, the adsorption process was endothermic with maximum adsorption capacity calculated as 7.53 mg g−1. The results of thermodynamic research showed the adsorption reaction was spontaneous (ΔG° < 0), endothermic (ΔH° > 0) and reversible (ΔS° > 0 and close to zero).