Utilization of groundwater treatment plant (GWTP) sludge for nickel removal from aqueous solutions: Isotherm and kinetic studies

• Published in: Journal of environmental chemical engineering 2017-12, Vol.5 (6), p.5746-5753
• Main Authors: Ong, Dennis C., Kan, Chi-Chuan, Pingul-Ong, Sheila Mae B., de Luna, Mark Daniel G.
• Format: Article
• Language: English
• Subjects: Adsorption; Groundwater; Groundwater treatment sludge; Isotherm; Kinetics; Nickel removal
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2017.10.046

[Display omitted] •Groundwater treatment sludge was reused for nickel adsorption from solutions.•Adsorption of nickel on the sludge was not pH-dependent at pH 4.5–7.5.•Chemisorption was the rate-limiting step for the adsorption of Ni(II) ions.•Complexation with the sludge functional groups governed the Ni(II) adsorption. In this study, the potential of groundwater treatment sludge reuse in the adsorption of nickel ions from aqueous solutions was evaluated. The effects of varying solution pH (4.5, 5.5, 6.5, 7.5), initial nickel concentrations (10, 50, 100, 200mgL−1) and contact time (10, 30, 60 120min) on Ni(II) removal were investigated. Results showed that the pH level had no significant effect on the Ni(II) removal. At all pH levels, the amount of nickel adsorbed increased from 1.3mgg−1 to a maximum of 11.6mgg−1 as the initial Ni(II) concentration was increased from 10 to 200mgL−1. The nickel adsorption on the sludge at all pH levels was described by the Freundlich model, as implied by the high coefficient of determination (R2) values of 0.9890 to 0.9977 for this model. The adsorption affinity constant (n value) obtained from the Freundlich equation, which ranged from 2.98 to 3.10, suggests chemical adsorption of nickel on the sludge. The kinetic data of nickel adsorption on the sludge at pH 6.5 and initial Ni(II) concentrations of 50, 100 and 200mgL−1 was best described by the pseudo-second order adsorption kinetic rate model, with coefficient of determination values ranging from 0.9945 to 0.9995, indicating that chemisorption between the sludge binding sites and Ni(II) governs the adsorption process. The results of the study confirm the applicability of the groundwater treatment sludge as a low-cost alternative for nickel removal from wastewater.