The kinetics of fluoride sorption by zeolite: Effects of cadmium, barium and manganese

• Published in: Journal of contaminant hydrology Vol. 177-178; pp. 136 - 147
• Main Authors: Cai, Qianqian, Turner, Brett D, Sheng, Daichao, Sloan, Scott
• Format: Journal Article
• Language: English
• Published: Netherlands 01.06.2015
• Subjects: Barium - chemistry; Cadmium; Cadmium - chemistry; Contaminants; Criteria; Diffusion; Fluorides; Fluorides - chemistry; Hydrology - methods; Kinetics; Manganese - chemistry; Mathematical models; Models, Theoretical; Reaction kinetics; Solutions - chemistry; Sorption; Temperature; Waste Water - chemistry; Water Pollutants, Chemical - chemistry; Water Purification - methods; Zeolites; Zeolites - chemistry; Natural zeolite; Hill model; Kinetics; Pseudo-second order; Fluoride removal; Metal ions
• ISSN: 0169-7722; 1873-6009
• DOI: 10.1016/j.jconhyd.2015.03.006

Industrial wastewaters often consist of a complex chemical cocktail with treatment of target contaminants complicated by adverse chemical reactions. The impact of metal ions (Cd(2+), Ba(2+) and Mn(2+)) on the kinetics of fluoride removal from solution by natural zeolite was investigated. In order to better understand the kinetics, the pseudo-second order (PSO), Hill (Hill 4 and Hill 5) and intra-particle diffusion (IPD) models were applied. Model fitting was compared using the Akaike Information Criterion (AIC) and the Schwarz Bayesian Information Criterion (BIC). The Hill models (Hill 4 and Hill 5) were found to be superior in describing the fluoride removal processes due to the sigmoidal nature of the kinetics. Results indicate that the presence of Mn (100 mg L(-1)) and Cd (100 mg L(-1)) respectively increases the rate of fluoride sorption by a factor of ~28.3 and ~10.9, the maximum sorption capacity is increased by ~2.2 and ~1.7. The presence of Ba (100 mg L(-1)) initially inhibited fluoride removal and very poor fits were obtained for all models. Fitting was best described with a biphasic sigmoidal model with the degree of inhibition decreasing with increasing temperature suggesting that at least two processes are involved with fluoride sorption onto natural zeolite in the presence of Ba.