Keywords
How to Cite
Abstract
The growing discharge of cobalt ions to the aquatic environment is a major public health and environmental problem, so there is an urgent demand for inexpensive and sustainable remediation materials. In the present study, new bio-based adsorbents were prepared by free-radical copolymerization of Ocimum basilicum hydrogel with polyacrylic acid and an ammonia-cross-linked 3D hydrogel copolymer bearing carboxyl functional group was generated. The structure modification is beneficial to improve surface charge density, binding site accessories as well as adsorption affinity towards Co (II). The adsorption properties of the OBH-co-AA copolymer was systematically investigated by batch experiments and the effects of solution pH, contact time, initial Co (II) concentration, sorbent dosage, and temperature were determined. The optimum pH for the adsorption was found to be 6 and the process reached equilibrium within 60 min. The adsorption capacity of copolymer increased upon a shift towards alkaline range. The isotherm data could be well fitted by Langmuir, Temkin and Elovich isotherms presenting that the adsorption capacity in monolayer was 150.38 mg g-1 and surface was heterogeneous. Kinetics was found to be well described by the pseudo-second-order model, thus revealing chemisorption as the predominant adsorption process and diffusion models indicated that intra particle and pore diffusion took place in the end of uptake. Thermodynamics investigation indicated that the Co (II) adsorption on OBH-co-AA copolymer is a spontaneous, endothermic and entropy driven process. In conclusion, these results indicate that acrylic acid modified Ocimum basilicum hydrogel presents high effectiveness, environmental-friendly and economically competitive among other characteristics considered as an organic adsorbent and its potential for application in water treatment systems for removal of cobalt contamination.