Abstract
In order to prepare low-cost, biodegradable and processable adsorbent materials for adsorption of heavy metal ion, two kinds of novel modified cottons (C-4-APD and C-2-APZ) were obtained by introducing 4-aminopyridin and 2-aminopyrazine into the surface of degreasing cotton, respectively, and used for the removal of Cr(VI) ions from aqueous solution. The two modified cottons were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), which confirmed the amino groups, pyridine groups and pyrazine groups grafted onto the surface of modified cottons. The maximum adsorption capacities of C-4-APD and C-2-APZ were 89.66 mg/g and 54.92 mg/g, respectively, at the optimum pH of 2 and an initial concentration of 300 mg/g. Kinetic, isotherm and thermodynamic studies were carried out to investigate the adsorption behavior of the modified cottons on Cr(VI) ions. The results showed that the adsorption of Cr(VI) ions by modified cottons followed a pseudo-second-order kinetic model, the equilibrium data were in good agreement with the Langmuir isotherm model, and the thermodynamic analysis indicates that the adsorption proceeds spontaneously. The recovery and reuse of modified cotton were achieved by washing with 2 wt% thiourea-hydrochloric acid solution (0.5 mol/L concentration of HCl), and the adsorption capacities of C-4-APD and C-2-APZ were maintained above 90% and 85%, respectively, after six cycles.
Highlights
Degreasing cotton; Chromium; Adsorption; Aminopyridine; The presence of chromium in the environment is generally Cr(III) and Cr(VI).Trace amounts of Cr(III) can reduce the blood glucose concentration in the human body to a certain extent, accelerate the metabolic process of sugar and substances required by the body, and the human insulin activity and stress response capacity can be regulated by Cr(III)(Kooshki et al 2021, Moradi et al 2019)
Most of the adsorbents reported in the literature for the removal of hexavalent chromium are prepared under complicated process conditions, raw materials are not available, costs are high, and they are difficult to degrade in the natural environment, which may cause secondary pollution to the environment in practical applications
The adsorption behavior of Cr(VI) on C-4-APD and C-2-APZ was investigated by Langmuir and Freundlich models, and the experimental data were fitted by two kinetic models, pseudo-first-order and pseudo-second-order(Simonin 2016), to analyze the mechanism of Cr(VI) adsorption, and its reusability was evaluated by repeated adsorption-elution, and the modification effect of the two groups on cotton fibers was compared
Summary
Degreasing cotton; Chromium; Adsorption; Aminopyridine; The presence of chromium in the environment is generally Cr(III) and Cr(VI). Most of the adsorbents reported in the literature for the removal of hexavalent chromium are prepared under complicated process conditions, raw materials are not available, costs are high, and they are difficult to degrade in the natural environment, which may cause secondary pollution to the environment in practical applications. For crude processed biomass materials such as cotton, hemp, and agricultural wastes, the corresponding reports are less available and have a low Cr(VI) adsorption capacity. The crude processed biomass material is more widely available and if it is utilized to improve and increase its adsorption capacity for Cr(VI), the processing steps for preparing biomassbased adsorbents can be more simplified and less costly. In order to further reduce costs and prepare environmentally friendly adsorbent materials, 4-aminopyridine and 2-aminopyrazine were introduced to the surface of degeasing cotton using one-pot method in this study. The adsorption behavior of Cr(VI) on C-4-APD and C-2-APZ was investigated by Langmuir and Freundlich models, and the experimental data were fitted by two kinetic models, pseudo-first-order and pseudo-second-order(Simonin 2016), to analyze the mechanism of Cr(VI) adsorption, and its reusability was evaluated by repeated adsorption-elution, and the modification effect of the two groups on cotton fibers was compared
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
