Abstract
Water contaminated with toxic dyes poses serious problems for human health and environmental ecosystems. Unfixed reactive dyes and their hydrolyzed form are soluble in water, thus, their removal is particularly challenging. Among the different methodologies, adsorption is probably the most common since it is easy to handle and has a low cost. Here, the removal by adsorption of hydrolyzed Reactive Black 5 (hydRB5) from a model wastewater through cellulose acetate/hematite membranes (CA/α-Fe2O3), designated as M1, M2 and M3, was performed. The pristine cellulose acetate membrane (CA) was designated as M0. Toward understanding the adsorption mechanism of hydRB5 on membranes, the rate of adsorption and maximum value of the adsorption capacity were evaluated using kinetic and isothermal studies, respectively. The results showed that the adsorption mechanism follows pseudo-first-order kinetics, and data are best fitted by the Langmuir isotherm method with a maximum adsorption capacity of 105.26 mg g−1 in pH~7. Furthermore, these membranes can be also regenerated by washing with NaOH and NaCl solutions, and the regeneration efficiency remains effective over five cycles. To complete the work, two statistical models were applied, an Analysis of Variance (ANOVA) and a Response Surface Methodology (RSM). The optimum value found is located in the usable region, and the experimental validation shows good agreement between the predicted optimum values and the experimental data. These composite membranes are also good candidates for the adsorption of other pollutants, even at industrial scale, due to their effective regeneration process and low production costs.
Highlights
To know the adsorption capacity of each one, the performance of each adsorbent in hydrolyzed Reactive Black 5 (hydRB5) removal was estimated under the same experimental conditions
cellulose acetate membrane (CA) was superior to the hematite NPs, which can be attributed to the larger pore size in comparison to NPs
Comparing the maximum adsorption capacity of hydRB5 in the nanocomposite membranes studied here with that of other adsorbents, in the period from 2015 to 2021, we found that only one article addressed the issue of hydrolyzed Reactive Black 5 (RB5) adsorption [22], and the others referred to the adsorbate in the unfixed form
Summary
The optimum value found is located in the usable region, and the experimental validation shows good agreement between the predicted optimum values and the experimental data. These composite membranes are good candidates for the adsorption of other pollutants, even at industrial scale, due to their effective regeneration process and low production costs. Depending on the type of dye used, about 10−50% of the dye’s residual water is released into the environment, resulting in an increase in the chromaticity of polluted water and reducing the amount of incident light, which affects the ecological balance of water [3].
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