Efficient and environmentally friendly removal of azo textile dye using a low-cost adsorbent: Kinetic and reuse studies with application to textile effluent
01 Jun 2023-Materials today communications-Vol. 35, pp 106433-106433
TL;DR: In this article , a highly efficient, non-toxic, low-cost MgO particles were prepared by sol-gel technique and utilized for the removal of Reactive Red 21 azo dye by adsorption process.
Abstract: Recently, there has been an increasing interest in environmentally friendly methods for the removal of toxic dyes to enable sustainable textile dyeing processes. In this study, a highly efficient, non-toxic, low-cost MgO particles were prepared by sol-gel technique and utilized for the removal of Reactive Red 21 azo dye by adsorption process. The prepared MgO particles were characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, and Particle Size Analysis. The batch adsorption studies were performed for optimizing the parameters affecting adsorption. The adsorption behavior of Reactive Red 21 was accurately characterized by the Langmuir model. The adsorption process was found to be thermodynamically spontaneous at room temperatures as indicated by the negative Gibbs free energy change (∆G) value of −30.65 kj/mol. The kinetic studies indicate that the pseudo-second-order model provides a good fit to the adsorption of Reactive Red 21. The adsorption capacity of the prepared MgO particles for Reactive Red 21 was determined to be 355 mg/g at room temperature over a wide pH range of 5–9, with a contact time of 20 min. The regeneration of dye-adsorbed MgO particles was conducted at 500 °C for 2 h. The regenerated MgO particles were then utilized for adsorbing Reactive Red 21 five times with a sufficiently high dye removal efficiency. The prepared MgO particles provided a 98 % dye removal in real textile wastewater containing Reactive Red 21 dye.
TL;DR: In this article, the absorption index at the wave length of the band maximum was found to be proportional to the total concentration of metal at shorter wave lengths, however, deviations were observed, the absorption increasing more rapidly with concentration than Beers' law would demand.
Abstract: solutions investigated, the absorption index diminishing approximately 1% for a rise in temperature of one degree. 6. In liquid ammonia rough measurements of concentration showed the absorption index to be proportional to the total concentration of metal. 7. In methylamine the absorption index, at the wave length of the band maximum is also proportional to the total concentration of metal. At shorter wave lengths, however, deviations were observed, the absorption increasing more rapidly with concentration than Beers’ law would demand. The ratio of the absorption index a t 650pp to that a t 53opp increases not only with increasing concentration of the metal but also with increasing concentration of the reaction product of the metal with methylamine, and probably also with increasing temperature. 8. These observations can be accounted for by the following hypotheses: The color in all cases is due to electrons combined with the solvent. In ammonia the dissociation of the metal into electrons is nearly complete, and the concentration of electrons uncombine4 with solvent is negligible compared with that of the solvated electrons. In other words, the solvation of the electrons is nearly complete. In methylamine, on the other hand, the concentration of un-ionized metal is no longer negligible and is responsible for the increased absorption a t the shorter wave lengths. The solvation of the electrons in methylamine is incomplete and diminishes as the temperature is increased.
TL;DR: The main limitation of this approach is the treatment of the concentrate stream as discussed by the authors, which is a segment of the research dealing with the separate handling of speci-c sub-streams such as dyebath effluents to which membrane -ltration is sometimes applied.
Abstract: New ecolabels for textile products and tighter restrictions on waste- water discharges are forcing textile wet processors to reuse process water and chemicals. This challenge has prompted intensive research in new advanced treatment technologies, some of which currently making their way to full-scale installations. These comprise polishing treatments such as -ltration, chemical oxidation and specialized Nocculation techniques and pre-treatment steps includ- ing anaerobic digestion, -xed--lm bioreactors, FentonIs reagent oxidation, elec- trolysis, or foam Notation. Though several of these new technologies are promising in terms of cost and performance, they all su†er limitations which require further research and/or need broader validation. A segment of the research deals with the separate handling of speci-c sub-streams such as dyebath effluents to which membrane -ltration is sometimes applied. The main limitation of this approach is the treatment of the concentrate stream. The spectrum of available technologies may, in the future, be further broadened to include oxidation, specialized bio-sorptive processes, solvent extrac- fungi/H 2 O 2 -driven tion, or photocatalysis. 1998 SCI ( J. Chem. T echnol. Biotechnol. 72, 289E302 (1998)
TL;DR: Experimental results indicate that the prepared MgO powder can remove more than 98% of both dyes under optimum operational conditions of a dosage of 0.2g, pH 8 and a contact time of 5 min for initial dye concentrations of 50-300 mg/L.
TL;DR: In this paper, the specific surface areas of the MgO samples were determined by the BET technique, which gave a feature of high surface area generally larger than 100 m2/g.
Abstract: Mg(OH)2 nanocrystallines with rod-, tube-, needle-, or lamella-like morphologies have been synthesized by a hydrothermal reaction using different magnesium precursors and solvents as the reactants. The products appeared to have narrow size distributions with a monodisperse nature. Subsequent thermal decomposition at 450 °C gave nanosized MgO, which preserved well the morphological features of the Mg(OH)2 samples. The specific surface areas of the MgO samples were determined by the BET technique, which gave a feature of high surface area generally larger than 100 m2/g. The channels formed in the thermal dehydroxylation process may account for this feature of the MgO nanocrystallines.
TL;DR: In this article, a novel adsorbent, copper oxide nanoparticle loaded on activated carbon (CuO-NP-AC), was synthesized by a simple, low cost and efficient procedure.