The valorization of a low-cost and an abundant material is a significant work for environmental protection. The objective of this work was to investigate the adsorption of two dyes: Basic Red 46 (BR46) and Reactive Yellow 181 (RY181) onto raw (S1) and modified clays. These modifications were carried out by calcination at different temperature (S2, S3, ..., S9), acidic activation, and acetylation. The surface properties of the adsorbents were characterized by the cation exchange capacity, Fourier transform infrared, and X-ray diffraction analyses. Batch studies were performed to evaluate the effect of the contact time and initial dye concentrations on the removal capacities of adsorbents. Among the kinetic models tested, the adsorption kinetics was best described by the pseudo-second-order equation. The isotherm data fitted well with Langmuir model. The maximum adsorption capacities onto the raw clay (S1), calcined clay at 600˚C (S5), acidic activated clay (AC), and acetylated clay (MC) were 2.805, 4.232, 1.968, and 2.756 mmol/g for CI Basic Red 46 and 0.031, 0.030, 0.046, and 0.050 mmol/g for CI Reactive Yellow 181, respectively.
Industrial processes in everyday life need to take into consideration environmental safety. This is the major goal of today's scientific research. Textile research is no exception. This paper illustrates a green process in which indigo is converted into its water-soluble leuco form by using a reducing agent that is ecologically friendly: 3-hydroxybutanone (C4H8O2). The effect of alkalinity and reducing temperature on the reducing power of C4H8O2 has been evaluated in the absence and presence of indigo. The dyeing quality of the modified cotton resultant of the exhaust process is studied. Cotton modification is carried out by using Denitex BC 200% in order to improve the quality of the exhaustion dyeing process. Modified cotton fibres are characterized through a morphology analysis (by using a SEM), Fourier transform infrared spectroscopy and X-ray diffraction analysis. The performances of the indigo dyeing process are evaluated by measuring the redox potentials generated in the medium with and without indigo, dyeing bath exhaustion (E(%)), and colour yield (K/S) of the coloured cotton at 660 nm, brightness index (B(%)) and dyeing fastness of both the untreated and modified cotton fabrics.
Article Highlights• Development of a clean process for indigo dyeing • Substitution of conventional sodium dithionite by green alternatives in reducing indigo• Study of synergy effect of mixture α-hydroxycarbonyls in reducing indigo • Determination of the optimum mixture of α-hydroxycarbonyls for reducing indigo Abstract Textile industries use different chemicals in dyeing processes, consuming large quantities of water and producing large volumes of wastewater. For the particular case of indigo dyeing processes, its reduction is performed chemically by the addition of sodium dithionite. However, this is considered environmentally unfavorable because of the resulting contaminated wastewaters. Therefore, it is important to replace sodium dithionite with other alternatives in order to achieve cleaner processes. α-hydroxycarbonyls have been suggested as possible environmentally friendly alternatives to reduce indigo. However, each one applied alone is unable to attain the dyeing performances offered by the conventional reductant. Thus, the study of the synergy of some selected α-hydroxycarbonyls was proposed. In this paper, a mixture design of experimental (DOE) methods was used to determine the optimum combination of α-hydroxycarbonyls to be applied in the indigo reduction process. Based on the design expert software, quadratic models were established as functions of α-hydroxycarbonyls ratios. The diagnostics of models were investigated by using mixture contour plots. Finally, a model was proposed to predict the optimum conditions leading to dyeing performances exceeding those obtained from the reduction of indigo by the conventional sodium dithionite.Keywords: green reducing agent, α-hydroxycarbonyls, synergetic effect, mixture design, clean process.As a vat dye, indigo is considered the oldest dye known to man. It is an organic compound with a distinctive blue color. Historically, it was naturally extracted from plants, and this was important economically because blue dyes were rare. Nearly all indigo dyes produced today -several thousand tons each year -are synthetic. Indigo and other vat dyes consumption reaches about 33×10 6 kg annually [1]. This
More widespread use of metallothionein (MT) as a biomarker for trace metal pollution continues to be partly dependent on obtaining reliable baseline concentrations and identifying increased induction of the enzyme with only modest increases in metal concentrations. In this study, new data on metals and MT levels in whole clams tissue, gills, and digestive glands from field samples and in sediments are presented. Concentrations of Cd, Cu, Fe, and Zn in depurated (24 h) clam samples of digestive glands, gills, and the whole clam Merceneria merceneria from the Indian River Lagoon, Florida, varied with location and showed moderate to strong correlations among Zn, Cu, and Fe. Concentrations of metallothionein (dry wt.) ranged from 34─270 μg/g in gills and 150-440 μg/g in digestive glands and showed moderate to strong correlations between organs and with metal concentrations in those organs. Observed trends support increased synthesis of metallothionein with only moderate increases in metal values and in response to statistically higher sediment metal concentrations.
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