The textile industry is a major contributor to environmental pollution, particularly by discharging dye-containing wastewater into water bodies, which can harm both flora and fauna. A significant portion of textile dyeing occurs in the Global South, where environmental regulations are often less stringent than in other regions. Traditional adsorption methods for treating textile wastewater can be prohibitively expensive, leading to a growing interest in low-cost alternatives. Among these, cementitious materials have shown potential as effective adsorbents for dye removal, with the formation of gypsum correlating with enhanced dye adsorption.
This study investigates gypsum as an adsorbent for anionic dyes in textile wastewater, as it is a common phase present in cementitious systems. The adsorption capacity of gypsum was tested using a dosage of 5.4 g/L for three anionic dyes: Reactive Blue 19 (RB19), Acid Orange 7 (AO7), and Acid Green 1 (AG1). To simulate real textile wastewater, the pH of the dye solutions was adjusted using HCl and NaOH, and common dyeing salts such as magnesium sulfate, sodium bisulfate, and sodium chloride were added.
The adsorption performance of commercially available gypsum was compared to that of gypsum precipitated in situ from portlandite (Ca(OH)2) in an MgSO4 solution, as the latter more accurately simulates gypsum formation in sulfate-rich cementitious environments. Previous studies have indicated that the decolourisation properties of gypsum can vary significantly depending on its crystal habit [1].
UV-Vis spectroscopy with flow-through cells monitored dye adsorption for three hours. Follow-up analyses of the solids include X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and chemical analysis. Initial results show that commercial gypsum exhibits limited decolourisation of Reactive Blue 19, with only 5-10% removal. In the presence of dyeing salts, the decolourisation capacity is further reduced. Experiments using AO7 or AG1 and precipitated gypsum are currently ongoing.
This research contributes to ongoing efforts to develop cost-effective and efficient methods for mitigating the environmental impact of dyed wastewater.
Literature: [1] Jia, Xin-Jian; Wang, Jinshu; Wu, Junshu; Du, Yucheng; Zhao, Bingxin; Engelsen, Daniel den; RSC Adv., 2015, 5, 72321–72330.
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The textile industry is a major contributor to environmental pollution, particularly by discharging dye-containing wastewater into water bodies, which can harm both flora and fauna. A significant portion of textile dyeing occurs in the Global South, where environmental regulations are often less stringent than in other regions. Traditional adsorption methods for treating textile wastewater can be prohibitively expensive, leading to a growing interest in low-cost alternatives. Among these, cement...
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