Uptake of Hexavalent Chromium in Electroplating Wastewater by Hydrothermally Treated and Functionalized Sand and Its Sustainable Reutilization for Glass Production

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• 作者：Shiquan LiuShivani Bhardwaj Mishra ; Yun Zhang ; Ling Qi
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：5
• 期：2
• 页码：1509-1516
• 全文大小：467K
• ISSN：2168-0485

文摘

Sand used for glass production was first hydrothermally treated in a sodium hydroxide solution followed by silica coating that created nanoporosity in the residual sand particles increasing the surface area by ca. 740 times when compared to parent sand particles. The hydrothermally treated sand was named as reconstructed sand (R-sand) and was further functionalized with 3-aminopropyltriethoxysilane (F-Sand) and both sands were later used as adsorbents to remove toxic chromium from aqueous solutions. The influence of pH, initial ion concentration, contact time, adsorption temperature, and dosage of adsorbent on the adsorption performance of both sands were investigated and compared. The kinetics of Cr⁶⁺ adsorption by both sands follows the pseudo-second-order kinetic model, while the adsorption of Cr⁶⁺ of R-sand and F-sand fits Langmuir and Freundlich models, respectively. The F-sand has shown improved adsorption performance and was used to adsorb chromium from electroplating wastewater. Since the hydrothermal treatment and the followed silica coating did not cause changes in the chemical properties of the sand as glass ingredient, the spent adsorbents containing homogeneously distributed chromium were successfully applied in preparing clear green glasses. The visible light spectra of the glasses prepared by the adsorbed chromium from either the aqueous solutions or the electroplating wastewater were compared with those by the chemical and commercial chromium colorants, confirming the feasibility using the adsorbed metal ions for glass colorization. Chromium from the electroplating wastewater was thus permanently immobilized and indefinitely recyclable in glasses. The present route can be extended to other heavy metal ion contaminants (such as Ni, Cu, Cd, Mn, Co, Zn, Pb, etc). In addition, the study also provides a method to treat used adsorbents, avoiding the generation of solid pollutants which greatly hinder the application of adsorption method in purifying metal ion-containing wastewater.