The Development Of Organic Modified Bentonite Based On Treating Heavy Metalions In Smelting Wastewater

Each year wastewater with heavy metal ions are produced in large amounts in smelting industry of Xinjiang. Copper and nickel ions in smelting water are on the high side, far beyond the national sewage discharge standards. After years of scientific research, people discover that bentonites have beautiful physicochemical properties, which specific performances of properties are in:high ion exchange, high surface activity, strong water imbibition, big specific surface area, strong plasticity and bonding, etc. Based on these unique physical and chemical properties, bentonites have strong adsorption ability for environmental pollutants, and bentonites after adsorption are recycling and reusing, therefore, they have broad prospect for application in wastewater treatment.In this paper, with Layigelaike bentonite of Xinjiang as research object, there are some work have been carried on for mineralogical analysis and appraisal, high-speed centrifugation purification, chemical refining, organic intercalation, etc. Also, the testing and characterization including infrared spectra (FTIR), X-ray diffraction(XRD) and thermogravimetric-differential thermal (TG-DTA) have been finished, and the adsorption performance of bentonites for copper, nickel ions in smelting wastewater has been studied. Finally, the mechanism of bentonites adsorbing Cu2+and Ni2+has been explored in an elementary level.The results showed that:the Layigelaike bentonite is typical sodium base bentonite although its ore grade is low its physical and chemical performances are good, so it has great application potential; it’s montmorillonite content in bentonite is up to92.7%and97%after high speed centrifugation and chemical purification method; when the intercalating agent in the tendency between70-90mmol/100g soil, reaction temperature is60℃intercalating effect is better, and the quaternary ammonium salt exchange rate is more than90%at the moment. FTIR spectra shows that organic intercalation agents have entered the interlayer of bentonite. The displacement of XRD characteristic peak shows that the layer spacing of bentonite from1.23nm increases to3.84nm. By thermo weight loss to do a simple calculation shows that the ion exchange capacity between bentonite ores and1631is81.25mmol/100g soil, and ion exchange capacity is94.05mmol/100g soil for1831. Organic modified bentonite have increased greatly on the removal of Cu2+and Ni2+than a purified bentonite, and the removal rate can reach about78%, and organic composite bentonites have removal rate of Cu2+and Ni2+more than95%, and if appropriate adsorption conditions are controlled, after treatment by organic composite bentonites the content of Cu2+and Ni2+in smelting wastewater can reach national secondary sewage discharge standard. Finally, through two aspects of exploration and research for the mechanism of modified bentonite adsorbing Cu2+and Ni2+, we discover that the adsorption process of Cu2+and Ni2+for modified bentonite is a predominantly monolayer adsorption with multilayer adsorption process.