Study On Modification Of The Bentonite With Microwave Heating And Its Adsorption Properties

As an important physico-chemical wastewater treatment method, adsorption has already been used widely because it is simple and efficient, especially it is effective in treating wastewater containing low concentration pollutants. The key to use the adsorption in treating wastewater is to choose the suitable adsorbents. In recent years, the exploitation of the new, cheap and effective adsorption materials in treating wastewater to save the money has attracted the interest of many scholars in environmental engineering.To explore the bentonite of Ningming, Guangxi Zhuang Autonomous Region, and manufacture wastewater treatment adsobents of bentonite with high adsorption efficiency, we adopt three methods and get the products of the bentonite modified by purification and sodium, microwave activation and muffle oven. The modification products enhance the adsorption ability greatly. Microwave activation and its modification products are investigated intensively to treat the wastewater containing Cu2+ Cr3+ and anilineThrough the study, the following conclusions can be obtained.(1)Bentonite has great adsorption capacity in absorbing Cu2+ Cr3+,while weak in absorbing Cr6+ and aniline. All the three methods, activated by muffle oven, microwave and purification and sodium, can improve and enhance adsorption capacity of the bentonite, but microwave activation is the most prospective methods because it is simple, easy to handle, little time comsuption and energy comsuption, most important of all, its product has high adsorption capacity.(2)Temperature and activation time are the most important factors that influence the efficiency of the bentonite, which are not only heated by microwavebut by muffle oven. Under the conditions of the experiment, the optimum temperature is 4 min and 160C respectively.(3)Compared to the heating activation by muffle oven, microwave-heating activation was simpler and easier, and could greatly reduce heating time and energy consumption.(4)The factors that influence the adsorption of Cu2+ Cr3+ on bentonites include: dosage of bentonites, pH, initial continotration of the wastewater, adsorption time, etc. With the increment of the bentonite dosage, the removal of Cu2+ and Cr3+ are enhanced. The adsorption properties of the bentonite are greatly influenced by the pH. Under the acute acidic conditions, the removal efficiency of the Cu2+ and Cr3+ is lower by far than in the acute alkali conditions. At the same time, proper rotation time and rotation speed of the oscillator should be selected in obtaining optimum removal efficiency. The higher of the initial contiontration, the less of the removal of the Cu2+ and Cr3+ .(5)The mechanism of bentonite modification is ion exchange, inner-layers combination and surface combination. Its adsorption is related with the electronic property of the adsorbents; The adsorption of Cu2+ is fit with Freundlich equation; The adsorption of Cr3+ is fit with Langmuir equation...