Study On The Adsorption Of Heavy Metal Ion From Wastewater By Modified Bentonite

Bentonite is a kind of clay mineral that is abundant in our country. It has unique sandwich structure, which has the good exchangeability and the selectivity. Bentonite has lots of advantages in the treatment of wastewater, such as simple process, high efficiency and low cost. Modification of bentonite can improve its adsorption ability greatly and so makes it adsorb the contaminants such as heavy metal ions in wastewater more effectively.This experiment had firstly carried on the sodium to the raw bentonite, then made the organic modified bentonite in this foundation by using cationic-anionic surfactants as ion exchanger on the Na-bentonite. The main research content of the present paper is: Taking heavy metal ion Cu²⁺, Cd²⁺, Zn²⁺ as an example, has carried on the adsorption research about the Na-bentonite and the organic modified bentonite to the waste water in the heavy metal ion. The adsorption experimental study about organic modified bentonite to dual mix system. The experimental preliminary study about the organic modified bentonite desorption and regeneration. Organic modified bentonite to actual waste water processing research. The main findings are as follows:1.Through the uniform temperature adsorption experiment to Cu²⁺,Cd²⁺,Zn²⁺,it was found that the uniform temperature adsorption behaviors of the Na-bentonite to Cu²⁺,Cd²⁺,Zn²⁺ conform to Langmuir,Langmuir,Freundlich equation separately, that the uniform temperature adsorption behaviors of the organic modified bentonite to Cu²⁺,Cd²⁺,Zn²⁺ conform to Langmuir,Langmuir,Freundlich equation separately; The experiment data showed that the organic modified bentonite has the bigger adsorption capacity compared to the Na–bentonite. The paper has carried on the discussion about the adsorption mechanism of Cu²⁺,Cd²⁺,Zn²⁺ by organic modified bentonite.2.The experiment carried on systematically the study in the factor such as adsorption time, pH value, bentonite quantity, temperature, which had obtained the best adsorption condition of the Na-bentonite and the organic modified bentonite separately adsorbing Cu²⁺,Cd²⁺,Zn²⁺. Under this condition, the adsorption rate of Na - bentonite to Cu²⁺,Cd²⁺,Zn²⁺ respectively is 93.5%, 91.9%, 89.2%,But the organic modified bentonite respectively is 99.3%, 98.8%, 97.9%. 3. The experiment indicated that Cu²⁺ adsorbed by organic modified bentonite in dual mix system was much better than that by unitary system. But the removing rate of Cd²⁺,Zn²⁺ in organic modified bentonite in dual competition adsorption are much lower than that in unitary system。According to the test result, the paper has carried on the preliminary discussion about the competition adsorption mechanism from the bentonite internal structure, heavy metal ion radius and effective hydrated ion radius and so on.4. The experiment which was eluted by hydrochloric acid was indicated that the organic modified bentonite adsorbing the heavy metal ion was eluted easily,which reached 97.35%.Then the organic modified bentonite eluted was carried on the regeneration adsorption experiment,and it indicated the organic modified bentonite has the good reuse.5.The wastewater of the galvanization factory was treated by the organic modified bentonite,under the solid-fluid ratio of 5.0g/L,the main heavy metal ion Cu²⁺, Zn²⁺ was lower than that of the country discharge standard.According to all experiment dates and analysis of theory, the modified bentonites play a great role on the wastewater treatment and environment remediation. In a word, the modified bentonites have extensive prospect on the treatment of contaminate environment.