Study of Oil-bearing Wastewater Treatment by Chitosan-bentonite and PDMDAAC-bentonite

Oil-bearing wastewater pollution has noxious effects on human health and the ecological environment. Oil-bearing wastewater treatments are less efficient by traditional methods (flotation method, flocculation technology, electrochemistry method, membrane separation and biological method) which yield than 91% recovery. Therefore, it is urgent to develop a new kind of high efficiency and cheap adsorbent. Bentonite is an excellent adsorbent, but the effect to oil-bearing wastewater treatment could be improved significantly. The main purpose of this study is to prepare a high efficient modified bentonite for oil-bearing wastewater treatment. Chitosan and PDMDAAC as modifiers were used respectively to prepare a series of cationic polymer modified bentonite. The optimal conditions and properties for modified bentonite to adsorb oil in oil-bearing wastewater were investigated and compared. Experimental results show that removing rates were improved to 87.8% and 89.3% by using chitosan-bentonite and PDMDAAC-bentonite, respectively. The processing time is shorter than 15 min. Compared with the traditional method, the new method is less time-consuming and has a higher efficiency. With Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM), the results show that chitosan and PDMDAAC is coated as Na⁺-bentonite. Comparisons of adsorption performance show that PDMDAAC-bentonite is an improvement on chitosan-bentonite. PDMDAAC-bentonite has high efficiency, low cost and is easy to operate, and can be used in wastewater treatment extensively.