Studt On Lead-containing Wastewater Treatment With Gemini Micellar-enhanced Ultrafiltation

As we all known, lead is a heavy metal element with accumulation toxicity. it could enrich in the human body through diet. When taken at levels exceeding 5 mg/Kg,the lead will pose a threat to the health of people especially for our kidney, liver and reproductive system. What worse,it is even harmful to our body cell regeneration and brain function. Therefore, the treatment of lead waste water has significance for human beings as a whole. However, industrial sewage is the main sources of water pollution and the most effective way to control water pollution is to pretreat waste water containing lead until it reached the regulations and standards.Currently, there are a lot of lead waste water treatment methods, such as chemical precipitation, ion exchange adsorption, electrochemical method, etc. but they still has some shortcomings which greatly limit the application and promotion. such as: energy consumption, process complexity, harsh treatment conditions and so on.Nowadays, As a new method in environmental fields, the membrane filtration technology has own extensive attention,which shows great promise for heavy metal removal due to their high efficiency, easy operation and space saving. However, with the in-depth study, we have found this method always caused problem of secondary pollution because of the high surfactant concentration in the permeated solution and limited its development.In this paper, a new Gemini surfactant G-NMED is introduced to replace the traditional surfactant in MEUF process to remove lead in wastewater. Due to the special structure, G-NMED surfactants is easier to form micelles at low concentrations, which can reduce the amount of feeding surfactants to avoid the emergence of secondary water pollution situation. The main contents of this paper are as follow:(1)The anion Gemini surfactant was synthetized with some inexpensive materials. The characterization of IR, NMR, elemental analysis and thermogravimetry demonstrated that the synthetized compound was the target anion Gemini surfactant with high purity and stability.(2)The micelles characters of synthetized anion Gemini surfactant were studied. The critical micelle concentration(CMC) was 1.273×10-4 mol/L, which only is the 1% of SDS.The micelle of synthetized anion Gemini surfactant is most stabile when its concentration is 1 CMC.(3)The study of Gemini surfactant in micellar-enhanced ultrafiltration to deal with lead-containing wastewater(the"Micellar-Enhanced Ultrafiltration with Gemini surfactants will be abbreviated as GMEUF). The results exhibited that dosage of surfactant of GMEUF decreased 100 times than traditional MEUF; the retention rate of surfactant of GMEUF increased 2 times than traditional MEUF; the discharge of surfactant of GMEUF decreased 300 times than traditional MEUF. Finally, the process conditions were optimized. Under this optimized process conditions, the concentration of Pb2+ in permeate fluid is 0.1919 mg/L(0.5 mg/L for the standard of our contury);the concentration of surfactant in permeate fluid is 1.343×10-5 mol/L;the retention rate of Pb2+ is 98.08%;the retention rate of surfactant is 89.42%;the permeate flux is 55.67 L·m-2·h-1;the recovery ratio is 31.69%.At the same time,we found the membrane fouling model is intermediate pore blocking;Freundlich isotherm model has been found to provide the best correlation for surfactant adsorption.This thesis firstly used the GMEUF method to treat with the lead-containning wastewater.The problem of second pollution in MEUF was solved by GMEUF. The Gemini surfactant and the technology of GMEUF is this thesis not only can apply for the treatment of lead-containning weastwater, but also is suitable to the treatment of other metal-containning weastwater. Therefore,GMEUF method will reveal expansive prospect in the field of treatments of heavy metal-containing weastwater.