Study Of Membranes To Purify Heavy Metals In Wasterwater

The heavy metals pollution is becoming a serious problem, poses a serious threat to theenvironment and human health. To effective treatment of heavy metal wastewater, avoid orreduce the emissions of heavy metals in the aquatic environment, people increasingly attachimportance to it. This paper studied using three kinds of chromium adsorption materialblending modified polyvinylidene fluoride (PVDF) membrane to preparation a kind ofmodified PVDF membrane for adsorption and purification of hexavalent chromium.This study selected the PVDFas membrane material,2-Aminobenzothiazole,2-Amino-4-thiazoleacetic acid and2-Mercaptobenzothiazole as chromium ion adsorptionmaterial, polyethylene glycol400as additive, Twain80as surfactant, N,N-dimethyl acetamideas organic solvent, with the phase conversion, blended modification to prepare the modifiedPVDF membrane for adsorption of hexavalent chromium. In the process of experiment,measured the pure water flux, bovine serum albumin filtrate rate and chromium ion adsorptioncapacity of membrane to research the influence of polymer content, reaction temperature,reaction time on membrane performance, and determined the best conditions of preparation.Through infrared spectroscopy to analysis the blend situation of membranes, scanning electronmicroscope to observe the morphology and structure of the membranes, optical contact Anglemeasuring device to measure the contact angle of membranes which revealed the hydrophilic ofthem.Determined by a series of experiments, the optimum conditions for preparation oftraditional PVDF membrane were: the content of PVDF was15wt%, the content of additivesPEG400was11wt%, coagulation bath temperature was40℃. Under these conditions, thepure water flux of membrane was291.82L/m2·h, the bovine serum albumin filtrate rate was76.96%and the contact Angle was79.3°.Determined by a series of experiments, the optimum conditions for preparation of2-Aminobenzothiazole modified PVDF membrane were: the content of PVDF was15wt%, thecontent of additives PEG400was11wt%, the content of Twain80was1wt%, the content of2-Aminobenzothiazole was0.6wt%, the reaction time was4h, the reaction temperature was75℃and the coagulation bath temperature was40℃. Under these conditions, the pure water flux of membrane was231.27L/m2·h, the bovine serum albumin filtrate rate was91.71%, thecontact Angle was76.1°and the adsorption capacity of chromium ion was157μg/cm2.Determined by a series of experiments, the optimum conditions for preparation of2-Amino-4-thiazoleacetic acid modified PVDF membrane were: the content of PVDF was15wt%, the content of additives PEG400was11wt%, the content of Twain80was1wt%, thecontent of2-Amino-4-thiazoleacetic acid was0.4wt%, the reaction temperature was80℃, thereaction time was8h and the coagulation bath temperature was40℃. Under these conditions,the pure water flux of membrane was318.11L/m2·h, the bovine serum albumin filtrate rate was81.02%, the contact Angle was81.2°and the adsorption capacity of chromium ion was241μg/cm2.Determined by a series of experiments, the optimum conditions for preparation of2-Mercaptobenzothiazole modified PVDF membrane were: the content of PVDF was15wt%,the content of additives PEG400was11wt%, the content of Twain80was1wt%, the contentof2-Mercaptobenzothiazole was0.2wt%, the reaction temperature was70℃, the reactiontime was6h and the coagulation bath temperature was40℃. Under these conditions, the purewater flux of membrane was255.57L/m2·h, the bovine serum albumin filtrate rate was87.85%,the contact Angle was80.1°and the adsorption capacity of chromium ion was241μg/cm2.The performance of these modified membranes was also not identical for the differentchromium adsorption materials. From the pure water flux,2-Amino-4-thiazoleacetic acidmodified of PVDF membrane> traditional PVDF membrane>2-Mercaptobenzothiazolemodified PVDF membrane>2-Aminobenzothiazole modified PVDF membrane. From thebovine serum albumin filtrate rate,2-Aminobenzothiazole modified PVDF membrane>2-Mercaptobenzothiazole modified PVDF membrane>2-Amino-4-thiazoleacetic acidmodified of PVDF membrane> traditional PVDF membrane. From the adsorption capacity ofchromium ion,2-Mercaptobenzothiazole modified PVDF membrane>2-Amino-4-thiazoleacetic acid modified of PVDF membrane>2-Aminobenzothiazolemodified PVDF membrane. From the hydrophilicity of membrane,2-Aminobenzothiazolemodified PVDF membrane> traditional PVDF membrane>2-Mercaptobenzothiazolemodified PVDF membrane>2-Amino-4-thiazoleacetic acid modified of PVDF membrane.