jmst
Abstract : Electrodialytic Removal of Cadmium from Brackish Water: Effects of Operating Parameters
|
|
Abstract: The continuous increase of environmental regulations make interesting to find effective and efficient methods for processing effluents containing metal ions. This research focuses on cadmium removal from brackish water by an electro-membrane process: The electrodialysis. Experiments were carried out on synthetic brackish water solutions and using a laboratory scale electrodialysis system. The influence of several parameters on process efficiency was investigated. The efficiency of this process was assessed by the determination of five parameters: The demineralization rate, the removal rate and the transport flux of cadmium, the current efficiency and the specific power consumption. The applied voltage, the feed flow rate, the pH and cadmium initial concentration of the feed solution have a significant effect on the process efficiency and mainly on the cadmium transfer from dilute to concentrate compartment. In contrast, feed ionic strength seems to affect only the SPC and not the R(Cd). Keywords: Electrodialysis, Synthetic brackish water, Demineralization rate, Cadmium removal, Process efficiency.Download Full Article |
Abstract : Preparation of PVDF UF Membranes under an External Electric Field with PVP as Additive
|
|
Abstract: In this study, PVDF UF membraneswere prepared with PVP as additive via a favorable method of applying high voltage external electric field (2kV) through the immersion precipitation phase inversion process. The influence of external electric field on the structure, surface functional groups, membrane potential, and surface hydrophilicity of the membranes were researched. In addition, anti-fouling property and separation performance of the membranes were also investigated. The results indicated that the protein adsorption amount on the electric treated membranes was distinctly reduced. Especially for the electric treated PVDF membrane with PVP K70 as additive, the value of water contact angle reached 75.4° and the protein adsorption amount decreased 76 %, reaching 20.39 µg·cm-2. The separation performance of the electric treated membrane was also superior to that of the un-treated membrane. All the experimental results indicatedthat this electric treated approach open a promising way for the modification of PVDF membrane because it combined membrane preparation and modification in only one physical step without additional chemical reagents. Keywords: Electric field, membrane potential, PVDF membrane, ultrafiltration, adsorption.Download Full Article |
Abstract : Maltodextrins Based Solid Membranes for the Enantioanalysis of L-Cysteine
|
|
Abstract: Three enantioselective membranes based on maltodextrins with different values of dextrose equivalent (DE) were proposed for the enantioanalysis of L-cysteine. The membranes were used for the design of potentiometric sensors. The slopes of the sensors were near-Nernstian (higher than 58.00mV/decade of concentration) with limits of detection of magnitude order of 10-11 and 10-12 mol/L. The surfaces of the membranes were stable for more than 6 months of continuous use. They can be renewed by polishing on alumina paper. Keywords: L-cysteine, solid enantioselective membrane, maltodextrin, enantioselective, potentiometric membrane electrode. |
Abstract : Preparation and Characterization of Superhydrophobic Modification of Polyvinylidene Fluoride Membrane by Dip-Coating
|
|
Abstract: The superhydrophobicity polyvinylidene fluoride (PVDF) membranes were modified via reducing surface energy by dip-coating perfluoroalkyl methacrylic copolymer (Zonyl 8740) onto the membranes prepared on mat glass. The chemical component of the unmodified and modified PVDF membranes surface was investigated by ATR-FTIR. Morphology and hydrophobicity of the unmodified and modified PVDF membranes were examined by scanning electronic microscopy and water contact angle, respectively. The effects of concentration of Zonyl 8740, coating time, conditions of heat treatment on hydrophobic capability of PVDF membranes were investigated. The results showed that the water contact angle increased from 141˚ to 151˚ by the dip-coating modification, therefore getting superhydrophobic PVDF membrane. Moreover, the porosity and the morphology of modified PVDF membrane were unchanged by the dip-coating modification. This results suggested that the hydrophobicty stability of the modified PVDF membrane was also good. Keywords: Polyvinylidene fluoride, Superhydrophobic, Coating modification, Perfluoroalkyl methacrylic copolymer, Membrane preparation. Download Full Article |
Abstract : Operating Conditions of Hollow Fiber Supported Liquid Membrane for Phenol Extraction from Coal Gasification Wastewater
|
|
Abstract: The extraction and recycling of phenol from high concentration coal gasification wastewater has been studied using polypropylene (PP) hollow fiber membrane and polyvinylidene fluoride (PVDF) hollow fiber membrane as liquid membrane support, the mixture of tributyl phosphate (TBP) and kerosene as liquid membrane phase, and sodium hydroxide as stripping agent in the process of extraction. The experiments investigated the effect of the operating conditions of the hollow fiber supported liquid membrane, such as aqueous phase temperature and the connection forms of membrane modules, on the extraction efficiency of phenol from high concentration coal gasification wastewater. The conclusions obtained from lab scale experiments provided guidance for scale-up experiments. So, in the scale-up experiments, three membrane modules connected in parallel, then three membrane modules connected in series were used to increase the treatment capacity and improve the treatment effect, under the operating conditions of wastewater temperature 20 ˚C, PH 7.5~8.1, flow rate 100 L/h and the concentration of stripping phase 0.1 mol/L, stripping phase flow rate 50 L/h, the extraction efficiency of the PP-TBP supported liquid membrane system was 87.02% and the phenol concentration of effluent was 218.14mg/L. And the phenol concentration of effluent met the requirements of further biodegradation treatment. Keywords: Coal gasification wastewater, Extraction efficiency, Hollow fiber membrane, Scale-up experiments. Download Full Article |