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CONTENTS
Volume 8, Number 3, May2017
 

Abstract
In this work, an attempt was made to compare the effects of UV irradiation on the intrinsic and separation properties of membranes made of two different polymeric materials, i.e., polyvinylidene fluoride (PVDF) and polyetherimide (PEI). The changes on membrane structural morphologies and chemical characteristics upon UV-A exposure (up to 60 h) were studied by FESEM and FTIR, respectively. It was found that cracks and fractures were detected on the PVDF-based membrane surface when the membrane was exposed directly to UV light for up to 60 h. Furthermore, the mechanical strength and thermal stability of irradiated PVDF-based membrane was reported to decrease with increasing UV exposure time. The PEI membrane surface meanwhile remained almost intact throughout the entire UV irradiation process. Filtration experiments showed that the permeate flux of UV-irradiated PVDF membrane was significantly increased from approximately 11 to 16 L/m2.h with increasing UV exposure time from zero to 60 h. Oil rejection meanwhile was decreased from 98 to 85%. For the PEI-based membrane, oil rejection of >97% was recorded and its overall structural integrity was marginally affected throughout the entire UV irradiation process. The findings of this work showed that the PEI-based membrane should be considered as the host for photocatalyts incorporation if the membrane was to be used for UV-assisted wastewater treatment process.

Key Words
ultrafiltration; polymer; UV irradiation; degradation; morphology

Address
C.S. Ong and B. Al-anzi : Department of Environment Technology and Management, College of Life Sciences, Kuwait University, Kuwait
W.J. Lau and A.F. Ismail : Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia,
81310 Skudai, Johor, Malaysia

Abstract
A novel thin-film nanocomposite (TFN) reverse osmosis (RO)/non-woven fabric (NWF) membrane was prepared by adding zinc oxide (ZnO) nanospheres (30+-10 nm) during the interfacial polymerization process of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on self-made polysulfone (PSF) membrane/polyester (PET) non-woven fabric support. The improved performance of TFN RO membrane was verified in terms of water contact angle (WCA), water flux, salt rejection, antifouling properties and chlorine resistance. The results showed that the WCA value of TFN RO surface had a continuous decrease with the increasing of ZnO content in MPD aqueous solution. The water flux of composite TFN RO membranes acquired a remarkable increase with a stable high solute rejection (94.5 %) in 1 g.L-1 NaCl aqueous solution under the optimized addition amount of ZnO (1 wt%). The continuous testing of membrane separation performance after the immersion in sodium hypochlorite solution indicated that the introduction of ZnO nanospheres also dramatically enhanced the antifouling properties and the chlorine resistance of composite RO membranes.

Key Words
nanocomposite membrane; reverse osmosis; hydrophilicity; antifouling properties; chlorine resistance

Address
Hongbin Li, Wenying Shi, Yuheng Su, Haixia Zhang and Xiaohong Qin : School of Textiles Engineering, Henan Engineering Laboratory of New Textiles Development,
Henan Institute of Engineering, Zhengzhou 450007, P.R. China
Hongxiang Hou : Xinxiang Xinli Purification Technology Co., Ltd., Xinxiang, 453000, P.R. China
Qiyun Du : State Key Laboratory of Hollow Fiber Membrane Materials and Processes, Tianjin Polytechnic University, Tianjin 300387, P.R. China
Xiaohong Qin : School of Textiles Science, Donghua University, Shanghai 201620, P.R. China

Abstract
The separation of nicotine and tobacco-specific N-nitrosamines is a tough problem in tobacco industry. In this study, separation of nicotine from 4-(methylnitrosamino) -1-(3-pyridyl)-1-butanone (NNK) mixtures was investigated using electrodialysis by taking the principle of the protonation status difference between these two components. The results indicated that the solution pH has a dominant impact on the separation process. In a pH range of 5-7, nicotine molecules are existed as mono- and di-protonated ions and can be separated from the uncharged NNK molecules. The acidic electrolyte is conducive to the separation process from the point of flux and energy consumption; while the alkaline electrolyte has negative impact on the separation process. A current density of 10 mA/cm2 is an appropriate value for the separation process. The lowest energy consumption of the separation process is 0.58 kWh/kg nicotine with the process cost to be estimated at only $0.208 /kg nicotine. Naturally, electrodialysis is a high-efficiency, cost-effective, and environmentally friendly process to separate and purify nicotine from tobacco juice.

Key Words
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK); nicotine; electrodialysis; ion exchange membranes

Address
Shaolin Ge, Chuanrun Li and Yaoming Wang : CAS Key Laboratory of Soft Matter Chemistry, Laboratory of Functional Membranes,
School of Chemistry and Materials Science, University of Science and Technology of China,
Hefei, Anhui 230026, P.R. China
Shaolin Ge and Zhao Zhang : China Tobacco Anhui Industrial Co., LTD, Hefei, Anhui, 230088, P.R. China
Chuanrun Li and Yaoming Wang, Wei Li : Hefei ChemJoy Polymer Materials, Co., LTD, Hefei, Anhui, 230601, P.R. China


Abstract
Adsorption is a widely used technique for the removal of dyes from wastewaters by variety of adsorbents. In this work, the main focus is on the potential assessment of anion exchange membrane for the removal of different dyes using batch system and investigation of experimental data by applying various kinetic and thermodynamic models. The removal of anionic dyes i.e., Eosin-B, Eriochrome Black-T and Congo Red by anion exchange membrane BII from aqueous solution was carried out and effect of various parameters such as contact time, membrane dosage, temperature and ionic strength on the percentage removal of anionic dyes was studied. The experimental data was assessed by kinetic models namely pseudo-first-order, pseudo-second-order, Elovich liquid film diffusion, Bangham and the modified Freundlich models equation have been used to analyze the experimental data. These results indicate that the adsorption of these anionic dyes on BII follows pseudo-second-order kinetics with maximum values of regression coefficient (0.992-0.998) for all the systems. The adsorption of dyes was more suitable to be controlled by a liquid film diffusion mechanism. The adsorptive removal of dye Eosin-B and Eriochrome Black-T were decreased with temperature and thermodynamic parameters such as free energy (del Go), enthalpy (del Ho) and entropy (del So) for adsorption of dyes on membrane BII were calculated at 298 K, 308 K and 318 K. The values of enthalpy and entropy were negative for EB and EBT representing that the adsorption of these dyes on BII is physiosorptive and exothermic in nature. Whereas the positive values of enthalpy and entropy for CR adsorption on BII, indicating that its adsorption is endothermic and spontaneous in nature. It is evident from this study that anion exchange membrane has shown good potential for the removal of dyes from aqueous solution and it can be used as adsorbent for dues removal on commercial levels.

Key Words
adsorption; anion exchange membrane; anionic dyes; Kinetics; thermodynamics

Address
Muhammad Ali Khan :Key Laboratory of Optoelectronic Materials chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of sciences, Fuzhou, Fujian 350002, P.R. China / University of Chinese Academy of Sciences, Beijing 100039, P.R. China
Muhammad Imran Khan : CAS Key Laboratory of Soft Matter Chemistry, Lab of Functional Membranes, School of Chemistry and Material Science, University of Science and Technology of China, Hefei, Anhui 230026, P.R China
Shagufta Zafar : Department of Chemistry, The Govt. Sadiq College Women University, Bahawalpur 63000, Pakistan

Abstract
This study was aimed at ultrafiltration (UF) as a pretreatment before reverse osmosis (RO) within the scheme of hybrid reverse osmosis-multistage flush (RO-MSF) desalination. Seawater at elevated temperature (after MSF heat-exchangers) was used as a feed in this process. The pretreatment system was represented as a set of functionally-linked technological segments such as: UF filtration, backwashing, chemical- enhanced backwashing, cleaning, waste disposal, etc. The process represents the sequences of operating cycles. The cycle, in turn, consists of the following unit operations: filtration, backwashing and chemical-enhanced backwashing (CEB). Quantitative assessment was based on the following indicators: normalized permeability, transmembrane pressure, specific energy and water consumption, specific waste generation. UF pre-treatment is accompanied by the following waste streams: W1=1.19x10 power of -2 m3 (disposed NaOCl with 0.0044% wt.)/m3(filtrate); W2=5.95x10 power of -3 m3 (disposed H2SO4 with 0.052% wt.)/m3 (filtrate); W3=7.26x10 power of -2 m3(disposed sea water)/m3(filtrate). Specific energy consumption is 1.11x10 power of -1 kWh/m3 (filtrate). The indicators evaluated over the cycles with conventional (non-chemical) backwashing were compared with the cycles accompanied by CEB. A positive impact of CEB on performance indicators was demonstrated namely: normalized UF resistance remains unchanged within the regime accompanied by CEB, whereas the lack of CEB results in 30% of its growth. Those quantitative indicators can be incorporated into the target function for solving different optimization problems. They can be used in the software for optimisation of operating regimes or in the synthesis of optimal flow- diagram. The cycle characteristics, process parameters and water quality data are attached.

Key Words
hybrid desalination; elevated temperature; UF pre-treatment; UF cycle; chemical-enhanced backwashing; performance indicators; waste intensity indicators

Address
Sergey Agashichev and Jayesh Kumar : NEWRC (ADWEA), PO Box 54111, Abu Dhabi, UAE

Abstract
An ultrasonic assisting vacuum membrane distillation (VMD) system was designed to promote the heat and mass transfer in membrane distillation (MD) process. Both the effects of operating conditions and ultrasonic parameters to permeation flux in this process were investigated; the heat and mass transfer mechanism was also being discussed in this paper. The results showed that the performance of VMD process was improved significantly by ultrasonic assisting. The permeation flux was boosted at a certain feed solution temperature, pressure at permeate side and feed solution velocity whether or not to PP and PTFE. The results also indicated that ultrasonic power and frequency also was the key factor affecting the mass and transfer efficiencies. The feed side transfer coefficient (Kf), corresponding to ultrasonic power (Kf=4.406−0.026xP+7.824x10-5xP2) and ultrasonic frequency (Kf=0.941+0.598xf−0.012xf2+6.283x10-5f3), was obtained and employed in the modeling of ultrasonic assisting VMD process. The modeling results showed that the calculated value of Kf aligned with experimental results well. Both variations of temperature polarization coefficient (TPC) and concentration polarization coefficient (CPC) were studied based on the obtained data. The results showed that both TPC and CPC were improved obviously by the ultrasonic parameters.

Key Words
vacuum membrane distillation; ultrasonic assisting; heat and mass transfer; permeation flux; transfer coefficient

Address
Hao Guo, Changsheng Peng,Hetao Yuan1 and Ke Yang : Key Laboratory of Marine Environment and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, P.R. China
Hao Guo : Beijing Institute of High-tech Environmental Science, Beijing 101111, P.R. China
Weifang Ma : College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, P.R. China


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