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M Kargar, F Khashei Varnamkhasti, A Lohrasebi
Multilayer graphene membranes could be considered as an efficient membrane in water desalination processes based on the reverse osmosis (RO) method. In this study, we designed multilayer graphene channels using the molecular dynamics (MD) simulation approach. The effects of different parameters, such as channel width and length, and the pressure on the operation of the designed channels were examined, in the absence and presence of electric fields with various amplitudes and directions. The results indicated that the ion separation and water flow through the channels were modified under the application of the electric fields...
August 18, 2018: Journal of Molecular Modeling
Mei Jiang, Kunfeng Ye, Jiajie Deng, Jiuyang Lin, Wenyuan Ye, Shuaifei Zhao, Bart Van der Bruggen
Use of tight ultrafiltration (UF) membranes has created a new pathway in fractionation of dye/salt mixtures from textile wastewater for sustainable resource recovery. Unexpectedly, a consistently high rejection for the dyes with smaller sizes related to the pore sizes of tight UF membranes is yielded. The potential mechanism involved in this puzzle remains unclear. In this study, seven tailored UF membranes with molecular weight cut-offs (MWCOs) from 6050 to 17530 Da were applied to separate dye/salt mixtures...
August 17, 2018: Environmental Science & Technology
Sayyed Jalil Mahdizadeh, Elaheh K Goharshadi, Golnoosh Akhlamadi
Herein, the applicability and efficiency of two types of pillared graphene nanostructures, namely, (6,6)@G and (7,7)@G, were investigated as membranes in reverse osmosis seawater desalination using extensive nonequilibrium molecular dynamics simulations. The water permeability for (6,6)@G and (7,7)@G membranes was estimated at 4.2 and 6.6 L h-1 cm-2 MPa-1, respectively. According to the results, a complete (100%) and pressure-independent salt rejection was estimated for both membranes. In addition, the mechanism of seawater desalination through the pillared graphene membranes was investigated via the density distribution profile of water molecules inside the pillar channels...
August 17, 2018: Physical Chemistry Chemical Physics: PCCP
Maqsud R Chowdhury, James Steffes, Bryan D Huey, Jeffrey R McCutcheon
Polyamide thickness and roughness have been identified as critical properties that affect thin-film composite membrane performance for reverse osmosis. Conventional formation methodologies lack the ability to control these properties independently with high resolution or precision. An additive approach is presented that uses electrospraying to deposit monomers directly onto a substrate, where they react to form polyamide. The small droplet size coupled with low monomer concentrations result in polyamide films that are smoother and thinner than conventional polyamides, while the additive nature of the approach allows for control of thickness and roughness...
August 17, 2018: Science
Dipak Aryal, Venkat Ganesan
The dynamics of ions and solvent molecules in polyelectrolyte desalination membranes is key to water purification technologies in which selective transport of the different components is desired. Recent experimental and our computational results have shown that nontrivial mechanisms underlie the transport properties of salt ions and water in charged polymer membranes. Explicitly, in polymer electrolytes, we found a reversal in the salt concentration dependence of the mobilities of Na+ , Cl- salt ions and water molecules when compared with aqueous solutions...
August 14, 2018: Journal of Physical Chemistry. B
Jay Ryan Werber, Cassandra J Porter, Menachem Elimelech
Reverse osmosis (RO) has become a premier technology for desalination and water purification. The need for increased selectivity has incentivized research into novel membranes, such as biomimetic membranes that incorporate the perfectly-selective biological water channel aquaporin or synthetic water channels like carbon nanotubes. In this study, we consider the performance of composite biomimetic membranes by projecting water permeability, salt rejection, and neutral-solute retention based on the permeabilities of the individual components, particularly the water channel, the amphiphilic bilayer matrix, and potential support layers that include polymeric RO, nanofiltration (NF), and porous ultrafiltration membranes...
August 14, 2018: Environmental Science & Technology
Tyler E Culp, Yue-Xiao Shen, Michael Geitner, Mou Paul, Abhishek Roy, Michael J Behr, Steve Rosenberg, Junsi Gu, Manish Kumar, Enrique D Gomez
As water availability becomes a growing challenge in various regions throughout the world, desalination and wastewater reclamation through technologies such as reverse osmosis (RO) are becoming more important. Nevertheless, many open questions remain regarding the internal structure of thin-film composite RO membranes. In this work, fully aromatic polyamide films that serve as the active layer of state-of-the-art water filtration membranes were investigated using high-angle annular dark-field scanning transmission electron microscopy tomography...
August 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Simone Perazzoli, Renan B Bastos, Fabrício B Santana, Hugo M Soares
Biological fuel cells, namely microbial desalination cells (MDCs) are a promising alternative to traditional desalination technologies, as microorganisms can convert the energy stored in wastewater directly into electricity and utilize it in situ to drive desalination, producing a high-quality reuse water. However, there are several challenges to be overcome in order to scale up from laboratory research. This study was conducted in order to better understand the performance of MDCs inoculated with marine sediments during the treatment of brackish water (5...
August 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Meng Jiang, Yun Qi, Huan Liu, Yinguang Chen
Nanomaterials and nanotechnologies (NNs) have been shaping the wastewater treatment process unprecedentedly. Bibliometric methods are regarded as an indispensable light to guide direction in scientific domain. The present study aims to investigate the role of NNs in wastewater treatment with bibliometric techniques based on SCI databases from 1997 to 2016. Results showed that China (962), USA (324) and Iran (140) are the most productive countries. Chinese Academy of Sciences (149), Tongji University (49), and Harbin Institute of Technology (40) from China are the most contributive institutions...
August 10, 2018: Nanoscale Research Letters
Qiyuan Li, Boyue Lian, Yuan Wang, Robert A Taylor, Michelle Dong, Tracey Lloyd, Xuefei Liu, Joel Tan, Md Mahfuz Ashraf, Divyang Waghela, Gregory Leslie
The consumption of saline groundwater has contributed to a growing incidence of renal diseases, particularly in coastal communities of India. Although reverse osmosis (RO) is routinely used to remove salt from groundwater, conventional RO systems (i.e. centralized systems using spiral wound RO elements) have limited utility in these communities due to high capital and maintenances costs, and lack of infrastructure to distribute the water. Consequently, there is a need to develop an appropriate solution for groundwater treatment based on small-scale, mobile and community-led systems...
August 2, 2018: Water Research
Jesús Morón-López, Lucía Nieto-Reyes, Jorge Senán-Salinas, Serena Molina, Rehab El-Shehawy
Increased harmful cyanobacterial blooms and drought are some negative impacts of global warming. To deal with cyanotoxin release during water treatment, and to manage the massive quantities of end-of-life membrane waste generated by desalination processes, we propose an innovative biological system developed from recycled reverse osmosis (RO) membranes to remove microcystins (MC). Our system, named the Recycled-Membrane Biofilm Reactor (R-MBfR), effectively removes microcystins, while reducing the pollution impact of RO membrane waste by prolonging their life span at the same time...
August 1, 2018: Science of the Total Environment
Taimoor Hussain, Yanbo Wang, Zhubiao Xiong, Jianmao Yang, ZhengZheng Xie, Jianyun Liu
Trace nickel oxide-embedded hierarchical porous carbon nanofibers (CNF-NiO) were fabricated by electrospinning polyacrylonitrile-Ni(NO3 )2 (PAN-Ni) followed by stabilization, carbonization and acid treatment. The resultant CNF-NiO was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, thermo gravimetric analysis and nitrogen adsorption-desorption isotherm. The NiO amount and porous structure can be tuned by varying the PAN/Ni ratio and acid treatment time...
July 30, 2018: Journal of Colloid and Interface Science
N S Muchate, N S Rajurkar, P Suprasanna, T D Nikam
In this study, adaptive features of Spinacia oleracea to different levels of salinity, its use in desalination and production of 20-Hydroxyecdysone were studied. Plants showed survival up to EC 12 dS/m with reduced growth as compared with control. Net photosynthesis rate, transpiration, stomatal conductance, and water use efficiency of salt treated plants declines with increasing salinity stress. Higher antioxidant enzyme activities and compatible solutes accumulation were observed in salt treated plants as function of osmotic adjustment...
August 24, 2018: International Journal of Phytoremediation
Ashwin Ramachandran, Steven A Hawks, Michael Stadermann, Juan G Santiago
Capacitive deionization (CDI) performance metrics can vary widely with operating methods. Conventional CDI operating methods such as constant current and constant voltage show advantages in either energy or salt removal performance, but not both. We here develop a theory around and experimentally demonstrate a new operation for CDI that uses sinusoidal forcing voltage (or sinusoidal current). We use a dynamic system modeling approach, and quantify the frequency response (amplitude and phase) of CDI effluent concentration...
July 27, 2018: Water Research
Yingchao Dong, Lining Ma, Chuyang Y Tang, Fenglin Yang, Xie Quan, David Jassby, Michael J Zaworotko, Michael Dominic Guiver
Membrane distillation (MD) is a promising process for the treatment of highly saline wastewaters. The central component of MD is a stable porous hydrophobic membrane with a large liquid-vapor interface for efficient water vapor transport. A key challenge for current polymeric or hydrophobically modified inorganic membranes is insufficient operating stability, resulting in some issues such as wetting, fouling, flux and rejection decline. This study presents an overall conceptual design and application strategy for a superhydrophobic ceramic‒based carbon nanotube (CNT) desalination membrane having specially designed membrane structures with unprecedented operating stability and MD performance...
August 7, 2018: Nano Letters
Jingshi Wang, Xiao Chen, Rackel Reis, Zhiqiang Chen, Nick Milne, Bjorn Winther-Jensen, Lingxue Kong, Ludovic F Dumée
Although commercial membranes are well established materials for water desalination and wastewater treatment, modification on commercial membranes is still necessary to deliver high-performance with enhanced flux and/or selectivity and fouling resistance. A modification method with plasma techniques has been extensively applied for high-performance membrane production. The paper presents a mechanistic review on the impact of plasma gas and polymerization, at either low pressure or atmospheric pressure on the material properties and performance of the modified membranes...
August 3, 2018: Membranes
Jun-Ho Song, Hye-Weon Yu, Moon-Ho Ham, In S Kim
Graphene oxide (GO) membranes with notable ionic sieving properties have attracted significant attention for many applications. However, the swelling and unstable nanostructure of GO laminates in water results in enlarged interlayer spacing and low permeation cut-off, limiting their applicability for water purification and desalination. Herein, we propose novel nitrogen-doped graphene (NG) membranes for use in tunable ion sieving that are made via facile fabrication by a time-dependent N-doping technique. Doping reaction time-associated variation in atomic content and bonding configurations strongly contributed to the nanostructure of NG laminates by yielding narrower interlayer spacing and a more polarized surface than GO...
August 6, 2018: Nano Letters
Muhammad Irfan Siyal, Jong-Oh Kim
Membranes with amphiphobic properties are crucial for desalination of concentrated saline water with organic foulant by membrane distillation. In this research, we coated Fluorographite (FGi) particles on polyvinylidene-fluoride (PVDF) flat sheet membranes with 0.8% v/v polydimethylsiloxane (PDMS) as binder by filtration coating method. We evaluated its amphiphobicity via contact angles which were observed by DI water, canola oil and organic solutions as mimicking for oleophobicity. Surface modifications by FGi particles on the surface of membranes was introduced with PDMS binder which brought bifunctionality of amphiphobicity to enhance hydrophobicity and oleophobicity...
July 20, 2018: Environmental Research
Longbin Qi, Yunxia Hu, Zhongyun Liu, Xiaochan An, Edo Bar-Zeev
Forward osmosis (FO) has gained increasing attention in desalination, wastewater treatment, and power generation. However, biofouling remains a major obstacle for the sustainable development of the FO process. Both passive and active strategies have been developed to mitigate membrane biofouling. A comprehensive understanding of different strategies and mechanisms has fundamental significance for the antifouling membrane development. In this study, thin-film composite (TFC) FO membranes were modified with polydopamine (PDA) coating as a passive antibacterial moiety and silver nanoparticles (Ag NPs) as an active antibacterial moiety...
August 17, 2018: Environmental Science & Technology
Juhan Lee, Pattarachai Srimuk, Sidonie Carpier, Jaehoon Choi, Rafael Linzmeyer Zornitta, Choonsoo Kim, Mesut Aslan, Volker Presser
Faradaic deionization is a promising new seawater desalination technology with low energy consumption. One drawback is the low water production rate due to the limited kinetics of ion intercalation or insertion processes. We introduce redox activities of iodide confined in carbon nanopores for electrochemical desalination. A fast desalination process was enabled by diffusion-less redox kinetics governed by thin-layer electrochemistry. A cell was designed with an activated carbon cloth electrode in NaI aqueous solution which was separated from the feedwater channel by a cation exchange membrane...
July 31, 2018: ChemSusChem
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