Removal of micropollutants and NOM in carbon nanotube-UF membrane system from seawater

2011 ◽  
Vol 63 (11) ◽  
pp. 2737-2744 ◽  
Author(s):  
Jiyong Heo ◽  
Lesley Joseph ◽  
Yeomin Yoon ◽  
Yong-Gyun Park ◽  
Namguk Her ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Membrane Fouling ◽  
Endocrine Disrupting Compounds ◽  
Membrane System ◽  
Good Alternative ◽  
Adsorption Mechanisms ◽  
Fouling Control ◽  
Membrane Flux ◽  
Seawater Reverse Osmosis ◽  
Walled Carbon Nanotubes

One of the main problems for seawater reverse osmosis desalination is membrane fouling associated with natural organic matter. Bisphenol-A (BPA) and 17α-ethinylestradiol (EE2) are well-known endocrine-disrupting compounds that have been detected in wastewater and seawater. In this study, the contribution of carbon nanotubes (CNTs, single-walled carbon nanotubes) to membrane fouling control and the potential adsorption mechanisms of BPA and EE2 were investigated using artificial seawater (ASW) in a bench scale ultrafiltration (UF) membrane coupled with CNTs. For high ionic strength ASW, UVA254 nm is a good alternative for highly aromatic dissolved organic carbon (DOC) determination, with a very strong linear relationship (R2 ≥ 0.99) with increasing DOC concentrations. Approximately 80% of DOC in ASW was rejected by the CNT-UF system where 31% of DOC was removed due to adsorption by CNTs. The presence of CNTs shows a 20% increase in membrane flux in ASW. A strong linear correlation between retention and adsorption of BPA and EE2 was obtained. The percentage of adsorption/retention of BPA and EE2 in UF-CNTs follows the order: 94.0/96.6 (DI + CNTs, EE2) > 86.2/90.0 (ASW + CNTs, EE2) > 73.6/78.9 (DI + CNTs, BPA) ≥ 74.1/77.3 (ASW + CNTs, BPA) > 29.8/29.8 (ASW, EE2) ≅ 27.3/27.3 (ASW, BPA) ≥ 25.3/25.3 (DI, EE2) ≅ 24.8/24.8 (DI, BPA). This indicates that retention by the UF-CNT system is mainly due to adsorption. Overall, EE2 adsorption was greater than BPA during the UF-CNT experiments, presumably due to the higher hydrophobicity of EE2 than BPA.

scholarly journals Effect of Pre-Oxidation on Coagulation/Ceramic Membrane Treatment of Yangtze River Water

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 369
Author(s):  
Shengji Xia ◽  
Xinran Zhang ◽  
Yuanchen Zhao ◽  
Fibor J. Tan ◽  
Pan Li ◽  
...  
Keyword(s):  
Water Treatment ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Membrane Separation ◽  
Membrane System ◽  
Coagulation System ◽  
Fouling Control ◽  
Filtration System ◽  
Membrane Treatment

The membrane separation process is being widely used in water treatment. It is very important to control membrane fouling in the process of water treatment. This study was conducted to evaluate the efficiency of a pre-oxidation-coagulation flat ceramic membrane filtration process using different oxidant types and dosages in water treatment and membrane fouling control. The results showed that under suitable concentration conditions, the effect on membrane fouling control of a NaClO pre-oxidation combined with a coagulation/ceramic membrane system was better than that of an O3 system. The oxidation process changed the structure of pollutants, reduced the pollution load and enhanced the coagulation process in a pre-oxidation-coagulation system as well. The influence of the oxidant on the filtration system was related to its oxidizability and other characteristics. NaClO and O3 performed more efficiently than KMnO4. NaClO was more conducive to the removal of DOC, and O3 was more conducive to the removal of UV254.

scholarly journals Alleviation of Ultrafiltration Membrane Fouling by ClO2 Pre-Oxidation: Fouling Mechanism and Interface Characteristics

Membranes ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 78
Author(s):  
Bin Liu ◽  
Meng Wang ◽  
Kaihan Yang ◽  
Guangchao Li ◽  
Zhou Shi
Keyword(s):  
Natural Water ◽  
Membrane Fouling ◽  
Interaction Force ◽  
Interfacial Free Energy ◽  
Fouling Control ◽  
Membrane Flux ◽  
Flux Decline ◽  
Interface Characteristics ◽  
Cake Layer ◽  
Free Energy Analysis

In order to alleviate membrane fouling and improve removal efficiency, a series of pretreatment technologies were applied to the ultrafiltration process. In this study, ClO2 was used as a pre-oxidation strategy for the ultrafiltration (UF) process. Humic acid (HA), sodium alginate (SA), and bovine serum albumin (BSA) were used as three typical organic model foulants, and the mixture of the three substances was used as a representation of simulated natural water. The dosages of ClO2 were 0.5, 1, 2, 4, and 8 mg/L, with 90 min pre-oxidation. The results showed that ClO2 pre-oxidation at low doses (1–2 mg/L) could alleviate the membrane flux decline caused by humus, polysaccharides, and simulated natural water, but had a limited alleviating effect on the irreversible resistance of the membrane. The interfacial free energy analysis showed that the interaction force between the membrane and the simulated natural water was also repulsive after the pre-oxidation, indicating that ClO2 pre-oxidation was an effective way to alleviate cake layer fouling by reducing the interaction between the foulant and the membrane. In addition, ClO2 oxidation activated the hidden functional groups in the raw water, resulting in an increase in the fluorescence value of humic analogs, but had a good removal effect on the fluorescence intensity of BSA. Furthermore, the membrane fouling fitting model showed that ClO2, at a low dose (1 mg/L), could change the mechanism of membrane fouling induced by simulated natural water from standard blocking and cake layer blocking to critical blocking. Overall, ClO2 pre-oxidation was an efficient pretreatment strategy for UF membrane fouling alleviation, especially for the fouling control of HA and SA at low dosages.

Preparation of single-walled carbon nanotubes/polyvinylchloride membrane and its antibacterial property

2012 ◽  
Vol 66 (11) ◽  
pp. 2275-2283 ◽  
Author(s):  
Fangbo Zhao ◽  
Feng Qiu ◽  
Xiaohui Zhang ◽  
Shuili Yu ◽  
Han-Shin Kim ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Antibacterial Property ◽  
Single Walled Carbon Nanotubes ◽  
Pvc Membrane ◽  
Bacterial Cells ◽  
Single Walled Carbon ◽  
Membrane Flux ◽  
Morphological Differences ◽  
And Control ◽  
Walled Carbon Nanotubes

Polyvinylchloride (PVC) ultrafiltration membranes were modified by blending with single-walled carbon nanotubes (SWCNTs) to improve the membranes’ antibacterial property. Both modified and control samples were characterized for pore structure, roughness, hydrophilicity, permeability and mechanical properties. The membranes’ antibacterial property was accessed with Escherichia coli as the model microbes by several methods. It was found that, after being blended with SWCNTs, the surface roughness of the modified membrane increased. Also, the surface hydrophilicity was improved. The membrane flux increased accordingly. But the membrane elongation decreased obviously with the SWCNTs addition. The modified membranes did not show the antibacterial property as expected in this research. There was no bacterial inhibition circle around the SWCNTs/PVC membrane coupons in the culture plates. There were no morphological differences of the cells on the control and the modified membranes. Hoechst 33342/propidium iodide stain test showed that there were more than 90% living bacterial cells which could grow on the SWCNTs/PVC membranes. This study suggests that the polymer wrapping may reduce the SWCNTs' antibacterial property greatly.

Adsorption of sulfamethazine by multi-walled carbon nanotubes: effects of aqueous solution chemistry

RSC Advances ◽  
2015 ◽  
Vol 5 (32) ◽  
pp. 25541-25549 ◽  
Author(s):  
Quanquan Yang ◽  
Guangcai Chen ◽  
Jianfeng Zhang ◽  
Helian Li
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Ionic Strength ◽  
Electrostatic Interactions ◽  
Solution Chemistry ◽  
Adsorption Mechanisms ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The adsorption of SMZ by MWCNTs was studied under varied pH, ionic strength, cations and anions in solution. The results indicated that hydrophobic and electrostatic interactions were the main adsorption mechanisms, and π–π interaction also played an important role.

DESCRIPTION OF CHEMICALLY AND THERMALLY TREATED MULTI-WALLED CARBON NANOTUBES USING SEQUENTIAL DECOMPOSITION OF ADSORPTION ISOTHERMS

2016 ◽  
Vol 23 (04) ◽  
pp. 1650025
Author(s):  
ALBERTO G. ALBESA ◽  
MATÍAS RAFTI ◽  
JOSÉ LUIS VICENTE
Keyword(s):  
Carbon Nanotubes ◽  
Arc Discharge ◽  
Temperature Treatment ◽  
Theoretical Description ◽  
Multistep Method ◽  
High Temperature Treatment ◽  
Acid Oxidation ◽  
Adsorption Mechanisms ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The effect of wet acid oxidation by means of sulfuric/nitric acid mixtures, and high-temperature treatment of commercial arc-discharge synthesized multi-walled carbon nanotubes (MWCNTs) was studied. In order to analyze the adsorption capacities of differently treated MWCNTs, we employed a multistep method that considers separately different pressure ranges (zones) on the experimentally obtained isotherms. The method is based on simple gas isotherm measurements (N2, CO2, CH4, etc.). Low pressure ranges can be described using Dubinin’s model, while high pressure regimes can be fitted using different models such as BET multilayer and Freundlich equations. This analysis allows to elucidate how different substrate treatments (chemical and thermal) can affect the adsorbate–adsorbent interactions; moreover, theoretical description of adsorbate–adsorbate interactions can be improved if a combination of adsorption mechanisms are used instead of a unique model. The results hereby presented also show that, while MWCNTs are a promising material for storage applications, gas separation applications should carefully consider the effect of wide nanotube size distribution present on samples after activation procedures.

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