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CONTENTS
Volume 7, Number 5, September 2016
 

Abstract
To study the effect of titanium dioxide (TiO2) nanoparticles on membrane performance and structure and to explore possible improvement of using mixed solvents in the casting solution, composite polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc) and addition of TiO2 nanoparticles. Properties of the neat and composite membranes were characterized using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Atomic force microscopy (AFM) and contact angle and membrane porosity measurements. The neat and composite membranes were further investigated in terms of BSA rejection and flux decline in cross flow filtration experiments. Following hydrophilicity improvement of the PVDF membrane by addition of 0.25 wt.% TiO2, (from 70.53° to 60.5°) degree of flux decline due to irreversible fouling resistance of the composite membrane reduced significantly and the flux recovery ratio (FRR) of 96.85% was obtained. The results showed that using mixed solvents (DMAc/TEP) with lower content of TiO2 nanoparticles (0.25 wt.%) affected the sedimentation rate of nanoparticles and consequently the distribution of nanoparticles in the casting solution and membrane formation which influenced the properties of the ultimate composite membranes.

Key Words
polyvinylidene fluoride; mixed solvents; immersion precipitation; titanium dioxide; ultrafiltration membraneess

Address
(1) Maryam Tavakolmoghadam, Toraj Mohammadi:
Research and Technology Centre for Membrane Processes, Faculty of Chemical Engineering, Iran University of Science and Technology, Narmak, 16846, Tehran, Iran;
(2) Maryam Tavakolmoghadam, Mahmood Hemmati:
Research Institute of Petroleum Industry, Tehran, Iran.

Abstract
The possibility of using carica papaya leaf powder for removal of copper from wastewater as a low cost adsorbent was explored. Different parameters that affect the adsorption process like initial concentration of metal ion, time of contact, adsorbent quantity and pH were evaluated and the outcome of the study was tested using adsorption isotherm models. A maximum of 90%-94.1% copper removal was possible from wastewater having low concentration of the metal using papaya leaf powder under optimum conditions by conducting experimental studies. The biosorption of copper ion was influenced by pH and outcome of experimental results indicate the optimum pH as 7.0 for maximum copper removal. Copper distribution between the solid and liquid phases in batch studies was described by isotherms like Langmuir adsorption and Freundlich models. The adsorption process was better represented by the Freundlich isotherm model. The maximum adsorption capacity of copper was measured to be 24.51 mg/g through the Langmuir model. Pseudo-second order rate equation was better suited for the adsorption process. A dynamic mode study was also conducted to analyse the ability of papaya leaf powder to remove copper (II) ions from aqueous solution and the breakthrough curve was described by an S profile. Present study revealed that papaya leaf powder can be used for the removal of copper from the wastewater and low cost water treatment techniques can be developed using this adsorbent.

Key Words
adsorption; biosorption; carica papaya; freundlich isotherm; langmuir; pseudo-second order

Address
(1) Geetha Varma V.:
Department of Civil Engineering, New Horizon college of Engineering, Bangalore, India;
(2) Anil Kumar Misra:
Department of Civil and Environmental Engineering, The NorthCap University, Gurgaon, Haryana, India.

Abstract
Poly(vinylidene fluoride) (PVDF) powder was treated with aqueous sodium hydroxide to obtain partially defluorinated fluoropolymers with expected properties such as improving hydrophilicity and fouling resistance. Raman spectrum and FT-IR results confirmed the existence of conjugated carbon double bonds after alkaline treatment. As the concentration increased, the degree of defluorination increased. The morphology and structure of membranes were examined. The permeation performance was investigated. The results showed that membrane's hydrophilicity increased with increase of the percentage of alkaline treated PVDF powder. Moreover, in terms of the water contact angle, it decreased from 92° to a minimum of 68°; while water up take increased from 128 to 138%. Fluxof pure water and the cleaning efficiency increased with the increase of alkaline treated PVDF powder. The fouling potential also decreased with the increase of the percentage of alkaline treated PVDF powder. The reason that makes blending PVDF show different characteristics because of partial defluorination, which led the formation of conjugated C = C bonds and the inclusion of oxygen functionalities. The polyene structure followed by hydroxide attack to yield hydroxyl and carbonyl groups. Therefore, the hydrophilicity of blending membrane was improved. The SEM and porosity measurements showed that no obvious variations of the pore dimensions and structures for blend membranes were observed. Mechanical tests suggest that the high content of the alkaline treated PVDF result in membranes with less tolerance of tensile stress and higher brittleness. TGA results exhibited that the blend of alkaline treated PVDF did not change membrane thermal stability.

Key Words
PVDF; alkaline treatment; blend; hydrophilicity

Address
(1) Q.F. Liu, F.Z. Li, Y.Q. Guo, Y.L. Dong, J.Y. Liu, Z.M. Fu:
College of Environment and Resources, Inner Mongolia University, No. 235 West College Road, Hohhot, Inner Mongolia, Hohhot 010021, China;
(2) H.B. Shao:
Key Laboratory of Coastal Biology & Bioresources Utilization, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai 264003, China;
(3) H.B. Shao:
Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.

Abstract
The successful application of cleaning protocols is vital for optimized filtration processes. A series of experiments with an ultrafiltration ceramic tubular membrane were carried out for the foulants dextran and carboxymethyl cellulose. Firstly, the impact on fouling of concentration changes was investigated with the increase in resistance being used as the key parameter. In the second phase, removal of reversible fouling was also investigated by employing intermittent rinsing consisting of a cold water rinse followed by a hot one. A comparative analysis for both foulants is reported. Across a range of concentrations and for both foulants, the reduction in resistance due to rinsing was found to depend upon concentration (C); it changed as Cn where n was found to be 0.3. A plausible semi-theoretical explanation is given. Thirdly, for both foulants, the application of a combination of strong alkaline solutions with oxidizing agent (mainly sodium hypochlorite) followed by acid was found to be appropriate for cleaning of the ceramic membrane. The effect of increased temperature for cleaning agents followed by a warm water rinse contributed positively to the cleaning capability.

Key Words
membrane cleaning; reversible & irreversible fouling; dextran; carboxymethyl cellulose

Address
(1) Farrukh Arsalan Siddiqui, Robert W. Field:
University of Oxford, Department of Engineering Science, OX13PJ, United Kingdom;
(2) Farrukh Arsalan Siddiqui:
Bahauddin Zakariya University, Department of Mechanical Engineering, Multan 60800, Pakistan.

Abstract
The molecular weight of proteins and protein hydrolysis products (PHP) in the fractionated postproduction marinating brines left after herring marination process was determined by the HPLC. The proteins and PHP retention was evaluated in the three-stage purification process with the usage of polypropylene bag (25 μm) and ceramic membranes with the cut-off of 150 and 1 kDa. It was found that the process of marination contributes to high participation of compounds in the post-production marinating brines. Those are characterised by low molecular weight, formed as a result of protein hydrolysis. Each stage of the scavenging process was reducing the content of proteins and PHP. The lowest retention was observed in the stage at which a PP bag was used, while the highest in the UF process, with the usage of 150 kDa membrane. The total retention of proteins and PHP differed according to the type of post-production marinating brines and reached the level of 16-22%.

Key Words
herring (Clupea harengus); ceramic membrane; ultrafiltration

Address
Department of Aquatic Sozology, West Pomeranian University of Technology in Szczecin, Kazimierza Królewicza Street 4, 71-550 Szczecin, Poland.


Abstract
In this study, application of polypropylene hollow fiber membrane contactors for CO2 removal from water in liquid-liquid extraction (LLE) mode was simulated. For this purpose, a steady state 2D mathematical model was developed. In this model axial and radial diffusion was considered to CO2 permeation through the hollow fibers. CO2 laden water is fed at a constant flow rate into the lumen side, permeated through the pores of membrane and at the end of this process, CO2 solution in the lumen side was extracted by means of aqueous diethanolamine (DEA) and chemical reaction. The simulation results were validated with the experimental data and it was found a good agreement between them, which confirmed the reliability of the proposed model. Both simulation and experimental results confirmed the reduction in the percentage of CO2 removal by increment of feed flow rate.

Key Words
carbon dioxide; hollow fiber; DEA; diffusion; liquid-liquid extraction; simulation

Address
(1) Nahid Salimi, Sadegh Moradi:
Department of Chemical Engineering, Faculty of Engineering, Arak University, Arak, Iran;
(2) Afsaneh Fakhar, Seyed Mohammad Reza Razavi:
Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran, Iran.


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