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CONTENTS
Volume 12, Number 3, May 2021
 


Abstract
Carrier mediated liquid membrane (LM) processes are unique in a way where proper selection of a carrier can achieve complete separation of the targeted species. This aspect is particularly important in multi-component systems. However, resistance to transport across the membrane phase and low concentration gradient across the LM-strip interphase restricts the overall transport performance. This article proposes an improvised method in a LM transport by integrating adsorption sweep. The investigated species was Lignosulfonate (LS) and the preferred adsorbent was MIL-101 (Cr) metal organic framework (MOF). Pure adsorption study showed high affinity of MIL-101 (Cr) for LS with ca. 94% removal from its model solution. Langmuir isotherm best fits the equilibrium data and pseudo second order model best explains the kinetics. Adsorption sweep experiments showed an overall improvement in extraction percentage of LS from 92% (regular bulk liquid membrane study) to ca. 97%. The recovery percentage of LS was decreased from ca. 75% (regular bulk liquid membrane study) to <10% because of adsorption of LS from bulk stripping medium, leading to an increase in concentration gradient across LM-strip interphase. Favorable chemistry of the stripping medium was found to be important for maintaining suitable pH conditions for the success of adsorption sweep process. During LS transport this aspect was clearly observed when the pH of the stripping medium got reduced, owing to the formation of H2SO4, the resulting adsorption sweep was more pronounced.

Key Words
lignosulfonate; MIL-101 (Cr); MOFs; adsorption; liquid membrane; adsorption sweep

Address
Vikas Kumar, Prince George, Raghubansh K. Singh and Pradip Chowdhury: Department of Chemical Engineering, National Institute of Technology Rourkela, Odisha, India

Abstract
The paper presents the multiscale calculation results for the multiscale flow in micro/nano porous filtration membranes where the adsorbed layer effect is involved, by considering the adsorbed layer-fluid interfacial slippage. The analysis consists of the molecular scale analysis for the adsorbed layer flow and the continuum analysis for the intermediate fluid flow. The calculation results are respectively compared with the classical flow theory calculations and those based on the solid layer assumption. The adsorbed layer flow rate is also compared with the flow rate of the intermediate continuum fluid. It is shown that for a strong fluid-pore wall interaction or for a large adsorbed layer-fluid interfacial slippage the adsorbed layer can be treated as a solid layer; otherwise it should be treated as a flowing layer. The large interfacial slippage results in the flow rate through the pore far greater than the classical Hagen-Poiseuille equation calculation; it largely propels the flow of the intermediate continuum fluid and makes the adsorbed layer flow negligible particularly for the medium and strong fluid-pore wall interactions. The increasing fluid-pore wall interaction strength significantly reduces the flow rate through the pore.

Key Words
adsorbed layer; flow; interfacial slippage; micro/nano pore; multiscale

Address
Jian Li: College of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu Province, China

Yongbin Zhang: Changzhou High Technology Research Key Laboratory of Mould Advanced Manufacturing, Changzhou, Jiangsu Province, China

Abstract
The microporous PTFE membrane was used for membrane distillation (MD) experiment and presented ultra-high efficiency of desalination. A hybrid desalination system combining membrane distillation and mechanical vapor compression (MD+MVR) had been developed on the basis of the MD experiment. The system featured that the latent heat and part of sensible heat of vapor from the MVR were recovered to heat the MD process, and the heating process occurred in the same module as the MD process. Models were built according to the energy and mass conservation for the system description. Based on the simulation and experimental data, when the system was assigned a treatment capacity 1000 kg h-1 for 1% saline water and with corresponding 875 kg h-1 fresh water production, it would be stuffed with 75.24 m2 of PTFE membrane and expense only 3.31 kW of electrical power, under 353 K of feed temperature in membrane module and 26 kPa of compressor suction pressure. The compressor power requirement would trade off the heat transfer area with variation of the heat transfer temperature difference. The higher the salinity concentration in the residual concentrate after distillation was, the higher the compressor power, membrane area and heat exchanger area would be.

Key Words
membrane distillation; bi-axial stretching PTFE membrane; desalination; mechanical vapor recompression; process thermodynamics

Address
Yinan Wang, Boya Qiu, Zeyi Xiao, Jingyun Liu and Senqing Fan: School of Chemical Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu, China

Xiaoyu Tang: Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Nan Road, Chengdu, China

Abstract
Household or office wastewater consists of two parts of faecal and non-faecal wastewater. Non-faecal section, which accounts for more than 60% of household wastewater, is known as grey water. Treating this part of sewage and using it in various areas can greatly reduce the consumption of potable water. In this research, three methods of advanced oxidation processes including Fenton, UV/H2O2, and UV/TiO2 were investigated for treatment of two grey water sourced from Shif Island and Persian Gulf University restaurant in Bushehr province of Iran. These grey waters were highly polluted with COD content of 600 mg/L and 1400 mg/L, respectively. The efficiency of each process was determined by measuring the COD removal rate. Results showed that at optimum reaction conditions, the COD removal efficiency of the UV/H2O2 process was the best, compared to the other two processes. The COD removal efficiency of UV/H2O2 process at pH = 3 and H2O2 = 1500 and 750 mg/L for grey water of the Shif Island and Persian Gulf University restaurant were 88% and 90%, respectively. Therefore, the treated gray waters can be reused economically.

Key Words
grey water; Fenton process; UV/H2O2 process; UV/TiO2 process

Address
Fariba Heydari, Shahriar Osfouri, Mohsen Abbasi and Mohammad Javad Dianat: Department of Chemical Engineering, Faculty of Petroleum, Gas and Petrochemical Engineering, Persian Gulf University, 75169, Bushehr, Iran

Javad Khodaveisi: Water and Wastewater Company of Bushehr Province, Bushehr, Iran

Abstract
A water-filtration membrane made of SiC possesses some excellent properties, but its application is limited by high fabrication cost. In this study, two sets of mullite bonded porous SiC ceramics membranes were prepared at reduced temperature by oxidation bonding method using different processing conditions. Dead-end filtration mode was utilized for the determination of permeability and their efficiency towards removal of turbidity. It was found that all the membranes prepared using different composition, pore formers (graphite, PVC and PMMA) and sintering temperature exhibited high turbidity removal efficiency (> 99%). This study provides an efficient method to prepare porous SiC ceramics with excellent permeability and turbidity removal efficiency, which will be helpful for the design of low cost SiC ceramic filters for water treatment.

Key Words
membrane; microfiltration; SiC ceramic; turbidity

Address
Dulal Das and Nijhuma Kayal: CSIR-Central Glass and Ceramic Research Institute, CSIR, Kolkata-700 032, West Bengal, India

Murilo D.M. Innocentini and Daniel G.P. Filho: Course of Chemical Engineering, University of RibeirãoPreto (UNAERP), 14096-900 RibeirãoPreto, SP, Brazil


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