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CONTENTS
Volume 12, Number 2, March 2021
 


Abstract
The natural weathered sand of basalt (WSB) has been used for the removal of cadmium from aqueous solution. The influence of various parameters i.e., contact time, pH, weathered sand of basalt dosage, particle size of the weathered sand of basalt, temperature and initial cadmium concentration were analyzed. Cadmium adsorption kinetics was well described by the pseudo second order model. Adsorption equilibrium for cadmium was properly well fitted to Langmuir isotherm model with maximum adsorption capacity 0.50 mg/g. Compared with the other experimental results using various kinds of adsorbents at a low concentration (1.0 mg/L or so) similar to that of this study, the cadmium removal efficiency using weathered sand of basalt was higher. It has been demonstrated that weathered sand of basalt has a available alternative adsorbent for cadmium when its initial concentration is low.

Key Words
adsorption isotherms; adsorption kinetics; cadmium; weathered sand of basalt

Address
Jae Hong Park, Jae Kwan Lee and Dong Seok Shin: National Institute of Environmental Research, 42 Hwankyungro, Seogu, Incheon Metropolitan City, 22689, South Korea

Abstract
The rejection of sodium chloride (NaCl) and calcium chloride (CaCl2) single salt solutions were carried out for commercial nanofiltration NFDK membrane. Results showed that the NFDK membrane had a negative surface charge and had a higher observed rejection of 93.65% for calcium (Ca2+) ion and 78.27% for sodium (Na+) ions. Prediction of rejection for aqueous solutions of both salts was made using Donnan Steric Pore Model based on Extended Nernst-Planck Equation in addition to concentration polarization film theory. A MATLAB program was developed to execute the model calculations. Absolute Average Relative Error (% AARE) was found below 5% for real rejection of the NFDK membrane. This research could be used successfully to assess the membrane characterization parameter using a proposed procedure which can reduce the number of experiments.

Key Words
donnan-steric partitioning model; flat sheet; nanofiltration; Nernst Planck equation; real rejection

Address
Danial Qadir and Hilmi Mukhtar: Department of Chemical Engineering, University Teknologi PETRONAS, Sri Iskandar, 32610, Perak, Malaysia

Rizwan Nasir: Department of Chemical Engineering, University of Jeddah, Asfan Road, 23890, Jeddah, Saudi Arabia

Fahim Uddin: Department of Chemical Engineering, NED University of Engineering and Technology, University Road, 75270, Karachi, Pakistan



Abstract
Sponge ball cleaning can generate an abrasion effect, which leads to an attractive increasing in both permeate flux and membrane rejection. The aim of this study was to investigate the influence of the daily sponge ball cleaning (SBC) on the performance of different UF cross-flow membrane modules integrated with a bioreactor. Two 1"-membrane modules and one 1/2"-membrane module were tested. The parameters measured and controlled are temperature, pH, viscosity, particle size, dissolved organic carbon (DOC), total suspended solids (TSS), and permeate flux. The permeate flux could be improved by 60%, for some modules, after 11 days of daily sponge ball cleaning at a transmembrane pressure of 350 kPa and a flow velocity of 4 m/s. Rejection values of all tested modules were improved by 10%. The highest permeate flux of 195 L/m2.h was achieved using a 1"-membrane module with the aid of its negatively charged membrane material and the daily sponge ball cleaning. In addition, the enhancement in the permeate flux caused by daily sponge ball cleaning improved the energy specific demand for all tested modules. The negatively charged membrane showed the lowest energy specific demand of 1.31 kWh/m3 in combination with the highest flux, which is a very competitive result.

Key Words
energy specific demand; flux; rejection; sponge ball cleaning; UF cross-flow membrane

Address
Mohammad Issa: Department of Wastewater Process Engineering, CUTEC Forschungszentrum, Technische Universität Clausthal,
Leibniz Str. 21+23, 38678 Clausthal-Zellerfeld, Germany

Sven-Uwe Geiben: Chair of Environmental Process Engineering, Department of Environmental Technology, Technische Universität Berlin, Secr. KF 2, Strabe des 17. Juni 135, 10623 Berlin, Germany

Alfons Vogelpohl: Technocon GmbH, Tannenhöhe 2, 38678 Clausthal-Zellerfeld, Germany

Abstract
This study aimed to prepare a W/O nonionic microemulsion system(MEs) consisting of OP-4[polyoxyethylene(4) nonylphenol], OP-7[polyoxyethylene(7) nonylphenol], 1-hexanol, D2EHPA, kerosene and HCl solution and applied to the extraction of La(III) from chloride aqueous solution within the polysulfone hollow fiber contactor (HFC),laboratory-scale experiments were carried out to investigate the recovery of La(III) using as-prepared microemulsion from the simulation wastewater containing La(III),Al(III) and Fe(III). The right weight ratio(Rs) of OP-4 to OP-7 was firstly confirmed through determination of the solubilization capacity of HCl solution(W0,HCl) in microemulsion, the effect of several factors such as the HCl concentration, temperature and effective extraction time on the extraction efficiency of La(III) was discussed. Results showed that the acceptable Rs was 4:6 to prepare the W/O MEs. The extraction yield of La(III) increased with the increasing of HCl concentration, temperature and effective extraction time and reaches to 97.3% while using five-stage modules. The recovery yield of La(III) from simulation La-bearing wastewater was 90.6%.

Key Words
microemulsion; preparation; lanthanum; extraction; wastewater; hollow fiber contactor

Address
Huilin Ou, Fuzhong Gong, Yanxia Tang and Liheng Liu: College of chemistry and Chemical Engineering, Guangxi University,100 Daxue load, Xixiangtang, District, Nanning 530004, P.R China

Yan Luo: 2Guangxi zhuang autonomous region center for analysis and test research, 32 Xinghu load, Qingxiu, District, Nanning 530022, P.R China

Abstract
In this study, defluoridation efficiency by aluminium sulphate (alum) and polyaluminium chloride (PACl) were compared for recommended Nalgonda dose (100%) and 80 % of this dose in both batch and continuous modes. The residual turbidity was found to be higher in case of alum as compared to PACl with 80 % dose representing lesser efficient settling of suspensions, which primarily comprise alumino-fluoro complexes that result in high residual aluminium in the treated water and this was confirmed by TEM and Zeta analysis. Moreover, the application of PACl also resulted in much lesser addition to the TDS and also required lesser lime for pH compensation due to its lower acidity. Hence this reduced dose was recommended for defluoridation. It was also observed that in case of alum, residual aluminium in treated water was 0.88 mg/L (100% dose) & 0.72 mg/L (80% dose) and in case of PACl, it was 0.52 mg/L(100% dose) & 0.41 mg/L(80% dose). After subsequent microfiltration, residual aluminium was 0.28 & 0.21 mg/L for 100 % & 80 % dose respectively and in case of alum and in case of PACl, it was 0.16 & 0.11 for 100% & 80 % dose respectively, which conform to the Al standards(<0.2 mg/L).

Key Words
alum; polyaluminium chloride; defluoridation; microfiltration

Address
Swati Dubey: Department of Chemical Engg. Banasthali Vidyapith Rajasthan-304022, India

Madhu Agarwal: Department of Chemical Engg., Malaviya National Institute of Technology, Jaipur, 302017, Rajasthan, India

A. B. Gupta: Department of Civil Engg. Malaviya National Institute of Technology, Jaipur, 302017, Rajasthan, India


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