Chitosan as natural coagulant in hybrid coagulation-nanofiltration membrane process for water treatment

Water treatment industries are exploring the possibility to use environmental friendly chemicals and to discover the potential of advanced treatment technology in order to achieve sustainable development. Hybrid coagulation-membrane process has been introduced and proven to be a reliable water treatment process. In this study, the potential of chitosan as natural coagulant in hybrid coagulation-NF membrane process was studied. Three synthetic humic acid (HA) solutions with different ionic strength and composition will be used; without salt (Set 1), with NaCl only (Set 2), and with NaCl, CaCl2, and NaHCO3 (Set 3). Our findings indicated that gradual flux decline for Set 1 can be related to the continuous accumulation of neutral charged particles (pH 4.2) on the membrane surface. Formation of compact foulant layer due to further charge suppression of the foulants by dissolved ions (Set 2) resulted in severe membrane flux decline. When the pH of Set 1 and Set 2 supernatant solutions were increased to 7, fouling has been resolved due to the presence of strong electrostatic repulsion between the foulants and membrane. During the initial filtration process for Set 3, the flux has remained constant due to the strong repulsion between negatively charged foulants and membrane (pH 7). It was followed by severe flux decline which could be attributed to the effect of concentration polarization. Hence, this study highlighted that the impact of natural coagulant on the membrane process should be systematically studied in order to prevent unnecessary loss due to the incompatibility between both processes.This paper was made possible by NPRP grant #[5-1425-2-607] from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the author[s]. The authors also wish to acknowledge the Ministry of Education Malaysia for sponsoring W.L. Ang?s postgraduate study via MyBrain.Scopu

Metal-oxide nanotubes functional material tailored for membrane water/wastewater treatment

Titanium Dioxide Nano-Tubes (TNTs) synthesized by hydrothermal method were used to prepare new polysulfone thin film nanocomposite (TFN) membranes. The TFN membranes contained different TNTs proportions (0.1, 0.3 and 0.5 wt. %). A polyamide selective layer was formed on top of the TFN membrane surface using interfacial polymerization (IP). Nanofiltration experiments were performed using NaCl and MgSO4 salts solutions. The water flux was found to increase with increased TNT loading in the membrane due to high porosity of embedded nanoparticles and the formation of enlarged pores. The antifouling behaviour of the membrane was tested by bovine serum albumin (BSA) solution and found to improve with increased TNT content in the membrane. - 2019 IOP Publishing Ltd. All rights reserved.This paper was made possible by an NPRP10-0127-170270 and NPRP8-1115-2-473 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Corrosion Study of Carbon Steel in CO2 Loaded Amine-Amino Acid Solutions-Case of Mixtures of NMethyldiethanolamine and L-Arginine

© Published under licence by IOP Publishing Ltd. This research presents an electrochemical corrosion investigation to quantify the corrosiveness of carbon steel in blends of methyldiethanolamine (MDEA) and arginine (Arg) at two molar concentration and different solvent proportions. The selected temperatures range varied from 20 °C to 50 °C and the CO2 partial pressure was in the range of 49-100 kPa. The obtained data showed increased corrosion rate with increased CO2 partial pressure and increased the temperature of the solution. However, when added to MDEA, arginine was found to act as an inhibitor, the higher Arginine proportion in the mixture, the more inhibition effect was observed.This paper was made possible by an NPRP Grant # 7-1154-2-433 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors

Organically modified nanoclay filled thin-film nanocomposite membranes for reverse osmosis application

This study validates, for the first time, the effectiveness of two nanoclays, that is, cloisite (CS)-15A and montmorillonite (MNT) at the polyamide (PA) active layer in the reverse osmosis (RO) membrane. Cloisite-15A is natural montmorillonite modified with dimethyl dihydrogenated tallow quaternary ammonium salt. Thin-film composite (TFC) membranes were fabricated by the interfacial polymerization (IP) process between the trimesoylchloride (TMC)–n-hexane solution and m-phenylenediamine (MPD)–aqueous solution; the IP process took place on a polysulfone support sheet. The two types of nanoparticles were added in various weight ratios (0.005 wt.%–0.04 wt.%) in the n-hexane solution of TMC. Different characterizations like X-ray diffraction (XRD), contact angle, transmission electron microscopy (TEM), and membrane performance tests were performed to analyse the membrane properties. Both XRD and TEM studies proved that the two nanoclays are successfully anchored at the different sites of the PA layer. CS-15A could accelerate the water flux from 15 to 18.65 L/m2·h with NaCl rejection enhancement from 72% to 80%, relative to the control membrane. Conversely, MNT also enhanced the flux from 15 to 40 L/m2·h, but NaCl rejection reduced from 70% to 23%. The mechanism of water uptake in nanoclays was also discussed. The results pave the way for a complete future study, in which these phenomena should be studied in great detail.This research was funded by Qatar University, grant number IRCC-2019-004.The authors would like to acknowledge the support of Qatar University through project number IRCC-2019-004. Also, the authors acknowledge the assistance granted by KACST through the National Science, Technology, and Innovation Plan (NSTIP) unit of King Fahd University of Petroleum and Minerals (KFUPM) through NSTIP research grant number 08WAT-80-4. The assistance in membrane preparation by Matsuura group, Ottawa University, Canada and Rasel Das, Kyushu University Japan for discussion on the results are highly appreciated.Scopu

Effect of membrane performance including fouling on cost optimization in brackish water desalination process

Membrane selection is a crucial step that will affect the economic feasibility of the membrane water treatment process. A comprehensive evaluation consisting of Verberne Cost Model, assessment of membrane performance and fouling propensity, osmotic pressure differential (OPD) and specific energy consumption (SEC) was employed to determine the potential of nanofiltration (NF 270, NF 90 and TS 80) and low pressure reverse osmosis (XLE) membranes to be used in brackish water desalination process. The aim was to save costs by replacing the typical brackish water reverse osmosis (BW 30) membrane. Verberne Cost Model showed that higher flux NF membranes resulted in lower overall costs. However, after assessing the membrane performance, NF 270 and TS 80 were excluded due to their high fouling propensity and their failure to reduce total dissolved solids (TDS) in the solution. Instead, NF 90 membrane which produced water with acceptable TDS and has moderate permeability ended up to be more cost competitive compared to BW 30 membrane, with 17%-21% lower total costs and 13%-17% lower water costs. Apart from this, OPD and SEC were applied to justify the selection of optimal membrane recovery rate based on the water costs calculated. It was determined that the optimal recovery rate was 80% where the SEC and water costs were close to available water treatment plants. Overall, this study showed that the selection of membrane can be carried out by using Verberne Cost Model assisted by assessment of membrane performance and fouling propensity, OPD and SEC

Reaction kinetics of carbon dioxide in aqueous blends of N-methyldiethanolamine and L-arginine using the stopped-flow technique

Reduction of carbon dioxide emission from natural and industrial flue gases is paramount to help mitigate its effect on global warming. Efforts are continuously deployed worldwide to develop efficient technologies for CO 2 capture. The use of environment friendly amino acids as rate promoters in the present amine systems has attracted the attention of many researchers recently. In this work, the reaction kinetics of carbon dioxide with blends of N-methyldiethanolamine and L-Arginine was investigated using stopped flow technique. The experiments were performed over a temperature range of 293 to 313 K and solution concentration up to one molar of different amino acid/amine ratios. The overall reaction rate constant (k ov ) was found to increase with increasing temperature and amine concentration as well as with increased proportion of L-Arginine concentration in the mixture. The experimental data were fitted to the zwitterion and termolecular mechanisms using a nonlinear regression technique with an average absolute deviation (AAD) of 7.6% and 8.0%, respectively. A comparative study of the promoting effect of L-Arginine with that of the effect of Glycine and DEA in MDEA blends showed that MDEA-Arginine blend exhibits faster reaction rate with CO 2 with respect to MDEA-DEA blend, while the case was converse when compared to the MDEA-Glycine blend.The authors thank Ahmed Soliman and Dan Jerry Cortes for providing laboratory support This paper was made possible by an NPRP Grant # 7-1154-2-433 from the Qatar National Research Fund (a member of Qatar Foundation)

Development of novel thin film composite reverse osmosis membranes for desalination

Microporous Polyetherimide (PEI) membranes were prepared by wet phase inversion at different temperatures. The thin film composites (TFC) of polyamide on microporous PEI were prepared using meta-Phenylenediamine (MPD) and 1,3,5-Benzenetricarbonyl chloride (BTC). The ATR FTIR characterization showed the formation of polyamide (PA) on microporous PEI membrane, whereas scanning electron microscopy (SEM) revealed that a thin film of polyamide is formed on microporous PEI. The cross-sectional SEM of PEI prepared at 60 °C, showed finger like morphology and sparingly distributed balloon like morphology for PEI synthesized at 80 °C. The performance of PEI membranes and PA TFCs were ascertained by studying permeation of water and rejection of sodium chloride by reverse osmosis. The polyamide TFC with hydrophobic PEI support structures exhibited permeation of 28 to 50 lm-2h-1, with 98 – 95 % 2000 ppm NaCl rejection at 60 bar pressure

Carbon mineralization by reaction with steel-making waste: A review

Carbon capture and sequestration (CCS) is taking the lead as a means for mitigating climate change. It is considered a crucial bridging technology, enabling carbon dioxide (CO 2 ) emissions from fossil fuels to be reduced while the energy transition to renewable sources is taking place. CCS includes a portfolio of technologies that can possibly capture vast amounts of CO 2 per year. Mineral carbonation is evolving as a possible candidate to sequester CO2 from medium-sized emissions point sources. It is the only recognized form of permanent CO 2 storage with no concerns regarding CO 2 leakage. It is based on the principles of natural rock weathering, where the CO 2 dissolved in rainwater reacts with alkaline rocks to form carbonate minerals. The active alkaline elements (Ca/Mg) are the fundamental reactants for mineral carbonation reaction. Although the reaction is thermodynamically favored, it takes place over a large time scale. The challenge of mineral carbonation is to offset this limitation by accelerating the carbonation reaction with minimal energy and feedstock consumption. Calcium and magnesium silicates are generally selected for carbonation due to their abundance in nature. Industrial waste residues emerge as an alternative source of carbonation minerals that have higher reactivity than natural minerals; they are also inexpensive and readily available in proximity to CO 2 emitters. In addition, the environmental stability of the industrial waste is often enhanced as they undergo carbonation. Recently, direct mineral carbonation has been investigated significantly due to its applicability to CO 2 capture and storage. This review outlines the main research work carried out over the last few years on direct mineral carbonation process utilizing steel-making waste, with emphasis on recent research achievements and potentials for future research

Lymphomes malins non-hodgkiniens primitifs des amygdales palatines

Introduction: The most predominant localization for extranodal  non-hodgkinien lymphoma (NHL) in the head and neck region is the tonsil. The vast majority of NHL at this site is B-cell lymphomas.Materials and methods: The authors presented three cases of primary Non Hodgkin's Lymphoma of the tonsil, treated between 1995 and 2007Results: we report the cases of three men aged respectively 15, 42 and 72 years. They complained of a persistent odynophagia during three months ago. Clinical examination detected unilateral enlarged tonsil with ulcerated surface. All of them have bilateral tonsillectomy. The histopathologic examination concluded at a NHL with a B phenotype. The treatment consisted on chemotherapy for two patients and on radio and  chemotherapy for the third patient. We have noted one death for our three patients.Conclusion: Primary NHL of the tonsil is rare. An advanced diagnosis is often difficult. Both histopathologic identification of the tumor and evaluation of the patient are essentiel for the therapeutic decision. Prognostic depends on the stage of the lymphoma.Keywords: Non Hodgkin lymphoma, Oral cavity, Radiotherapy, Chemotherapy, antineoplastic agent, malignant hemopathy, Oral cavity disease