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

On the Performance of Hybrid PV/Unitized Regenerative Fuel Cell System in the Tropics

Solar hydrogen system is a unique power system that can meet the power requirements for future energy demands. Such a system uses the hydrogen as the energy carrier, which produces energy through the electrolyzer with assistance of the power from the PV during the sunny hours, and then uses stored hydrogen to produce energy through the fuel cell after sunset or on cloudy days. The current study has used premanufactured unitized regenerative fuel cells in which the electrolyzer and the fuel cell function within one cell at different modes. The system components were modeled and the one-day real operational and simulated data has been presented and compared. The measured results showed the ability of the system to meet the proposed load, and the total efficiency was about 4.5%

Inexpensive current-voltage system with electronically-controlled resistance under xenon arc light for solar cell efficiency measurements

Crystalline silicon solar cell efficiency is required in order to accurately determine its performance and evaluate the fabrication process. Extensive automation has led to development of expensive instrumentation. In this study, simple, inexpensive method for measuring solar cell efficiency is reported. A controllable direct current (dc) illumination intensity method based on low power xenon arc lamps was designed and constructed. Low resistance electrical contacts were formed with conventional front surface probes and back surface Au-plated metal plate with vacuum attachment. In order to measure current-voltage (I-V) response, variable resistance approach was chosen. Commercially available, low cost electronic loads power supply is used to precisely vary resistance while measuring cell voltage and current. The resistance is controllably varied from a short circuit to an open circuit position on the I-V curve while measuring cell voltage and current. Plotting current as a function of voltage generates the characteristic solar cell I-V response. Solar cell efficiency measurements were recorded and plotted using LabVIEW program. The light intensity was varied by increasing number of high intensity discharge (HID) 50 W from 1 to four in order to vary respective illumination intensities from 330 to 1200 W/m2 range. The variation in light intensity was aimed at investigation of the electronic loads power supply at low and high currents. This I-V tester has been applied to different types of solar cell to validate its performance. Solar cells measured as part of this study included commercial silicon solar cell and laboratory solar cells with phosphorus oxytrichloride (POCl3) and phosphoric acid (H3PO4) emitter formation. This I-V measurement system for commercial cell exhibited an efficiency of 15.83% and efficiency of 16.2% and 13.3% for solar cells with POCl3 and H3PO emitters

Transition Metal Complexes of a-Naphthylamine Dithiocarbamate

a-Naphthylamine dithiocarbamate and its complexes with Co(II), Ni(U), Cu(II), Ru(III) , Rh(III), Pd(II), Pt(IV), Zn(II), Cd(II) and Hg(II) have been prepared and characterized by chemical analysis, IR - and reflectance spectral studies and magnetic susceptibili ty measurements. In all these complexes the dithiocarbamato moiety acts as a chelate. The Ni(II), Cu(II) and Pd(Il) complexes have been found to be square planar while those of Ru(III), Rh(III) and Pt(IV) were proposed to be octahedral in nature. The Co(II) ion seems to have a tetrahedral geometry, unlike the other known square planar dithiocarbamato complexes of Co(II). No definite structure, however, could be proposed for Zn(II), Cd(II) and Hg(II) on the basis of limited studies

Characterization of Air-Based Photovoltaic Thermal Panels with Bifacial Solar Cells

Photovoltaic (PV) panels account for a majority of the cost of photovoltaic thermal (PVT) panels. Bifacial silicon solar panels are attractive for PVT panels because of their potential to enhance electrical power generation from the same silicon wafer compared with conventional monofacial solar panels. This paper examines the performance of air-based bifacial PVT panels with regard to the first and second laws of thermodynamics. Four air-based bifacial PVT panels were designed. The maximum efficiencies of 45% to 63% were observed for the double-path-parallel bifacial PVT panel based on the first law of thermodynamics. Single-path bifacial PVT panel represents the highest exergy efficiency (10%). Double-path-parallel bifacial PVT panel is the second preferred design as it generates up to 20% additional total energy compared with the single-path panel. However, the daily average exergy efficiency of a double-path-parallel panel is 0.35% lower than that of a single-path panel

Analisis arus-voltan bagi pengubahsuaian proses fabrikasi sel suria silikon jenis-p ke atas wafer silikon jenis-n

Sel suria adalah peranti semikonduktor yang menukar tenaga matahari kepada tenaga elektrik. Sel suria generasi pertama terdiri dari sel suria silikon (Si). Pada masa ini, hampir 90% daripada pasaran pengeluaran fotovolta (PV) adalah berdasarkan wafer Si. Ini disebabkan oleh kecekapan dan ketahanan yang tinggi serta jangka hayat yang lama iaitu selama 30 tahun. Proses pemfabrikasian piawai bagi sel suria Si dimulakan dengan proses pencucian dan penteksturan wafer Si, difusi Fosforus untuk pembentukan pemancar, pembentukan elektrod atas dan bawah melalui proses cetakan skrin dan proses pembakaran yang melengkapkan fabrikasi sel suria. Dalam industri, proses piawai ini dilakukan pada wafer Si jenis-p. Wafer jenis-n pula mempunyai potensi yang tinggi untuk menghasilkan sel suria Si yang berkecekapan tinggi. Namun, proses untuk menghasilkan sel suria silikon atas Si wafer jenis-n melalui proses yang lebih rumit dan lama seperti dua peringkat proses difusi menjadikan wafer jenis-p digunakan secara meluas kerana dapat merendahkan kos pemfabrikasian. Dalam penyelidikan ini, analisis bagi arus-voltan bagi sel suria Si jenis-n yang difabrikasi menggunakan adaptasi proses fabrikasi piawai bagi wafer Si jenis-p akan dibincangkan. Daripada kajian simulasi menggunakan perisian PC1D, didapati bahawa kecekapan bagi sel suria jenis-p dan jenis-n yang difabrikasi dengan kaedah yang sama adalah 19.63% dan 20.16%. Manakala keputusan eksperimen menunjukkan kecekapan sebanyak 9.44% dan 5.51% bagi sel suria jenis-p dan jenis-n

Kebergantungan suhu dengan penggunaan tiub kuarza relau ke atas sel suria dwi-muka

Sel suria digunakan untuk menawan foton untuk menjana tenaga. Walau bagaimanapun, penambahbaikan sel diperlukan untuk meningkatkan jumlah penangkapan foton dan juga untuk meningkatkan kecekapan sel. Ini melibatkan keseluruhan proses pembuatan sel, dengan proses penyepuhlindapan adalah salah satu daripada langkah penting yang perlu dioptimumkan. Percetakan perlogaman menggunakan dwi pembakaran merupakan kaedah yang paling biasa digunakan dalam penghasilan sel suria kristal secara komersial. Aluminium (Al) digunakan pada bahagian belakang sel sebagai medan permukaan belakang dan penyambung belakang manakala perak (Ag) dicetak pada bahagian hadapan sebagai grid pemungut. Proses dwi pembakaran bagi komponen ini adalah penting dalam menentukan kecekapan sel. Oleh itu, dalam kajian ini, rawatan pembakaran telah dikaji dengan menggunakan relau tiub kuarza (QTF) dengan perubahan suhu pembakaran (700, 750, 800 and 850°C) sebagai satu percubaan untuk mendapatkan kecekapan yang tinggi serta meningkatkan kesan pemirauan persimpangan Ag. Apabila suhu meningkat, sifat elektrik sel suria dwi-muka juga turut meningkat. Kebergantungan suhu menunjukkan rintangan pirau yang tinggi disebabkan oleh proses penyejukan yang pantas selepas proses pembakaran dan seterusnya membawa kepada faktor isi dan kecekapan sel yang tinggi

Radiative and magnetohydrodynamics flow of third grade viscoelastic fluid past an isothermal inverted cone in the presence of heat generation/absorption

A mathematical analysis is presented to investigate the nonlinear, isothermal, steady-state, free convection boundary layer flow of an incompressible third grade viscoelastic fluid past an isothermal inverted cone in the presence of magnetohydrodynamic, thermal radiation and heat generation/absorption. The transformed conservation equations for linear momentum, heat and mass are solved numerically subject to the realistic boundary conditions using the second-order accurate implicit finite-difference Keller Box Method. The numerical code is validated with previous studies. Detailed interpretation of the computations is included. The present simulations are of interest in chemical engineering systems and solvent and low-density polymer materials processing

Burden of musculoskeletal disorders in the Eastern Mediterranean Region, 1990–2013: findings from the Global Burden of Disease Study 2013

Moradi-Lakeh M, Forouzanfar MH, Vollset SE, et al. Burden of musculoskeletal disorders in the Eastern Mediterranean Region, 1990–2013: findings from the Global Burden of Disease Study 2013. Annals of the Rheumatic Diseases. 2017;76(8):annrheumdis-2016-210146