200 research outputs found
Engineering A Fertilizing Draw Solution For Irrigation Using Forward Osmosis / Reverse Osmosis Hybrid System
No full textLarge volumes of fresh water are consumed in the human’s daily activities,
producing large volumes of highly contaminated wastewater which exhibits a major
environmental problem. Wastewater is treated using multiple technologies to produce
Treated sewage effluent (TSE) which is considered to be less contaminated but
unusable by human daily activities.
This work investigates the application of a hybrid system that combines forward
osmosis (FO) and reverse osmosis (RO) processes for the supply of a fertilizing solution
that could be used directly for irrigation purposes. In the forward osmosis process,
treated sewage effluent (TSE) is used as the feed solution and two different types of
draw solutions were investigated namely, 0.5M NaCl solution and 0.5M NaCl and
0.01M diammonium phosphate ((NH4)2HPO4) solution. The impact of the feed
solution and the draw solution flowrates and the membrane orientation on the
membrane flux were investigated in the forward osmosis process. In the reverse
osmosis process, seawater RO membrane (SW30HR) and brackish water RO
membrane (BW30LE) were tested for the regeneration of the draw solution. In the
forward osmosis process, it was found that the highest membrane flux was 13.2 LMH
achieved at a flow rate of 2 LPM for the feed solution and the draw solution and when the 0.5M NaCl and 0.01M diammonium phosphate solution was used as the draw
solution in the FO mode membrane orientation. The FO process had high rejection rates
for total phosphorus and ammonium which were 99% and 97%, respectively. Reverse
osmosis achieved 99% total salts rejection rate using the seawater RO membrane. The
final product water had high quality in terms of total dissolved solids and nutrients
concentration. The final product meets the irrigation water quality
Fabrication of Fouling Resistant Ti3C2Tx(MXene) Cellulose Acetate Nanocomposite Membrane for Forward Osmosis Application
No full textForward Osmosis (FO) is one of the promising technologies that can be used to combat growing water scarcity. However, FO membrane fouling hinders the widespread application of this technology by significantly reducing the water flux and membrane lifecycle. Although forward osmosis has shown lower membrane fouling when compared to other membrane technologies, forward osmosis membrane resistance to fouling must still be improved. In this study, Ti3C2Tx (MXene) was used to improve the fouling resistance of FO flat-thin film membranes. The mixed-matrix Ti3C2Tx (MXene)/ cellulose acetate (CA) membranes with different (wt%) loading of MXene were fabricated by covalent crosslinking followed by phase inversion method. The fabricated membranes were characterized by X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), contact angle measurement and scanning electron microscopy (SEM). The performance of the fabricated FO membranes was evaluated utilizing seawater as draw solution (DS) and two feed solutions (FS) namely; distilled water (DI) and treated sewage effluent (TSE). The water flux, reverse solute flux and the rejection of dissolved solids were evaluated in the FO process. It was observed that the cross-linked cellulose acetate membrane with 8 wt% MXene (CCAM-8%) showed higher resistance to fouling when compared with commercial thin-filmcomposite (TFC) FO membrane, the water flux of CCAM-8% decreased by only 10.7% using TSE as FS compared to DI, where the water flux of the TFC commercial membrane decreased by 32.2% when using TSE as FS compared to DI
HARVESTING OF CHLORELLA SP. MICROALGAE BY DIELECTROPHORETIC FORCE USING TITANIUM DIOXIDE (TiO2) INSULATED ELECTRODES
No full textThe harvesting of microalgae using conventional technologies suffers from biomass contamination, high energy consumption and long processing time. In this study, titanium dioxide (TiO2) insulated stainless steel electrodes were used for the harvesting of Chlorella sp. microalgae by dielectrophoretic force. The new electrode configuration is expected to achieve high harvesting efficiency with zero contamination for the harvested biomass. The effect of various experimental parameters on the harvesting efficiency were evaluated using a bench scale setup. This includes settling time, applied voltage, interelectrode distance, application of pulsed electric field, and applied current frequency. The maximum harvesting efficiency of 76.6% was obtained at 4 mm interelectrode distance, 200 V applied voltage, 250 kHz frequency, and application of pulsed electric field for 30 minutes. Under these conditions, the energy consumption was 7.76 kWh/kg. The most significant impact of using the new electrode configuration is achieving high harvesting efficiency with no contamination for the biomass
Utilizing Steel Slag in the Removal of Suspended Solids from Dewatered Construction Water: A Mechanistic Study
No full textConstruction dewatering is an operation used to remove shallow groundwater infiltrated into a construction site; this technique is used in most of the construction projects. After collecting the water from the construction site, the water is either discharged to the sea, injected in deep groundwater aquifers, or treated and reused in some other applications. In this study, treatment of dewatered construction water by waste steel slag was performed. The impact of the mass of steel slag, the contact time, steel slag particle size and pH were studied on the quality of dewatered construction water. It was found that the maximum removal percentage of suspended solids was 97%, which occurred when 5 grams of steel slag were in contact with the dewatered construction water. The uptake amount (q) was 63.12 mg of suspended solid per gram of steel slag. It was observed that equilibrium was achieved after a contact time of about 40 minutes. The impact of steel slag particle size was studied, where two different sizes of steel slag particles were considered namely, 425 and 75 nm. An uptake value (q) of 72.24 mg/g and 64.36 mg/g were obtained for steel slag particle size 425 nm and 75 nm, respectively. The impact of pH was studied, where it was found that at pH value of 12, the removal percentage of suspended solids was higher than pH of 2, where the uptake amount of suspended solids was 80 mg/g. In addition, the performance of steel slag was compared to a commercial chemical coagulant, where steel slag had a higher uptake amount of 72.24 mg/g compared to 60.62 mg/g for the commercial coagulant
Dibenzyl ferrocene-1,1′-dicarboxylate
No full textIn the title compound, [Fe(C13H11O2)2], there are markedly different orientations of the two phenylmethoxycarbonyl substituents [O—C—C—C torsion angles = 84.5 (3) and 139.6 (2)°]. These orientations are mediated by a number of intermolecular C—H...O interactions, which result in a one-dimensional hydrogen-bonded network of molecules
Induction of preferential helical screw senses in optically inactive polysilanes via chiral solvation
No full textCommunication: Two optically active solvents were synthesised, (S)-(-)-2-methyl-1-propoxybutane and (S)-(-)-(2-methylbutoxymethyl)benzene. The main chain conformations of poly(methylphenylsilane) and poly(hexylmethylsilane) in these solvents were investigated using optical UV-visible and circular dichroism spectroscopy. It was observed that dissolving these inherently achiral polysilanes in optically active solvent induces the polymer chains to adopt preferred helical screw senses. This is the first example of induction of optical activity in conjugated polymers through chiral solvation
Predicting the performance of multi-media filters using artificial neural networks
No full textThe impact of flow rate and turbidity on the performance of multi-media filtration has been studied using an artificial neural network (ANN) based model. The ANN model was developed and tested based on experimental data collected from a pilot scale multi-media filter system. Several ANN models were tested, and the best results with the lowest errors were achieved with two hidden layers and five neurons per layer. To examine the significance and efficiency of the developed ANN model it was compared with a linear regression model. The R2 values for the actual versus predicted results were 0.9736 and 0.9617 for the ANN model and the linear regression model, respectively. The ANN model showed an R-squared value increase of 1.22% when compared to the linear regression model. In addition, the ANN model gave a significant reduction of 91.5% and 97.9% in the mean absolute error and the root mean square error, respectively when compared to the linear regression model. The proposed model has proven to give plausible results to model complex relationships that can be used in real life water treatment plants.This publication was made possible by UREP award [UREP 15 - 047 - 2 - 015] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu
Modeling and Sensitivity Analysis of the Forward Osmosis Process to Predict Membrane Flux Using a Novel Combination of Neural Network and Response Surface Methodology Techniques
No full textThe forward osmosis (FO) process is an emerging technology that has been considered as an alternative to desalination due to its low energy consumption and less severe reversible fouling. Artificial neural networks (ANNs) and response surface methodology (RSM) have become popular for the modeling and optimization of membrane processes. RSM requires the data on a specific experimental design whereas ANN does not. In this work, a combined ANN-RSM approach is presented to predict and optimize the membrane flux for the FO process. The ANN model, developed based on an experimental study, is used to predict the membrane flux for the experimental design in order to create the RSM model for optimization. A Box–Behnken design (BBD) is used to develop a response surface design where the ANN model evaluates the responses. The input variables were osmotic pressure difference, feed solution (FS) velocity, draw solution (DS) velocity, FS temperature, and DS temperature. The R2 obtained for the developed ANN and RSM model are 0.98036 and 0.9408, respectively. The weights of the ANN model and the response surface plots were used to optimize and study the influence of the operating conditions on the membrane flux
Novel azo disperse dyes derived from aminothiophenes: Synthesis and UV-visible studies.
No full textA number of red to violet thienyl-2-azo and thienyl-5-azo disperse dyes were prepared using Gewald's methodology. Structural characterization of these novel dyes was carried out using IR, NMR and mass spectroscopy. UV–visible studies of these azo dyes in a number of polar solvents showed a considerable difference in the λmax. The introduction of various substituents to these azo dyes as well as the polarity of solvents resulted in absorption in the visible region ranging from 461 to 555 nm
Intrathecal Drug Delivery Systems Survey: Trends in Utilization in Pain Practice [Corrigendum]
No full textAbd-Sayed A, Fiala K, Weisbein J, et al. J Pain Res. 2022;15:1305–1314.
The authors have advised there is an error in the author list on page 1305. The author name “Alaa Abd-Sayed” should read “Alaa Abd-Elsayed”.
The authors apologize for this error
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