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In this research, silver/graphene oxide (Ag/GO) nanohybrid was first synthesized and used in production of polysulfone (PSF) ultrafiltration (UF) membranes via phase inversion method for concentrating phycocyanin (PC) and treating methylene blue (MB) dye effluent. Designing the experiment (DOE) using Box-Behnken method by Design Expert software helped to calculate the optimal values of the variables under study. The studied variables included PSF polymer concentration, polyvinyl pyrrolidone (PVP) pore-former concentration and Ag/GO nanohybrid content, which were investigated for their effects on pure water flux (PWF) and MB pigment rejection. According to the results of the DOE, the membrane containing 19.485 wt% PSF, 0.043 wt% PVP and 0.987 wt% Ag/GO was selected as the optimal membrane. Due to the high price of PC as drug, and the importance of removing MB pigment from the effluent of dyeing and textile industries, the membranes were first optimized with MB pigment and then the optimal membrane was used for concentrating PC. The results showed that PWF reaches from 40.05 L.m − 2 .h − 1 (LMH) for the neat membrane to 156.73 LMH for the optimized membrane, which shows about 4 times improvement. Compared to the neat membrane, flux recovery ratio (FRR) of the optimized membrane increased by about 20% and its total fouling (R t ) decreased by about 10%. Also, the results showed that the optimized membrane can remove 81.6% of MB, as well as to reject 93.8% of PC.

High nitrate concentrations in water present serious risks to human health. This study evaluates two removal strategies: layered double hydroxide (LDH) nanoparticles (NPs) and LDH-incorporated thin‐film composite nanofiltration (TFC-NF) membranes to reduce nitrate concentration. First, Mg–Al, Ni–Fe, and Mn-impregnated Zn–Al LDH NPs were co-precipitated, characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscopy (FESEM), and zeta potential measurement, and tested in batch adsorption experiments (20 mg/L nitrate solution, 1 g/L adsorbent dosage). Among the LDH NPs tested, Ni–Fe LDH demonstrated the highest nitrate rejection, achieving 13–14% at this concentration, with no significant change with further calcination. Next, the TFC-NF membranes were fabricated by embedding LDH NPs into the support layer; one variant received additional layer-by-layer (LBL) surface modification. The membranes were also characterized using FESEM and then evaluated using a 50 mg/L nitrate solution at 6 bar pressure and 25 °C. The TFC-NF membrane containing 0.25 wt% Mn-impregnated Zn–Al LDH achieved nitrate rejection of 43% with pure water flux (PWF) of 4.5 L/m 2 h bar −1 . Under the same conditions, the LBL-TFC NF membrane showed lower nitrate rejection of 17% but higher PWF of 7.7 L/m 2 h bar −1 .

Phenolic wastewater was treated using anaerobic submerged membrane bioreactor (ASMBR). Effect of different solids retention times on MBR performance was studied. Various ratios of carbon to nitrogen were used in the synthetic wastewaters. During the operation, phenol concentration of feed was changed from 100 to 1000 mg L−1. Phenol concentration was increased stepwise over the first 30 days and kept constant at 1000 mg L−1, thereafter. For the first 100 days, a chemical oxygen demand (COD) to N ratio of 100:5.0 was used and this resulted in phenol and COD removal more than 99 and 95%, respectively. However, the ammonium removal decreased from 95 to 40% by increasing the phenol concentration of feed, from 100 to 1000 mg L−1. For the last 25 days, a COD to N ratio of 100:2.1 was used due to the ammonium accumulation in the ASMBR. This led to the complete ammonium removal and no ammonium was detected in the ASMBR permeate. These results suggest that in the ASMBR at high phenol loading of 1000 mg L−1, COD to N ratio of the phenolic wastewater must be 100:2.1 for ammonium removal, while at low phenol loading, COD to N ratio of 100:5.0 can be used.

Polyacrylonitrile (PAN) adsorptive membrane incorporated with nanosize-goethite (α-FeO(OH)) hydrous metal oxide particles (GNPs), prepared with optimal flux and Cu(II) removal in the previous study, was used to evaluate the process parameter on the Cu(II) removal. Box-Behnken Design (BBD) based on the Response Surface Methodology (RSM) was employed to evaluate the impact of Cu(II) feed solution characteristics such as pH, initial concentration of metal ion, and transmembrane pressure (TMP) on copper removal efficiency. The outcomes indicated that the RSM optimization technique could be utilized as an applicable method to find the optimum condition for the maximum Cu(II) removal with slight variance compared with the experimentally measured data. The effect of each process parameter and the coupling effect of parameters on the Cu(II) removal was assessed. Finally, the optimum condition of pH, Cu(II) concentration, and transmembrane pressure (TMP) to obtain high copper removal efficiency was decided. In the optimum condition of the Cu(II) removal, the removal of lead (Pb(II)) metal ion was evaluated by the same membrane.

The Plackett-Burman method was used to identify and rank most affective parameters on hydrothermal synthesis and properties of the 13X zeolite powder with gel composition of Al2O3:aSiO2:bNa2O:cH2O. The affective parameters of SiO2/Al2O3 ratio, synthesis mixture alkalinity, synthesis temperature, and water content were selected for further study of their impacts and gel composition optimization using the Taguchi method. The synthesized powders were characterized by XRD and SEM analysis. Synthesis temperature and mixture alkalinity were found as the most affecting parameters on the 13X zeolite synthesis at the best gel composition of Al2O3:5.4SiO2: 13Na2O: 840H2O. Then 13X zeolite membranes were synthesized on the seeded supports using the optimum gel composition and impacts of synthesis temperature and time and coating layer number on their H2 and CO2 permeances and ideal H2/CO2 selectivity were studied. The optimum 13X zeolite membrane for H2/CO2 separation was obtained by three layer coatings at 80 °C for 16 h with H2 permeance of 2.88 cm3 cm−2.Pa.s and ideal H2/CO2 selectivity of 4.72.

The management of global carbon dioxide (CO2) emissions is considered one of the main environmental problems facing the modern world. One of the potential techniques for CO2 capture is absorption, using membrane contactor modules. Most of the previous research that dealt with membrane contactor simulations considered the whole membrane surface as the active reaction surface. However, in this paper, a more realistic model of the membrane-contactor module is presented, taking into account the effects of the pore size and surface porosity. CO2 absorption into the monoethanolamine (MEA) solution in hollow fiber membrane-contactor modules was numerically investigated. A computational fluid dynamics simulation was established using essential basic fluid dynamics and mass transfer equations in reactive mode. An algorithmic function was used to present the relations between the CO2 absorption flux and the hollow fiber length, membrane surface pore size, and porosity. The simulation results were compared to previously obtained experimental results without using any fitting parameters, and a good agreement was found with an average error of 8.5%. The validated simulation was then used to predict the effects of the MEA inlet velocity and concentration, the membrane surface pore size, and porosity on the total CO2 absorption flux. A maximum absorption flux of about 1.8 mol/m2·s was achieved at an MEA concentration of 4 M with a pore size of 0.2 microns, a surface porosity of 1%, and an inlet velocity of 0.25 m/s. The extrapolation technique was then used to predict the values of the absorption flux at longer fiber lengths. The concentration profiles around the pores at the gas–liquid contact surface of the membrane were obtained and presented. The proposed model exhibited excellent potential to evaluate the effective reaction surface in hollow fiber membrane contactors. This model could be considered the first step to obtaining accurate predictions of the membrane contactor gas absorption performance based on its surface structure.

In this work, the nanostructured anatase mesoporous membranes were prepared for water ultrafiltration (UF) process with photocatalytic and physical separation capabilities. A macroporous substrate was synthesized from α-Al2O3, then a colloidal titania sol was used for the preparation of the intermediate layer. Also, the membrane top layer was synthesized by deposition and calcination of titania polymeric sol on the intermediate layer. The characterization was performed by DLS, TG-DTA, XRD, BET, FESEM, TEM, and AFM techniques. Also, the filtration experiments were carried out based on separation of methyl orange from aqueous solution by a membrane setup with a dead-end filtration cell. Photocatalytic activity of the membranes was evaluated by methyl orange photodegradation using UV-visible spectrophotometer. The mean particle size of the colloidal and polymeric sols was 14 and 1.5 nm, respectively. The anatase membranes exhibited homogeneity, with the surface area of 32.8 m2/g, the mean pore size of 8.17 nm, and the crystallite size of 9.6 nm. The methyl orange removal efficiency by the mesoporous membrane based on physical separation was determined to be 52% that was improved up to 83% by a coupling photocatalytic technique. Thus, the UF membrane showed a high potential due to its multifunctional capability for water purification applications.

In this study, polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc), which had different affinities with the nonsolvent (water). Properties of the prepared membranes were characterized using scanning electron microscope (SEM) and contact angle and membrane porosity measurements. The prepared membranes were further investigated in terms of pure water flux and BSA rejection in cross flow filtration experiments. The results showed that by using a mixture of DMAc and TEP as solvent and changing the mixed solvent composition, membranes with different morphologies from sponge-like to macrovoid containing were obtained. Maximum flux of the prepared membranes with different solvent mixing ratios was obtained for the one with 60%wt TEP in the casting solution of PVDF/TEP-DMAc/ PEG which equals to 76.8 lm-2h-1. The effect of addition of polyethylene glycol with different molecular weight on morphology and performance of the membranes has also been discussed.

In the present research, for the first time, lycopodium as a novel nanofiller was incorporated into a polyvinylidene fluoride matrix to fabricate lycopodium/polyvinylidene fluoride flat-sheet membrane for desalination applications by vacuum membrane distillation process. The prepared lycopodium/polyvinylidene fluoride membranes and lycopodium were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, energy dispersive X-ray, and mapping analyses. Water contact angle and liquid entry pressure measurements were also performed. Response surface methodology was applied to optimize membrane structure and performance. The optimized lycopodium/ polyvinylidene fluoride membrane exhibits superior performance compared to the neat polyvinylidene fluoride membrane in terms of flux, salt rejection, water contact angle, and hydrophobicity. In vacuum membrane distillation experiments, using a 15000 ppm NaCl solution as a feed at 70 °C, the neat polyvinylidene fluoride membrane, optimum membrane, and agglomerated membrane (with high lycopodium loading) demonstrated 3.80, 25.20, and 14.83 LMH flux and 63.30%, 99.99%, 99.96% salt rejection, respectively. This improvement in flux and salt rejection of the optimized membrane was related to the presence of lycopodium with hydrophobic nature and interconnected nano-channels in membrane structure. It was found that lycopodium, as the most hydrophobic material, effectively influences the membrane performance and structure for membrane distillation applications.

Submerged ceramic membrane bioreactors (SCMBRs) are more efficient combinations of traditional activated hazardous sludge and new membrane separation processes in wastewater treatment. Suspended solids are separated from hazardous effluent using microfilter ceramic membranes in SCMBRs. A high loaded wastewater was treated using an SCMBR employing a homemade tubular ceramic membrane in laboratory scale. Hydraulic Retention Time (HRT) was 32 h and COD range was varied from 2000 to 5000 mg/l. COD removal was evaluated to be more than 90% after a week and the lab scale SCMBR showed desired performance for the wastewater treatment. Mixed Liquor Suspended Solid (MLSS) was increased from 2000 to 4000 mg/L during the SCMBR operation time.