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A new type of magnetic mixed matrix cation exchange membrane was prepared by incorporating cobalt ferrite nanoparticles for chromium ions removal via electrodialysis. The CoFe2O4 nanoparticles were synthesized via a simple chemical precipitation method. The synthesized nanoparticles and mixed matrix lab-made membranes were characterized by XRD, FT-IR, EDX, SEM and SOM. The images showed a uniform particle distribution and a relatively uniform surface for the prepared membranes. Utilizing CoFe2O4 nanoparticles in the membrane matrix led to increase of the membrane electrical conductivity and surface hyrophilicity. The membrane potential, charge density, permselectivity, transport number, ion exchange capacity and water content in the membrane were enhanced by using CoFe2O4 nanoparticles loading ratios up to 2 wt% and then decreased again for concentrations above 2 wt%. The sodium flux was also increased sharply by using cobalt ferrite nanoparticles in the membrane matrix. The magnetic PVC-CoFe2O4 membrane showed more dialytic rate in chromium ions removal compared to pristine PVC membrane which could be linked to strong affinity of magnetic nanoparticles in heavy metal ions adsorption.

This paper focuses on introducing low-cost water treatment options by using waste products from the beer industry, thereby contributing to cleaner production. To this purpose, sorptive removal of fluoride from drinking water using locally available natural grade diatomite (NGD) and brewery waste diatomite (BWD) was studied in a batch adsorption system. The equilibrium was achieved within an adsorption time of 60 min for NGD and 30 min for BWD at the optimum pH of 5 and adsorbent dose of 60 g/L. The equilibrium data were best fitted to the Freundlich isotherm (R2 = 0.979 and 0.995) for NGD and BWD, respectively. The adsorption capacity (qmax) calculated from the Langmuir isotherm value obtained for NGD and BWD was 0.917 mg/g and 0.617 mg/g, respectively. The adsorption kinetics data for both adsorbents followed the pseudo-second-order model (R2 = 0.734 and 0.947 for NGD and BWD, respectively). The influence of other anions on fluoride removal process has a slight influence, following the order PO43− > HCO3− > CO32− > SO42− > NO3− > Cl- for both adsorbents. The materials can be used on a system level for real water sample of low fluoride concentration (≤ 5 mg/L) and could be regenerated. Though BWD is considered as a waste for the brewery, it is used as a useful material for removal of fluoride. This application can be a stepping stone for providing a solution for safe management of industrial waste while providing a resource for water treatment on a system level.

A heterogeneous anion exchange membrane was modified by introducing polyaniline nanoparticles, in order to enhance its electrochemical properties in view of chloride and sulfate ion removal from water. Polyaniline nanoparticles were synthesized by facile chemical polymerization technique. Nanoparticles were characterized by FTIR, FESEM, and XRD. In addition, SOM images showed a uniform surface for membranes. Utilizing PANI nanoparticles in membrane body led to increase of water content, ion exchange capacity, surface hydrophilicity, and electrical conductivity. Membrane transport number and permselectivity were improved in NaCl solution by incorporating PANI nanoparticles; in Na2SO4 solution, they showed an opposite trend. The chloride and sulfate flux were enhanced by a low PANI concentration and declined at higher concentration. Modified PANI membranes showed a lower selectivity and flux for bivalent ions compared to monovalent ions. Membrane mechanical resistance was increased by using PANI in concentrations up to 2 wt% and decreased at higher PANI ratios.

Ion exchange membranes are the heart of the electrodialysis process which is a well-known water treatment technology. Herein, a heterogeneous cation exchange membrane (CEM) is synthesized by using a polymeric blend and the effects of Fe2O3 and sulfate-functionalized (s-Fe2O3) nanoparticles incorporation on the properties of the membranes were investigated. The addition of Fe2O3 nanoparticles caused a reduction in electrical resistance up to 53%. Moreover, the ion exchanged capacity (IEC) and permselectivity were improved by 34% and 42%, respectively. Meanwhile, by sulfonation of the Fe2O3 nanoparticles, further cation exchange groups were introduced to the nanoparticles structure which significantly improved the membrane properties. Through addition of 0.5 wt% s-Fe2O3 nanoparticles to the CEM matrix, a 45% reduction in the electrical resistance, and 45% and 43% enhancement in the IEC and permselectivity were obtained, respectively.

In this study, the physico-chemical properties, separation performance and antifouling ability of mixed matrix PES-based nanofiltration membranes decorated by (Fe3O4–polyvinylpyrrolidone) composite nanoparticles were investigated. The morphology of resulted membranes was characterized by scanning electron microscopy)SEM), scanning optical microscopy (SOM) and 3D surface images. The effect of incorporated nanoparticles on membrane properties and performance was determined using water contact angle, water content, membrane pore size and porosity, tensile strength, water flux, salt rejection and BSA solution filtration. The membrane water content was enhanced slightly by embedding Fe3O4/PVP up to 0.1 wt.% in membrane body and then reduced again by more NPs ratio. The water contact angle also decreased from 65.18° for neat membrane to 50.5° for the modified ones. All mixed matrix membranes showed higher water flux compared to pristine membrane that measured 3.14 (L/m2 h) for bare membrane and 9.96 (L/m2 h) for the superior ones. Salt rejection measured 82% for the pristine membrane whereas that was between 77%–90% for the nanocomposite membranes. Membrane tensile strength also improved by increase of composite NPs ratio into the polymer matrix. The nanocomposite membranes showed more BSA solution flux and outstanding antifouling properties compared to bare ones. The FRR measured ∼ 46.2% for bare membrane whereas that was ( ∼ 69.9% to ∼ 89.5%) for the nanocomposite membranes.

A new type of electrodialysis mixed matrix (MM) cation exchange membrane was prepared by incorporating carbon nanofibers (CNFs) into membrane matrix. The microscopy images showed uniform surface for the membrane relatively. The use of CNFs into membrane body enhanced membrane surface hydrophilicity, potential, transport number, permselectivity, and ionic conductivity obviously, while water uptake decreased. The sodium flux was also enhanced by incorporation of CNFs into membrane matrix from 0 to 0.5%wt and 2 to 8%wt, while declined for the samples in the range of 0.5 to 2%wt CNF ratios. Compared to pristine membrane, a smoother surface was observed for PVC-CNF membrane. Electrodialysis showed the (K+/Na+) flux ratio about 2.14. The transport mechanism of K+ and Na+ ions through the membranes discussed by considering ionic and hydrated radius, hydration potential, hydration free energy, entropy of hydration, and the Jones-Dole coefficient. Optimal performance was achieved for PVC-0.5%wt CNF membrane.

In the current research, the surface of a polyethersulfone (PES) nanofiltration membrane was modified by polyvinyl alcohol (PVA) and iron-oxide nanoparticles (Fe3O4) through a crosslinking reaction with glutaraldehyde (GA).The effect of the coating layer on the morphology, physico-chemical properties, separation and antifouling performance of the membranes was studied. The analysis of FTIR spectra, scanning electron microscopy (SEM), atomic force microscopy (AFM), porosity and mean pore size measurement, contact angle analysis, salt rejection and filtration of a powder milk solution was the basis of membrane characterization. Surface and cross-sectional SEM images showed the formation of a dense layer on the PES based NF membrane after coating. The pure water flux, porosity and mean pore size were decreased; the water contact angle was slightly lower due to the hydrophilic nature of PVA and Fe3O4 nanoparticles. The surface roughness initially decreased for a coating with a low concentration of nanoparticles but increased when a higher amount of nanoparticles was used. The salt rejection significantly increased from 68.4% for a bare PES membrane to 94% for the modified ones (sample 6) by surface modification. Filtration of a powder milk solution revealed the best antifouling performance for the membrane modified by PVA/Fe3O4 (2 wt %).

Magnetic nickel ferrite (NiFe2O4) nanoparticles were synthesized and then modified by a novel hydrogel based on 2-acrylamido-2-methyl propane sulfonic acid (HAMPS). Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to prove the NiFe2O4/HAMPS nanocomposite formation decisively. The effect of NiFe2O4/HAMPS in the matrix of the heterogeneous cation exchange membrane on separation performance was studied. Adding of NiFe2O4/HAMPS into the membrane body up to 1%wt resulted in an increase of sodium flux obviously. The sodium flux showed a decreased trend at higher nanocomposite ratios slightly. Membrane potential, permselectivity, and transport numbers also showed improving trends. Results exhibited more value for Na+ dynamic transport numbers compared to static ones. Membrane water content and porosity increased from 13.07 to 27.7% and 9.6 to 20.2% by utilizing NiFe2O4/HAMPS, respectively. By adding NiFe2O4-HAMPS into the membrane structure a pronounced improvement in membrane mechanical resistance (~ 94%) and chemical stability was observed. Modified membrane containing 1.0%wt NiFe2O4-HAMPS showed effective separation in Pb2+ (~ 98%), Cu2+ (~ 48%), and Ni2+ (~ 34%) removal. This sample also showed highest current efficiency (78.9%) in Pb2+ removal and lowest energy consumption (6.97 W/mol) compared to others.

Mixed matrix polyvinyl chloride-copper ferrite nanoparticles cation exchange membranes were prepared by casting solution technique. The effect of CuFe2O4 nanoparticles concentration on electrochemical properties of prepared membranes was investigated. The CuFe2O4 nanoparticles were synthesized by chemical precipitation technique. The formation of copper ferrite nanoparticles was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Scanning microscopy images showed uniform distribution of particles in the membrane matrix. Membrane surface hydrophilicity and charge density, membranes potential, transport number (> 97%) and permselectivity (> 96%) were enhanced by using CuFe2O4 nanoparticles in the membrane body. Also, ion exchange capacity and cation flux were increased initially by utilizing CuFe2O4 nanoparticles up to 1 wt% in the casting solution and then followed by a decreasing trend by adding more concentration up to 8 wt%. The PVC-CuFe2O4 membranes displayed lower electrical resistance (

Horizontal subsurface flow constructed wetlands poorly remove phosphorus from wastewater, resulting in phosphorus levels above the required limits in constructed wetland effluents. Since a pellet reactor can recover phosphorus through calcium phosphate precipitation/crystallization, using it as a pre-treatment system prior to horizontal subsurface flow constructed wetland could be a sustainable solution for phosphate scarcity. The operational conditions required for phosphate recovery in a pellet reactor were evaluated and compared with the Visual MINTEQ version 3.0 with the aim of checking its suitability to simulate the pellet reactor removal efficiencies. Such conditions include the initial phosphate concentration, pH, [Ca]/[P] molar ratio and hydraulic loading rate. The results showed an increase in phosphate removal efficiency with increased initial phosphate concentration, pH, [Ca]/[P] molar ratio and decreased hydraulic loading rate. However, the model calculation gave higher removal efficiencies than experimental results due to its inability to take into account the system kinetics which is an important component in pellet reactor operation and its assumption that precipitation reactions take place at constant pH. The effects of carbonate on phosphate precipitation were also investigated, and the removal efficiency of 61.9% without carbonate was improved to 63.2, 64.3 and 66.4% with a carbonate concentration of 0.25 mM, 0.5 mM and 2 mM, respectively, at pH 9, initial phosphate concentration of 1 mM, [Ca]/[P] molar ratio of 1.5 and hydraulic loading rate of 57 m/h. Thus, the presence of carbonates in domestic wastewater is advantageous as it promotes calcium phosphate precipitation in a pellet reactor.

Textile wastewater from wet processing units is a major environmental problem. Most chemicals, including dyes, are only partly consumed, resulting in highly colored wastewater containing a variety of chemicals released into the environment. This paper gives information on the current management of textile wastewater in Tanzania. A semiquantitative analysis was done to identify the main types of chemicals used in wet processing units, wastewater characteristics and existing wastewater treatment methods in the textile industry. The performance evaluation of the existing wastewater treatment plants is also discussed. The advantages of integrating constructed wetlands with the existing treatment facilities for textile wastewater are explained. It has been observed that pretreatment and dying/printing of the fabrics are the main two processes that produce wastewater in many textile companies. Main pollutants are chemicals used from pretreatment and materials removed from de-sizing, bleaching and scouring processes. Dyes, printing pigments and dye auxiliaries are the main pollutants from the dyeing/printing process. Most of the textile companies in Tanzania are equipped with effluent treatment plants. Wastewater treatment plants have basically similar units, which are coagulation-flocculation, sedimentation through clarifiers and aerobic reactor. However, their effluents do not meet discharge limits stipulated by the Tanzania Bureau of Standards (TBS). HIGHLIGHTS Characteristics of textile wastewater effluents in Tanzania.; Textile wastewater treatment technologies used in Tanzania.; Perfomance of textile wastewater treatment plants in Tanzania.; Main pollutants in textile wastewater in Tanzania.; Use of constructed wetland for tertiary treatment of textile wastewater.

Inert-particles spouted bed reactor (IPSBR) is characterized by intense mixing generated by the circular motion of the inert particles. The operating parameters play an important role in the performance of the IPSBR system, and therefore, parameter optimization is critical for the design and scale-up of this gas–liquid contact system. Computational fluid dynamics (CFD) provides detailed modeling of the system hydrodynamics, enabling the determination of the operating conditions that optimize the performance of this contact system. The present work optimizes the main IPSBR operating parameters, which include a feed-gas velocity in the range 0.5–1.5 m/s, orifice diameter in the range 0.001–0.005 m, gas head in the range 0.15–0.35 m, mixing-particle diameter in the range 0.009–0.0225 m, and mixing-particle to reactor volume fraction in the range 2.0–10.0 vol % (which represents 0.01–0.1 kg of mixing particles loading). The effects of these parameters on the average air velocity and average air volume fraction in the upper, middle, and conical regions of the reactor were studied. The specific distance for each region has been measured from the orifice point to be 50 mm for the conical region, 350 mm for the middle region and 550 mm for the upper rejoin. The selected factors were optimized to obtain the minimum air velocity distribution (maximum gas residence time) and the maximum air volume fraction (maximum interfacial area concentration) because these conditions will increase the gas holdup, the gas–liquid contact area, and the mass transfer coefficient among phases. Response surface methodology (RSM) was used to determine the optimum operating conditions. The regression analysis showed an excellent fit of the experimental data to a second-order polynomial model. The interaction between the process variables was evaluated using the obtained three-dimensional surface plots. The analysis revealed that under the optimized parameters of a feed-gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.164 m, mixing-particle diameter of 0.0225 m, and mixing-particle loading of 0.02 kg, the minimum average air velocity and highest air volume fraction were observed throughout the reactor., Computational fluid dynamics; Eulerian model; Gas–liquid reactor; Regression analysis; Optimization; Response surface methodology

Anticancer drugs have been detected in the aquatic environment, they have a potent mechanism of action and their consumption is expected to drastically increase in the future. Consequently, it is crucial to routinely monitor the occurrence of anticancer drugs and to develop effective treatment options to avoid their release into the environment. Prior to implementing a monitoring program, it is important to define which anticancer drugs are more prone to be found in the surface waters. In this study the consumption of anticancer drugs in the Lisbon region (Portugal), Belgium and Haryana state (India) were used to estimate the concentrations that can be expected in surface waters. Moreover, one important aspect is to define the major entry route of anticancer drugs in the aquatic environment: is it hospital or household effluents? The results disclosed in this study showed that in Belgium and Lisbon, 94 % of the total amount of anticancer drugs were delivered to outpatients, indicating that household effluents are the primary input source of these drugs and thus, upgrading the treatment in the domestic wastewater facilities should be the focus.

Electrodialysis-mixed matrix tris(8-hydroxyquinolinato)aluminum (AlQ3) nanoparticles entrapped heterogeneous cation-exchange membrane was prepared by the solution casting technique. The effect of the concentration of AlQ3 in the casting solution on the physico-chemical properties of the homemade membranes was studied. AlQ3 nanoparticles were synthesized via a simple precipitation method and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. The use of AlQ3 nanoparticles in the membrane matrix led to an increase of the membrane electrical conductivity and surface hydrophilicity. The membrane ion-exchange capacity was enhanced by using AlQ3 loading ratios up to 1.5 wt%; the IEC decreased for concentrations above 1.5 wt%. The increase of AlQ3 content ratios up to 0.5 wt% in fabricated membrane initially caused to increase of water content. The membrane water content was decreased for the concentrations between 0.5 to 1.5 wt% and then showed an increasing trend again at higher additive loading ratios. The membrane potential, charge density, permselectivity, and transport number were improved obviously by the use of AlQ3 nanoparticles in membrane body. The ion flux/permeability enhanced sharply by using of AlQ3 up to 0.5 wt% in the membrane matrix and then began to decrease while the additive concentration was more than 0.5 wt%.

The main objective of this study was to assess the feasibility of using paraffin wax as an alternative surface treatment for rainwater harvesting in the high rainfall zone of Kabarole district, Western Uganda. Specifically, the paper assesses the efficiency of paraffin wax in terms of quantity and quality of runoff. A complete randomized block experimental design was setup in three replications based on a slope of 1%, 3% and 5%. The treatments included: wax on bare soil (W), wax on sand (WS), wax on gravel (WG), wax on rice husk ash (WA) and a bare surface with short grass (C). Daily rainfall and runoff was collected from each experimental unit between April 2016 to May 2017. Water quality analysis of runoff for physical, chemical and microbial contamination was conducted. Average monthly runoff efficiency ranged from 56 to 93% for WG, 35–81% for WS, 34–71 for W, 30–71% for WA and 12–56% for C. Rainfall threshold values were estimated at 0.4 mm, 0.5 mm, 1.1 mm, 1.8 mm, and 4.6 mm of rainfall for WG, WS, W, WA and C, respectively. All physiochemical parameters were within WHO guidelines while E. coli contamination was observed in some samples for all treatments. Both the control and WG treatments had the lowest yield cost/m3/yr compared to the other treatments.

In this study, the influence of various weight ratios of activated carbon (AC)-co-chitosan (CS) composite nanoparticles in the matrix of ion exchange membranes was examined to adapt their electrochemical characteristics based on the combination of high surface area and adsorptive property of activated carbon nanoparticles and the hydrophilicity and functionality of chitosan. Scanning electron microscopy (SEM), scanning optical microscopy (SOM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), water content, ion exchange capacity (IEC), water contact angle, membrane potential, transport number and permselectivity, sodium flux, and membrane electrical resistance were used in membrane characterization. The fabricated membranes were also utilized in copper removal from water. The SEM and SOM images exhibited a uniform distribution of nanoparticles (NPs) on the surface of membranes. The membrane surface hydrophilicity was decreased; surface roughness and water content increased by utilizing AC-co-CS composite NPs. Membrane IEC was initially enhanced by utilizing composite NPs up to 0.5% wt and then decreased by more increase in additive ratios from 0.5 to 2%. Increasing trend was observed again at higher NPs concentration. Similar trend was also found for sodium flux. Membrane potential, t-number, permselectivity, and membrane electrical resistance initially represented an enhancing trend by use of AC-co-CS composite NPs up to 0.5% wt in membrane body and then decreased by more increase of NPs concentration from 0.5 to 8% wt. The fabricated membranes containing AC-co-CS nanoparticles showed good capacity in Cu removal from water. Membrane mechanical strength was improved initially by utilizing AC-co-CS composite NPs and then decreased at high additive concentration.

In this study, bis (8-hydroxyquinoline) zinc (ZnQ2) nanoparticles were synthesized and used in heterogeneous cation exchange membranes. The resulting membranes were examined in terms of membrane morphology and electrochemical features. Scanning electron microscopy (SEM) images, Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) patterns confirmed the successful formation of ZnQ2 nanoparticles. Scanning Optical Microscopy (SOM) images of the prepared membranes showed a relatively uniform membrane surface. It was found that membrane water uptake and surface hydrophilicity were enhanced in the presence of ZnQ2 nanoparticles. The membrane potential, transport number and permselectivity were also improved by increasing the additive concentration up to 8 wt% and then showed a decreasing trend. In addition, the sodium permeability/flux, electrical conductivity and mechanical stability were significantly increased by using ZnQ2 content ratios up to 4 wt% and then declined by a further increase of the concentration from 4 to 16 wt%. Furthermore, the modified membranes containing ZnQ2 showed a rougher surface slightly compared to pristine membrane.

In this work, novel nanofiltration membranes with outstanding performance and antifouling properties were fabricated by incorporating composite graphene oxide/chitosan (GOC) nanoplates into the membrane structure. GOC composite nanoplates were prepared by surface modification of GO with chitosan. The GOC nanoplates were then introduced as additives in a polymeric phase in different concentrations (up to 1%) in view of membrane synthesis. these membranes were thoroughly characterized and assessed for their Na2SO4 and CrSO4 rejection and water flux. Furthermore, the antifouling performance of GO and GOC filled membranes in high concentration (1 wt%) was investigated. Modified membranes with addition of GOCs showed a higher hydrophilicity, pure water flux and rejection, and a smoother surface compared to a bare PES and a GO incorporated membrane. SEM surface images indicated a more uniformed distribution of GOCs at a high loading rate (1 wt%) compared to GO. Due to the uniform dispersion of GOCs, a better antifouling performance was observed than for GO filled membranes. The results indicate that surface modification of GO with chitosan can enhance the membrane performance and properties, due to availability of sites with higher activity.

Membrane distillation is a thermal membrane technology, commonly used for desalination. The industrial breakthrough of the technology requires high performing and inexpensive membranes. In this paper, an alternative for the traditional hydrophobic membrane materials has been explored through the deposition of a hydrophobic coating on a commercial hydrophilic membrane with a microporous structure. The coatings enable obtaining the required hydrophobicity and prevent membrane wetting. The effect of the surface chemistry and structure on the membrane distillation performance was investigated for 5 different coatings. The coatings were applied only on the top surface or on the entire membrane cross-section and the effect of this difference in morphology was investigated. The atmospheric toplayer coating and vacuum plasma coating on the entire cross-section were selected for further optimization. The stability of the coating and the relation of the membrane structure and performance at different salinities were also investigated using direct contact membrane distillation.

Anion exchange membranes (AEMs) with high monovalent/multivalent anion perselectivity are essential for wide range applications (e.g., electrodialysis (ED)). In this work, we have proposed a facile surficial adhesive modification process to fabricate a highly permselective AEM for ED application. Firstly, a novel sulfonated dopamine (SDA) adhesive was synthesized, followed by coating this kind of polymer-like adhesive on commercial AEMs under alkaline and aerobic conditions. We have found that the SDA coating can significantly enhance the monovalent permselectivity (Cl-/SO42-), with a permselectivity of 34.02, which is much higher than the corresponding values of dopamine (DA)modified AEM (i.e., 11.59) and of the pristine AEM (i.e., 1.00). In addition, fouling experiments show that the transition time (the point time in fouling experiment when a voltage dramatically increases; that's to say, foulant dramatically occurs) of the optimum membrane is 112 min, indicating the superior anti-fouling property of SDA modified AEM, compared with pristine AEM (76 min). The facile fabrication process and superior performance of modified AEM suggest that as-prepared is potentially applicable in ED for separation of monovalent and multivalent anions.

Membrane-coated tables were prepared to control the release rate of aluminum phosphide from rice tablets when this tablet comes into contact with water in the stomach. Mixed matrix polyvinyl chloride-co-activated carbon nanoparticles (ACNPs) membranes was used as a thin film to coat the rice tablets. The effect of ACNPs as additive in membrane matrix on release behavior of aluminum phosphide was evaluated. The scanning electron microscopy (SEM) images and X-ray diffraction patterns showed that nanoparticles are uniformly distributed in the prepared coatings. The membrane water contact angle was enhanced from 55° to 80° in the presence of ACNPs. The tear resistance of the prepared membranes was also improved from 4.34 to 5.01 (grf/mic) by using ACNPs. The membrane-coated tablets showed a controlled aluminum phosphide release rate compared to pristine rice tablet without cover. The fastest aluminum phosphide release rate for all samples is related to the first five days. In addition, the half-time and life-time of membrane-coated tablets were declined by an increase of the ACNPs ratio up to 15 wt%. Swelling of the fabricated cover in aqueous environment led to a decrease of the aluminum phosphide release rate.

Mixed matrix activated carbon nanoparticles (ACNPs) embedded polyethersulfone based nanofiltration membranes were prepared by solution casting technique. SEM images show that utilization of nanoparticles in the membrane matrix causes a decrease of the size of the channels in both top and sub layers. SOM images show a uniform nanoparticle distribution for the prepared membranes. SOM images also show agglomeration of nanoparticles at high additive concentrations. The surface images show a reduction of roughness for membranes filled with ACNPs. The flux decreases at 0.05 wt% nanoparticles loading rate and then increases again by an increase of the nanoparticles dosage from 0.05 to 0.1 wt%. The flux then decreases again at a nanoparticles ratio from 0.1 to 1 wt%. According to the performance test, the membrane with 0.5 wt% nanoparticles indicated the highest sulfate (95%) and Cu (97%) ions removal. The water contact angle was found to decrease from 54° to 43° by increasing the ACNPs concentration. This is assigned to a decrease of the membrane surface roughness due to migration of nanoparticles to the membrane surface during the fabrication process. The water content in the membrane and the porosity were also improved by increasing the nanoparticles ratio up to 0.1 wt%, but decreased for higher additive concentrations. The tensile strength of the membranes was enhanced by utilizing a nanoparticles ratio up to 0.05 wt%, but showed a decreasing trend for higher nanoparticles concentrations. The decrease of the flux ratio (J/Jo) was measured to be 5% for the modified membrane containing 0.5 wt% ACNPs and 63% for the pristine membrane.

A full lignin-to-chemicals valorisation chain – from hardwood over bissyringols to aromatic polyesters (APEs) – is established for renewable 4-n-propylsyringol (PS), the main product from catalytic hydrogenolysis of (native) hardwood lignin. To do so, reagent-grade PS was produced from birch wood via reductive catalytic fractionation (RCF) and isolated in 34 wt% yield on lignin basis. Additional early-stage theoretical calculations, based on both relative volatility (α) and distillation resistance (Ω) as well as Aspen Plus® simulations, predict that the isolation of PS by means of distillation is economically feasible at industrial scales ($85–95 per ton of propylphenolics at 200–400 kt a−1 scale). Subsequent stoichiometric acid-catalysed condensation with formaldehyde unveils a remarkably high 92 wt% selectivity towards the dimer 3,3′-methylenebis(4-n-propylsyringol) (m,m′-BSF-4P), which is isolated in >99% purity by facile single-step crystallisation. The striking dimer selectivity is ascribed to the synergetic interplay between the activating methoxy groups and the oligomerisation-inhibiting propyl chain. Next, an in vitro human oestrogen receptor α (hERα) assay was performed to ensure safe(r) chemical design. The bissyringyl scaffold displays reduced potency (∼19–45-times lower affinity than bisphenol A) and lower efficacy (∼36–45% of BPA's maximum activity). Lastly, to assess the functionality of the safe(r) bissyringol scaffold, it was converted into an APE. The APE displays a Mw = 43.0 kDa, Mn = 24.4 kDa, Tg = 157 °C and Td,5% = 345 °C. In short, (i) the feasibility and scalability of the feedstock, (ii) the simplified process conditions, (iii) the reduced in vitro oestrogenicity, and (iv) the functionality towards polymerisation, make this bissyringol a renewable and potentially benign bisphenol replacement, capable for production at bulk scale.

Radiation-induced grafted ion exchange membranes based on functionalized polystyrene were tested for the first time in reverse electrodialysis (RED). Сation and anion exchange membranes based on sulfonated and quaternized/chloromethylated poly(styrene-co-divinylbenzene) grafted on UV-oxidized polymethylpentene films with different conductivity and selectivity relationships were compared with each other and with different commercial ion-exchange membranes (IEMs), FujiFim® Type 1 and Type 2 and RALEX®. The synthesized grafted membranes provided the highest power density of lab-scale stacks with a total active membrane area of 72 cm2 with the use of 0.1 М/1 М NaCl (0.67 W m−2) and 0.1 М/5 М NaCl (2.1 W m−2) solutions. The use of grafted membranes with a low resistance ~0.5 Ω cm2 (0.5 М NaCl, 25 °C) did not benefit the stack resistance; the low selectivity of such membranes resulted in a lower voltage and a high non-selective diffusion current of the RED stack. Higher power densities and current efficiencies in some model systems are observed for stacks with grafted membranes with lower conductivity and higher selectivity.

Novel mixed-matrix electrodialysis heterogeneous ion exchange membranes were fabricated using polyaniline (PANI)-co-graphene oxide (GO) functionalized composite nanoplates. The PANI-co-GO functionalized composite nanoplates were prepared by in situ chemical oxidative polymerization of aniline in the presence of GO nanoplates. The synthesized PANI/GO were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The SEM images demonstrated that utilizing of PANI/GO in membrane matrix led to formation of membranes with a compact structure. Also, more uniform distribution was observed for the incorporated PANI/GO membrane compared to the embedded GO nanoplates ones. The surface hydrophilicity, water content, and ion exchange capacity were enhanced by utilizing PANI/GO composite nanoplates. The membrane potential, transport number, and selectivity were also enhanced in sodium and barium chloride ionic solutions in presence of functionalized nanoplates. The newly prepared membranes showed lower selectivity and transport number for barium ions compared to sodium ions. The sodium and barium flux were enhanced by using PANI/GO. Dialytic rate results showed that modified membranes in this study have good ability in lead ion removal from wastewater. The enhancement in lead flux was more than 50% for the modified membrane containing PANI/GO in comparison with pristine ones.

Graphene oxide nanoplates (GONs) embedded mixed matrix polyvinylchloride based heterogeneous cation exchange membranes were prepared by solution casting. The effect of the concentration of GONs on the physico-chemical properties of the membrane was studied. Scanning electron microscopy (SEM) and scanning optical microscopy (SOM) images showed a uniform particle distribution and a uniform surface for the modified membranes. Moreover, the cross-sectional SEM images showed a specific direction for GO nanoplates, perpendicular to the membrane surface. XRD patterns showed that the average particle size of was enhanced by increasing the GONs dosage. The surface hydrophilicity of the membranes was improved, and the water content was lower by increasing the GON content. The IEC of the membranes was enhanced from 1.15 to 1.40 meq/g by an increase of the GON concentration up to 0.5 wt% in the casting solution, and decreased by a further increase of the content of GONs. The membrane potential, transport number, selectivity and conductivity were improved by utilizing GONs. The ion permeability and flux decreased initially by using GONs up to 0.5 wt%, followed by a sharp increasing trend at higher concentrations of GONs.

In this paper, the synergetic influence of various weight ratios of TiO 2 nanoparticles (NPs)/graphene oxide nanoplates (GONs) in the matrix of ion exchange membranes was examined in order to adapt their electrokinetic properties based on the combination of the high specific surface area of GONs and the antifouling ability of TiO 2 nanoparticles. The morphology, physico-chemical features and ionic transport behavior of prepared membranes was studied. Scanning optical microscopy (SOM) and scanning electron microscopy (SEM) images showed a uniform surface for the lab-made membranes relatively. It was found that surface hydrophilicity of the membrane was increased in the presence of GONs and TiO 2 NPs. All modified membranes showed a higher water uptake than unmodified membranes. Furthermore, a higher ion exchange capacity, fixed ionic concentration, ionic permeability and flux were observed for all modified membranes in comparison with unmodified membranes. The membrane potential, transport number and selectivity improved in NaCl solutions by using GONs and TiO 2 nanoparticles. Furthermore, the membrane ionic conductivity showed an increasing trend by utilizing TiO 2 -co-GONs NPs. As an overall conclusion, the modified membrane containing 3 wt% GONs and 1 wt% TiO 2 NPs with superior transport number and permselectivity (∼99%), highest current density and cation flux and the lowest areal electrical resistance (∼4–5 Ω cm 2 ) showed the best performance.

Membrane distillation separates liquids and solutes using a hydrophobic microporous membrane. Different configurations have been investigated at lab scale, among which direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD). Lab scale studies comparing different configurations show higher flux for DCMD, while AGMD is more energy efficient. However, no straightforward directions are given yet on how to translate these results to pilot scale. As membrane distillation is currently shifting from lab environment towards pilot experiments, a good understanding of pilot scale modules and the differences with lab modules are important. In this study, DCMD and AGMD were compared both at lab and pilot scale using the same membrane. At lab scale, it was found that the flux of DCMD is a factor 4 higher compared to the flux of AGMD. However, at pilot scale, the AGMD modules showed a higher flux and lower energy consumption compared to DCMD. As it is important for further upscaling of the technology, this study focusses on the explanation behind these unexpected higher fluxes of AGMD modules. Since the AGMD modules showed better performance and do not require an additional recuperating heat exchanger, this configuration is preferred over DCMD for larger scale applications.

Graphene oxide with lamellar structure has attracted research interest in various fields. In this study, sulfonated reduced graphene oxide (S-rGO) nanosheets with negatively charged sulfonic acid groups were synthesized via a facile distillation-precipitation polymerization, followed by hydrazine reduction. The sulfanilic acid was grafted on the graphene oxide sheets to separate GO nanosheets each other and provide anion channels for anions selectivity. These nanosheets were used to modify anion exchange membranes (AEMs), and to enhance the membrane monovalent anions selectivity and the modification layer conductivity, in order to meet industrial requirements. The permselectivity and separation efficiency were used to evaluate selectivities of the modified membranes. The results show that the unmodified AEM has no monovalent selectivity, while the permselectivity and separation efficiency of S-rGO modified AEMs (reduced by hydrazine hydrate steam in 10 min) increases from 0.65 to 1.80 and from −0.13 to 0.31 (in 40 min), respectively; and from 0.72 to 2.30 and from −0.07 to 0.28 (in 80 min), respectively.

Membrane distillation (MD) is an emerging thermal separation technique, using a hydrophobic microporous membrane. Initially, the process used MF membranes with a hydrophobic character, such as PTFE and PVDF membranes. These membranes are not wetted by aqueous feed liquids and their microporous structure allows the transport of water vapor molecules through the membrane due to an applied temperature difference. On average 23% of the publications on MD focus on membrane engineering. Besides the traditional stretching and phase inversion technique, many novel techniques are proposed, including electrospinning, the use of carbon nanotubes, surface modification techniques and the design of novel polymers. This article provides guidelines for the evaluation of these membranes measured using a large variety in process conditions at lab scale. In the second part, an overview of the synthesis methods used for MD was given and the advantages, disadvantages and the performance of the respective membrane types in MD were evaluated.

In membrane distillation, the liquid phase including dissolved components is retained by a hydrophobic membrane, while the microporous structure allows transport of vapor through the membrane. The vapor pressure difference over the membrane is the driving force and is applied using a variety of configurations. This paper directly compares the flux and energy efficiency of a lab scale direct contact membrane distillation (DCMD), air gap membrane distillation (AGMD), permeate gap membrane distillation (PGMD) and vacuum membrane distillation (VMD) using the same bulk driving force. The highest flux was observed for VMD, followed by DCMD > PGMD > AGMD. Furthermore, it was observed that the different configurations are not equally sensitive to the applied process conditions, including temperature difference, flow velocity and salinity. For the first time, also the importance of the specific requirements for the membrane for each configuration was investigated.

A novel anion exchange membrane (AEM) is developed through poly (sodium 4-styrene sulfonate) (PSS) and hydroxypropyltrimethyl ammonium chloride chitosan (HACC) alternate electro-deposition to enhance the monovalent selectivity. Compared to the commercial original AEM, coating of the (PSS/HACC)N alternate electro-deposition multilayer on the membrane surface dramatically enhance the selectivity of anions. In addition, the permselectivity for monovalent anions of the membranes was investigated by electrodialysis experiments. For comparison, the corresponding Cl−/SO42− were chosen and the average values of permselectivity and separation efficiency of commercial AEM are 0.66 and −0.19 respectively. As result of alternate electro-deposition of PSS/HACC layers, the permselectivity raised up to 2.90 and the separation efficiency also increased up to 0.28 for nine PSS/HACC bilayers needed. Under the optimal fabricating conditions, the area resistance of membrane arrived at 4.52 Ω cm2 with nine PSS/HACC bilayers. Meanwhile, the polarization current-voltage curves and ζ-potential of membranes were also tested to characterize the electrochemical behavior of the modified membrane. The high selectivities of these membranes may enable electrodialysis applications in separation of monovalent and divalent anions.

Anticancer drugs are currently widely used for the treatment of cancer and have been detected in hospital effluents, wastewater treatment plant effluents and river water samples in concentrations up to the µg·L−1 range. Within the next two decades, the annual number of cancer cases is expected to rise, which will lead to an increase in the consumption of anticancer drugs. These drugs are extremely important due to their highly potent mechanism of action and their potential risk for humans and the environment. Therefore, the development of effective treatment options is crucial to avoid the release of these emerging contaminants in the aquatic environment. The aim of this study was to assess the viability of nanofiltration for remediation, using as benchmark two representative membranes (Desal 5DK and NF270) to remove four widely consumed anticancer drugs (paclitaxel, etoposide, cyclophosphamide and ifosfamide) from different matrices (laboratory grade water, synthetic urine and real secondary effluent). Experimental results showed that the Desal 5DK membrane is more effective than the NF270 membrane for the rejection of these compounds. It presented average rejections higher than 89% for all the target anticancer drugs spiked in synthetic urine and real secondary effluent, showing no significant matrix influence on the rejection results. Daphnia magna toxicity tests showed that the immobilization effect observed in the permeate samples was lower than the feed samples. The target compounds have very different structures and physico-chemical properties and thus the high effectiveness reported for the Desal 5DK membrane is a good indication of what can be expected to a multitude of compounds.

Membrane distillation is an emerging technology to separate non-volatile components from an aqueous feed stream. Mathematical models have proven useful to pursue breakthrough in the economics of the technology and for further improvement through module design and operational optimization. However, before this can be done, all of the resistances in the system must be identified correctly and the model must be carefully calibrated to ensure its predictive power. In this work the typical structure of a direct contact membrane distillation (DCMD) model is studied, where the mass transfer inside the membrane is simulated using the Dusty Gas Model and Nusselt type equations are used to simulate the heat transfer inside the channels. We demonstrate that an off-the-shelf Nusselt equation cannot directly be applied to simulate the heat transfer in the spacer filled channels. Instead, the equations should be calibrated to match the behaviour of the particular spacer. A Monte Carlo filtering method was applied to calibrate and study the structure of the DCMD model for the membrane region. The method proved useful to identify which parameters need to be included in the calibration as it highlighted parameter correlations. Additionally, a submodel selection was performed for the heat and mass transfer inside the membrane. A simple, yet physical method for the simulation of supported membranes was tested and validated on 3 supported membranes, resulting in an excellent fit.

Membrane distillation (MD) uses a microporous hydrophobic membrane for the separation of non-volatile solutes from liquid streams. The microporous structure should be designed for optimal vapor transport through the membrane, whereas the hydrophobicity is required to retain the liquid phase. Currently, different types of commercially available hydrophobic microfiltration membranes are used for membrane distillation. However, no comparison is available between these membranes, complicating the selection of a proper membrane and the evaluation of new membranes. In this study, over 20 (semi-)commercial hydrophobic membranes are characterized and tested in a lab scale direct contact membrane distillation set-up. These membranes include the standard PTFE, PVDF and PP membranes, but also less known PE and PES membranes. These membranes are synthesized using the phase inversion technique, stretching or electrospinning, resulting in a wide variety of membrane structures. In this study, a method is proposed to evaluate the suitability of membranes. The membrane performance in MD is evaluated with a performance chart including flux and energy efficiency using realistic process conditions. From this chart a benchmark performance is proposed, which depends on the salt concentration.

The influence of various additives including potassium lysinate (PL), potassium glycinate (PG), potassium carbonate (K2CO3), 2-(1-piperazinyl)-ethylamine (PZEA), trisodium phosphate (TSP) and tetraethylenepentamine (TEPA) to monoethanolamine (MEA) as solvent for carbon dioxide (CO2) was evaluated experimentally. In order to determine the absorption rate and solubility of carbon dioxide into aqueous solutions of MEA in the presence of these activators, a vapor-liquid equilibrium (VLE) apparatus was used to measure pressure changes versus time at a constant total blend concentration of 2.5 mol dm−3 (M) and CO2 partial pressures between 0 and 50 kPa at 313.15 K. In all the experiments, the molar ratio of the additive to MEA was set to 0.25, 0.66 and 1. The results indicate that the 1.25 M MEA + 1.25 M TEPA system reaches the maximum loading capacity (mole CO2/mole solution) of 1.32 and has the highest absorption rate. It can be concluded that the 1.25 M MEA + 1.25 M TEPA blend solution can be a good candidate for CO2 capture.

In the context of the production of n-butyl acetate, acetic acid or ethyl acetate from methyl acetate, a pervaporation module was employed in order to retrofit the extractive distillation unit used to recover methyl acetate from a methanol/methyl acetate industrial waste stream. The PolyAl TypM1® membrane (from PolyAn™) was first tested using a wide feed concentration range (11–90 mol% methanol) and three temperatures (30, 36, 44 °C). Then, it was compared with other commercial membranes reported in literature (at 40–45 °C) at the methanol/methyl acetate azeotropic composition, resulting in a medium/low separation factor and with the highest flux. This ensured the simulation of a very challenging condition for the retrofitting from an energetic point of view (i.e., for moderate or low separation factor membranes: the higher the flux, the higher the process energy requirement). The retrofitting permits to avoid the use of a solvent during azeotropic separation. Moreover, during comparison of the retrofitted hybrid pervaporation-distillation unit with the source industrial extractive distillation unit, an overall energy saving up to ∼38% was demonstrated (∼23% when only the energy consumed by the heaters is taken into account). In addition, major hydraulic modifications could be avoided employing structured packing and membranes of higher separation factors.

This study investigates the exergy concept for use in chemical engineering applications, and compares the energy and exergy methodology for the production process of biodiesel. A process for biodiesel production was suggested and simulated in view of the energy and exergy analysis. A method was developed to implement the exergy concept in Aspen Plus 7.3. A comparison between the energy and the exergy approach reveals that the concepts have similarities but also some differences. In the exergy study, the reaction section has the largest losses whereas in the energy study separation steps are the most important. An optimization, using both concepts, was carried out using the same parameters. The optimized results were different depending on the objective function. It was concluded that exergy analysis is crucial during the design or redesign step in order to investigate thermodynamic efficiencies in each part of the process.

In view of the separation and purification of salt streams, the permselectivity of ion-exchange membranes between different counter-ions is of interest. This paper investigates the permselectivity of two cation-exchange membranes (Neosepta CMS and Neosepta CMX). The separation between either sodium/calcium, sodium/protons or calcium/protons was studied and the influence of operating parameters was tested. It was found that a change in concentration ratio did not have a significant effect on the permselectivity. Furthermore, the monovalent selective membrane enables the preferential removal of sodium in an excess amount of calcium. The separation of sodium or calcium from protons is hampered because of the high mobility of protons in aqueous solutions. In the presence of weak bases, such as acetate and formate, the permselectivity (Na + relative to H + ) is increased more than 100 times. As a solvent either water or a solvent mixture of water with methanol or ethanol was used. Generally, the permselectivity changed according to the variation in ion mobility in the solvent mixture. The permselectivity between sodium and protons was enhanced, while the permselectivity between sodium and calcium was decreased. Hereby, the more nonpolar co-solvent, ethanol, has a larger influence than methanol.

The absorption rate and solubility of carbon dioxide (CO 2 ) into 35 wt% aqueous potassium carbonate (K 2 CO 3 ) solution in the presence of different promoters were evaluated experimentally. A vapor–liquid equilibrium (VLE) apparatus was used to measure the equilibrium partial pressure of CO 2 and CO 2 partial pressure changes with time in CO 2 partial pressures ranging from 0 to 50 kPa (low partial pressures) and at temperature 313.15 K. The activators considered are Piperazine (PZ), 2-(1-piperazinyl)-ethylamine (PZEA), Monoethanolamine (MEA), Tetraethylenepentamine (TEPA) and Boric acid (BA). Different molar ratios of the activator to K 2 CO 3 (0.25, 0.66 and 1.5) at constant total blend concentration of 2.5 mol dm −3 (M) were investigated to find the optimal molar ratio. Among studied promoters, the highest absorption rate and CO 2 solubility was achieved with the TEPA + K 2 CO 3 solution with molar ratios of 0.66 and 1.5 respectively. As an overall conclusion, TEPA + K 2 CO 3 solution could be a potential candidate for CO 2 capture.

The use of biodiesel in engines requires a high purity (99.65 wt.%), which is to be obtained by the removal of a large water amount and a large number of distillation steps. Membrane extraction was studied as a more efficient and environmentally friendly process to purify a synthetic biodiesel stream composed of methyl esters from rapeseed oil, methanol and glycerol. The potential of several flat sheet membranes to remove impurities was evaluated. All hydrophobic membranes showed breakthrough pressure values higher than 0.5 bar. A PTFE membrane from Sterlitech was selected due to its high chemical resistance against biodiesel. The effect of the concentration of solutes and of the flow rate on the flux was investigated. The overall mass transfer coefficient was calculated and compared with experimentally observed values, which are in the range of 3.5–7 E-03 (cm/min) for methanol. Thus, this membrane technique allows purifying biodiesel, suggesting its potential in industrial applications.

Selectivity for monovalent cations is an important property of cation exchange membranes (CEMs). The cation exchange membranes of the CSO modified with polyethyleneimine type have a higher selectivity for monovalent cations than the multivalent cations. Unfortunately, the loss of selectivity for these kinds of CSO seems to be unavoidable due to fouling and degradation of polyethyleneimine groups. In this situation, a “re-modification” technique was developed for recovery of fouled CSO, activating the fouled CSO by methanol and a sulfuric acid solution with ultrasonic vibration, followed by a layered surfacial electro-deposition method to prolong the lifetime of cation exchange membranes. A series of electrodialysis experiments for Na+/Ca2+ separation was performed for evaluating and comparing the monovalent cation selectivity of the samples. The restoration of the surface and cross section morphology after “re-modification” was demonstrated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). As a result of the re-modification method the membranes with chemically degraded polyethyleneimine were again made functional. The ion exchange groups of the CSO modified with polyethyleneimine were successfully recovered, giving the membrane a high permselectivity again.

Membrane distillation is an emerging thermal membrane technology for the separation of salts and other non-volatile inclusions from water streams. The process offers a solution for the treatment of concentrated solutions, which are out of the scope of reverse osmosis. However, only few studies focused on the optimal membrane properties and operational conditions in the high concentration regime. In this paper, membranes with variations in thickness, porosity and structure are experimentally investigated in direct contact membrane distillation (DCMD) as well as simulated, using the Dusty Gas Model. Operational conditions, including the temperature difference over the membrane, the flow velocity and the feed stream salinity up to saturation are varied. It is confirmed that for pure water, thinner membranes show higher fluxes, while energy efficiency is unaffected by membrane thickness. At higher salinities, an optimal membrane thickness depending on membrane parameters and process conditions exists. The optimal membrane thickness is calculated in this article for concentrations of NaCl ranging from 0 up to 320 g/l and variations in bulk temperature difference and flow velocities for four different membranes. publisher: Elsevier articletitle: Influence of membrane thickness and process conditions on direct contact membrane distillation at different salinities journaltitle: Journal of Membrane Science articlelink: http://dx.doi.org/10.1016/j.memsci.2015.07.037 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Journal of Membrane Science vol:498 pages:353-364 status: published

Industrial residue management is a critical element of sustainable development. The aim of this research was to investigate the potential of different coffee waste fractions for bioethanol fermentation and its purification by pervaporation; these fractions and the role of pervaporation in this application have not been studied before. Bioethanol production from different coffee waste fractions has now been studied by acid or acid and enzymatic hydrolysis. The fermentation was conducted using two different yeasts (baker’s yeast and lignocellulosic yeast). By using the cellulolytic enzymes and lignocellulosic yeast, a higher bioethanol yield was achieved. Further purification of the fermented filtrate was carried out by an alcohol selective pervaporation membrane at four temperatures (23, 30, 40 and 50 °C). Hydrolysis of the samples using cellulose complex and β-glucosidase enzymes and fermentation with lignocellulosic yeast, followed by purification using pervaporation resulted a superior bioethanol yield of 51.7 ± 7.4 g/l for spent coffee and 132.2 ± 40 g/l for husk. Husk hydrolysis using cellulolytic enzymes and fermentation with lignocellulosic yeast, followed by product recovery through pervaporation membrane, was found to be the optimal procedure, producing ethanol at a concentration of 132.2 ± 40 g/l. In general, husk hydrolysis using acid and cellulolytic hydrolysis and fermentation with lignocellulosic yeast GSE16-T18 followed by pervaporation was found to be the best process for producing the highest ethanol yield compared to the other fractions of coffee waste samples.

The influence of addition of 2-(1-piperazinyl)-ethylamine (as a promoter) on the solubility and absorption rate of carbon dioxide (CO2) in aqueous potassium carbonate solution (as a main solvent) was investigated experimentally, using a vapor liquid equilibrium (VLE) equipment in temperatures from 303.15 to 323.15 K and CO2 initial partial pressures between 25 and 75 kPa. The experimental data showed that the addition of 2-(1-piperazinyl)-ethylamine to potassium carbonate solution results in a significant enhancement in the solubility and absorption rate of CO2. The response surface methodology was applied to explore the relationship between independent parameters on the CO2 loading capacity of blended solution.

The main functionality of ion-exchange membranes is to selectively permeate either cations or anions. However, co-ions may permeate as well to some extent through these membranes. For the production of chemicals with electrodialysis metathesis and conventional electrodialysis, these co-ion fluxes are a major source of impurities in the produced chemicals. The present paper studies the co-ion fluxes and the influence of operating parameters. The results clearly indicate that co-ion fluxes are predominately determined by the difference in ion concentration across the membrane. A more than linear increase in co-ion flux with respect to the ion concentration was observed. The current density has no significant influence on the co-ion fluxes. Therefore, a high current density leads to a smaller transport number of co-ions and improves the product purity in electrodialysis metathesis. Moreover, the co-ion flux can be decreased by the use of bulky counter-ions. In a conventional electrodialysis configuration, cation impurities are mainly caused by a diffusional flux. This flux is approximately three times larger than the co-ion flux. In contrast, the anion impurities are predominantly initiated by a co-ion flux and in magnitude smaller than the cation impurities. publisher: Elsevier articletitle: Co-ion fluxes of simple inorganic ions in electrodialysis metathesis and conventional electrodialysis journaltitle: Journal of Membrane Science articlelink: http://dx.doi.org/10.1016/j.memsci.2015.05.066 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Journal of Membrane Science vol:492 issue:492 pages:263-270 status: published