Maximum Chromium Removal Research Articles

Adsorption of hazardous chromium (VI) ions from aqueous solutions using modified sawdust: kinetics, isotherm and thermodynamic modelling

ABSTRACT The presence of chromium in aquatic streams due to the discharge of industrial effluents is of great concern because of its toxic nature. Removal of Cr(VI) ion from wastewater is a necessary task. To enhance the adsorption capacity of sawdust for heavy metals, sawdust was modified with formaldehyde and used for the adsorption of heavy metal Cr(VI). The process of modifying was characterised by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The effects of various parameters such as pH, contact time, adsorbent dose and initial metal ion concentration on the adsorption process were investigated. The maximum removal of chromium (VI) was found to be 100% at pH 2.0, initial Cr(VI) concentration of 10 mg/L, and adsorbent dose of 4 g/L. Equilibrium isotherms for the removal of Cr(VI) were analysed by the Langmuir, Freundlich, and Temkin isotherm models and the experimental data were well explained by the Freundlich isotherm model. The maximum adsorption capacity was found to be 8.84 mg/g. Kinetic studies were performed by pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich models. The R2 value of the pseudo-second-order model is higher than other kinetic models. Therefore, the obtained data were the best fit with the pseudo-second-order kinetic model. The thermodynamics indicated that the adsorption process of sawdust for Cr(VI) was endothermic and spontaneous in nature.

Remediation of bio-refinery wastewater containing organic and inorganic toxic pollutants by adsorption onto chitosan-based magnetic nanosorbent

AbstractThe novelty of the current study deals with the application of magnetic nanosorbent, chitosan-coated magnetic nanoparticles (cMNPs), to be utilized for the management of lignocellulosic bio-refinery wastewater (LBW) containing three heavy metals and 26 phenolic compounds. The magnetic property of the adsorbent, confirmed by elemental and vibrating sample magnetometer analysis (saturation magnetization of 26.96 emu/g), allows easy separation of the particles in the presence of an external magnetic field. At pH 6.0, with optimized adsorbent dosage of 2.0 g/L and 90 min contact time, maximum removal of phenol (46.2%), copper (42.2%), chromium (18.7%) and arsenic (2.44%) was observed. The extent of removal of phenolic compounds was in the order: polysubstituted > di-substituted > mono-substituted > cresol > phenol. Overall, the adsorption capacity (qe) of cMNPs varies among the different contaminants in the following manner: copper (1.03 mg/g), chromium (0.20 mg/g), arsenic (0.04 mg/g) and phenol (0.56 mg/g). Post-adsorption, retrieving the cMNPs using an external magnetic field followed by single-step desorption via acid–base treatment is attractive for implementation in industrial settings. Reusability of the adsorbent was studied by recycling the cMNPs for five consecutive rounds of adsorption followed by desorption, at the end of which, cMNPs retained 20% of their initial adsorption capacity.

Removal of Hexavalent Chromium from Aqueous Solution by the Pod of Acacia gerrardii

Abstract This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

Electrokinetic (EK) and Bio-electrokinetic (BEK) Remediation of Hexavalent Chromium in Contaminated Soil Using Alkalophilic Bio-anolyte

The present investigation deals with remediation of chromium (Cr(VI)) by electrokinetic (EK) and bio-electrokinetic (BEK) processes. The experiments were conducted using spiked concentration of 1 g/kg of chromium in the soil. The results showed a maximum chromium removal of 40.12% and 90.4% by EK and BEK, respectively, at the end of 7 days. Chromium-resistant alkalophilic bacterial strain, Bacillus licheniformis SR3, was used as bio-anolyte counterpart in BEK. During the process, the variations in electrical gradient and pH were studied and compared between EK and BEK. Chromium removal was further confirmed by UV spectroscopy, FTIR and XRD studies. The results of FTIR showed notable difference in the intensities of the peak, thus confirming the effective remediation by BEK. The obtained results have found to support BEK integrated system as an effective remediation option for cleaning up chromium-contaminated soil environments.

Fast chromium removal by Shewanella sp.: an enzymatic mechanism depending on serine protease

Environmental pollutions with heavy metals pose serious health and ecological risks. Sabzevar in the northeast of Iran has natural chromic mines and then chromium-polluted soils and groundwater. In the present work, the metal-tolerant bacterial strain KR2 was identified as Shewanella sp. following 16S rDNA gene sequence analysis. Bioremediation ability of isolated bacterial from agricultural soils that irrigated by groundwater, Shewanella sp., was evaluated for uptaking of chromium with varying Cr(VI) concentrations from 50 to 500 ppm in aerobic conditions (pH 7.0, 37 °C). The Shewanella sp. strain KR2 showed an obvious heavy metal tolerant in the wide range of heavy metals including: Cr6+, pb2+, and Hg2+. After 20 min, the maximum removal of chromium (89%) was obtained by Shewanella sp. in a medium containing 500 ppm Cr(VI). Our results showed that KR2 is able to tolerate high concentration of Cr(VI) through at least two different mechanisms: serine protease overexpression immediately after immersion in high concentration of chromium, and after a long time, an unknown mechanism causes in bacterial deformation, that confirmed with the SEM technique. It is concluded that Shewanella sp. KR2 potentially could be a suitable candidate for heavy metals removal from polluted environment.

Modified coconut coir to remove hexavalent chromium from aqueous solution

Hexavalent chromium (Cr(VI)) was removed from aqueous solution by adsorption using chemically modified lignin-rich low-cost coconut coir. The equilibrium time, adsorption isotherm and adsorption kinetics at certain conditions such as pH, particle size and the initial concentration of adsorbate were investigated. The coconut coir was modified by sodium chlorite for adsorption studies. The scanning electron microscopic image depicted the morphology of SCM-CC of different particle sizes whereas the elemental composition of this sort of bioadsorbent was determined by using energy dispersive spectroscopic data. Fourier transform infrared (FTIR) spectrometry analysis indicated that the carbonyl (C=O) groups and hydroxy (O–H) groups from the lignin structure in coconut coir may be involved in the mechanism of Cr(VI) adsorption. The maximum Cr(VI) adsorption capacity of sodium chlorite modified coconut coir (SCM-CC) was found to be 28.03 mg Cr(VI) g-1 SCM-CC at pH 2.00 for the particle size of 75-100 μm with the dose of 7.5 g/L. The equilibrium was established within three hours resulting in the maximum removal (99.92%) of chromium. Freundlich isotherm was better fitted than Langmuir isotherm at pH 2.00 on the basis of the regression coefficient (R2). The kinetic data well-fitted with Ho’s pseudo second order kinetics. The SCM-CC can be treated as an excellent adsorbent for the remediation of chromium toxicity.
 Bangladesh J. Sci. Ind. Res.54(1), 89-98, 2019

Photocatalytic removal of cyanide and Cr(IV) from wastewater in the presence of each other by using TiO 2 /UV

Cyanide (CN) and chromium (VI) are hazardous, toxic pollutants whose presence in water and wastewater can seriously affect human and its environment, hence the necessity of controlling these contaminants. In this work, by using TiO 2 /UV, the simultaneous photocatalytic reduction of Cr(VI) and oxidation of CN in aqueous suspensions were investigated. Variations of this study were pH, pollutant concentration, and reaction time. CN and total chromium were determined by Titrimetric method, and Colourimetric method, respectively. Maximum removal of chromium and CN occurs at pH 2.3 and 10, respectively. In the binary system, the electron-hole recombination is blocked and as a result, total efficiency increases. An increase in the initial concentrations of CN and Cr(VI) led to a rise in the reduction efficiency of Cr(VI) and CN up to an optimum amount, and then it went into decline as the concentration of the pollutants increased any further. The maximum quantum efficiency of Cr(VI) photoreduction with CN being present was calculated to be 23% at room temperature. Furthermore, the kinetic experimental was investigated and it became evident that the pseudo-first-order kinetic model is capable of defining Cr(VI) and CN both. Finally, based on the obtained results, a TiO 2 system is proposed to remove both pollutants.

Biosorption of Cr(III) from aqueous solution using an agricultural by-product jute stick powder: Equilibrium and kinetic studies

The adsorption capacity of chromium(III) from synthetic waste water solution by a low cost biomaterial, Jute Stick Powder (JSP)was examined. A series of batch experiments were conducted at different pH values, adsorbent dosage and initial chromium concentration to investigate the effects of these experimental conditions. To analyze the metal adsorption on to the JSP, most common adsorption isotherm models were applied. To study the reaction rate, the kinetic and diffusion models were also applied. The morphological structure and variation of functional groups in the JSP before and after adsorption was examined by scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FT-IR). Maximum chromium removal capacities of JSP was 84.34%with corresponding equilibrium uptake 8.4 mg/g from 50 mg/L of synthetic metal solution in 60 minutes of contact time at pH = 6.0 and 28 °C with continuous stirring at 180 rpm. The percent sorption of the biomass decreased with increasing concentration of metal ion but increased with decreasing pH, increasing contact time and adsorbent doses. Data for this study indicated a good correspondence with both isotherms of Langmuir and Freundlich isotherm. The analysis of kinetic indicated that Chromium was consistent with the second-order kinetic adsorption model. The rate of removal of Cr(III) ions from aqueous solution by JSP was found rapid initially within 5-30 minutes and reached in equilibrium in about 40 minutes. The investigation revealed that JSP, a low cost agricultural byproduct, was a potential adsorbent for removal of heavy metal ions from aqueous solution.

Kinetics, isotherm, and optimization of the hexavalent chromium removal from aqueous solution by a magnetic nanobiosorbent.

Sorption is the most effective approach to the treatment of acid mine drainage (AMD) and wastewaters, but the removal of the adsorbents from water has always been a challenging problem which may be resolved by using magnetic separation. In this work, a magnetic bioadsorbent was prepared using low cost and high-performance sources and applied in Cr(VI) removal from a synthetic solution. Initially, magnetite nanoparticles were synthesized from iron boring scraps by chemical co-precipitation method. Results of dynamic light scattering (DLS) and vibrating sample magnetometry (VSM) analyses showed that the synthesized nanoparticles were around 40nm in size and had a significant magnetization. Then, the magnetite nanoparticles were attached to the dead and alkaline activated biomass of Aspergillus niger. Central composite design (CCD) was applied to determine the optimal condition of Cr(VI) adsorption on the produced magnetic nanobiocomposite. The maximum chromium removal (~ 92%) was achieved at pH 5.8, Cr concentration 23.4mg/l, adsorbent dose 3.72g/l, agitation rate 300rpm, and duration 11min. Kinetic studies showed that regardless of temperature, the process was controlled by mass transfer and intraparticle diffusion with an equilibrium constant of 0.74mg/gmin1/2 at 40°C. Also, the adsorption isotherms followed the Temkin model, which indicated the physical adsorption of Cr(VI) on the produced sorbent. Therefore, the magnetic nanobiocomposite has a perfect ability to be used as the chromium adsorbent and can be collected by a low external magnetic field. Graphical abstract Synthesis of the magnetic nanobiosorbent and its application in the removal of Cr(VI) from wastewaters.

Emulsion breakage behaviour on chromium (VI) removal using emulsion liquid membrane containing quaternary ammonium compounds

Environmental pollution caused by heavy metals such as chromium, nickel, and lead has become a serious worldwide issue due to their threats to humans, animals and plants as well as to the stability of the overall ecosystem. Its removal from effluents such as electroplating rinse wastewater and tannery effluents is of primordial importance. In this study, the emulsion liquid membrane (ELM) technology was employed as a remediation technique that capable of removing Cr (VI) efficiently from wastewater where extraction and stripping processes are performed in a single operation. The ELM is consists of trioctylmethylammonium chloride (Alamine 336) as an extractant, palm oil as an organic diluent, sodium hydroxide (NaOH) as a stripping solution and sorbitan monooleate (Span-80) as a surfactant to stabilize the emulsion phase. The effect of operational parameters such as the agitation speed, phase contact time, extractant concentration and stripping agent concentration were studied to optimize the conditions for emulsion stability and maximum removal of chromium. The best removal efficiency was obtained at 350 rpm of agitation speed and 3 minutes of phase contact time with 0.04 M Alamine 336 as extractant and 0.1 M NaOH as stripping agent. In this condition, the maximum removal efficiency of 100% was obtained with a minimum breakage rate of 5%.

Improved removal of hexavalent chromium from 10 mg/L solution by new micron sized polymer clusters of aniline formaldehyde condensate

Removal of hexavalent chromium by aniline-formaldehyde condensate polymer coated on silica gel, in the past, showed poor removal at low concentration range with high adsorbent dose (∼30% removal at 10 mg/L with a adsorbent dose of 8 g/L). We have now synthesized a new form of the support less polymer which brings down residual concentration to less than 1 mg/L with a 2 g/L dose. The maximum removal of total chromium was observed between pH 3–8 (94–98% removal at 2 g/L dose). Removal is susceptible to processing of the polymer and batch to batch variation has been observed. Field emission scanning Electron microscope (FESEM) showed polymer consists of micron-sized (1–2 µm diameter) clusters. Phosphate and nitrate strongly inhibited total chromium uptake while effect of sulphate and chloride were less. Desorption was 86% with 1 N HCl and reuse of the micron sized AFC was possible for four cycles. Ion exchange as well as redox interaction between chromate ion and protonated amine group of polymer was found to be the key factor for adsorption.

Removal of Cr (III) and Ni (II) from tannery effluent using calcium carbonate coated bacterial magnetosomes

Heavy metal contamination of surface water bodies and ground water has been a major problem around the world. Calcium-based adsorbents are effective but cannot be separated easily after the treatment. Magnetosomes are biogenic magnetite synthesised as highly ordered chain-like structures by magnetotactic bacteria. In this study, we have prepared magnetically controlled calcite microcrystals using magnetosomes for the adsorption experiment. The ability of magnetic calcite as adsorbent was investigated for the removal of Cr (III) and Ni (II) ions from synthetic solution. Critical parameters, such as the effect of pH, temperature, contact time, initial ion concentration, and adsorbent dose, were optimised in comparison with calcite, magnetosomes, and activated carbon for maximum metal ion removal. The study showed that equilibrium was established in 1 h for both Cr (III) and Ni (II) at a pH of 6.0 and 8.0, respectively. The adsorption process follows pseudo-second-order reaction kinetics, along with Langmuir and Freundlich adsorption isotherms. The thermodynamics of adsorption of both metal ions on magnetic calcite showed that the adsorption was spontaneous and endothermic in nature. Magnetically controlled calcite crystals successfully removed Cr (III) and Ni (II) from collected tannery effluent and separated from the solution by applying magnetic field. Maximum removal of chromium and nickel (94 and 84%) by magnetic calcite is similar to calcite crystals but higher than magnetosomes and activated carbon. The results indicated that magnetic calcite could be used as an alternative adsorbent for removing heavy metals from tannery effluent.

Assessment on removal efficiency of chromium by the isolated manglicolous fungi from Indian Sundarban mangrove forest: Removal and optimization using response surface methodology

Abstract The use of heavy metals in industries has increased recently. The effluents discharged from these industries are causing pollution on the surrounding environment and also causes wide spread damage. Fungi being an efficient mycosystem can treat these heavy metals successfully. In this study, Aspergillus sp. was isolated from soil from the Sunderban mangrove forest, West Bengal and was used in removing chromium (VI) from the aqueous solution. The parameters are optimized for enhancing the removal capacity of fungus to treat the chromium solution. This optimization process was done by single parameter optimization i.e., by taking different cultural media, inoculum volume % (0.5, 1, 2, 3) , pH (2, 3, 4, 6, 7, 9), temperature (20oC , 27oC, 37oC) and by using Response Surface Methodology (RSM) software to know the inter parameter interactions among the selected parameters and to optimize the parameters by which maximum removal of Chromium (VI) is obtained. It was observed that 98.96% removal was obtained using the isolated species and also observed that RSM optimization can better represent the experimental results.

Statistical analysis of the removal of Chromium(VI)by Iron Oxide Nanoparticle (Fe3O4)

Investigation of the adsorption of Chromium (VI) on Fe3O4 is carried out using batch scale experiments according to statistical design using a software program minitab17 (Box-Behnken design). Experiments were carried out as per Box-Behnken design with four input parameters such as pH (2-8), initial concentration (50–150mg/L), adsorbent dosage (0.05–0.3 g) and time of adsorption (10–60min). The better conditions were showed at pH: 2; contact time: 60 min; chromium concentration: 50 mg/L and magnetite dosage: 0.3 g for maximum Chromium (VI) removal of (98.95%) with an error of 1.08%. The three models (Freundlich, Langmuir, and Temkin) were fitted to experimental data, Langmuir isotherm has better described the adsorption process. Whereas, the kinetics results of the adsorption process obeyed the pseudo-second-order.

Optimization of chromium and tannic acid bioremediation by Aspergillus niveus using Plackett\u2013Burman design and response surface methodology

A chromium and tannic acid resistance fungal strain was isolated from tannery effluent, and identified as Aspergillus niveus MCC 1318 based on its rDNA gene sequence. The MIC (minimum inhibitory concentration) of the isolate against chromium and tannic acid was found to be 200 ppm and 5% respectively. Optimization of physiochemical parameters for biosorption of chromium and tannic acid degradation was carried out by Plackett–Burman design followed by response surface methodology (RSM). The maximum chromium removal and tannic acid degradation was found to be 92 and 68% respectively by A. niveus. Chromium removal and tannic acid degradation was increased up to 11 and 6% respectively after optimization. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) was used to investigate biosorption phenomena.

Studies on adsorption behavior of an industrial waste for removal of chromium from aqueous solution

An investigation on the adsorption characteristics of an industrial waste (Dolochar) for removal of Cr (VI) from aqueous solutions was studied varying various parameters such as contact time, adsorbent dose, adsorbate concentration, pH. The study was conducted varying contact time, adsorbent dose, adsorbate concentration, pH from 0 to 70 min, 10–25 g/l, 10–50 mg/l and 2 to 7.5 respectively. The results of this study showed that adsorption of chromium by dolochar reached to equilibrium after 60 min and after that a little change of chromium removal efficiency was observed. Maximum chromium removal (≈95%) was obtained at pH of 2 for adsorbent and adsorbate dose of 20 g/l and 10 mg/l respectively. The obtained results showed that the adsorption of chromium (VI) follows Langmuir isotherm equation with a correlation coefficient equal to 0.997. In addition, the kinetics of the adsorption process follows the pseudo second-order kinetics model with a rate constant value of 0.821 min−1. Further, the potential of dolochar for the removal of heavy metal was evaluated in a fixed-bed column at bed depth of 2.5 cm with initial concentration of 10 mg/l. The breakthrough time and exhaust time were found to be 19.5 h and 90 h respectively. Total volume of water treated during the exhaust time was 23 L. The results indicate that this industrial waste can be employed as a low cost alternative to commercial adsorbents for removal of chromium (VI) from water and wastewater.

Adsorption on activated carbon derived from tannery fleshing waste: Adsorption isotherms, thermodynamics, and kinetics

Fleshings, an abundant protein source are disposed in large quantity as a solid tannery wastes. Herein, an approach for complete utilization of pre‐treated fleshing waste has been developed to obtain functional rich activated carbon, which can be used as bio‐adsorbent for the removal of chromium(VI) from aqueous solution. In this study, Functional rich Fleshing Waste Activated Carbon (FWAC) was characterized by Thermogravimetric analysis (TGA), (Brunauer–Emmett–Teller) BET, Fourier Transform Infrared Spectroscopy (FT‐IR) and (Scanning Electron Microscope) SEM analysis. The thermal and FT‐IR studies showed innovative functionalities with superior physico‐chemical properties. The functional rich bio‐adsorbent provided greater opportunity to utilise this material as an adsorbent for trapping toxic metal ions. The maximum adsorption capacity of functional rich bio‐adsorbent was found to be 60.8 mg g−1. Effect of pH, temperature, adsorbent dose and metal ion concentration on adsorption of metal ions were thoroughly investigated also the kinetics and thermodynamic study were carried out. The maximum removal of chromium was obtained at pH 3 with ≥97% for about 0.5 g adsorption dose of 100 mg L−1 initial concentration. The fleshings dealt out as solid tannery wastes, now provides ample solution for ecological crisis of toxic chromium(VI). © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1725–1733, 2017

Optimization of Chromium Biosorption by Fungal Adsorbent, Trichoderma sp. BSCR02 and its Desorption Studies

Heavy metal pollution in water because of the discharge of industrial effluent imposes serious environmental concern. Chromium is one of such pollutants which is considered as toxic, non-biodegradable and persistent in nature. In the present study, the fungal strains isolated from the water samples of Manjakkudi lake were screened for their resistance towards the heavy metal, chromium. The Trichoderma sp. BSCR02 showing resistance towards increased chromium concentration (4 mg/mL) was selected for the biosorption studies. The chromium biosorption ability of the untreated and alkali-treated mycelium of Trichoderma sp. BSCR02 was compared and found the alkali treatment as better biosorbent. The process parameters governing chromium biosorption by the dead biomass of Trichoderma sp. were optimized and maximum chromium removal was observed at pH 5 with 200 mg/L initial metal concentration at 35°C when supplemented 1.6 mg/mL of biosorbent for the contact time of 120 min. The biosorbent was found to be active for five cycles of biosorption. The results revealed the applicability of the Trichoderma sp. BSCR2 for the effective removal of chromium from the contaminated water bodies.

Comparison of fast elimination of Cr(VI) by alumina nanofiber and alumina nanoporous

The goal of this study is examination of the mixture between adsorption and permeation process for removing chromium (VI) from the water. Two types of supported membranes are developed: The first one which was made by sol–gel method is called nanoporous and the second one which was made by electrospinning is called nanofiber. The sorption capacity of nanoporous and nanofiber is examined in single batch experiments at various pH values, and it is found that maximum chromium removal is observed for both nanoporous and nanofiber at pH 3.5. Adsorption studies illustrated that the Cr(VI) adsorption onto alumina nanoporous and nanofiber is affected by changes in pH, contact time, dosage of adsorbent, concentration of chromium and solution volume. Langmuir and Freundlich isotherms can be used to explain the adsorption equilibria of Cr(VI) onto alumina nanoporous and nanofiber. It was found that balance adsorption data adequate Langmuir isotherm more than Freundlich model. Adsorption kinetics was found to be fitted to pseudo-second order and Weber and Morris model. The output of multiple linear regressions was run for the second-order response surface model implied that the linear agents of pH, sorbent dosage and Cr(VI) concentration are more significant factors. Manufacturing electrospun alumina nanofiber and sol–gel nanoporous with these cheap materials, renewable and fast methods are so important although the removal percentage is significant.

Removal of chromium from synthetic wastewater using MFI zeolite membrane supported on inexpensive tubular ceramic substrate

A mordenite framework inverted (MFI) type zeolite membrane was produced on inexpensive tubular ceramic substrate through hydrothermal synthesis and applied for the removal of chromium from synthetic wastewater. The fabricated ceramic substrate and membrane was characterized by diverse standard techniques such as X-ray diffraction, field emission scanning electron microscope, porosity, water permeability and pore size measurements. The porosity of the ceramic substrate (53%) was reduced by the deposition of MFI (51%) zeolite layer. The pore size and water permeability of the membrane was evaluated as 0.272 μm and 4.43 × 10–7 m3/m2s.kPa, respectively, which are lower than that of the substrate pore size (0.309 μm) and water permeability (5.93 × 10–7 m3/m2s.kPa) values. To identify the effectiveness of the prepared membrane, the applied pressure of the filtration process and initial chromium concentration and cross flow rate were varied to study their influence on the permeate flux and percentage of removal. The maximum removal of chromium achieved was 78% under an applied pressure of 345 kPa and an initial feed concentration of 1,000 ppm. Finally, the efficiency of the membrane for chromium removal was assessed with other membranes reported in the literature.