Insights into engineered graphitic carbon nitride quantum dots for hazardous contaminants degradation in wastewater.

Increased environmental pollution is a critical issue that must be addressed. Photocatalytic, adsorption, and membrane filtration methods are suitable in environmental governance because of their high selectivity, low cost, environment-friendly nature, and excellent treatment efficiency. Graphitic carbon nitride (g-C3N4) quantum dots (QDs) have been considered as photocatalysts, adsorbents, and membrane materials for wastewater treatments, owing to their stability, adsorption capacity, photochemical properties, and low toxicity and cost. This review summarizes g-C3N4 QD synthesis techniques, operating parameters affecting the removal performance in the treatment process, modification effects with other semiconductors, and benefits and drawbacks of g-C3N4 QD-based materials. Furthermore, this review discusses the practical applications of g-C3N4 QDs as adsorbents, photocatalysts, and membrane materials for organic and inorganic contaminant treatments and their value-added product formation potential. Modified g-C3N4 QD-based material adsorbents, photocatalysts, and membranes present potentially applicable effects, such as removal of most waterborne contaminants. Excellent results were obtained for the reduction of methyl orange, bisphenol A, tetracycline, ciprofloxacin, phenol, rhodamine B, E. coli, and Hg. Overall, this paper provides comprehensive background on g-C3N4 QD-based materials and their diverse applications in wastewater treatment, and it presents a foundation for the enhancement of similar unique materials in the future.

New dithiocarbamate-based polymer (DTCP) as an additive to improve microporous polysulfone membrane efficiency in lead and dye removal.

For fabricating a membrane with hydrophilic and complexing agent groups, a new dithiocarbamate-based polymer (DTCP) containing dithiocarbamate, thioamide, and ethereal oxygen groups was synthesized and blended in polysulfone (PSF) matrix with 1, 2, 5, and 10 wt% proportion. The membranes were produced by the nonsolvent induced phase separation method. For DTCP characterization, NMR, FTIR, TGA and GPC techniques were used. SEM images show that no morphological change can be seen even in 10 wt% blended membranes. AFM surface images show that the roughness of 5 and 10 wt% membranes extremely increased. The performance of the DTCP/PSF membranes were investigated in the separation of lead ions and Reactive Yellow 39 dye from the contaminated water. The outcomes indicated that by increasing the amount of DTCP up to 10 wt%, the pure water flux, bovine serum albumin flux, and the lead removal increased very efficiently compared to the bare one. Blending of more than 1 wt% DTCP, cause to removal of 99.6% lead ions. The water contact angle decreased by the adding of DTCP, caused to increase fouling resistance. The results of this research shows that the synthesized DTCP can be used as a good additive for improving membrane permeability, anti-fouling and especially heavy metal removal efficiency.

Modification of reinforced hollow fiber membranes with WO3 nanosheets for treatment of textile wastewater by membrane bioreactor.

In this study, performance of braid reinforced hollow fiber membrane containing polyvinylidene fluoride (PVDF) embedded with tungsten trioxide (WO3) nanosheets in a membrane bioreactor (MBR) was examined for textile wastewater treatment. The WO3 nanosheets was synthesized and blended at different concentrations (0.1-0.02 wt%) in casting solutions of the membranes. The WO3 nanosheets characterized using various tests such as XRD, FTIR, SEM, EDS, dot-mapping, and TEM. Furthermore, the effects of the increased WO3 nanosheets into the PVDF matrix on the membrane morphology, hydrophilicity, permeability, antifouling, and COD and color removal efficiency was investigated. The addition of 0.1 wt% of the nanosheets reduces the water contact angle from 69.3° to 62.5° while increasing overall porosity from 37.5 to 43.2%. COD and color removal for PVDF/0.10 wt% WO3 membrane was between 86-89% and 72-76%, respectively. While the TMP of modified WO3 membranes did not significantly increase due to antimicrobial properties of the WO3 nanosheets, the TMP of the pure PVDF membrane increase, indicating considerable cake layer fouling. The results of this study showed that modification of PVDF braid reinforced hollow fiber membrane using WO3 nanosheets is promising membrane for MBR systems.

Optimization of Coagulation-Flocculation Process in Efficient Arsenic Removal from Highly Contaminated Groundwater by Response Surface Methodology.

Elevated arsenic (As) contamination in water, especially groundwater, has been recognized as a major problem of catastrophic proportions. This work explores As(V) removal via the coagulation-flocculation process by use of ferric chloride coagulant and polyacrylamide k16 co-coagulant as a first time. The effects of major operating variables such as coagulant dosing (50, 125 and 200 mg/L), co-coagulant dosing (5, 12.5 and 20 mg/L), pH (6, 7and 8), fast mixing time (1, 2 and 3 min), and fast mixing speed (110, 200 and 300 rpm) on As(V) removal efficiency were investigated by a Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM). According to factors F values, coagulant dosing, rapid mixing speed, pH, and co-coagulant dosing showed the most effect on As(V) removal efficiency, and the rapid mixing time factor indicated the slightest effect. The proposed quadratic model was significant with a p value < 0.0001 and has satisfactorily described the experimental data with R2 and adjusted R2 values of 0.9855 and 0.9738, respectively. Predicted model optimal conditions with target of complete As(V) removal were coagulant dosing = 197.63 ppm, co-coagulant dosing = 19.55 ppm, pH = 7.37, fast mixing time = 1.43 min and fast mixing speed = 286.77 rpm. The treatment of Nazarabad well water sample with an initial As(V) concentration of 5 mg/L under the optimal conditions removed 100% As(V) with the volume of produced sludge of 10.7 mL/200 mL. Increasing coagulant dosing, co-coagulant dosing, fast mixing time and fast mixing speed operation parameters from low-level to high-level values indicated 78%, 20%, 10.52% and 9.47% increases in volume of the produced sludge, respectively. However, a reduction of 13.63% in volume of the produced sludge resulted via pH increases.

Fabrication of chitosan-aminopropylsilane graphene oxide nanocomposite hydrogel embedded PES membrane for improved filtration performance and lead separation.

In the present study chitosan-aminopropylsilane graphene oxide (CS-APSGO) nanocomposite hydrogel was synthesized and utilized as a hydrophilic additive in different dosages (0.5, 1, 2 and 5 wt%) in fabrication of porous polyethersulfone (PES) membranes via the phase inversion induced process by immersion precipitation method for heavy metal ion and dye removal. The modified membranes were characterized using ATR-FTIR, AFM, SEM, water contact angle, overall porosity and mean pore radius evaluations and zeta potential measurement. The addition of CS-APSGO nanocomposite hydrogel to PES doping solutions enhanced membranes hydrophilicity and consequently pure water flux permeability. Filtration performance of the CS-APSGO embedded membranes showed promising antifouling properties during BSA filtration test (FRR> 90%) and 1 wt% membranes showed the highest pure water flux of 123.8 L/m2 h with BSA rejection more than 98% and removal capability more than 82% for lead (II) ion, 90.5% and 98.5% for C.I. Reactive Blue 50 and C.I. Reactive Green 19, respectively. Therefore, the CS-APSGO nanocomposite hydrogel blending in order to modification of PES-based membranes have a noticeable potential in improving filtration performance of blended membranes.

Improvement of polyvinyl chloride nanofiltration membranes by incorporation of multiwalled carbon nanotubes modified with triethylenetetramine to use in treatment of dye wastewater.

Multiwalled carbon nanotubes modified with triethylenetetramine (TETA) as an organic nanofiller was used in fabrication of polyvinyl chloride (PVC) nanofiltration membranes. The membranes were prepared by the phase separation method and immersion precipitation technique. For this purpose, various percentages of the TETA-MWCNTs were added to the casting solutions and the membrane films were formed and placed in a bath water. In order to identify the membranes and their properties, SEM images, contact angle and FTIR-ATR analyses were taken from the prepared nanocomposite membranes. The membranes performance in terms of water/protein/dye permeability, protein rejection and Lanasol blue 3R dye rejection were investigated. Establishing hydrogen bond between the water molecules and the functional groups of MWCNTs enhanced the hydrophilicity of the fabricated membranes and caused an increase in permeability. The permeability in the membrane containing 0.25 wt% of TETA-MWCNTs reached its highest value, and adding more amounts reduced flux by blocking the membrane pores. There was also a significant decrease in the rate of membrane fouling for the hybrid membranes. Flux recovery ratio reached from 62.2% to 76.1%. Also, rejection of BSA and Lanasol blue 3R combination dye was increased for the modified membranes.

Surface Bioengineering of Mo2Ga2C MAX Phase to Develop Blended Loose Nanofiltration Membranes for Textile Wastewater Treatment.

The potential of blended loose nanofiltration membranes (LNMs) to fractionate dyes and inorganic salts in textile wastewater has become a focus of attention in recent years. In this research work, we fabricated LNMs based on polysulfone (PSf) membranes blended with l-histidine amino acid-functionalized Mo2Ga2C MAX phase (His-MAX). Scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), contact angle, ζ-potential, porosity, and pore size analyses were employed to characterize the LNMs. Blending 0.75 wt % of His-MAX additive with the PSf tailored the LNM's features by making it more water-friendly, increasing its porosity, enlarging its pores, and making its surface smoother. The pure water flux of 127.6 L/m2 h was achieved by LNM containing 0.75 wt % His-MAX, which was 2.5 times greater than the bare one. The mentioned LNM displayed a flux recovery ratio (FRR) of 68.27 and 98.57, 98.31, and 99.7% rejections for Direct red 23, Acid brown 75, and Reactive blue 21 solutions (100 mg/L), respectively. The 0.75 wt % His-MAX LNM could reject 99.1% of dye and 11.5% of salt while maintaining an FRR of 91.19% after four cycles of filtering a binary mixture solution containing Reactive blue 21 and Na2SO4. These findings highlight the potential of the fabricated LNM for desalinating dye solutions.

Recent Progress on Synthesis and Properties of Black Phosphorus and Phosphorene As New-Age Nanomaterials for Water Decontamination.

Concerted efforts have been made in recent years to find solutions to water and wastewater treatment challenges and eliminate the difficulties associated with treatment methods. Various techniques are used to ensure the recycling and reuse of water resources. Owing to their excellent chemical, physical, and biological properties, nanomaterials play an important role when integrated into water/wastewater treatment technologies. Black phosphorus (BP) is a potential nanomaterial candidate for water and wastewater treatment, especially its monolayer 2D derivative called phosphorene. Phosphorene offers relative adjustability in its direct bandgap, high charge carrier mobility, and improved in-plane anisotropy compared to the most extensively studied 2D nanomaterials. In this study, we examined the physical and chemical characteristics and synthetic processes of BP and phosphorene. We provide an overview of the latest advancements in the main applications of BP and phosphorene in water/wastewater treatment, which are categorized as photocatalytic, adsorption, and membrane filtration processes. Additionally, we explore the existing difficulties in the integration of BP and phosphorene into water/wastewater treatment technologies and prospects for future research in this field. In summary, this review highlights the ongoing necessity for significant research efforts on the integration of BP and phosphorene in water and wastewater applications.

Preparation of mixed matrix self-cleaning membrane incorporated by Z-scheme heterostructure via robust engineering in terms of dimension for decreasing cake fouling in a cross-flow reactor.

Reducing irreversible fouling in polymer membranes by integrating photocatalytic and membrane processes as the self-cleaning photocatalytic membrane is a promising candidate for improving membrane filtration performance. In this study, mixed matrix photocatalytic membranes were prepared from the combination of different morphologies ZnO-g-C3N4 heterostructure in the polymer matrix by the phase-separation method. To investigate the self-cleaning and performance properties of mixed matrix photocatalytic membranes prepared from different morphologies heterostructures, the photocatalytic membrane reactor with a visible-light source was applied. Nanoflower/nanosheet (NF/NS) ZnO-g-C3N4 photocatalytic membrane showed good self-cleaning performance owing to the high photocatalytic performance of NF/NS ZnO-g-C3N4 heterostructure by the reduction of irreversible membrane fouling, thus improving the antifouling and filtration performance of the membrane. Also, the morphology and the uniform distribution of the NF/NS ZnO-g-C3N4 heterostructure in the membrane matrix caused good hydrophilic properties, high porosity, and a more symmetrical structure in the (NF/NS) ZnO-g-C3N4 photocatalytic membrane (F4). For the F4 membrane, the permeability and rejection values increased from 40.35 L m-2 h-1 and 90.9% in the dark environment to 84.37 L m-2 h-1 and 97.4% under visible-light for dye pollutants. Accordingly, F4 had the best filtration and self-cleaning performance, which can be used as a promising visible-light photocatalytic membrane in wastewater treatment processes.

pH-responsive membranes: Mechanisms, fabrications, and applications.

Understanding the mechanisms of pH-responsiveness allows researchers to design and fabricate membranes with specific functionalities for various applications. The pH-responsive membranes (PRMs) are particular categories of membranes that have an amazing aptitude to change their properties such as permeability, selectivity and surface charge in response to changes in pH levels. This review provides a brief introduction to mechanisms of pH-responsiveness in polymers and categorizes the applied polymers and functional groups. After that, different techniques for fabricating pH-responsive membranes such as grafting, the blending of pH-responsive polymers/microgels/nanomaterials, novel polymers and graphene-layered PRMs are discussed. The application of PRMs in different processes such as filtration membranes, reverse osmosis, drug delivery, gas separation, pervaporation and self-cleaning/antifouling properties with perspective to the challenges and future progress are reviewed. Lastly, the development and limitations of PRM fabrications and applications are compared to provide inclusive information for the advancement of next-generation PRMs with improved separation and filtration performance.

Performance improvement of polyethersulfone membranes with Ti3AlCN MAX phase in the treatment of organic and inorganic pollutants.

In this work, the hydrophobic polyethersulfone (PES) membrane was modified by incorporating Ti3AlCN MAX phase. Synthesis of Ti3AlCN MAX phase was performed using the reactive sintering method. The scanning electron microscopy (SEM) images showed a 3D compressed layered morphology for the synthesized MAX phase. The Ti3AlCN MAX phase was added to the casting solution, and the mixed-matrix membranes were fabricated by the non-solvent induced phase inversion method. The performance and antifouling features of bare and modified membranes were explored by pure water flux, flux recovery ratio (FRR), and fouling resistance parameters. Through the modification of membranes by introducing the Ti3AlCN MAX phase, the enhancement of these features was observed, in which the membrane containing 1 wt% of MAX phase showed 17.7 L/m2.h.bar of permeability and 98.6% for FRR. Also, the separation efficiency of all membranes was evaluated by rejecting organic and inorganic pollutants. The Ti3AlCN MAX membranes could reject 96%, 95%, and 88% of reactive blue 50, Rose Bengal, and azithromycin antibiotics, respectively, as well as 98%, 80%, 86%, and 36% of Pb2+, As5+, Na2SO4, and NaCl, respectively. Finally, the outcomes indicated the Ti3AlCN MAX phase was an excellent and efficient novel additive for modifying the PES membrane.

Modification of PAN electrospun nanofiber membranes with g-C3N4 nanotubes/carbon dots to enhance MBR performance.

This study is dedicated to the enhancement of electrospun polyacrylonitrile (PAN) nanofiber membranes for their application in membrane bioreactor (MBR) processes. The improvement is achieved through the incorporation of graphitic carbon nitride nanotubes/carbon dots (g-C3N4 NT/CDs) and subsequent heat post-treatments at varying temperatures. Notably, the hot-pressing methodology effectively mitigates surface roughness and significantly reduces issues related to peeling during nanofiber experimentation. Our results demonstrate that the introduction of 0.5 wt% of g-C3N4 NT/CDs leads to a substantial enhancement in water flux. In particular, nanocomposite membranes subjected to hot-pressing at 90 °C for 10 min exhibited an impressive flux recovery ratio (FRR) of 70%. Furthermore, the heat-treated nanocomposite membranes exhibited remarkable antifouling properties and significantly reduced fouling rates when compared to their heat-treated bare counterparts. This study underscores the noteworthy potential of g-C3N4 NT/CDs-modified PAN nanofiber membranes to substantially elevate MBR performance, firmly positioning them as highly promising candidates for critical applications in the domains of water and wastewater treatment. However, it is imperative to underscore that the existing written material necessitates a comprehensive overhaul to align with the provided structural framework.

Antifouling thin-film nanocomposite NF membrane with polyvinyl alcohol-sodium alginate-graphene oxide nanocomposite hydrogel coated layer for As(III) removal.

Removal of As(III) from the polluted waters is a challenge. It should be oxidized to As(V) for increasing its rejection by RO membranes. However, in this research, As (III) is directly removed by a high permeable and antifouling membrane prepared through the surface coating and in-situ crosslinking procedure of polyvinyl alcohol (PVA) and sodium alginate (SA) as coating materials containing graphene oxide as a hydrophilic additive on a polysulfone support with glutaraldehyde (GA) chemical crosslinking agent. The properties of the prepared membranes were evaluated through contact angle, zeta potential, ATR-FTIR, SEM, and AFM. The addition of GO in the polymeric networks of SA and PVA hydrogel coating layers led to a better hydrophilicity and a smoother surface and a higher negative surface charge resulted in improvment of permeability and rejection of membranes. Among the prepared hydrogel-coated modified membranes, SA-GO/PSf indicated the highest pure water permeability (15.8 L m-2 h-1 bar-1) and BSA permeability (9.57 L m-2 h-1 bar-1), respectively. The best desalination performance (NaCl, MgSO4, and Na2SO4 rejections of 60.0%, 74.5%, and 92.0%, respectively) and As(III) removal (88.4%) along with satisfactory stability and reusability in cyclic continuous filtration was reported for PVA-SA-GO membrane. In addition, the PVA-SA-GO membrane indicated improved fouling resistance toward BSA foulant with the lowest flux decline of 7%.

Evaluation the feasibility of using clinoptilolite as a gravel pack in water wells for removal of lead from contaminated groundwater.

The ability of clinoptilolite zeolite as a filter in water wells to remove lead from polluted groundwater was tested in batch and fixed-bed column experiments. XRF, XRD, SEM, and BET were used to characterize the zeolite. Because of the pH variation in groundwater, batch experiments were performed at pH = 6, 7, and 8, with the highest removal efficiency (84.2%) at pH = 6 and 298 K within 90 min. The Freundlich model accurately predicted metal ion adsorption behavior and indicated a multilayer adsorption of Pb(II) molecules on the inhomogeneous surface of clinoptilolite. The best-fitting kinetic model for clinoptilolite is the pseudo-second order equation, highlighting that the rate of adsorption is dependent on absorbent capacity. Next, the effect of flow rate, bed depth, and grain size of clinoptilolite on lead removal was investigated in column experiments at an initial concentration of 450 mg pb/L. The highest removal efficiency was achieved in column experiments with a flow rate of 1 mL/min, a bed height of 10 cm, and a grain size of 0.6 to 0.8 mm. Breakthrough curves were predicted by the Thomas and Yoon-Nelson models, with excellent agreement with the corresponding experimental data. This research will be used to develop a new in situ remedial approach for removing lead from polluted groundwater.

A review of cellulose-based derivatives polymers in fabrication of gas separation membranes: Recent developments and challenges.

Due to low-cost, sustainability and good mechanical stability, cellulose-based materials are frequently used in fabrication of polymeric gas separation membrane as potential carbohydrate polymers to substitute traditional petrochemical-based materials. In this review, the performance of cellulose-based polymeric membranes i.e. cellulose acetate, cellulose diacetate, cellulose triacetate, ethyl cellulose and carboxymethyl cellulose in the separation of different gases were investigated. This review paper provides the main features and advantages in the fabrication of cellulose-based gas separation membranes. The influence of the functionalization of cellulose on gas separation and permeability performance of related membranes is considered. Influence of different modification procedures such as blending with polymers, nanomaterials and ionic liquids on the gas separation ability of cellulose-based membranes were reviewed. Moreover, a brief inquiry of the potential of cellulose-based gas separation membranes for industrial applications, by examining the performance of different cellulose derivatives and identifying potential strategies for membrane modification and optimization are given, along with the current restrictions and the future perspectives are discussed.

Membrane Fabrication and Modification by Atomic Layer Deposition: Processes and Applications in Water Treatment and Gas Separation.

Membrane-based separation processes are part of most water purification plants worldwide. Industrial separation applications, primarily water purification and gas separation, can be improved with novel membranes or modification to existing ones. Atomic layer deposition (ALD) is an emerging technique that is proposed to upgrade certain kinds of membranes independent of their chemistry and morphology. ALD deposits thin, defect-free, angstrom-scale, and uniform coating layers on a substrate's surface by reacting with gaseous precursors. The surface-modifying effects of ALD are described in the present review, followed by a description of various types of inorganic and organic barrier films and how these can be used in combination with ALD. The role of ALD in membrane fabrication and modification is categorized into different membrane-based groups according to the treated medium, i.e., water or gas. In all membrane types, the ALD-based direct deposition of inorganic materials, mainly metal oxides, on the membrane surface can improve antifouling, selectivity, permeability, and hydrophilicity. Therefore, the ALD technique can broaden the applications of membranes to the treatment of emerging contaminants in water and air. Finally, the advancement, limitations, and challenges of ALD-based membrane fabrication and modification are compared to provide a comprehensive guideline for developing next-generation membranes with improved filtration and separation performance.

Ti2NTx quasi-MXene modified polyamide thin film composite reverse osmosis membrane with effective desalination and antifouling performance.

In this study, considering the serious problem of lack of fresh water worldwide and the effectiveness of reverse osmosis (RO) membranes in water purification, we prepared improved RO membranes with two-dimensional quasi-MXene nanosheets. In this study, the MAX phase with the chemical formula of Ti2AlN was prepared through the reactive sintering route. Prosperous preparation of the MAX phase with the hexagonal crystalline structure was approved by an X-ray diffraction pattern. Compacted sheets morphology was recognized for the prepared MAX phase from transmittance electron microscopy and scanning electron microscopy micrographs. Then, Ti2NTx quasi-MXene nanosheets were prepared by selective ultrasonic-assisted exfoliation of the MAX phase. Polyamide (PA) thin-layer composite RO membranes with different weight percentages of Ti2NTx quasi-MXene were fabricated by the interfacial polymerization (IP) method. The addition of ultrasonic-assisted prepared quasi-MXene creates numerous and coherent nanochannels on the surface of the membrane. The optimum membrane with 0.01 wt% of quasi-MXene showed the highest pure water flux of 31.9 L m-2. h-1 with an improved salt rejection of 98.2%. Therefore, these nanosheets showed that they can partially solve the trade-off between water permeability and salt rejection, which is a serious challenge in RO membranes. Also, the membranes containing quasi-MXene showed good resistance against fouling by humic acid. This research can be a scalable development in making high-performance membranes.

Fabrication of the PES Membrane Embedded with Plasma-Modified Zeolite at Different O2 Pressures.

In this research, the non-thermal glow discharge plasma process was implemented to modify the surface of natural clinoptilolite zeolite before incorporation into the polyethersulfone (PES) membrane. The influence of plasma gas pressure variation on the fouling resistance and separation performance of the prepared membranes was studied. Fourier transform infrared, field emission scanning electron microscopy, and X-ray diffraction analyses of the unmodified and modified clinoptilolites revealed the Si-OH-Al bond's development during plasma treatment and the change in surface characteristics. In terms of performance, increasing the plasma gas pressure during clinoptilolite treatment resulted in the twofold enhancement of water flux from 91.2 L/m2 h of bare PES to 188 L/m2 h of the membrane containing plasma-treated clinoptilolite at 1.0 Torr pressure. Meanwhile, the antifouling behavior of membranes was improved by introducing more hydrophilic functional groups derived from the plasma treatment process. Additionally, the enhanced dye separation of membranes was indicated by the separation of 99 and 94% of reactive green 19 and reactive red 195, respectively.

Zeolitic imidazolate framework (ZIF-8) modified cellulose acetate NF membranes for potential water treatment application.

In this study, cellulose acetate (CA)-based nanofiltration membranes, modified with zeolitic imidazole framework-8 (ZIF-8) particles, were prepared with various ZIF-8 contents (0, 0.1, 0.25, 0.5, 1 and 2 wt%), to obtain membranes with improved flux and filtration performance by combining advantages of CA polymer and ZIF-8 metal-organic frameworks. Removal efficiency studies were carried out with bovine serum albumin and two different dyes, along with antifouling performance evaluation. Results of experiments disclosed that as the ZIF-8 ratio increased, the contact angle values decreased. With ZIF-8 addition, the pure water flux of the membranes increased. Besides, the flux recovery ratio value was approximately 85 % for the bare CA membrane, while it increased to above 90 % by blending ZIF-8. Also, in all ZIF-8 doped membranes, a fouling decrease was observed. Importantly, it was observed that the dye removal efficiency increased with the addition of ZIF-8 particles from 95.2 to 97.7 % for Reactive Black 5 dye.

Electrochemical-based processes for produced water and oily wastewater treatment: A review.

The greatest volume of by-products produced in oil and gas recovery operations is referred to as produced water and increasing environmental concerns and strict legislations on discharging it into the environment cause to more attention for focusing on degradation methods for treatment of produced water especially electrochemical technologies. This article provides an overview of electrochemical technologies for treating oily wastewater and produced water, including: electro-coagulation, electro-Fenton, electrochemical oxidation and electrochemical membrane reactor as a single stage and combination of these technologies as multi-stage treatment process. Many researchers have carried out experiments to examine the impact of various factors such as material (i.e, electrode material) and operational conditions (i.e., potential, current density, pH, electrode distance, and other factors) for organic elimination to obtain the high efficiency. Results of each method are reviewed and discussed according to these studies, comprehensively. Furthermore, several challenges need to be overcome and perspectives for future study are proposed for each method.