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In this study, hematite graphene oxide (αFe2O3-GO) powder nanocomposites and thin-film hematite graphene oxide (αFe2O3-GO) were synthesized for application in the removal of Rhodamine B (RhB) from textile wastewater. αFe2O3-GO nanomaterials were placed onto the FTO substrate to form a thin layer of nanocomposites. Different analysis including XRD, FTIR, Raman spectra, XPS, and FESEM were done to analyze the morphology, structure, and properties of the synthesized composites as well as the chemical interactions of αFe2O3 with GO. The photocatalytic performance of two synthesized composites was compared with different concentrations of αFe2O3-GO. The results showed that powder nanocomposites are more effective than thin-film composites for the removal of RhB dye. αFe2O3-GO-5% powder nanocomposites removed over 64% of dye while thin-film nanocomposites had less removal efficiencies with just under 47% removal rate. The reusability test was done for both materials in which αFe2O3-GO-5% powder nanocomposites removed a higher rate of dye (up to 63%) in more cycles (6 cycles).

Waste cooking oil (WCO) appears to be a potential carbonaceous source for the synthesis of graphene sand composite (GSC) adsorbent in removing pollutants. This study presents a green synthesis method of GSC using WCO as a sustainable carbon source for the synthesis of GSC through the thermal graphitization method. Characterization analysis conducted on GSCWCO verified the successful coating of WCO onto sand surface and conversion to graphene, which possessed distinct functional groups and features of graphene materials. GSCWCO adsorbent effectiveness in removing Congo Red dye through batch adsorption was studied under the influence of different initial concentrations, and the optimum pH, contact time, and temperature were investigated. The highest pollutant removal was achieved at an initial dye concentration of 20 mg L-1, 1.0 g of adsorbent dosage, a temperature of 25℃, and 150 min of contact time. The GSCWCO exhibited the maximum capacity of 5.52 mg g-1, was well-fitted to the Freundlich isotherm model, and had an adsorption mechanism that followed the pseudo-second-order kinetic model. The regeneration of GSCWCO adsorbent declined after four cycles, possibly due to the chemisorption of dyes with GSC that resulted in inefficient adsorption. Being a waste-to-wealth product, GSCWCO possessed a great potential to be used for water treatment and simultaneously benefited the environment through the effort to reduce the excessive discharge of WCO.

Sugar molasses from agricultural waste could be a sustainable carbon source for the synthesis of graphene adsorbent introduced in this work. The sugar molasses was successfully converted to graphene-like material and subsequently coated on the sand as graphene sand composite (GSC), as proven by XRD, XPS, Raman spectroscopy, and SEM with EDX mapping analyses. The adsorption performance of GSC was evaluated against the removal of Tetracycline (TC) and methylene blue (MB) pollutants from an aqueous solution in a fixed bed column continuous-flow adsorption setup. The effect of different process conditions: bed height (4-12 cm), influent flow rate (3-7 mL/min), and contaminants' concentration (50-150 ppm) was investigated. The results revealed that column performance was improved by increasing the bed depth and lowering the flow rate and concentration of the pollutants. The best removal efficiency was obtained when the bed height was 12 cm, the influent flow rate of 3 mL/min, and the pollutants' initial concentration was 50 mg/L. Thomas, Adams-Bohart, and Yoon-Nelson models were attempted to fit the breakthrough curves. Regeneration of the GSC indicated the decline of breakthrough time from 240-280 to 180 min, reflecting the decrease in adsorptive sites due to the incomplete regeneration process. Overall, sugar molasses was shown to be a low-cost precursor for synthesizing valuable graphene material in the form of GSC, which can reduce the problem for industrial waste management of sugar molasses, and the GSC could be used as an adsorbent for environmental application.

Graphene oxide is a very high capacity adsorbent due to its functional groups and π−π interactions with other compounds. Adsorption capacity of graphene oxide, however, can be further enhanced by having synergistic effects through the use of mixed-matrix composite. In this study, silica-decorated graphene oxide (SGO) was used as a high-efficiency adsorbent to remove Congo red (CR) and Cadmium (II) from aqueous solutions. The effects of solution initial concentration (20 to 120 mg/l), solution pH (pH 2 to 7), adsorption duration (0 to 140 min) and temperature (298 to 323 K) were measured in order to optimize the adsorption conditions using the SGO adsorbent. Morphological analysis indicated that the silica nanoparticles could be dispersed uniformly on the graphene oxide surfaces. The maximum capacities of adsorbent for effective removal of Cd (II) and CR were 43.45 and 333.33 mg/g based on Freundlich and Langmuir isotherms, respectively. Langmuir and Freundlich isotherms displayed the highest values of Qmax for CR and Cd (II) adsorption in this study, which indicated monolayer adsorption of CR and multilayer adsorption of Cd (II) onto the SGO, respectively. Thermodynamic study showed that the enthalpy (ΔH) and Gibbs free energy(ΔG) values of the adsorption process for both pollutants were negative, suggesting that the process was spontaneous and exothermic in nature. This study showed active sites of SGO (π-π, hydroxyl, carboxyl, ketone, silane-based functional groups) contributed to an enormous enhancement in simultaneous removal of CR and Cd (II) from an aqueous solution, Therefore, SGO can be considered as a promising adsorbent for future water pollution control and removal of hazardous materials from aqueous solutions.

In this study, the impact of urine diversion on the treatment capacity, treatment process, and capital costs of a decentralised wastewater treatment plant (WWTP) was simulated using BioWin. The data for simulation including for economic analysis were obtained from a real decentralised WWTP at Sydney. Simulation was conducted for two alternative process design scenarios of a WWTP: membrane bioreactor (MBR) without denitrification and anaerobic MBR in place of aerobic MBR and compared to existing process design. The simulation shows that with about 75% urine diversion (through source separation), the treatment capacity of the existing WWTP can be doubled although above 40% urine diversion, the impact appears less rapid. When the urine diversion exceeds 75%, it was found that the anoxic tank for biological denitrification becomes redundant and the current wastewater treatment process could be replaced with a simpler and much less aeration intensive membrane bioreactor (MBR) producing similar effluent quality with a 24% reduction in capital expenditure (footprint) cost. Anaerobic MBR can be a potential alternative to aerobic MBR although pre-treatment becomes essential before reverse osmosis treatment for water reuse applications. Sensitivity analysis has revealed that by operating the bioreactor at higher mixed liquor suspended solids concentrations (9 g/L instead of 5 g/L) could help increase the WWTP treatment capacity by about 3.5 times at 75% urine diversion. Hence, urine diversion (until nitrogen-limiting conditions occur above 75% urine diversion) can increase the treatment capacity of an existing WWTP and reduce the capital expenses due to reduced plant footprint.

Environmental pollution has threatened the life of all living organisms on earth. The removal of pollutants from wastewater and contaminated water is desired to prevent the pollution issues from becoming worse. In this context, polymer-based nanocomposites have been developed and emerged as one of the advanced materials that can be used to solve the environmental pollution challenges. This composite material is produced by combining nanomaterials with polymers and usually appears in the form of membranes, adsorbents, hydrogels, and aerogels. These polymer-based nanocomposites possess improved characteristics and properties compared to the original individual material. Subsequently, the pollutants removal capability of the polymer-based nanocomposites has been enhanced significantly, with some even attaining new functionalities such as antibacterial and photocatalytic. This chapter features the development and application of four major classes of polymer-based nanocomposites (membrane, adsorbent, hydrogel, and aerogel) for environmental remediation. Various examples and latest findings are discussed, which provides up-to-date information for readers interested in this topic.

This project analyses water consumption data in residential college of Universiti Kebangsaan Malaysia (UKM) by eliciting the main water metre reading from each residential college. The study found that the average water consumption per student in colleges ranged above 200 litres/day, much higher than the World Health Organization’s recommended level of 165 litres/day. The high water consumption could be related to irrational use of water among the students and staff as well as water loss due to leakage. To detect the water loss in a water network, the reading of water metre during minimum night flow (MNF) time was taken between 1 a.m. and 5 a.m. From the study, it could be seen that most of the residential colleges recorded high MNF level (more than 0.97 litres/second), which indicates the presence of leakage within the water network in the college. The findings from this study indicated that the water consumption in UKM can be reduced by minimising the loss of non-revenue water and educating the people to use water moderately. Saving the water resources will help to reduce water utility bill and strengthen UKM against the threat of water crisis.

Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill effluent (An-POME). The process parameters affecting FO were studied and optimized, which were then applied to fertilizer selection based on FO performance and fouling propensity. Six commonly used fertilizers were screened and assessed in terms of pure water flux (Jw) and reverse salt flux (JS). Ammonium sulfate ((NH4)2SO4), mono-ammonium phosphate (MAP), and potassium chloride (KCl) were further evaluated with An-POME. MAP showed the best performance against An-POME, with a high average water flux, low flux decline, the highest performance ratio (PR), and highest water recovery of 5.9% for a 4-h operation. In a 24-h fouling run, the average flux decline and water recovered were 84% and 15%, respectively. Both hydraulic flushing and osmotic backwashing cleaning were able to effectively restore the water flux. The results demonstrated that FDFO using commercial fertilizers has the potential for the treatment of An-POME for water recovery. Nevertheless, further investigation is needed to address challenges such as JS and the dilution factor of DS for direct use of fertigation.

This study investigated the effect of temperature (40, 50, and 60 °C) and sample mass (100, 200, and 300 g) on the drying characteristics and product quality of Roselle calyx using heat pump dryer. It was observed that higher drying temperature and lower sample mass led to a shorter drying time (faster drying rate). Higher temperature supplied more heat to the Roselle sample, which increased the activity of water molecules and moisture diffusion. This can be seen where the effective moisture diffusivity increased from 7.87 × 10−10 to 2.05 × 10−9 m2/s when air temperature of heat pump dryer was increased from 40 ᵒC to 60 ᵒC. The drying rates for all samples shared the same drying pattern: warming-up period where the drying rate started to increase due to the breakdown of the waxy layer on Roselle and falling rate period where it decreased gradually as the drying progressed. The Roselle sample dried with heat pump dryer at 40 ᵒC (100 g) possessed the least degradation of quality, maintaining 86.8%, 63.2%, 98%, and 63.3% for color, catechin, protocatechuic acid, and vitamin C, respectively. Overall, heat pump dryer outperformed the sun drying method by recording a much shorter drying period without compromising the product quality.

Graphene oxide (GO) has gained popularity in scientific research and industry due to its superior properties, which can be controlled by the synthesis method and graphite feedstock. Despite the availability of different graphite sources, most of the reported studies used natural graphite flake (NGF) as a source of oxidation for GO synthesis. The effect of various alternative graphite feedstocks on the GO properties has not been investigated systematically. This study investigated the influence of graphite feedstock (natural and synthetic) on the characteristics and properties of GO via modified Hummer's method. Natural graphite flake (NGF), natural graphite powder (NGP), and synthetic graphite powder (SGP) were used as graphite feedstock in the study. Energy-dispersive X-ray analysis revealed that the GO produced using NGP (NGP-GO) has higher oxygen to carbon ratio in comparison to GO made from NGF (NGF-GO) and GO made from SGP (SGP-GO) (35.4, 32.7, and 32.2%, respectively), indicating higher oxidation degree for NGP-GO. Zeta potential analysis for NGP-GO, NGF-GO and SGP-GO were 47.8, ?42.6 and ?39.4 mV, respectively. Morphological analysis revealed that the structures of GO varied according to graphite feedstock, in which (NGP-GO) and (NGF-GO) were highly exfoliated (single-layered structure) while (SGP-GO) showed a multi-layered structure. Further testing was conducted by decorating silver (Ag) nanoparticles on the GO. The results showed that Ag could be uniformly decorated (no agglomeration) on the surface of GO-NGP, due to the presence of more functional groups. Subsequently, the antimicrobial property of Ag-NGP was the highest with an inhibition diameter of 14.7 - 1.2 mm (30% higher than the other samples). In conclusion, the properties of GO can be tuned by selecting the suitable graphite feedstock and this might pave the way to new developments in the GO-based applications This study was financially supported by the Grant MI-2017-002 from Universiti Kebangsaan Malaysia and NPRP-10-0127-170270 from Qatar National Research Fund (QNRF). Scopus

In this study, hematite graphene oxide (αFe2O3-GO) powder nanocomposites and thin-film hematite graphene oxide (αFe2O3-GO) were synthesized for application in the removal of Rhodamine B (RhB) from textile wastewater. αFe2O3-GO nanomaterials were placed onto the FTO substrate to form a thin layer of nanocomposites. Different analysis including XRD, FTIR, Raman spectra, XPS, and FESEM were done to analyze the morphology, structure, and properties of the synthesized composites as well as the chemical interactions of αFe2O3 with GO. The photocatalytic performance of two synthesized composites was compared with different concentrations of αFe2O3-GO. The results showed that powder nanocomposites are more effective than thin-film composites for the removal of RhB dye. αFe2O3-GO-5% powder nanocomposites removed over 64 % of dye while thin-film nanocomposites had less removal efficiencies with just under 47 % removal rate. The reusability test was done for both materials in which αFe2O3-GO-5 % powder nanocomposites removed a higher rate of dye (up to 63 %) in more cycles (6 cycles).

In the past few decades, membrane filtration has emerged as one of the most versatile separation technologies that have found widespread applications in various sectors. Among the membrane processes currently present in the market, nanofiltration (NF) membranes are expected to observe increasing interest due to their unique properties and versatility as a separation process. NF membranes typically possess a membrane pore size of 0.5–2.0 nm (corresponding to a molecular weight cutoff of 100–5000 Da), which is in between the range of ultrafiltration (UF) and reverse osmosis (RO). NF membranes also exhibit a certain level of surface charge due to the presence of a few particular functional groups on the membrane surface. These characteristics grant the NF membranes the ability to reject impurities based on two main mechanisms: electrostatic repulsion and steric hindrance. Consequently, NF membranes have found niche applications where not only it can remove the impurities that UF membranes fail to but also enjoy the benefits of having higher water flux (lower energy consumption and cost) compared to RO. Thus NF has found wide applications across different industrial sectors such as used for water and wastewater treatment, desalination, food industry, biorefinery applications, and organic solvent separation to name a few.

This chapter revises integrated and hybrid treatment processes and their application for treating a vast variety of water and wastewater sources. The design approach of these processes encompasses resources recovery and consumption, optimal performance, physical and environmental footprints, zero liquid discharge concept, and is regulation driven. Challenges and future prospects of integrated treatment process in achieving sustainable development are also denoted.

The selection of wastewater treatment (WWT) processes is normally the result of design based on technical and economic criteria. Attention should also be given to the complexity of other issues associated with the WWT plant (WWTP), such as greenhouse gas emissions, energy consumption, and land use (construction of the plant and landfill of sludge), when designing the treatment processes. All these factors and criteria should be taken into consideration for decision makers and stakeholders during the selection or design of WWT processes such that the balance between effective treatment efficiency and sustainability of the processes could be attained. To achieve this goal, contextualized sustainability criteria should be developed specifically for small- and large-scale WWTPs; urban and rural area or decentralized facilities; well-developed and developing or underdeveloped countries; and established or emerging new technologies. The importance of such sustainability criteria developed according to different scenarios is that the performance could reflect the real sustainability level of the plants.

In the present work, palm kernel shell (PKS) biomass waste has been used as a low-cost and easily available precursor to prepare carbon dots (CDs) via microwave irradiation method. The impacts of the reacting medium: water and diethylene glycol (DEG), and irradiation period, as well as the presence of chitosan on the CDs properties, have been investigated. The synthesized CDs were characterized by several physical and optical analyses. The performance of the CDs in terms of bacteria cell imaging and copper (II) ions sensing and removal were also explored. All the CDs possessed a size of 6–7 nm in diameter and the presence of hydroxyl and alkene functional groups indicated the successful transformation of PKS into CDs with carbon core consisting of C = C elementary unit. The highest quantum yield (44.0%) obtained was from the CDs synthesised with DEG as the reacting medium at irradiation period of 1 min. It was postulated that the high boiling point of DEG resulted in a complete carbonisation of PKS into CDs. Subsequently, the absorbance intensity and photoluminescence intensity were also much higher compared to other precursor formulation. All the CDs fluoresced in the bacteria culture, and fluorescence quenching occurred in the presence of heavy metal ions. These showed the potential of CDs synthesised from PKS could be used for cellular imaging and detection as well as removal of heavy metal ions.

Study of forward osmosis (FO) has been increasing steadily over recent years with applications mainly focusing on desalination and wastewater treatment processes. The working mechanism of FO lies in the natural movement of water between two streams with different osmotic pressure, which makes it useful in concentrating or diluting solutions. FO has rarely been operated as a stand-alone process. Instead, FO processes often appear in a hybrid or integrated form where FO is combined with other treatment technologies to achieve better overall process performance and cost savings. This article aims to provide a comprehensive review on the need for hybridization/integration for FO membrane processes, with emphasis given to process enhancement, draw solution regeneration, and pretreatment for FO fouling mitigation. In general, integrated/hybrid FO processes can reduce the membrane fouling propensity; prepare the solution suitable for subsequent value-added uses and production of renewable energy; lower the costs associated with energy consumption; enhance the quality of treated water; and enable the continuous operation of FO through the regeneration of draw solution. The future potential of FO lies in the success of how it can be hybridized or integrated with other technologies to minimize its own shortcomings, while enhancing the overall performance.

The present work demonstrates the coupling of titanium dioxide, TiO

Oil palm industry contributes significantly to the economic growth in Malaysia. At the same time, it generates a huge amount of palm oil mill effluent (POME) which contains valuable resources for energy, water and nutrients recovery. Currently, it has been used as feed for anaerobic biogas reactor to produce methane, a renewable energy source. The effluent discharged from the anaerobic digester, known as digestate, still contains abundant water and nutrients for recovery. However, the presence of suspended solids in digestate hinders the downstream water and nutrients recovery processes. Cake filtration process that has been successfully employed in water industry to remove suspended solids appears to be an attractive option for the removal of suspended solids in digestate. This paper investigates the performance of cake filtration process in removing suspended solids in digestate. Various types of filter aid such as perlite, diatomaceous earth (DE), bleaching earth (BE), powdered activated carbon (PAC), and boiler ash (BA) are used in this study. The amount of filter aid used as precoat and body feed was also varied (with ratio 1:1 from 1.0 g to 3.0 g) in the process. The effectiveness of cake filtration process was evaluated based on the quality of filtered digestate and the filtration flux. Overall, the particle size and size distribution of filter aids have huge influence on the cake filtration process. Turbidity removal above 90 % can be achieved regardless the type and amount of filter aids used. Due to the presence of plenty fine pores (as shown by FESEM image) on perlite particles and its narrow particle size distribution, the permeation of water was the highest flux (1 ml/cm2.min) and retention of suspended solids also was among the highest compared to other filter aids. This study shows that cake filtration process has the potential to be used to remove suspended solids in digestate so that the nutrient and water can be recovered in the following downstream process.

The saline wastewater from various sources including agriculture and industrial activities, appears to have high salt concentration, organic content and other pollutants which can harm the environment. Thus, saline wastewater treatment has become one of the major concerns in many countries. Membrane technology offers great potential in saline wastewater treatment due to its high permeate quality, flexibility, and desalination capability. This paper highlights the current development in various types of membrane processes such as pressure driven-based membranes, forward osmosis, membrane distillation, electrodialysis and membrane bioreactor, either as a stand-alone or integrated process for saline wastewater treatment. The membranes performance in terms of water reclamation as well as resource recovery is discussed. Besides, the membrane fouling issue is highlighted, and the efficiency of various fouling mitigation strategies when dealing with real/challenging saline wastewater are reviewed. Finally, the future challenges and outlook in the context of membrane application for saline wastewater treatment are discussed.

The present research aims to study the long-term impacts of soil extractable carbohydrate content from the conversion of forest to paddy field, using three environmentally friendly methods: ultrasound assist (37 Hz/30 min), hot water (80 °C/4 h), and cold water (25 °C/30 min). Soil samples collected at the depth of 0–15 cm from natural forest, rice paddy, and border area were extracted by distilled water at the ratio 1:10 (soil: water). Contents of soil organic carbon (SOC) and extracted carbohydrate (ECH) in the natural forest and rice paddy were similar, and higher than in border area by 50%. Results showed the highest content of ECH was extracted using hot water (304–691 mg.Carbohydrate/kg soil, 4% of SOC), followed by ultrasound (102–305 mg.Carbohydrate/kg soil, 1.7% of SOC), and the lowest amount addressed to cold-water extraction (65–252 mg.Carbohydrate/kg soil, 1.2% of SOC). The ECH/SOC ratios in three soil types were the same and ranged from 0.9% to 4.2%. We conclude the long-term conversion of forest to rice paddy maintain both SOC and ECH, furthermore, hot water extraction at 80 °C/4 h is the optimum method for extraction of carbohydrate using non-chemical solvents.

In this study, heteroatoms doped carbon quantum dots were synthesized using rice husk as a biowaste precursor. The effects of nitrogen and bismuth doping are investigated by adjusting the amount of ethylenediamine (EDA) as the nitrogen source, and bismuth nitrate pentahydrate as the bismuth source. HRTEM analysis depicted the formation of spherical carbon quantum dots, with a size of less than 10 nm. FTIR and XPS analysis confirmed the presence of essential functional groups and chemical composition in both of the doped carbon quantum dots. UV–Vis spectra showed peaks which are associated to the electronic transition of the C = C bonding. The addition of EDA and bismuth nitrate pentahydrate tuned the fluorescence intensity and shifted the emission wavelength from the blue region to green one. The performance of the doped rice husk derived carbon quantum dots (RHCQDs) was evaluated via photodegradation of the methylene blue (MB), under a 300 W Xenon lamp. as well as via copper (II) removal. N-RHCQDs (10 vol%) and Bi-RHCQDs (5 wt%) demonstrated the highest MB degradation performance, at 72.16% and 68.91%, respectively. The degradation of MB of the two doped RHCQDs fitted with the pseudo-second kinetic model. The doped RHCQDs were then tested for copper (II) removal, obtaining removal performance of 56.23% and 33.13%, respectively. The results suggest that the Cu (II) adsorption onto the N-RHCQDs and Bi-RHCQDs agrees with the pseudo-second kinetic model and the Langmuir isotherm, with maximum adsorption capacity of 5.73 and 4.08 mg/g, respectively.

The hydrophobic property of polymeric membrane is one of the major issues in water treatment application as it leads to a lower membrane efficiency and performance during separation process. Hence, a mixed-matrix membrane (MMM) that incorporates polymeric substance, natural additive and nanomaterial could be adopted to resolve this issue. This study portrays the preparation of a hydrophilic graphene oxide-based MMM by employing polysulfone (PSf) polymer, graphene oxide (GO) nanomaterial and eco-friendly natural additive gum Arabic (GA). The membranes were prepared via phase inversion by varying the concentration of GO (0.2, 0.6 and 1.0 wt%) at constant amount of GA and PSf at 1.5 wt% and 18 wt%, respectively. These fabricated membranes underwent several characterization tests in terms of surface hydrophilicity, pore size, porosity measurement and field emission scanning electron microscopy (FESEM). The characterization analysis indicated that MMM fabricated with 0.6 wt% of GO possessed highest porosity, largest mean pore size, and improved hydrophilicity due to the presence of oxygen containing functional groups associated with GO and GA. This contributed to the highest water flux result at an average of 63.55 L/m2·h at 4 bar operating pressure. At the same time, it also exhibited a considerably good rejection property and stronger antifouling property with humic acid rejection rate of 95% and flux recovery ratio of 88%, respectively. The finding showed that the incorporation of GO and GA could attain synergy benefits in improving the membrane properties and performance.

Membrane process is considered an effective and economical treatment technology to palm oil mill effluent (POME) which is a major pollution source discharged from the palm oil industry. In this study, graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) were used as nano additive in coagulation bath to prepare polyvinylidene fluoride (PVDF) membrane via in-situ colloidal precipitation method. The successful synthesis of carbon nanomaterials GO and OMWCNTs were validated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and observed using field emission scanning electron microscopy (FESEM). In general, incorporation of GO and OMWCNTs into membrane matrix via in-situ colloidal precipitation method have significant effect on membrane characterization including contact angle, surface charge, porosity and pore size of the membrane. As observed using FESEM images, GO nanosheets had blocked some areas of the membrane surface thus reducing the effective filtration area. The mixed-matrix membranes M1c, M3a, and M5b demonstrated improved water permeability of 43.99 L/m 2 ·h·bar, 52.62 L/m 2 ·h·bar, and 43.38 L/m 2 ·h·bar, respectively owing to thinner skin layer, bigger voids, and increased hydrophilicity. The rejection performance of fabricated membrane was evaluated using diluted aerobic POME on physical characteristics (color, turbidity, total suspended solids (TSS), total dissolved solids (TDS), pH) and chemical properties (chemical oxygen demand (COD), hardness, total chlorine, and phosphorus). As compared to pristine membrane, the mixed-matrix membrane, M1c had improved the rejection of TDS, phosphorus, hardness, COD, chlorine, turbidity, color, and TSS with maximum rejection percentage of 1.51%, 6.55%, 21.79%, 75.5%, 76%, 81.94%, 86.3%, and 100%, respectively. This research demonstrated that the deposition of carbon nanomaterials increased the membrane hydrophilicity and formed a repulsive boundary barrier that enhanced antifouling properties.

Nanomaterials can be incorporated in the synthesis of membrane to obtain mixed-matrix membrane with marked improvement in properties and performance. However, stability and dispersion of the nanomaterials in the membrane matrix, as well as the need to use high ratio of nanomaterials for obvious improvement of membrane properties, remain a major hurdle for commercialization. Hence, this study aims to investigate the improvement of polyamide 6,6 membrane properties with the incorporation of silver nanoparticles decorated on graphene oxide (Ag-GO) nanoplates and at the same time focus is given to the issues above. Graphene oxide nanoplates were synthesized using the modified Hummers’ method and decorated with silver before embedded into the polyamide 6,6 matrix. Physicochemical characterizations were conducted on both nanoplates and the mixed-matrix Ag-GO polyamide 6,6 membrane. The issues of Ag agglomeration and leaching were not observed, which could be attributed to the decoration of Ag on GO that helped to disperse the nanomaterials and provided a better anchor point for the attachment of Ag nanoparticles. The synthesized membrane showed marked improvement regarding flux (135% increment) and antifouling (40% lower irreversible fouling), which could be ascribed to the more negative charge of membrane surface (−14 ± 6 to −31 ± 3.8 mV) and hydrophilicity (46% enhancement) of the membranes. With minimal embedment of Ag nanoparticles, the membrane showed superior antibacterial property where the E. coli bacteria could not form a single colony on the membrane surface. Overall, the decoration of Ag on GO nanoplates could be a promising approach to resolve the agglomeration and leaching issues as well as reduce the amount of precious Ag in the synthesis of Ag-GO polyamide 6,6 membrane.

Issues of water scarcity and water security have driven the rapid development of various technologies to ensure water sustainability. The forward osmosis (FO) membrane process has been widely recognized as one of the more promising technologies to play an important role in alleviating the issues of water sustainability. Extensive research has been carried out worldwide to explore the potential of FO in desalination, water and wastewater treatment and reclamation. It is of the utmost importance to understand the topics of interest and research trends to further advance the development of FO process technology. In this study, a bibliometric analysis based on the Scopus database was carried out to identify and understand the global research trends of FO process based on 6 main analyses: basic growth trends, journals, countries, institutions, authors, and keywords. A total of 1462 article records published between 1967–2018 were extracted from Scopus and used as the raw data for bibliometric analysis using VOSviewer software. The total number of FO articles has sharply increased since 2009 and stabilized at around 250 publications in the past three years. The increase could be associated with the breakthrough in FO membrane science, where the contributions were from the 5 most productive countries: USA, China, Singapore, Australia, and South Korea. FO research started to diversify after the appearance of commercial FO membranes with improved characteristics, enabling the researchers to employ them for various application studies. Keywords analysis showed that the main directions of FO research could be categorized into three clusters: application of FO, membrane fouling study, and FO membrane synthesis. These bibliometric results provide a valuable reference and information on current research directions of FO for researchers and industry practitioners who are interested in FO technology.

Acceleration in global industrialisation has led to increasing release of various emerging, highly toxic refractory organic pollutants in water bodies. These contaminants have been very concerning due to their detrimental impacts on human beings as well as aquatic life even at low concentrations. Conventional wastewater treatment technology has proven to be ineffective in eliminating these pollutants, hence creating substantial attention for a more advanced Electro-Fenton (EF) technology. A systematic bibliometric analysis has been carried out based on Scopus database to comprehend the extensive research development of EF technology for the past 2 decades (2000–2019). Several aspects were analysed, namely general growth trend, journal, country, institutional, authorship and keywords analysis. VOSViewer was utilised to present a clear collaboration between authors, countries and co-occurrences between research keywords. Exponentially high publication growth was observed during the recent decade (2010–2019) highlighting the main EF research areas such as electrode and catalyst synthesis, application, mathematical modelling, technology integration and process comparison. Energy consumption analysis reveals the substantial impact of various EF operational and design parameters on the energy consumed by EF system, which then significantly define its economic viability. Future research prospects are suggested to encourage continuous development of technical, environmental and economically feasible EF system.