This paper intends to review the state of the art of new generation nanomaterials – carbon nanotubes (CNTs), graphene, zeolites, aquaporin (AQP) for water desalination. The major applications of ...these nanomaterials in water desalination are critically discussed based on their functions in different types of processes. In addition, the potential impact of these nanomaterials on human health and ecosystem as well as its potential interference with treatment processes was also briefly discussed. It can be seen that the use of these advanced materials in membranes for reverse osmosis, membrane distillation, forward osmosis, pervaporation, and electrodialysis, formed the bulk of the reported works in the literature. Apart from that, these nanomaterials also have been reported to be utilized as adsorbents, supercapacitor, and capacitive deionization (CDI) for desalination purpose. However there has been very limited works reported on the environmental impact of these nanomaterials. Future works should focus on the process that would have the best potential to be cost-effectively commercialized at industrial scale which, based on this review, looks to be the CDI technology.
•Overview of recent advanced nanomaterials - carbon nanotubes, graphene, zeolites, and aquaporin for various water desalination technologies.•Major applications of these nanomaterials in water desalination are critically reviewed based on their functions in unit operation processes.
Persistent organic pollutants (POPs) are carbon-based chemical substances that are resistant to environmental degradation and may not be completely removed through treatment processes. Their ...persistence can contribute to adverse health impacts on wild-life and human beings. Thus, the solar photocatalysis process has received increasing attention due to its great potential as a green and eco-friendly process for the elimination of POPs to increase the security of clean water. In this context, ZnO nanostructures have been shown to be prominent photocatalyst candidates to be used in photodegradation owing to the facts that they are low-cost, non-toxic and more efficient in the absorption across a large fraction of the solar spectrum compared to TiO2. There are several aspects, however, need to be taken into consideration for further development. The purpose of this paper is to review the photo-degradation mechanisms of POPs and the recent progress in ZnO nanostructured fabrication methods including doping, heterojunction and modification techniques as well as improvements of ZnO as a photocatalyst. The second objective of this review is to evaluate the immobilization of photocatalyst and suspension systems while looking into their future challenges and prospects.
In this study, two biomass-based adsorbents were used as new precursors for optimizing synthesis conditions of a cost-effective powdered activated carbon (PAC). The PAC removed dyes from an aqueous ...solution using carbonization and activation by KOH, NaOH, and H
SO
. The optimum synthesis, activation temperature, time and impregnation ratio, removal rate, and uptake capacity were determined. The optimum PAC was analyzed and characterized using Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), a field emission scanning electron microscope (FESEM), Zeta potential, and Raman spectroscopy. Morphological studies showed single-layered planes with highly porous surfaces, especially PAC activated by NaOH and H
SO
. The results showed that the experimental data were well-fitted with a pseudo-second-order model. Based on Langmuir isotherm, the maximum adsorption capacity for removing methylene blue (MB) was 769.23 mg g
and 458.43 mg g
for congo red (CR). Based on the isotherm models, more than one mechanism was involved in the adsorption process, monolayer for the anionic dye and multilayer for the cationic dye. Elovich and intraparticle diffusion kinetic models showed that rubber seed shells (RSS) has higher α values with a greater tendency to adsorb dyes compared to rubber seed (RS). A thermodynamic study showed that both dyes' adsorption process was spontaneous and exothermic due to the negative values of the enthalpy (ΔH) and Gibbs free energy (ΔG). The change in removal efficiency of adsorbent for regeneration study was observed in the seventh cycles, with a 3% decline in the CR and 2% decline in MB removal performance. This study showed that the presence of functional groups and active sites on the produced adsorbent (hydroxyl, alkoxy, carboxyl, and π - π) contributed to its considerable affinity for adsorption in dye removal. Therefore, the optimum PAC can serve as efficient and cost-effective adsorbents to remove dyes from industrial wastewater.
Display omitted
•Bibliometric analysis was conducted to evaluate forward osmosis research trend.•FO process has been widely applied in desalination and wastewater treatment.•FO research strength is ...heavily influenced by national policy and institutions.•Main FO research category from keyword analysis: fouling, performance & membrane.•Future prospect and research direction of FO were highlighted in the article.
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.
Ultrafiltration process has been applied widely in food processing industry for the last 20 years due to its advantages over conventional separation processes such as gentle product treatment, high ...selectivity, and lower energy consumption. Ultrafiltration becomes an essential part in food technology as a tool for separation and concentration. However, membrane fouling compromises the benefits of ultrafiltration as fouling significantly reduces the performance and hence increases the cost of ultrafiltration. Recent advances in this area show the various intensive studies carried out to improve ultrafiltration, focusing on membrane fouling control and cleaning of fouled membranes. Thus, this paper reviews recent developments in ultrafiltration process, focusing on fouling mechanisms of ultrafiltration membranes as well as the latest techniques used to counter membrane fouling.
Nanomaterial-based adsorbents have garnered increasing attention in water and wastewaters treatment applications due to their attractive properties and strong adsorption capabilities for various ...organic compounds. The current review appraises the use of nanomaterial adsorbents (NAs); namely: carbon nanotubes (CNTs), graphene sheets (GS), and metal oxides (MO) for environmental remediation applications. The adsorption capacities for organic dyes, aromatic compounds, phenolic derivatives, pharmaceuticals, and antibiotics are comprehensively reviewed. The current study critically investigates the role of physicochemical properties of the adsorbents, solution chemistry of the adsorbates, and the uptake mechanism on the sorption performance of NAs. The adsorption isotherms reveal Langmuir and Freundlich models to be the best fit of the experimental data in most of the studies, whilst the adsorption kinetics is well described by the pseudo-second-order model. This review attempts to present a prior knowledge about the adsorption capability of CNTs, GS, and MO for the removal of organic pollutants (OPs) from wastewaters by assessing outcomes of peer-reviewed articles published between 2000 and 2019.
•Comparison between maximum adsorption capacity of CNTs, graphene, and metal oxides•Langmuir and Freundlich are the most fitted models in adsorption by nanomaterials.•The adsorption kinetics is predominantly based on the pseudo-second-order model.
Rapid development of nanotechnology has been in high demand, especially for silver nanoparticles (AgNPs) since they have been proven to be useful in various fields such as medicine, textiles, and ...household appliances. AgNPs are very important because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including wound care management. This review aimed to elucidate the underlying mechanisms of AgNPs that are responsible for their antiviral properties and their antibacterial activity towards the microorganisms. AgNPs can be synthesized through three different methods-physical, chemical, and biological synthesis-as indicated in this review. The applications and limitations of the AgNPs such as their cytotoxicity towards humans and the environment, will be discussed. Based on the literature search obtained, the properties of AgNPs scrutinizing the antibacterial or antiviral effect shown different interaction towards bacteria which dependent on the synthesis processes followed by the morphological structure of AgNPs.
Abstract
In this study, hematite graphene oxide (αFe
2
O
3
-GO) powder nanocomposites and thin-film hematite graphene oxide (αFe
2
O
3
-GO) were synthesized for application in the removal of ...Rhodamine B (RhB) from textile wastewater. αFe
2
O
3
-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 αFe
2
O
3
with GO. The photocatalytic performance of two synthesized composites was compared with different concentrations of αFe
2
O
3
-GO. The results showed that powder nanocomposites are more effective than thin-film composites for the removal of RhB dye. αFe
2
O
3
-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 αFe
2
O
3
-GO-5% powder nanocomposites removed a higher rate of dye (up to 63%) in more cycles (6 cycles).
This study presents a nature-inspired, and metaheuristic-based Marine predator algorithm (MPA) for solving the optimal power flow (OPF) problem. The significant insight of MPA is the widespread ...foraging strategy called the Levy walk and Brownian movements in ocean predators, including the optimal encounter rate policy in biological interaction among predators and prey which make the method to solve the real-world engineering problems of OPF. The OPF problem has been extensively used in power system operation, planning, and management over a long time. In this work, the MPA is analyzed to solve the single-objective OPF problem considering the fuel cost, real and reactive power loss, voltage deviation, and voltage stability enhancement index as objective functions. The proposed method is tested on IEEE 30-bus test system and the obtained results by the proposed method are compared with recent literature studies. The acquired results demonstrate that the proposed method is quite competitive among the nature-inspired optimization techniques reported in the literature.
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.
PDF
