Publications by authors named "Kuan Shiong Khoo"

39 Publications

Future advances and challenges of nanomaterial-based technologies for electromagnetic interference-based technologies: A review.

Environ Res 2021 Nov 24:112402. Epub 2021 Nov 24.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The emerging growth of the electronic devices applications has arisen the serious problems of electromagnetic (EM) wave pollution which resulting in equipment malfunction. Therefore, polymer-based composites have been considered good candidates for better EMI shielding due to their significant characteristics including, higher flexibility, ultrathin, lightweight, superior conductivity, easy fabrication processing, environmentally friendly, corrosion resistive, better adhesion with physical, chemical and thermal stability. This review article focused on the concept of the EMI shielding mechanism and challenges with the fabrication of polymer-based composites. Subsequently, recent advancements in the polymer composites applications have been critically reviewed. In addition, the impact of polymers and polymer nanocomposites with different fillers such as organic, inorganic, 2D, 3D, mixture and hybrid nano-fillers on EMI shielding effectiveness has been explored. Lastly, future research directions have been proposed to overcome the limitations of current technologies for further advancement in EMI shielding materials for industrial applications. Based on reported literature, it has been found that the low thickness based lightweight polymer is considered as a best material for excellent material for next-generation electronic devices. Optimization of polymer composites during the fabrication is required for better EMI shielding. New nano-fillers such as functionalization and composite polymers are best to enhance the EMI shielding and conductive properties.
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http://dx.doi.org/10.1016/j.envres.2021.112402DOI Listing
November 2021

Recent Progress in Nanomaterials Modified Electrochemical Biosensors for the Detection of MicroRNA.

Micromachines (Basel) 2021 Nov 17;12(11). Epub 2021 Nov 17.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Selangor 43500, Malaysia.

MicroRNAs (miRNAs) are important non-coding, single-stranded RNAs possessing crucial regulating roles in human body. Therefore, miRNAs have received extensive attention from various disciplines as the aberrant expression of miRNAs are tightly related to different types of diseases. Furthermore, the exceptional stability of miRNAs has presented them as biomarker with high specificity and sensitivity. However, small size, high sequence similarity, low abundance of miRNAs impose difficulty in their detection. Hence, it is of utmost importance to develop accurate and sensitive method for miRNA biosensing. Electrochemical biosensors have been demonstrated as promising solution for miRNA detection as they are highly sensitive, facile, and low-cost with ease of miniaturization. The incorporation of nanomaterials to electrochemical biosensor offers excellent prospects for converting biological recognition events to electronic signal for the development of biosensing platform with desired sensing properties due to their unique properties. This review introduces the signal amplification strategies employed in miRNA electrochemical biosensor and presents the feasibility of different strategies. The recent advances in nanomaterial-based electrochemical biosensor for the detection of miRNA were also discussed and summarized based on different types of miRNAs, opening new approaches in biological analysis and early disease diagnosis. Lastly, the challenges and future prospects are discussed.
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http://dx.doi.org/10.3390/mi12111409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8618943PMC
November 2021

Effect of process parameters over carbon-based ZIF-62 nano-rooted membrane for environmental pollutants separation.

Chemosphere 2021 Nov 20:133006. Epub 2021 Nov 20.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The paper evaluates the routes towards the evaluation of membranes using ZIF-62 metal organic framework (MOF) nano-hybrid dots for environmental remediation. Optimization of interaction of operating parameters over the rooted membrane is challenging issue. Subsequently, the interaction of operating parameters including temperature, pressure and CO gas concentration over the resultant rooted membranes are evaluated and optimized using response surface methodology for environmental remediation. In addition, the stability and effect of hydrocarbons on the performance of the resulting membrane during the gas mixture separation are evaluated at optimum conditions to meet the industrial requirements. The characterization results verified the fabrication of the ZIF-62 MOF rooted composite membrane. The permeation results demonstrated that the CO permeability and CO/CH selectivity of the composite membrane was increased from 15.8 to 84.8 Barrer and 12.2 to 35.3 upon integration of ZIF-62 nano-glass into cellulose acetate (CA) polymer. Subsequently, the optimum conditions have been found at a temperature of 30 °C, the pressure of 12.6 bar and CO feed concentration of 53.3 vol%. These optimum conditions revealed the highest CO permeability, CH permeability and CO/CH separation factor of 47.9 Barrer, 0.2 Barrer and 26.8. The presence of hydrocarbons in gas mixture dropped the CO permeability of 56.5% and separation factor of 46.4% during 206 h of testing. The separation performance of the composite membrane remained stable without the presence of hydrocarbons for 206 h.
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http://dx.doi.org/10.1016/j.chemosphere.2021.133006DOI Listing
November 2021

Application progress of bioactive compounds in microalgae on pharmaceutical and cosmetics.

Chemosphere 2021 Nov 16:132932. Epub 2021 Nov 16.

Institute of Biological Sciences, Faculty of Science, Universiti Malaya, 50603, Kuala Lumpur, Malaysia. Electronic address:

Microalgae is an autotrophic organism with fast growth, short reproduction cycle, and strong environmental adaptability. In recent years, microalgae and the bioactive ingredients extracted from microalgae are regarded as potential substitutes for raw materials in the pharmaceutical and the cosmetics industry. In this review, the characteristics and efficacy of the high-value components of microalgae are discussed in detail, along with the sources and extraction technologies of algae used to obtain high-value ingredients are reviewed. Moreover, the latest trends in biotherapy based on high-value algae extracts as materials are discussed. The excellent antioxidant properties of microalgae derivatives are regarded as an attractive replacement for safe and environmentally friendly cosmetics formulation and production. Through further studies, the mechanism of microalgae bioactive compounds can be understood better and reasonable clinical trials conducted can safely conclude the compliance of microalgae-derived drugs or cosmetics to be necessary standards to be marketed.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132932DOI Listing
November 2021

A review on sensing and catalytic activity of nano-catalyst for synthesis of one-step ammonia and urea: Challenges and perspectives.

Chemosphere 2021 Nov 13:132806. Epub 2021 Nov 13.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

One of the most significant chemical operations in the past century was the Haber-Bosch catalytic synthesis of ammonia, a fertilizer vital to human life. Many catalysts are developed for effective route of ammonia synthesis. The major challenges are to reduce temperature and pressure of process and to improve conversion of reactants produce green ammonia. The present review, briefly discusses the evolution of ammonia synthesis and current advances in nanocatalyst development. There are promising new ammonia synthesis catalysts of different morphology as well as magnetic nanoparticles and nanowires that could replace conventional Fused-Fe and Promoted-Ru catalysts in existing ammonia synthesis plants. These magnetic nanocatalyst could be basis for the production of magnetically induced one-step green ammonia and urea synthesis processes in future.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132806DOI Listing
November 2021

Biodiesel synthesis from Prunus bokhariensis non-edible seed oil by using green silver oxide nanocatalyst.

Chemosphere 2021 Nov 9:132780. Epub 2021 Nov 9.

Faculty of Applied Sciences, UCSI University. No. 1, Jalan Menara Gading, UCSI Heights, 56000, Cheras Kuala Lumpur, Malaysia. Electronic address:

The present work investigates the proficiency of green silver oxide nanocatalyst synthesised from Monotheca buxifolia (Falc.) Dcne. leaves extract, and their application for biodiesel synthesis from novel Prunus bokhariensis seed oil (non-edible). The seed oil content of 55% and FFA content of 0.80 mg KOH/g were reported. Several analytical tools (EDX, FT-IR, SEM and XRD) were used to characterise the AgO nanocatalyst. Maximum (89%) FAME yield of the PBSOB (Prunus bokhariensis seed oil biodiesel) was achieved at ambient transesterification conditions i.e. 3.5 wt% nanocatalyst loading, 2.5 h reaction time, 130 °C of reaction temperature and 12:1 alcohol to oil ratio. The synthesised PBSOB was additionally characterised by analytical methods like, GC-MS and FT-IR. The different aspects of fuel were identified i.e. flash point (84 °C), kinematic viscosity (4.01 cSt @ 40 °C), sulphur content (0.0003 wt %), density (0.853 kg/L) and acid number (0.167 mg KOH/g). All the above properties were verified and agreed well with biodiesel international standards (European Union (14214), China GB/T (20828) and ASTM (6751, 951). In general, Prunus bokhariensis seed oil and AgO nanocatalyst seem to be remarkably active, cheap and stable candidates for the biodiesel industry in future.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132780DOI Listing
November 2021

Recent advances biodegradation and biosorption of organic compounds from wastewater: Microalgae-bacteria consortium - A review.

Bioresour Technol 2021 Oct 19;344(Pt A):126159. Epub 2021 Oct 19.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.
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http://dx.doi.org/10.1016/j.biortech.2021.126159DOI Listing
October 2021

Recuperation and characterization of calcium carbonate from residual oyster and clamshells and their incorporation into a residential finish.

Chemosphere 2021 Oct 14:132550. Epub 2021 Oct 14.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

The final disposal of waste generated by human activities has been turned into a great challenge; until now, little attention has been paid to organic waste, particularly from the restaurant sector. This work describes the process of obtaining calcium carbonate contained in oyster and clam shells re-collected in seafood restaurants. The IR absorption spectra of all the samples revealed the presence of characteristic bands of the carbonate group located at 872, 712 and 1414 cm; the peak at 1081 cm of the clamshells confirms the presence of the aragonite phase. The SEM images allow observing a granular morphology whose agglomerates having a size within the range of 0.5-15 μm in brown shells, and a lower dispersion prevails in the grey species and oyster shells that go from 0.3 to 5.9 μm. All of the shells were found to be composed of carbon (C), oxygen (O) and calcium (Ca) in different concentrations. The calcium carbonate obtained from clamshells has an orthorhombic crystalline structure, while the oyster carbonate has a rhombohedral structure as the calcium carbonate used in the construction industry; the morphology particles also coincide with each other. The material obtained combined with a mixture composed of resin, cellulose, and granules were used to prepare a paste, which was used as a residential finish.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132550DOI Listing
October 2021

An integration study of microalgae bioactive retention: From microalgae biomass to microalgae bioactives nanoparticle.

Food Chem Toxicol 2021 Oct 12;158:112607. Epub 2021 Oct 12.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae metabolites include biologically active compounds with therapeutic effects such as anticancer, anti-inflammatory and immunomodulation effects. One of the most recent focuses is on utilizing microalgae lipid-based biologically active compounds in food applications. However, most microalgae biological active compounds in their natural forms have common drawbacks like low solubility, low physicochemical stability and strong susceptibility to degradation, which significantly limits their application in foods, therefore, it is important to find solutions to retain their functional properties. In the present work, a comprehensive review on multi-product biorefinery was carried out from upstream processing stage to downstream processing stage, and identify critical processes and factors that impact bioactive material acquisition and retention. Furthermore, since nanoencapsulation technology emerges as an effective solution for microalgae nutraceutical product's retention, this work also focus on the nanoparticle perspective and comprehensively reviews the current nanoencapsulation solutions of the microalgae bioactive extract products. The aim is to depict advances in the formulations of microalage bioactive nanoparticles and provide a critical analysis of the reported nanoparticle formation. Overall, through the investigation of microalgae from biomass to bioactive nanoparticles, we aim to facilitate microalgae nutraceuticals incorporation as high value-added ingredients in more functional food that can improve human health.
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http://dx.doi.org/10.1016/j.fct.2021.112607DOI Listing
October 2021

Phyllosilicate derived catalysts for efficient conversion of lignocellulosic derived biomass to biodiesel: A review.

Bioresour Technol 2022 Jan 7;343:126068. Epub 2021 Oct 7.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The efforts have been made to review phyllosilicate derived (clay-based) heterogeneous catalysts for biodiesel production via lignocellulose derived feedstocks. These catalysts have many practical and potential applications in green catalysis. Phyllosilicate derived heterogeneous catalysts (modified via any of these approaches like acid activated clays, ion exchanged clays and layered double hydroxides) exhibits excellent catalytic activity for producing cost effective and high yield biodiesel. The combination of different protocols (intercalated catalysts, ion exchanged catalysts, acidic activated clay catalysts, clay-supported catalysts, composites and hybrids, pillared interlayer clay catalysts, and hierarchically structured catalysts) was implemented so as to achieve the synergetic effects (acidic-basic) in resultant material (catalyst) for efficient conversion of lignocellulose derived feedstock (non-edible oils) to biodiesel. Utilisation of these Phyllosilicate derived catalysts will pave path for future researchers to investigate the cost-effective, accessible and improved approaches in synthesising novel catalysts that could be used for converting lignocellulosic biomass to eco-friendly biodiesel.
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http://dx.doi.org/10.1016/j.biortech.2021.126068DOI Listing
January 2022

Biohydrogen from organic wastes as a clean and environment-friendly energy source: Production pathways, feedstock types, and future prospects.

Bioresour Technol 2021 Dec 24;342:126021. Epub 2021 Sep 24.

Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung, Taiwan; Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan. Electronic address:

Microbial fermentation of organic matter under anaerobic conditions is currently the prominent pathway for biohydrogen production. Organic matter present in waste residues is regarded as an economic feedstock for biohydrogen production by dark and photo fermentative bacteria. Agricultural residues, fruit wastes, vegetable wastes, industrial wastewaters, and other livestock residues are some of the organic wastes most commonly used for biohydrogen production due to their higher organic content and biodegradability. Appropriate pretreatments are required to enhance the performance of biohydrogen from complex organic wastes. Biohydrogen production could also be enhanced by optimizing operation conditions and the addition of essential nutrients and nanoparticles. This review describes the pathways of biohydrogen production, discusses the effect of organic waste sources used and microbes involved on biohydrogen production, along with addressing the key parameters, advantages, and difficulties in each biohydrogen production pathway.
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http://dx.doi.org/10.1016/j.biortech.2021.126021DOI Listing
December 2021

A critical review on various remediation approaches for heavy metal contaminants removal from contaminated soils.

Chemosphere 2022 Jan 25;287(Pt 4):132369. Epub 2021 Sep 25.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Heavy metal pollution remains a global environmental challenge that poses a significant threat to human life. Various methods have been explored to eliminate heavy metal pollutants from the environment. However, most methods are constrained by high expenses, processing duration, geological problems, and political issues. The immobilization of metals, phytoextraction, and biological methods have proven practical in treating metal contaminants from the soil. This review focuses on the general status of heavy metal contamination of soils, including the excessive heavy metal concentrations in crops. The assessment of the recent advanced technologies and future challenges were reviewed. Molecular and genetic mechanisms that allow microbes and plants to collect and tolerate heavy metals were elaborated. Tremendous efforts to remediate contaminated soils have generated several challenges, including the need for remediation methodologies, degrees of soil contamination, site conditions, widespread adoptions and various possibilities occurring at different stages of remediation are discussed in detail.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132369DOI Listing
January 2022

Advances in production of bioplastics by microalgae using food waste hydrolysate and wastewater: A review.

Bioresour Technol 2021 Dec 17;342:125947. Epub 2021 Sep 17.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae have emerged as an effective dual strategy for bio-valorisation of food processing wastewater and food waste hydrolysate which favours microalgae cultivation into producing value-added by products mainly lipids, carbohydrates, and proteins to the advantages of bioplastic production. Moreover, various microalgae have successfully removed high amount of organic pollutants from food processing wastewater prior discharging into the environment. Innovation of microalgae cultivating in food processing wastewater greatly reduced the cost of wastewater treatment compared to conventional approach in terms of lower carbon emissions, energy consumption, and chemical usage while producing microalgae biomass which can benefit low-cost fertilizer and bioplastic applications. The study on several microalgae species has all successfully grown on food waste hydrolysates showing high exponential growth rate and biomass production rich in proteins, lipids, carbohydrates, and fatty acids. Multiple techniques have been implemented for the extraction of food wastes to be incorporate into the bioplastic production.
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http://dx.doi.org/10.1016/j.biortech.2021.125947DOI Listing
December 2021

Challenges and recent trends with the development of hydrogel fiber for biomedical applications.

Chemosphere 2022 Jan 23;287(Pt 1):131956. Epub 2021 Aug 23.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Hydrogel is the most emblematic soft material which possesses significantly tunable and programmable characteristics. Polymer hydrogels possess significant advantages including, biocompatible, simple, reliable and low cost. Therefore, research on the development of hydrogel for biomedical applications has been grown intensely. However, hydrogel development is challenging and required significant effort before the application at an industrial scale. Therefore, the current work focused on evaluating recent trends and issues with hydrogel development for biomedical applications. In addition, the hydrogel's development methodology, physicochemical properties, and biomedical applications are evaluated and benchmarked against the reported literature. Later, biomedical applications of the nano-cellulose-based hydrogel are considered and critically discussed. Based on a detailed review, it has been found that the surface energy, intermolecular interactions, and interactions of hydrogel adhesion forces are major challenges that contribute to the development of hydrogel. In addition, compared to other hydrogels, nanocellulose hydrogels demonstrated higher potential for drug delivery, 3D cell culture, diagnostics, tissue engineering, tissue therapies and gene therapies. Overall, nanocellulose hydrogel has the potential for commercialization for different biomedical applications.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131956DOI Listing
January 2022

How does the Internet of Things (IoT) help in microalgae biorefinery?

Biotechnol Adv 2021 Aug 25:107819. Epub 2021 Aug 25.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae biorefinery is a platform for the conversion of microalgal biomass into a variety of value-added products, such as biofuels, bio-based chemicals, biomaterials, and bioactive substances. Commercialization and industrialization of microalgae biorefinery heavily rely on the capability and efficiency of large-scale cultivation of microalgae. Thus, there is an urgent need for novel technologies that can be used to monitor, automatically control, and precisely predict microalgae production. In light of this, innovative applications of the Internet of things (IoT) technologies in microalgae biorefinery have attracted tremendous research efforts. IoT has potential applications in a microalgae biorefinery for the automatic control of microalgae cultivation, monitoring and manipulation of microalgal cultivation parameters, optimization of microalgae productivity, identification of toxic algae species, screening of target microalgae species, classification of microalgae species, and viability detection of microalgal cells. In this critical review, cutting-edge IoT technologies that could be adopted to microalgae biorefinery in the upstream and downstream processing are described comprehensively. The current advances of the integration of IoT with microalgae biorefinery are presented. What this review discussed includes automation, sensors, lab-on-chip, and machine learning, which are the main constituent elements and advanced technologies of IoT. Specifically, future research directions are discussed with special emphasis on the development of sensors, the application of microfluidic technology, robotized microalgae, high-throughput platforms, deep learning, and other innovative techniques. This review could contribute greatly to the novelty and relevance in the field of IoT-based microalgae biorefinery to develop smarter, safer, cleaner, greener, and economically efficient techniques for exhaustive energy recovery during the biorefinery process.
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http://dx.doi.org/10.1016/j.biotechadv.2021.107819DOI Listing
August 2021

Multi-objective optimization of thermophysical properties of multiwalled carbon nanotubes based nanofluids.

Chemosphere 2022 Jan 27;286(Pt 2):131690. Epub 2021 Jul 27.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

The experimental determination of thermophysical properties of nanofluid (NF) is time-consuming and costly, leading to the use of soft computing methods such as response surface methodology (RSM) and artificial neural network (ANN) to estimate these properties. The present study involves modelling and optimization of thermal conductivity and viscosity of NF, which comprises multi-walled carbon nanotubes (MWCNTs) and thermal oil. The modelling is performed to predict the thermal conductivity and viscosity of NF by using Response Surface Methodology (RSM) and Artificial Neural Network (ANN). Both models were tested and validated, which showed promising results. In addition, a detailed optimization study was conducted to investigate the optimum thermal conductivity and viscosity by varying temperature and NF weight per cent. Four case studies were explored using different objective functions based on NF application in various industries. The first case study aimed to maximize thermal conductivity (0.15985 W/m C) while minimizing viscosity (0.03501 Pa s) obtained at 57.86 °C and 0.85 NF wt%. The goal of the second case study was to minimize thermal conductivity (0.13949 W/m °C) and viscosity (0.02526 Pa s) obtained at 55.88 °C and 0.15 NF wt%. The third case study targeted maximizing thermal conductivity (0.15797 W/m °C) and viscosity (0.07611 Pa s), and the optimum temperature and NF wt% were 30.64 °C and 0.0.85,' respectively. The last case study explored the minimum thermal conductivity (0.13735) and maximum viscosity (0.05263 Pa s) obtained at 30.64 °C and 0.15 NF wt%.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131690DOI Listing
January 2022

Development of proton-exchange membrane fuel cell with ionic liquid technology.

Sci Total Environ 2021 Nov 24;793:148705. Epub 2021 Jun 24.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Broga Road, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Fuel cells (FCs) are a chemical fuel device which can directly convert chemical energy into electrical energy, also known as electrochemical generator. Proton exchange membrane fuel cells (PEMFCs) are one of the most appealing FC systems that have been broadly developed in recent years. Due to the poor conductivity of electrolyte membrane used in traditional PEMFC, its operation at higher temperature is greatly limited. The incorporation of ionic liquids (ILs) which is widely regarded as a greener alternative compared to traditional solvents in the proton exchange membrane electrolyte shows great potential in high temperature PEMFCs (HT-PEMFCs). This review provides insights in the latest progress of utilizing ILs as an electrochemical electrolyte in PEMFCs. Besides, electrolyte membranes that are constructed by ILs combined with polybenzimidazole (PBI) have many benefits such as better thermal stability, improved mechanical properties, and higher proton conductivity. The current review aims to investigate the newest development and existing issues of ILs research in electrolyte and material selection, system fabrication method, synthesis of ILs, and experimental techniques. The evaluation of life cycle analysis, commercialization, and greenness of ILs are also discussed. Hence, this review provides insights to material scientists and develops interest of wider community, promoting the use of ILs to meet energy challenges.
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http://dx.doi.org/10.1016/j.scitotenv.2021.148705DOI Listing
November 2021

Microalgal-Bacterial Consortia as Future Prospect in Wastewater Bioremediation, Environmental Management and Bioenergy Production.

Indian J Microbiol 2021 Sep 22;61(3):262-269. Epub 2021 Feb 22.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan Malaysia.

In the recent years, microalgae have captured researchers' attention as the alternative feedstock for various bioenergy production such as biodiesel, biohydrogen, and bioethanol. Cultivating microalgae in wastewaters to simultaneously bioremediate the nutrient-rich wastewater and maintain a high biomass yield is a more economical and environmentally friendly approach. The incorporation of algal-bacterial interaction reveals the mutual relationship of microorganisms where algae are primary producers of organic compounds from CO, and heterotrophic bacteria are secondary consumers decomposing the organic compounds produced from algae. This review would provide an insight on the challenges and future development of algal-bacterial consortium and its contribution in promoting a sustainable route to greener industry. It is believed that microalgal-bacterial consortia will be implemented in the near-future for sub-sequential treatment of wastewater bioremediation, bioenergy production and CO fixation, promoting sustainability and making extraordinary advancement in life sciences sectors.
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http://dx.doi.org/10.1007/s12088-021-00924-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8263830PMC
September 2021

Perspective of Spirulina culture with wastewater into a sustainable circular bioeconomy.

Environ Pollut 2021 Sep 2;284:117492. Epub 2021 Jun 2.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Spirulina biomass accounts for 30% of the total algae biomass production globally. In conventional process of Spirulina biomass production, cultivation using chemical-based culture medium contributes 35% of the total production cost. Moreover, the environmental impact of cultivation stage is the highest among all the production stages which resulted from the extensive usage of chemicals and nutrients. Thus, various types of culture medium such as chemical-based, modified, and alternative culture medium with highlights on wastewater medium is reviewed on the recent advances of culture media for Spirulina cultivation. Further study is needed in modifying or exploring alternative culture media utilising waste, wastewater, or by-products from industrial processes to ensure the sustainability of environment and nutrients source for cultivation in the long term. Moreover, the current development of utilising wastewater medium only support the growth of Spirulina however it cannot eliminate the negative impacts of wastewater. In fact, the recent developments in coupling with wastewater treatment technology can eradicate the negative impacts of wastewater while supporting the growth of Spirulina. The application of Spirulina cultivation in wastewater able to resolve the global environmental pollution issues, produce value added product and even generate green electricity. This would benefit the society, business, and environment in achieving a sustainable circular bioeconomy.
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http://dx.doi.org/10.1016/j.envpol.2021.117492DOI Listing
September 2021

Computational Lock and Key and Dynamic Trajectory Analysis of Natural Biophors Against COVID-19 Spike Protein to Identify Effective Lead Molecules.

Mol Biotechnol 2021 Oct 22;63(10):898-908. Epub 2021 Jun 22.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

New pandemic infection of coronaviridae family virus spread to more than 210 countries with total infection of 1,136,851 and 62,955 (4.6%) deaths until 5th April 2020. Which stopped the regular cycle of humankind but the nature is consistently running. There is no micro molecule remedy found yet to restore the regular life of people. Hence, we decided to work on natural biophores against the COVID proteins. As a first step, major phytoconstituents of antiviral herbs like Leucas aspera, Morinda citrifolia, Azadirachta indica, Curcuma longa, Piper nigrum, Ocimum tenuiflorum, and Corallium rubrum collected and performed the lock and key analysis with major spike protein of COVID-19 to find the best fitting lead biophore using computational drug design platform. The results of protocol run showed, phytoconstituents of Morinda citrifolia and Leucas aspera were found lower binding energy range of - 55.18 to - 25.34 kcal/mol, respectively and compared with Hydroxychloroquine (HCQ) (- 24.29 kcal/mol) and Remdesivir (- 25.38 kcal/mol). The results conclude that, core skeletons chromen, anthracene 9, 11 dione and long-chain alkyl acids/ester-containing biophores showen high stable antagonistic affinity with S-protein. Which leads the breakdown of spike protein and ACE2 receptor complex formation and host mechanism of corono virus. In addition, the dynamic trajectory analysis confirmed the complete denaturation of spike protein by the molecule 4-(24-hydroxy-1-oxo-5-n-propyltetracosanyl)-phenol from Leucas aspera and stability of spike-ligand complex. These biophores will aid the researcher to fabricate new promising analogue and being recommended to assess its COVID-19 treatment.
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http://dx.doi.org/10.1007/s12033-021-00358-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8219180PMC
October 2021

Recent advances on food waste pretreatment technology via microalgae for source of polyhydroxyalkanoates.

J Environ Manage 2021 Sep 27;293:112782. Epub 2021 May 27.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyester which are biosynthesized from the intracellular cells of microalgae through the cultivation of organic food waste medium. Before cultivation process, food waste must undergo several pre-treatment techniques such as chemical, biological, physical or mechanical in order to solubilize complex food waste matter into simpler micro- and macronutrients in which allow bio-valorisation of microalgae and food waste compound during the cultivation process. This work reviews four microalgae genera namely Chlamydomonas, Chlorella, Spirulina, and Botryococcus, are selected as suitable species due to rapid growth rate, minimal nutrient requirement, greater adaptability and flexibility prior to lower the overall production cost and maximized the production of PHAs. This study also focuses on the different mode of cultivation for the accumulation of PHAs followed by cell wall destabilization, extraction, and purification. Nonetheless, this review provides future insights into enhancing the productivity of bioplastic derived from microalgae towards low-cost, large-scale, and higher productivity of PHAs.
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http://dx.doi.org/10.1016/j.jenvman.2021.112782DOI Listing
September 2021

Plastic waste associated with the COVID-19 pandemic: Crisis or opportunity?

J Hazard Mater 2021 09 13;417:126108. Epub 2021 May 13.

School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor, Malaysia; College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China. Electronic address:

Coronavirus Diseases 2019 (COVID-19) pandemic has a huge impact on the plastic waste management in many countries due to the sudden surge of medical waste which has led to a global waste management crisis. Improper management of plastic waste may lead to various negative impacts on the environment, animals, and human health. However, adopting proper waste management and the right technologies, looking in a different perception of the current crisis would be an opportunity. About 40% of the plastic waste ended up in landfill, 25% incinerated, 16% recycled and the remaining 19% are leaked into the environment. The increase of plastic wastes and demand of plastic markets serve as a good economic indicator for investor and government initiative to invest in technologies that converts plastic waste into value-added product such as fuel and construction materials. This will close the loop of the life cycle of plastic waste by achieving a sustainable circular economy. This review paper will provide insight of the state of plastic waste before and during the COVID-19 pandemic. The treatment pathway of plastic waste such as sterilisation technology, incineration, and alternative technologies available in converting plastic waste into value-added product were reviewed.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126108DOI Listing
September 2021

A comprehensive review on the techniques for coconut oil extraction and its application.

Bioprocess Biosyst Eng 2021 Sep 19;44(9):1807-1818. Epub 2021 May 19.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

Virgin coconut oil is a useful substance in our daily life. It contains a high percentage of lauric acid which has many health benefits. The current industry has developed several methods to extract the oil out from the coconut fruit. This review paper aims to highlight several common extraction processes used in modern industries that includes cold extraction, hot extraction, low-pressure extraction, chilling, freezing and thawing method, fermentation, centrifugation, enzymatic extraction and supercritical fluid carbon dioxide. Different extraction methods will produce coconut oil with different yields and purities of lauric acid, thus having different uses and applications. Challenges that are faced by the industries in extracting the coconut oil using different methods of extraction are important to be explored so that advancement in the oil extraction technology can be done for efficient downstream processing. This study is vital as it provides insights that could enhance the production of coconut oil.
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http://dx.doi.org/10.1007/s00449-021-02577-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8132276PMC
September 2021

Waste biorefinery towards a sustainable circular bioeconomy: a solution to global issues.

Biotechnol Biofuels 2021 Apr 7;14(1):87. Epub 2021 Apr 7.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

Global issues such as environmental problems and food security are currently of concern to all of us. Circular bioeconomy is a promising approach towards resolving these global issues. The production of bioenergy and biomaterials can sustain the energy-environment nexus as well as substitute the devoid of petroleum as the production feedstock, thereby contributing to a cleaner and low carbon environment. In addition, assimilation of waste into bioprocesses for the production of useful products and metabolites lead towards a sustainable circular bioeconomy. This review aims to highlight the waste biorefinery as a sustainable bio-based circular economy, and, therefore, promoting a greener environment. Several case studies on the bioprocesses utilising waste for biopolymers and bio-lipids production as well as bioprocesses incorporated with wastewater treatment are well discussed. The strategy of waste biorefinery integrated with circular bioeconomy in the perspectives of unravelling the global issues can help to tackle carbon management and greenhouse gas emissions. A waste biorefinery-circular bioeconomy strategy represents a low carbon economy by reducing greenhouse gases footprint, and holds great prospects for a sustainable and greener world.
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http://dx.doi.org/10.1186/s13068-021-01939-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8028083PMC
April 2021

A practical approach for synthesis of biodiesel via non-edible seeds oils using trimetallic based montmorillonite nano-catalyst.

Bioresour Technol 2021 May 17;328:124859. Epub 2021 Feb 17.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

The potential of new trimetallic (Ce, Cu, La) loaded montmorillonite clay catalyst for synthesizing biodiesel using novel non-edible Celastrus paniculatus Willd seed oil via two-step transesterification reaction has been reported along with catalyst characterization. Transesterification reaction was optimized and maximum biodiesel yield of 89.42% achieved under optimal operating reaction states like; 1:12 oil to methanol ratio, 3.5% of catalyst amount, 120 °C of reaction temperature for 3 h. The predicted and experimental biodiesel yields under these reaction conditions were 89.42 and 89.40%, which showing less than 0.05% variation. Additionally, optimum biodiesel yield can be predicted by drawing 3D surface plots and 2D contour plots using MINITAB 17 software. For the characterization of the obtained biodiesel, analysis including the GC/MS, FT-IR, H NMR and C NMR were applied. The fuel properties of obtained biodiesel agrees well with the different European Union (EU-14214), China (GB/T 20828), and American (ASTM-951, 6751) standards.
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http://dx.doi.org/10.1016/j.biortech.2021.124859DOI Listing
May 2021

Meeting Sustainable Development Goals: Alternative Extraction Processes for Fucoxanthin in Algae.

Front Bioeng Biotechnol 2020 4;8:546067. Epub 2021 Jan 4.

Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, Selangor, Malaysia.

The ever-expanding human population puts tremendous pressure on global food security. With climate change threats lowering crop productivity and food nutritional quality, it is important to search for alternative and sustainable food sources. Microalgae are a promising carbon-neutral biomass with fast growth rate and do not compete with terrestrial crops for land use. More so, microalgae synthesize exclusive marine carotenoids shown to not only exert antioxidant activities but also anti-cancer properties. Unfortunately, the conventional method for fucoxanthin extraction is mainly based on solvent extraction, which is cheap but less environmentally friendly. With the emergence of greener extraction techniques, the extraction of fucoxanthin could adopt these strategies aligned to UN Sustainable Development Goals (SDGs). This is a timely review with a focus on existing fucoxanthin extraction processes, complemented with future outlook on the potential and limitations in alternative fucoxanthin extraction technologies. This review will serve as an important guide to the sustainable and environmentally friendly extraction of fucoxanthin and other carotenoids including but not limited to astaxanthin, lutein or zeaxanthin. This is aligned to the SDGs wherein it is envisaged that this review becomes an antecedent to further research work in extract standardization with the goal of meeting quality control and quality assurance benchmarks for future commercialization purposes.
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http://dx.doi.org/10.3389/fbioe.2020.546067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7863972PMC
January 2021

Algae biopolymer towards sustainable circular economy.

Bioresour Technol 2021 Apr 12;325:124702. Epub 2021 Jan 12.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The accumulation of conventional petroleum-based polymers has increased exponentially over the years. Therefore, algae-based biopolymer has gained interest among researchers as one of the alternative approaches in achieving a sustainable circular economy around the world. The benefits of microalgae biopolymer over other feedstock is its autotrophic complex to reduce the greenhouse gases emission, rapid growing ability with flexibility in diverse environments and its ability to compost that gives greenhouse gas credits. In contrast, this review provides a comprehensive understanding of algae-based biopolymer in the evaluation of microalgae strains, bioplastic characterization and bioplastic blending technologies. The future prospects and challenges on the algae circular bioeconomy which includes the challenges faced in circular economy, issues regard to the scale-up and operating cost of microalgae cultivation and the life cycle assessment on algal-based biopolymer were highlighted. The aim of this review is to provide insights of algae-based biopolymer towards a sustainable circular bioeconomy.
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http://dx.doi.org/10.1016/j.biortech.2021.124702DOI Listing
April 2021

Prospects and development of algal-bacterial biotechnology in environmental management and protection.

Biotechnol Adv 2021 Mar-Apr;47:107684. Epub 2020 Dec 30.

Department of Chemical and Materials Engineering, Tunghai University, Taichung 407, Taiwan; Research Center for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan. Electronic address:

The coexistence of algae and bacteria in nature dates back to the very early stages when life came into existence. The interaction between algae and bacteria plays an important role in the planet ecology, cycling nutrients, and feeding higher trophic levels, and have been evolving ever since. The emerging concept of algal-bacterial consortia is gaining attention, much towards environmental management and protection. Studies have shown that algal-bacterial synergy does not only promote carbon capture in wastewater bioremediation but also consequently produces biofuels from algal-bacterial biomass. This review has evaluated the optimistic prospects of algal-bacterial consortia in environmental remediation, biorefinery, carbon sequestration as well as its contribution to the production of high-value compounds. In addition, algal-bacterial consortia offer great potential in bloom control, dye removal, agricultural biofertilizers, and bioplastics production. This work also emphasizes the advancement of algal-bacterial biotechnology in environmental management through the incorporation of Industry Revolution 4.0 technologies. The challenges include its pathway to greener industry, competition with other food additive sources, societal acceptance, cost feasibility, environmental trade-off, safety and compatibility. Thus, there is a need for further in-depth research to ensure the environmental sustainability and feasibility of algal-bacterial consortia to meet numerous current and future needs of society in the long run.
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http://dx.doi.org/10.1016/j.biotechadv.2020.107684DOI Listing
April 2021

Algae utilization and its role in the development of green cities.

Chemosphere 2021 Apr 15;268:129322. Epub 2020 Dec 15.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor, Malaysia.

With the rapid urbanisation happening around the world followed by the massive demand for clean energy resources, green cities play a pivotal role in building a sustainable future for the people. The continuing depletion of natural resources has led to the development of renewable energy with algae as the promising source. The high growth rate of microalgae and their strong bio-fixation ability to convert CO into O have been gaining attention globally and intensive research has been conducted regarding the microalgae benefits. The focus on potential of microalgae in contributing to the development of green cities is rising. The advantage of microalgae is their ability to gather energy from sunlight and carbon dioxide, followed by transforming the nutrients into biomass and oxygen. This leads to the creation of green cities through algae cultivation as waste and renewable materials can be put to good use. The challenges that arise when using algae and the future prospect in terms of SDGs and economy will also be covered in this review. The future of green cities can be enhanced with the adaptation of algae as the source of renewable plants to create a better outlook of an algae green city.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129322DOI Listing
April 2021
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