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While experimental studies indicate that concentration, temperature, and membrane properties have significant impact on membrane distillation (MD) performances, a systematic numerical modelling linking all variables with operation condition is lacking. With such model, we can quantitatively analyze, optimize, and predict how variations in membrane properties affect the process performance under varied operational conditions. In this study, a simulation model was created using MATLAB-Simulink to analyze the influence of membrane properties specifically membrane thickness, porosity, pore size, and contact angle on MD performance over a wide variety of operational settings. The simulation result showed a decrease in permeate flux from 66.79 to 24.61 kg/m².h as membrane thickness increased from 60 µm to 180 µm, while greater porosity from 0.5 to 0.9 led to around five times greater permeate flux. However, both properties had no effect on liquid entry pressure (LEP) value. Next, bigger pore size was found to enhance the permeate flux and mass transfer coefficient but lessened the LEP. Contact angle was discovered to be critical for LEP as it rose from zero to 529.8 kPa for contact angle 90 to 150°, but it had no effect on permeate flux and mass transfer coefficient. Overall, the study proves the suitability of using programmable MATLAB model in predicting MD performance. [ABSTRACT FROM AUTHOR]

Combination of enzymatic catalysis and membrane technology is advantageous in biotechnology processes. To this regard, a simple technique to immobilize the enzyme in the membrane support via reverse filtration will be applied. Alcohol dehydrogenase (ADH) (EC 1.1.1.1) was chosen as the enzyme to be immobilized on the commercial ultrafiltration membrane in this study. ADH catalyzed formaldehyde (CHOH) to methanol (CH3OH) and simultaneously oxidized nicotinamide adenine dinucleotide (NADH) to NAD+. An integrated, hydrophilic graphene oxide-based polymer membrane was used as a support to immobilize the enzyme. The objective of the study is to assess the performance of the biocatalytic membrane reactor when graphene oxide (GO) nanoparticles is co-deposited together with ADH enzyme within the polyethersulfone (PES) membrane in terms of its membrane permeability, hydrophilicity, enzyme loading, reaction conversion and biocatalytic productivity. The results showed that the membrane permeability increased with the addition of GO which indicating improved membrane hydrophilicity. Enzyme loading is highest for PES/GO 0.1 membrane at 79 %. The reaction conversion for all the membranes recorded between 60 % to 84 %, however the PES/GO membranes showed to be higher than the pristine membrane. The enrichment of GO improved the activity of ADH in 5 cycles. The cumulative biocatalytic productivity of PES/GO membranes in 5 consecutive cycles were higher with 455.4 µmol CH3OH/mgADH·h and 390.5 µmol CH3OH/mgADH·h respectively in comparison to only 359.5 µmol CH3OH/mgADH·h for pristine membrane. The synergy between enzyme catalysis and membrane filtration is beneficial because it allows for both enzyme immobilization and simultaneous product separation. [ABSTRACT FROM AUTHOR]

Quantum dots are semiconductor nanoparticles with optical and electronic (optoelectronic) properties that vary with size and composition. They distinguish themselves from traditional fluorescence dyes due to their high visibility, long-lasting, size-tuneable, and narrow luminescence. Quantum dots are being used for a wide range of biological applications, including fluorescent assays for drug development, disease detection, single protein monitoring, and intracellular reporting. This mini review will focus on the overview of bioconjugation techniques which include the covalent and non-covalent conjugation of quantum dots surface to the active functional groups of carboxyl, amine, thiol, epoxy, hydroxyl and aldehyde. The various type of bioconjugation should be carefully selected based on the application of the quantum dots and the critical criteria of a biocompatible quantum dots will be also discussed. Recent application of quantum dots in biological system in bioimaging, bioanalytical, biosensing and drug delivery were laid out. The future outlook and the reality of quantum dots application in biological system were highlighted as the conclusion of this mini review. [ABSTRACT FROM AUTHOR]

Discharging of coloured dyes into wastewater has become one of the crucial issues around the world. Among various established alternatives to treat dye-contaminated water, photocatalytic degradation is a promising method to remove various dyes from water and wastewater due to their excellent photocatalytic activity and minimal final by-products. Nowadays, an immense number of photocatalysts have been synthesized and modified to achieve efficient treatment of photocatalytic degradation on dyes. On top of that, criteria include appropriate band gap energy of photocatalysts, applicability for solar light irradiation, good stability, and maximum recyclability have become the main prioritized. Herein, this review summarised the progress of emerging photocatalysts, graphene oxide, graphitic carbon nitride (g-C3N4) and molybdenum disulfide (MoS2) in treating dyes. Furthermore, the performance of photocatalyst, the type of dyes treated, and significant findings from the treatment was also discussed. Finally, the future trends and challenges in applying photocatalysts to treat dyes in wastewater are comprehensively deliberated. [ABSTRACT FROM AUTHOR]

Recently, a thermally-driven membrane process known as membrane distillation (MD) has emerged as an alternative to the high-pressure membrane process for contaminants removal from water. The driving force for MD is a vapor pressure gradient produced by a temperature differential across a hydrophobic porous membrane, which results in the transfer of water vapor from hot to cold side. However, the feasibility of MD for industry adoption is hampered by several issues such as temperature polarisation effects, low permeate flux, membrane wetting, and fouling. The membrane properties are known to have a significant role in controlling the final performances of MD. This review first looks into the feature of ideal MD membrane properties. Then, the use of graphenebased materials for the development of high performances MD membrane is discussed. Besides enhancing the water permeability and selectivity of MD, the incorporation of graphene offers additional properties such as anti-fouling, antibacterial, and photodegradation. The future direction of using graphene-based photothermal material in MD for heat generation under solar irradiation is also reviewed. It is found that the localised heating at membrane surfaces by photothermal material can minimise temperature polarisation effects and subsequently enhance the driving force for effective vapour transport. Thus, a more energy-efficient MD system can be developed. [ABSTRACT FROM AUTHOR]

This paper discusses the response surface methodology (RSM) study on a recent direct contact membrane distillation (DCMD) system. The DCMD system is reviewed due to its myriad attention on desalination process, especially on water treatment of high salinity and reclamation of industrial process water. The fundamental of DCMD, as well as the mass and heat transfer principles for modelling the system, are firstly explained and compared with previous studies. Then, the researcher highlighted the parameters involved in the modelling of DCMD process, such as feed temperature, velocity, and concentration, simultaneously with common membrane properties in mass and heat transfer models. The correlation of these frequently studied parameters with the conventional model was included and summarised. Subsequently, RSM was performed for the model development of the DCMD system, which included common design matrix applications, such as Box–Behnken, central composite design, and full factorial design. Finally, this work reviews the most recent application for the DCMD modelling of the model, comparing its experimental number runs, independent input number, model levels, and accuracy for optimising the DCMD process using RSM. [ABSTRACT FROM AUTHOR]