Publications

Thermal, structural, and optical properties of γ‐irradiated poly(vinyl alcohol)/poly(ethylene glycol) thin film

Poly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) copolymer was prepared using casting technique. The obtained PVA/PEG thin films have been irradiated with gamma rays with doses ranging from 1.5 to 20 Gy. The resultant effect of gamma irradiation on the thermal properties of PVA/PEG has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The onset temperature of decomposition T o and activation energy of thermal decomposition E a were calculated, results indicating that the PVA/PEG thin film decomposes in one main weight loss stage. Also, the gamma irradiation in dose range 4–12 Gy led to a more compact structure of PVA/PEG copolymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with gamma dose has been determined using DTA. The PVA/PEG thermograms were characterized by the appearance of an endothermic peak due to melting of crystalline phase. In addition, structural property studies using X‐ray diffraction and infrared spectroscopy were performed on both nonirradiated and irradiated samples. Furthermore, the transmission of the PVA/PEG samples and any color changes were studied. The color intensity ( E was greatly increased with increasing the gamma dose and was accompanied by a significant increase in the blue and green color components. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Contribution of zeolitic imidazolate framework-8 in improving the performance of polymer electrolyte membrane for direct methanol fuel cell

Introducing ZIF-8 into the PES-cSMM membranes played a pivotal role in the development of proton-conducting pathways and an effective methanol barrier. We employed dry-wet phase inversion techniques to fabricate PES-cSMM, finding that a 3 wt% cSMM content yielded optimal results. The resulting PES-cSMM exhibits impressive performance, with a 38% higher selectivity and a 95% greater methanol barrier compared to Nafion® 117. The imidazole-N-H linker in the terminal PES-cSMM/ZIF-8 promotes proton transport through a hydrogen bond chain, while the hydrophobic backbone acts as an effective methanol filter. As a result, PES-cSMM/ZIF-8 boasts a 13-fold higher water uptake than Nafion® 117 and achieves a 99% improvement in methanol sieving performance, a highly promising breakthrough for DMFC systems. Proton conductivity for the PES-cSMM/ZIF-8 immersion membrane reaches 19.5 × 10-3 Scm-1, comparable to Nafion® 117, which is 20.4 × 10-3 Scm-1. The structural flexibility of ZIF-8 within PES-cSMM facilitates efficient proton conduction, while the ZIF-8 cage acts as a robust methanol barrier. Computational analysis revealed covalent bonding within the PES-cSMM system. We characterized the chemical interactions in PES-cSMM/ZIF-8 using topology analysis, specifically the Atom in Molecules/Non-covalent analysis (AIM/NCI) technique.

Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

No abstract is provided for this article.

Photocatalytic degradation of nonylphenol by immobilized TiO2 in dual layer hollow fibre membranes

Nonylphenol (NP) is one of refractory degradation intermediates of nonylphenol ethoxylates (NPEO) surfactant and among the most toxic and prevalent endocrine disrupting compounds (EDCs) found in the environment. This paper reports an effort in removing nonylphenol in water using novel photocatalytic dual layer hollow fibre membrane, where the outer layer comprised of polyvinylidene fluoride (PVDF)/titanium dioxide (TiO2) while the inner layer was 100% PVDF. Single layer hollow fibre membrane which consists of PVDF/TiO2 was also fabricated as the control sample. The presence of TiO2 on the outer surface of both dual and single layer hollow fibres was confirmed by scanning electron microscopy (SEM), energy dispersion of X-ray (EDAX) and contact angles analysis. The removal of 85% in NP concentration was achieved for dual layer hollow fibre after 4h UVA irradiation in submerged membrane photoreactor, compared to 70% for the single layer one. The kinetic rate of dual layer membranes was calculated to be 0.0092min−1 against 0.0062min−1 for the single layer counterpart. In general, dual layer hollow fibre membranes exhibited superior photocatalytic performance in comparison to single layer hollow fibre membranes due to the better dispersion of TiO2 on the outer membrane surface.

Modification of PVDF hollow fiber membrane with ZnO structure via hydrothermal for enhanced antifouling property in membrane distillation

This study aims to provide a close insight into the possibilities and constraints associated with the development of ZnO structures on polyvinylidene fluoride (PVDF) hollow fiber membranes using the hydrothermal method to enhance membrane surface roughness for improved fouling resistance in membrane distillation (MD). Due to the flexible nature of polymeric hollow fiber membranes, there is a considerable risk of the ZnO structure detaching from the membrane surface when the membrane is bent. To address this issue, the hydrothermal duration was varied between 4 and 16 h to optimize the ZnO structure for high integrity, followed by fluorination. The results reveal that the membrane treated with hydrothermal for 8 h exhibits stable coating integrity, imparting the membrane with the highest contact angles with various liquids. This membrane demonstrates a flux of 4.0 kg/m2h and excellent salt rejection (>99.9 %) in direct contact MD (DCMD) when treating a 35 g/L saline solution. Additionally, the membrane exhibits outstanding antifouling performance with minimal flux reduction over 24 h when treating a saline solution containing humic acid. However, the upscaling of the hydrothermal approach may pose challenges due to the difficulty in maintaining the consistency of ZnO structure formation.

Rapid systhesis of graphene nanosheets and its structural properties study for direct methanol fuel cell

Titanium dioxide nanofibers with diameter ranging to several nanometers were synthesized via electrospinning technique. The precursor solution was prepared by mixing the polyvinylpyrrolidone, PVP (MW-l,300,OOO) in ethanol, meanwhile titanium tetraisopropoxide, TTIP in acetic acid was slowly added into the solution under a vigorous stirring. The precursor solutions were then used in the electrospinning process under high voltage supply. As-spun nanofibers were heatted. under different temperature 400°C, 500°C and 600°C. The TiO2 nanofibers were characterized by using ,scanning electron microscopy (SEM), Brunauer Emmett-Teller (BET) and X-raY .diffraction (XRD). The results indicated that the heat treated Ti02 nanofibers consist of anatase and rutile phases. As the calcination temperature increased (400-500C), the anatase phase are greater than rutile phase and specific surface area are decreases while the calcination process influenced the nanofibers diameter.

Surface matrix functionalization of ceramic-based membrane for oil-water separation: A mini-review

No abstract is provided for this article.

Particle dispersion for indoor air quality control considering air change approach: A novel accelerated CFD-DNN prediction

Computational Fluid Dynamics (CFD) is a well-established tool to study fluid dynamics and particle movement, while Artificial Neural Network (ANN) models offer machine learning capabilities to accelerate indoor airflow predictions, but they still maintain a reasonable level of accuracy for prediction purposes. This study pioneers the integration of Deep Neural Network (DNN) models into indoor airflow dynamics, aiming to provide an accurate and accelerated prediction efficiency. The objective is to train two DNN models (classical and modified DNN models) to capture the complex relationships between ventilation rate, airflow patterns, and particle dispersion characteristics within buildings. Using a dataset generated from CFD simulations encompassing various air change rates, the trained modified DNN model significantly enhances prediction efficiency in term of the computational cost by 67 % reduction of CFD computational time (1 h to 20 min) while also resulting in very similar accuracy compared to the CFD outputs. The R 2 values of classical and modified DNN models (plane 1) at air flow rate equals to 4 ach are 0.6867 and 0.9567 in term of the DPM distribution, respectively. The similar pattern is observed as the accuracy of modified DNN is higher than the classical DNN for other air flow rates in terms of the DPM and velocity distributions. Accordingly, the number of prediction errors is significantly decreased as the model alters from the classical DNN to modified DNN model. The significance of this research lies in its potential to enhance the efficiency of assessing particle dispersion, allowing for the more efficient design of targeted ventilation strategies and indoor air quality control measures tailored to diverse pollutant sources emitted from humans. Integrating DNN and CFD in assessing particle dispersion characteristics is promising for improving the understanding of indoor air dynamics and facilitating data-driven decision-making for ensuring healthier and safer indoor environments.

Physico-chemical study of sulfonated poly(ether ether ketone) membranes for direct methanol fuel cell application

Sulfonated poly(ether ether ketone) (SPEEK) membranes have been prepared as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cell (DMFC) application. The SPEEK polymer was dissolved into N, N-dimethylacetamide (DMAc) in a subsequent step after sulfonating the raw polymer with concentrated sulfuric acid. The polymer solutions were then cast by pneumatic casting machine. The influence of sulfonation reaction temperature on ion exchange capacity (IEC) and degree of sulfonation (DS) havebeen investigated. The results showed that the IEC and DS are increased with the temperature. The resulting membranes were then characterized by evaluating their physicochemicalproperties such as methanol permeability and proton conductivity as a function of DS. The overall results showed that sulfonation process successfully enhanced the protonconductivity of the membrane and the values were comparable with commercial membrane, Nafion® 117, at room temperature. Although the methanol permeability of membrane alsoincreased after sulfonation process and proportional with DS, the value was still lower than Nafion® 117.

Dual-layer hollow fibres with different anode structures for micro-tubular solid oxide fuel cells

In this study, a high performance micro-tubular solid oxide fuel cell (SOFC) has been developed by depositing a multi-layer cathode onto an improved electrolyte/anode dual-layer hollow fibre fabricated via a single-step co-extrusion/co-sintering technique. The use of 0–20wt.% of ethanol in the inner layer spinning suspension allows the control over the asymmetric structure of the Ni–CGO anode layer, i.e. finger-like voids structure covering about 50–85% of the anode layer thickness with the rest volume occupied by sponge-like structure, and at the same time affects the morphology of the CGO electrolyte layer. The presence of finger-like voids significantly facilitates the fuel gas diffusion inside the anode, and as a result, the maximum power density increases from 1.84Wm−2 to 2.32Wcm−2, when the finger-like voids is increased from 50% to 70% of the asymmetric anode layer. However, further growth of finger-like voids, i.e. 85% of the anode layer, dramatically reduce the number of triple-phase boundary (TPB) region and conductivity in the anode, as well as the gas-tightness property of the electrolyte, which consequently decreases the maximum power density to 0.99Wcm−2. Based on the results obtained, therefore, dual-layer hollow fibres with 50–70% of finger-like voids in the anode layer can be considered as the ideal structure for producing high performance micro-tubular SOFCs.

Preparation of High Performance SPEEK/Cloisite 15A Nanocomposite Membrane via Advanced Membrane Formulation Method

Sulfonated poly (ether ether ketone) (SPEEK)/Cloisite 15A® nanocomposite membranes were prepared via solution intercalation method. For better dispersion of nanoclay in the polymer matrix, the solution intercalation method was modified and a compatibilizer was introduced. The state of nanoclay dispersion was determined by FESEM. The effect of the solution formulation preparation method and compatibilizer on the performance properties such as proton conductivity and methanol permeability of all membranes was studied. FESEM analysis confirmed that SPEEK/Cloisite 15A® nanocomposite membrane prepared via modified solution intercalation method and in the presence of compatibilizer was the best membrane in terms of its morphological structure. Due to its well nanoclay distribution in polymer matrix, this kind of membrane exhibited the highest selectivity owing to its high proton conductivity and low methanol permeability. SPEEK/Cloisite 15A® with compatibilizer prepared via modified solution intercalation method was found to be the best membrane.

Preparation and characterization of hydrophilic surface modifier macromolecule modified poly (ether sulfone) photocatalytic membrane for phenol removal

A modified poly (ether sulfone) (PES) by hydrophilic surface modifying macromolecules (LSMM) incorporated with oxygenated graphitic carbon nitride (OGCN) photocatalyst (PES/OGCN-LSMM) was successfully prepared as a hybrid photocatalytic membrane. The effect of solvent evaporation time during membrane fabrication was studied by focusing on the positioning of LSMM in order to provide the desirable properties of the PES/OGCN-LSMM hybrid membrane for phenol removal performance by photocatalytic and separation. The PES/OGCN-LSMM membranes exhibited a decreased value of contact angle as the solvent evaporation time increased. The SEM images revealed a dense top layer supported by finger-like structures underneath, which was formed for the membranes at 0–4 min solvent evaporation time, while a sponge-like microvoid structure was observed at 5 min of solvent evaporation time. It is interesting to highlight that as the evaporation time increased, the pure water flux decreased as the result of compact denser membrane. Benefitting the special feature of LSMM that tends to migrate upwards upon mixing, the LSMM effectively assisted OGCN photocatalyst to the top layer of the membrane. This was revealed by SEM top surface images that more OGCN photocatalyst particles were seen distributed on the dense top layer of the membrane upon longer solvent evaporation time supported by the membrane topography analysis. It was found that the phenol reduction by rejection and photocatalytic tests was the highest at 5 min solvent evaporation time, whilst water flux was the lowest. The obtained results showed that the LSMM has indeed assisted the positioning of OGCN towards the top layer of the membrane and consequently increased the photocatalytic activity of the membrane on phenol.

Hydrocarbon degradation and separation of bilge water via a novel TiO₂-HNTs/PVDF-based photocatalytic membrane reactor (PMR)

This paper focuses on the potential of a novel flat sheet nanocomposite titanium dioxide (TiO₂)-halloysite nanotubes (HNTs)/polyvinylidene fluoride (PVDF) membrane as a photocatalytic separator in the photocatalytic membrane reactor (PMR).

Braid-reinforced PVDF hollow fiber membranes for high-efficiency separation of oily waste water

Several efforts to produce mechanically robust polymeric hollow fiber membranes have led to the use of polyethylene terephthalate (PET) hollow braided tubes, which offer rigidity to hollow fiber membranes. However, a compensation of flux exists with increased filtration pathway occasioned by braid substrate and thick polymer coating. It is often difficult to control the fabrication parameters to achieve uniformly coated and thin separation layer. In this work, we report a modification of the erstwhile dry-jet wet spinning process for braided hollow fiber by introducing a loop-system to increase resident time in the coagulation bath for effective solvent exchange and leaching of pore former additive. A combination of air gap (5, 15 and 25 cm), polymer concentration (15%, 17% and 19%) and take-up speed (1.2, 2.4 and 3.6 m/min) were varied to produce membranes with optimum filtration performance against crude oil emulsion feed. BRP-HM8 spun with 15 wt% PVDF, 15 cm air gap and take-up speed of 2 rpm exhibited thin and uniform coating outside of braid, well-developed pore structure resulting in high flux up to 620 L/m2h, good hydrophilic/oleophobic characteristics with > 98% rejection of crude oil as well high mechanical properties against harsh feed and elevated pressure.

Development of Ceramic (Inorganic) Membranes for Oil/Water Separation

This chapter describes the implementation of ceramic (inorganic) membranes for oil/water separation in oily wastewater treatment or hydrocarbon-based wastewater in produced water (PW). Generally, ceramic membranes are fabricated from oxide materials due to their hydrophilic properties to adsorb water and repel oil. Recently, alternative ceramic materials from natural and waste oxides such as kaolin, bauxite, fly-ash and mullites were considered starting materials for ceramic membrane fabrication due to their low cost and abundance, especially in oil/water separation. In membrane technologies, such as the use of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), forward and reverse osmosis (FO and RO) have been implemented in many oil/water separations. In fact, with the advance of technologies, the modification of ceramic membranes surface to be used for oily wastewater and hydrocarbon was being made to be applied in membrane technologies such as membrane distillation. Finally, the future developments and challenges are briefly discussed. Throughout this chapter, the use of ceramic membrane technologies for oily wastewater treatment and hydrocarbon separation will be explained, along with the impact of the studies for this application.

Challenges, Opportunities and Future Directions of Membrane Technology for Natural Gas Purification: A Critical Review

Natural gas is an important and fast-growing energy resource in the world and its purification is important in order to reduce environmental hazards and to meet the required quality standards set down by notable pipeline transmission, as well as distribution companies. Therefore, membrane technology has received great attention as it is considered an attractive option for the purification of natural gas in order to remove impurities such as carbon dioxide (CO2) and hydrogen sulphide (H2S) to meet the usage and transportation requirements. It is also recognized as an appealing alternative to other natural gas purification technologies such as adsorption and cryogenic processes due to its low cost, low energy requirement, easy membrane fabrication process and less requirement for supervision. During the past few decades, membrane-based gas separation technology employing hollow fibers (HF) has emerged as a leading technology and underwent rapid growth. Moreover, hollow fiber (HF) membranes have many advantages including high specific surface area, fewer requirements for maintenance and pre-treatment. However, applications of hollow fiber membranes are sometimes restricted by problems related to their low tensile strength as they are likely to get damaged in high-pressure applications. In this context, braid reinforced hollow fiber membranes offer a solution to this problem and can enhance the mechanical strength and lifespan of hollow fiber membranes. The present review includes a discussion about different materials used to fabricate gas separation membranes such as inorganic, organic and mixed matrix membranes (MMM). This review also includes a discussion about braid reinforced hollow fiber (BRHF) membranes and their ability to be used in natural gas purification as they can tackle high feed pressure and aggressive feeds without getting damaged or broken. A BRHF membrane possesses high tensile strength as compared to a self-supported membrane and if there is good interfacial bonding between the braid and the separation layer, high tensile strength, i.e., upto 170Mpa can be achieved, and due to these factors, it is expected that BRHF membranes could give promising results when used for the purification of natural gas.

Forward Osmosis for Desalination Application

Biosorption of heavy metals from aqueous solutions using activated sludge, Aeromasss hydrophyla, and Branhamella spp based on modeling with GEOCHEM

This work tests the technical applicability of sewage sludge and isolated dead cells of Aeromasss hydrophyla and Branhamella spp for the elimination of inorganic pollutants such as Zn(II), Pb(II), Cd(II), and/or Cu(II) using synthetic wastewater with their initial concentrations of 100 mg/L, respectively. The sludge samples were collected from local sewage treatment plants. The effects of dose and pH on heavy metals removal were evaluated in batch studies and their removal performances were compared to those of previous studies. Both the Freundlich and the Langmuir models were plotted to study their biosorption using activated sludge and the bacteria. Isotherm data, resulting from the batch studies, were compared to the modeling results of Geochem. It was evident that the activated sludge could achieve 99% of Zn(II), Cd(II), Cu(II) and Pb(II) removal with 100 mg/L of concentration at pH 6.0 and 3 g/L of dose. Under the same conditions, 97% of Cd(II), Cu(II) and/or Pb(II) was removed by Aeromasss hydrophyla and Branhamella spp, as indicated by their adsorption capacities (activated sludge: 99.07 mg Pb2+/g; dewatered sludge: 57.15 mg Pb2+/g; digested sludge: 83.58 mg Pb2+/g; 24.47 mg Cd2+/g; Aeromasss hydrophylla: 71.91 mg Pb2+/g; Branhamella spp: 37.52 mg Cu2+/g). Of the four heavy metals studied, Pb(II) had the highest metal adsorption capacity for all adsorbents studied (Pb2+>Cu2+> Cd2+>Zn2+). The modeling results of the Geochem fitted well with the isotherm data of the batch studies at varying concentrations from 20 to 100 mg/L. The thermodynamic constant at pH 4 were comparable to those obtained from previous works. This indicates a reliable prediction over varying metal concentrations and pHs of the batch studies. In spite of the promising results, the treated effluents still could not meet the required effluent limits set by local legislation. Therefore, it is necessary to subsequently treat the samples using biological processes such as activated sludge.