Publications

A binary particle system optimization approach for routing in PCB holes drilling process

No abstract is provided for this article.

Optimizing Ammonia Removal from Landfill Leachate Using Natural and Synthetic Zeolite Through Statically Designed Experiment

No abstract is provided for this article.

Selectively mixed matrix hemodialysis membrane for adequate clearance of <i>p</i>-cresol by the incorporation of imprinted zeolite

The adequacy in uremic toxin removal upon hemodialysis treatment is essential in patients with kidney failure diseases as poor removal leads to heart failure, hypertension, and stroke. The combination of adsorption and diffusion processes has become very advantageous for hemodialysis membranes. By this mechanism, water-soluble uremic toxins (WSUTs) and protein-bounded uremic toxins (PBUTs) could be removed at one time. Therefore, this study aimed to develop a novel imprinted zeolite by p-cresol (IZC) and then incorporated it into polyethersulfone (PES) and poly(vinyl pyrrolidone) (PVP) to produce hollow fiber mixed matrix membrane (HF-MMM). The IZC proved to be sensitive in attracting the adsorbate, classifying it as having a strong adsorption behavior. Accordingly, IZC is very promising to be applied as an adsorbent in the hemodialysis treatment. In this study, IZC as p-cresol's adsorbent was incorporated into a PES-based polymeric membrane with a small addition of PVP to produce HF-MMM using a dry/wet spinning process. The effect of air gap distance between the spinneret and coagulant bath and percentage loading for PES, PVP, and IZC were studied and optimized to obtain the best performance of HF-MMM. The 40 cm of air gap distance, 16 wt% of PES, 2 wt% of PVP, and 1 wt% of IZC loading were able to produce a superior hemodialysis membrane. These optimized parameters showed sufficient uremic toxin removal, i.e., 60.74% of urea, 52.35% of p-cresol in the phosphate buffer saline solution, and 66.29% of p-cresol in bovine serum albumin solution for 4 h permeation using the dialysis system. These HF-MMMs also achieved pure water flux of 67.57 L m-2 h-1 bar-1 and bovine serum albumin rejection of 95.05%. Therefore, this membrane has proven to be able to clean up WSUT and PBUT through a one-step process. Moreover, as compared to the neat PES membrane, MMM was able to remove p-cresol at 186.22 times higher capability.

Contributors

Correction: Nanosilica-incorporated polyethersulfone-polytetrafluoroethylene dual-layer hollow fibers for direct contact membrane distillation

Heavy Metal Removal from Aqueous Solutions Using Biomaterials and/or Functional Composites: Recent Advances and the Way Forward in Wastewater Treatment Using Digitalization

Due to its low cost, over the past decades, biosorption technology has been extensively carried out to treat heavy metal-laden wastewater using biosorbents. Recent studies on heavy metal biosorption mechanisms and the simulation of mathematical modeling on the biosorption process have enhanced scientific understanding about the binding between target metal cations and the functional group on different surfaces of biomasses as a biosorbent. However, so far, none have provided an overview of mechanistic studies on heavy metal removal from aqueous solutions using inexpensive biosorbents. To close this knowledge gap, this article discusses the applicability of the surface complexation (SC) model for biosorption of a target pollutant. Insightful ideas and directions of future research in wastewater treatment using digital technologies are also presented. It was conclusive from a literature survey of 115 articles (1987–2023) that Aspergillus niger, Penicillium chrysogenum, and Rhizopus nigricans represent biomaterials that have substantial adsorption capacities, up to 200 mg of Au(I)/g, 142 mg of Th/g, and 166 mg of Pb(II)/g, respectively. The metal-binding mechanisms involved include ion exchange, surface complexation, and micro-precipitation. Ion exchange is the only mechanisms that play key roles in sequestering heavy metal using fungal cells with chitin and chitosan. X-ray energy dispersion (XED) and scanning electron microscopy (SEM) analysis were used to evaluate biosorption mechanisms of the inorganic pollutants using physico-chemical characterization on the cell surfaces of the biomass. As metal removal by the biosorbent is affected by its surface properties, surface complexation also occurs. The affinity of the surface complexation depends on the type of functional groups such as phosphate, carboxyl, and amine.

Enhanced Water Purification Performance of Composite Pva–Zno–Al2o3 Hollow Fiber Membrane: A Breakthrough Approach for High-Temperature Stability, Low-Pressure Water Separation

No abstract is provided for this article.

Polysulfone/amino-silanized poly(methyl methacrylate) dual layer hollow fiber membrane for uremic toxin separation

A new strategy to recycle dialysate within a system is needed to foster the progress of developing wearable artificial kidney as an alternative to conventional hemodialysis practices. This study presents an attractive approach to collectively remove uremic toxins by combining membrane filtration and adsorption process. In this work, dual layer hollow fiber (DLHF) membranes consisting of polysulfone (PSf) inner layer well attached to PSf/amino-silanized poly(methyl methacrylate (N-PMMA) outer layer were prepared via co-extrusion spinning process based on non-solvent induced phase separation. The PSf/N-PMMA DLHF membranes were characterized and evaluated in terms of urea adsorption capacity and filtration performance. It was revealed that the urea adsorption onto N-PMMA is a non-spontaneous physical process that follows Freundlich isotherm model and pseudo-second-order kinetic model. Results showed that the membrane exhibited urea adsorption capacity of up to 27.6 mg/g depending on N-PMMA content. Under dynamic filtration condition, the membranes demonstrated significant urea removal (39.2%) and showed desired sieving characteristics for other solutes. The design of DLHF membrane with adsorptive property is an exciting prospect that would become a key solution for dialysate regeneration.

Performance of Void-Free Electrospun SPEEK/Cloisite as a Function of Degree of Dispersion State on Nanocomposite Proton Exchange Membrane for Direct Methanol Fuel Cell Application

One of the main problems in direct methanol fuel cell (DMFC) application is methanol crossover. In order to solve the problem, an exfoliated void-free electrospun Sulfonated Poly(Ether Ether Ketone) (SPEEK)/cloisite nanocomposite membrane was developed. The membrane was prepared by immersing electrospun SPEEK/cloisite fiber mats onto incomplete solidified SPEEK polymer matrix. A well dispersed and reduction size of cloisite particles that ranges from 0.29⁻0.39 µm was observed by using Scanning Electron Microscopy Analysis (SEM) and Atomic Force Microscope (AFM). The effect of the morphology of the composite membrane in terms of degree of dispersion state of the Cloisite on the membrane performance was discussed. SP/e-spunCL15 with fully exfoliated structure exhibited the highest performance as compared to other tested membranes and Nafion® 115 with current density of 1042.2 mAcm-2 and power density of 1.18 mWcm-2. Improved morphological, dimensional change properties, and performance assigned to well-dispersed cloisite15A induced by the electrospinning technique make the membranes more efficient for direct methanol fuel cell applications.

Study of microstructure modification on La0.7Sr0.3Co0.2Fe0.8O3-δ (LSCF 7328) asymmetric flat membrane

The LSCF 7328 (La0.7Sr0.3Co0.2Fe0.8O3-δ) asymmetric flat membranes were successfully prepared via a phase-inversion method followed by sintering at 1200 °C. In this study, a variety of poly(ethylene glycol) (PEGs) as the pore-forming agent, with 3 wt% composition and a wide ranges of molecular weight (Mw) (200 to 8000 Da) were used to tests its’ effect to the properties of LSCF membranes. The results show that the PEGs, as additives, were able to modify the pore morphology and mechanical properties of the LSCF 7328 membrane. The morphological evidence from SEM images showed that the LSCF membranes have an asymmetric configuration, comprised of sponge-like and finger-like pores which are integrated with a dense layer. The variation in average pore size is clearly seen, starting from 13.00 to 135.33 μm, following the increase in PEGs molecular weight. The LSCF membranes which were prepared using PEG additive have higher hardness (1.2 – 13.6 Hv) than the membrane with no PEG (0.2 Hv). In contrast, the porosity and pore volume of the membranes decrease with the increase of PEGs molecular weight. The decrease might be due to the formation of various closed macro-voids as the molecular weight of PEGs increases. Furthermore, the thermal expansion coefficient of the membrane with different PEGs molecular weight (ie. 400, 600, 4000 and 6000) Da posses no significant different, i.e. around 16 x 10-6 °C-1, although the membrane showed different morphology and mechanical properties.

Cultivating sustainability: Harnessing biochar-derived composites for carbon-neutral wastewater treatment

Wastewater treatment plants (WWTPs) are responsible for greenhouse gas (GHG) emissions due to the release of CH4 and N2O from biological processes. To reduce their carbon footprint in WWTPs, novel solutions are needed to ensure a sustainable wastewater treatment. Biochar-derived composites (BDCs) can play a key role in minimizing GHG emissions. Biochar is a carbon-rich solid from biomass pyrolysis, which can be further modified with certain functional groups to enhance its adsorption capacity. They also can contribute to carbon sequestration and climate change mitigation by converting waste biomass into stable carbon forms. This work reviews recent progress in the application of BDCs for wastewater treatment and discusses their challenges. While providing an overview of synthesis methods, adsorption mechanisms, and regeneration strategies of BDCs, and their technological benefits, this work also identifies knowledge gaps and research directions for BDCs in wastewater treatment. A literature survey of published articles (1998–2023) shows their promising findings in wastewater treatment applications. A complete removal of 100 mg/L Cr(VI) was attained by 1.25 g/L of BC-CMC-nZVI at pH 5.5, enabling it to meet the effluent limit mandated by legislation. Fe2O3@BC had a high Cr(VI) adsorption capacity (142.86 mg/g), higher than those of magnetic BCs made by co-precipitation (23.85 mg/g), impregnation-pyrolysis (43.122 mg/g), and reductive co-deposition (58.82 mg/g). Iron-loaded magnetic burley tobacco stem biochar achieved 54.92 mg/g of Cr(VI) adsorption capacity, higher than that of raw burley tobacco biochar (3.84 mg/g). This difference could be due to their benefits such as high surface area, porosity, exchange capacity, and tunable surface chemistry. Due to their advantages, BDCs are promising solutions for achieving carbon neutrality in wastewater treatment, one of the major sources of GHG emissions. By adopting BDCs as adsorbents, WWTPs not only can contribute to net zero emissions, but also can improve their environmental performance and economic viability.

Effect of fabrication parameters on physical properties of metakaolin-based ceramic hollow fibre membrane (CHFM)

Ceramic hollow fibre membranes (CHFMs) are known to have superior characteristics including excellent thermal, mechanical, and chemical stability. Major limitations include their high cost and brittleness, traits which have hindered the commercial adoption of this technology. This paper studies the effects of three main fabrication parameters, i.e. ceramic content, bore fluid flowrate, and sintering temperature, on morphology and mechanical strength of low-cost CHFM from a well-known material in producing high strength concrete, i.e. metakaolin. The novel CHFM from metakaolin was prepared via a combined phase inversion and sintering technique. Scanning electron microscopy (SEM) and three-point bending strength were employed to examine the hollow fibre's morphology and mechanical strength. Response surface methodology (RSM) based on historical data design (HDD) was used to further verify experimental and predicted values for mechanical strength in terms of the three operating parameters mentioned above. The highest mechanical strength of 225.8MPa was obtained with 37.5wt% metakaolin content and 3mL/min of BF flowrate at a sintering temperature of 1500°C. The desirability of this work is 0.985, indicating that RSM is a suitable approach to validate the effects of fabrication parameters on the mechanical strength of metakaolin-based CHFM.

Low Nickel, Ceria Zirconia-Based Micro-Tubular Solid Oxide Fuel Cell: A Study of Composition and Oxidation Using Hydrogen and Methane Fuel

The study examines the effect of using low nickel (Ni) with high ceria (CeO2) anode content towards the oxidation of H2 and CH4 fuel by evaluating the activation energy of the ohmic process and charge transfer process. Using a micro-tubular solid oxide fuel cell (MT-SOFC), the anodes are made up of 50% YSZ with varying NiO:CeO2 percentages from 0% NiO, 50% CeO2 to 50% NiO, 0% CeO2. The performance is measured based on maximum power density (MPD), electrochemical impedance spectroscopy (EIS) and activation energy, Ea of the ohmic (Rohm) and charge transfer (Rct) processes. We found that by lowering the Ni content to lower than 50% NiO, anode conductivity will drop by 7-fold. An anode containing 37.5% NiO, 12.5% CeO2 yield MPD of 41.1 and 2.9 mW cm−2 when tested on H2 and CH4 fuels thus have the lowest Ni content without an abrupt negative effect on the MPD and EIS. The significant effect of conductivity drops on MPD and EIS are observed to occur at 25% NiO, 25% CeO2 and lower NiO content. However, anode content of 25% NiO, 25% CeO2 has the lowest Ea for Rct (29.74 kJ mol−1) for operation in CH4, making it the best anode composition to oxidize CH4. As a conclusion, an anode containing 25% NiO:25% CeO2:50% YSZ and 37.5% NiO:12.5% CeO2:50% YSZ shows promising results in becoming the low Ni anode for coking-tolerant SOFC.

A recent development on core-shell-based material and their application in membranes for water and wastewater treatment

The increasing demand for clean water urges many attempts to treat wastewater. The excessive presence of organic waste and many pollutants threatens human health, potentially resulting in various forms of discomfort and negative consequences. Many materials used have been modified vividly to solve the problem mentioned. Core-shell-based material as a catalyst and adsorbent is one of the modifications that increase nowadays, and the material used is believed to be the foremost point in the characteristic and application of the material. On the other hand, when used in the form of powder or solid, there are various challenges associated with its application, including the complications of separation, susceptibility to saturation, and the issue of leaching. Hence, one of the solutions is to develop core–shell-based materials in the form of membranes or incorporate them into a membrane matrix. Due to its low cost and practicality, membrane technology emerges as an efficient method. Various membrane modifications and configurations, such as core–shell-based membrane matrix, as membrane filler, or as coating layer, have been carried out to achieve excellent filtration performance. Nanofiber membrane which adopts a core–shell configuration in its matrix has shown better performance. Furthermore, fouling is a prevalent problem for membranes that can be addressed by using fillers made from core-shell structured materials. The enhanced filler dispersion and matrix stability lead to the high permeation flux and selectivity. Nevertheless, the particular synthesis and preparation conditions of the material remain a limitation, particularly when it comes to scaling up its application. This review focuses on core–shell-based material as a catalyst and adsorbent, encompassing variations in their core materials, synthesis methods, and their application in membranes which involves the core–shell configuration of membranes, the synthesis process, and the performance of the membrane with the presence of the structured material as a matrix, filler, and others. In addition, comprehensive applications of the core–shell-based membrane as a photocatalytic and adsorptive membrane in wastewater treatments are discussed. Furthermore, the review outlines a forward-looking perspective on the potential evolution of core-shell-based membranes, underscoring their continued significance in advancing wastewater treatment methodologies.

Preparation, characterizations and performance evaluations of alumina hollow fiber membrane incorporated with UiO-66 particles for humic acid removal

Humic acid removal requires ceramic membranes incorporated with metal organic framework (MOF) to display remarkable stability over water. Recent work has shown UiO-66, a Zr-based MOF, as an emerging material with the potential to fulfill this requirement. This work investigated the preparation, characterization and performance of UiO-66 particles deposited on alumina hollow fiber membranes. Concentrations of Zr precursors and synthesis period were varied in the preparation of UiO-66 using solvothermal synthesis. The presence of UiO-66 particles was characterized using the field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) mapping, x-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. Pure water flux and humic acid rejection tests were carried out on both pristine alumina hollow fiber membranes and alumina hollow fiber membranes deposited with UiO-66 particles. In the former, a high pure water flux value of 231.24 L m−2 h−1 was recorded, while in the latter the recorded value dropped to 9.36 L m−2 h−1. Pristine ceramic hollow fiber membranes used to separate humic acid (1 g L−1) from an aqueous solution showed a rejection rate of 98%. When UiO-66 particles were deposited on the ceramic membranes, the solute flux of the membranes increased to 68.36 L m−2 h−1. Surprisingly, it was found that 99% humic acid was rejected from a feed solution using the membranes incorporated with UiO-66 particles. Findings showed that the weight loading of the UiO-66 particles on the alumina hollow fiber membranes was very low, showing a reading of only approximately ~ 0.01 g. Based on the adsorption-desorption analysis, at high pH values (≥ 9), UiO-66 particles and humic acid displayed a similar surface charge, creating a repulsion effect during the filtration process. UiO-66 particles on alumina hollow fiber membranes showed excellent stability, making it viable for water purification applications.

Preparation and characterization of dual layer thin layer lanthanum strontium cobalt ferrite /alumina hollow fiber membrane using dip-coating and brush-coating techniques

This paper reports the preparation of the dual layer ceramic hollow fiber membrane that made of alumina and a mixed ion electron conducting (MIEC) material for simultaneous reaction and separation applications. Alumina hollow fiber membrane was prepared using the phase inversion process followed by a sintering technique at elevated temperature. The alumina hollow fiber membrane was used as membrane support onto which a thin and dense layer of lanthanum strontium cobalt ferrite (LSCF) was deposited. The main objective of this study was to investigate the LSCF coating formulations used in the deposition of LSCF layer onto alumina substrate membrane. The sintering temperature of thin LSCF layer was varied to investigate gas-tightness properties of LSCF membrane. A series of characterizations were conducted for both the support and the LSCF membrane. The result showed that the thin layer membranes with thicknesses ranging from 3 to 20 μm were successfully deposited on the surface of alumina hollow fiber support. The sintering process improved the gas-tightness properties but the sintering temperature above 1150°C caused defects on the surface of LSCF membrane.

Copper-substituted cobalt ferrite nanoparticles: Structural, optical and antibacterial properties

Economic and simple co-precipitation technique was used to synthesize cobalt ferrite nanoparticles (CuxCo(1-x)Fe2O4) where x = 0.0, 0.3, 0.5, 0.7 and 1.0. We systematically studied the crystal structure and antibacterial properties of samples as a function of Cu-substituted content. Increasing Cu concentration causes decrease in the nanoparticle size from ~30 to ~20 nm. Specific saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) of the spinel ferrites are diminished by the substitutions of Cu+2 ions. FTIR spectra exhibit two prominent fundamental absorption bands at ~595 cm-1 and 419 cm-1. These bands correspond to intrinsic stretching vibrations of metal at tetrahedral and octahedral site respectively. The Raman scattering results reveal that increase in the Cu content enhances the local disorder at both tetrahedral and octahedral sub lattices. Moreover, we found that substitution of cobalt with copper leads to high reactive oxygen species (ROS) which in turn enhance the antibacterial ability, as exhibited by optical density and inhibition zone diameter (IZD). The results indicate that the substitution of Co with Cu in Co ferrite nanoparticles strongly influences the microstructure, crystal structure and particle diameter.

Development of Dual-Mode Grass Cutter Robot

A grass cutter is a machine that uses a revolving blade or blades to cut a lawn grass. Many designs have been made, each suited to a particular purpose and this robot used string trimmer as the cutting blade. This robot is designed to operate by a rechargeable battery and can be described as an intelligent robot because the micro-controller will receive information from sensors connected to it in avoiding obstacle to ensure a neat pattern of cut and use the information to actuate the left and right motors driving the wheels and the centre motor driving string trimmer and at the same time it obeys all parameters of work and its program database. As it is well known that random motion for a lawn mower would sometimes lead to uncovered spaced, it all depends on how random is random. Few features were added with more advanced option which allows the user to manually control the lawn mower with a PS2 controller. This, in fact, where the user can manually control the grass cutting robot that looks like a tank. The data analysis was listed in the table to test the development of grass cutter. This robot is safe to use, environmental friendly, easy to operate, and have various modes such as manual and automated mode.