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Nickel-chromium alloys are often utilized in high-resistance and heating metamaterials because of their passivity; however, their reducibility behavior has never been reported. Herein, Ni-Cr reduction has been conducted in H2 and CO atmospheres. Nickel oxide (NiO) catalysts were impregnated with chromium and subsequently subjected to temperature-programmed reduction (TPR) at low concentrations of CO and H2 to determine their reduction performance. The TPR profile fitting using a Gaussian function indicated the Cr-NiO reduction transformation of Cr6+→Cr3+ at temperatures below ∼300 °C for both reductant gasses. Furthermore, the addition of Cr shifted the reduction peaks to a lower temperature owing to the interaction of Cr and Ni atoms, leading to increased reducibility. The characterizations of the Cr-NiO catalyst using X-ray diffraction, Brunauer–Emmet–Teller surface area, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) analyses demonstrated the formation of NiCrxOy alloy with increasing surface area and porosity. The kinetic analysis using the Kissinger method demonstrated the reducibility of the catalysts with a low Ea value after the addition of Cr, where an Ea value of 68.0 kJ mol−1 (NiO) decreased to 49.3 kJ mol−1 (Cr-NiO) in the H2 atmosphere and an Ea value of 95.8 kJ mol−1 (NiO) decreased to 91.9 kJ mol−1 (Cr-NiO) in the CO atmosphere. The synergistic effects between Cr and Ni contributed to the increase in catalyst active sites by the transformation of the nickel oxidation state, which demonstrated the formation of oxygen vacancies and alloys, as proven via XPS analysis.

In recent years, previously reported studies revealed a high efficiency of pollutant degradation by coupling photocatalysis and electrochemical processes (PECs) using titanium dioxide (TiO2) photoelectrode rather than using photocatalysis or electrocatalysis alone. However, some of the TiO2 photoelectrodes that have been reported were not cost-effective. This is due to the use of expensive chemicals and certain expensive equipment in the fabrication process, other than involving complicated preparation steps. Therefore, this study is aimed at investigating the PEC performance and stability of low-cost TiO2-polyvinyl chloride (TiO2-PVC) composite photoelectrode for Reactive Orange 16 (RO16) degradation. The materials characterisation using the ATR-FTIR, XRD and UV-Vis DRS proved that TiO2 and TiO2-PVC were successfully synthesised. The micrograph obtained for the surface characterisation using the FESEM showed that the smooth surface of freshly prepared photoelectrodes turned slightly rough with tiny pits formation after five continuous PEC processes. Nevertheless, the photoelectrode retained its original shape in good condition for further PEC processes. By PEC process, the fabricated photoelectrode showed 99.4% and 51.1% of colour and total organic carbon (TOC) removal, respectively, at optimised PEC parameters (1.0 mol L−1 NaCl concentration, 10 V applied voltage, 120 min degradation time and initial pH 2). Moreover, the fabricated photoelectrode demonstrated sufficient reusability potential (~ 96.3%) after five cycles of PEC processes. In summary, a low-cost and stable composite photoelectrode with high efficiency in RO16 degradation was successfully fabricated and could be potentially applied for other emerging pollutants degradation via the PEC degradation technique.

The persistence of inappropriate dumping of used cooking oil (UCO) containing triglyceride into water flow has become a significant complication for the purification process in wastewater treatment. UCO conversion using transesterification process still conquer as famous method to produce biodiesel especially in an industrial scale. This study was conducted to reveal the awareness in food premises in Bintulu, Sarawak, Malaysia, in the handling of UCO and support toward biodiesel production. A questionnaire was distributed to 200 owners of various food premises which were randomly selected regardless of gender or occupation. It was found that 13.1% of the participants generate 5 L of UCO per day, demonstrating promising frequency. The survey revealed that 8.4% of respondents discarded the UCO into the dustbin, while another 9.2% and 18.3% discarded the UCO into soil and drainage system, respectively. The remaining 48.1% sold the UCO and or completely consumed it during cooking. It is worth nothing that only 24% of respondents were expressed the interest to donate UCO for free by collecting from their premises. Meanwhile, 64% were reluctant to send UCO to the biorefinery centre due to the location distance of their premises. This study reveals a lack of awareness among local respondents regarding efficient UCO management, mandating the implementation of a proper UCO management workshop.

The chemical reduction progression behaviour of transition metals (Mo, Zr, W, Ce, and Co) doped on NiO was studied using temperature programmed reduction (TPR) analysis. A wet impregnation method was applied to synthesise the doped NiO series catalysts. The reduction progress of the catalysts was attained by using a reductant gas at the concentration of 40% v/v CO/N2. X-ray diffraction (XRD) was employed to determine the composition of the reduced phases. Undoped NiO was reduced at 384℃ to obtain a cubic phase of NiO. It was observed that Ce/NiO exhibited the lowest reduction temperature of 370℃ among all catalysts. This phenomenon might be due to a higher surface area of Ce/NiO compared to undoped NiO, which facilitated a faster reduction reaction. The rest of the doped NiO series catalysts (Co/NiO, Mo/NiO, W/NiO and Zr/NiO) demonstrated a higher reduction temperature compared to undoped NiO. New peaks in the XRD pattern were observed only for the reduced catalysts of Mo/NiO and W/NiO, which were associated with monoclinic MoO2 and WO2.72 phases, respectively. The formation of new compounds or more stable nickel alloys led to a slower reduction reaction than undoped NiO. Therefore, Ce/NiO was the most efficient catalyst in promoting the formation of Ni under the CO atmosphere.

Owing to their eccentric thermostable ability, thermophiles are among the most utilized extremophiles in various industries, such as manufacturing, and clinical research. Researchers believe that many unknown thermophiles are yet to be discovered. This study aimed to genotypically characterize the diversity of thermophiles and screen them for the potential production of enzymes in the recreational hot springs located at Northwest Coast of Borneo. Water samples were collected at 45 °C–50 °C from Annah Rais and Panchor hot springs during the sampling period from January 2018 to January 2019. Three samples (water and sediment) were collected twice in a 3-week interval from each pool of the sampling sites. Each water sample was diluted up to 10−3 and plated on thick nutrient agar at 55 °C for 24 h. Customized nutrient agar plus Bacto-agar plates were used for the optimum growth analysis of the isolates at 40 °C–90 °C for 24 h. The thermophiles were isolated, characterized biochemically, and amplified molecularly using DNA fingerprinting and 16S rRNA gene sequencing. Lipase, protease, gelatinase, amylase, catalase, and nitrate reductase enzymatic production was examined. Twenty-one thermophilic isolates were successfully characterized into seven clusters of Amnoxybacillus spp. and Geobacillus spp. by studying their phylogenetic dendrograms. Isolates AR10 and AR15 could produce most of the tested enzymes. All the isolates showed negative results in gelatinase and lipase production. PC14 was the only isolate that did not produce any of the enzymatic reactions in this experiment. The results showed that most of the thermophiles isolated from the two Borneo hot springs can synthesize enzymes and have potential to be thermostable. In conclusion, the search for the thermophilic producers of novel enzymes in Borneo is successful; further research must focus on their applications.

The present study evaluates the impact of charging speeds on the long-term performance of paraffin-based thermal energy storage (TES) up to 10,000 actual thermal cycles. Paraffin and form-stable phase change material (FSPCM) is used as the reference materials. The FSPCM is made of paraffin (80 wt%) and high-density polyethylene (HDPE, 20 wt%). The thermal cycling treatment is applied to the samples using slow (1 °C/min), normal (5 °C/min) and fast-charging cycles (10 °C/min). Performance assessment is conducted using an active thermal storage model. According to the assessment, thermal stress and hysteresis effect occur severely after 10,000 fast-charging cycles. It disrupts the heat transfer process, reducing the power and charging rate. Scanning electron microscope (SEM) shows the void formation for paraffin which correspond to a lower efficiency (62.5 %) than FSPCM (66.6 %). The presence of HDPE reduces the impact of the fast-charging effect on paraffin. The SEM micrograph for FSPCM indicates that a chemi-crystallization leads to phase-separation between paraffin and HDPE. It helps to maintain the charging and discharging duration after 10,000 fast-charging cycles. Furthermore, the decrement of melting enthalpy of FSPCM (5.5 %) is much lower than paraffin (12.7 %). Hence, FPSCM maintains the storage capacity after 10,000 fast-charging cycles at a sufficient level. The multi-step transition and power curve during the charging/discharging cycle are discussed in detail within the article. Further improvement can be taken to minimize the performance degradation of fast-charging paraffin-based TES by compositing paraffin to withstand thermal stress or modifying the system operation after a certain fast-charging cycle.

Exposure to high concentrations of ammonia can be harmful to human health. Ammonia is a strong irritant and can cause respiratory problems, such as coughing, wheezing, and shortness of breath. Prolonged exposure to high concentrations of ammonia can also cause damage to the lungs, and in severe cases, can lead to death. In addition to respiratory effects, ammonia exposure can also cause eye, nose and throat irritation, skin rashes and other symptoms. At high concentrations, ammonia can also cause chemical burns to the skin and eyes. The severity of the health effects will depend on the concentration of ammonia, the duration of exposure, and the specific characteristics of the individual exposed, such as their age, health, and any pre-existing respiratory condition. Wind can affect the migration of ammonia by influencing the dispersion and diffusion of the gas. Strong winds can disperse ammonia over a wide area, reducing the concentration in any one location. Conversely, calm winds can cause ammonia to accumulate in a specific area, leading to higher concentrations. The direction and strength of the wind can also affect the direction of ammonia migration, potentially carrying the gas towards or away from sensitive areas such as residential neighbourhoods or wildlife habitats. A wind rose is a graphical representation of the distribution of wind speeds and directions at a specific location. It is often used to understand the dominant wind patterns and how they may influence the dispersion of pollutants such as ammonia. The direction from which the wind is blowing is represented on the outer circle, with the wind speed represented on the inner circles. When it comes to ammonia dispersion, the wind rose can be used to understand how the dominant wind patterns in a specific location may influence the spread of ammonia emissions. For example, if the wind rose shows that the dominant winds are blowing from the direction of an ammonia source, such as a fertilizer plant, tow

A hybrid sorbent of ionic liquid immobilized silica could enhance the adsorption capacity of CO2 capture compared to ionic liquid itself. This study emphasizes the physical and chemical adsorption-desorption study using 1-butil-3-methylimidazolium trifluoromethanesulfonate immobilized on silica, [bmim][CF3SO3]/SiO2. Different loading (1–10% mol/mol) of [bmim][CF3SO3] on silica were synthesized using sol-gel method. This work shows the most efficient adsorbent of 1%[bmim][CF3SO3]/SiO2 exhibits an adsorption capacity of 73.88 mg CO2/g. CO2 capture is dependent on the physical and chemical properties of the [bmim][CF3SO3]/SiO2 hybrid sorbent system. The studied shows the physical adsorption of CO2 is controlled by the porous nature of the sorbent. The formation of micro-partial pores on 1%[bmim][CF3SO3]/SiO2 is a major factor that contribute the higher physical adsorption capacity of CO2. Meanwhile, chemical properties i.e the base strength of the sorbent was found to affect the chemical adsorption-desorption of CO2. The presence of anions which consist of fluroalkyl functional group enhanced the capacity adsorption of CO2. There is a mixture between CO2 and CO was found during the chemical desorption process which indicates the occurrence of CO2 released and decomposition of [bmim][CF3SO3] at medium range temperature of 450–500 °C due to the Boudouard reaction. The sorbents used in this work were characterized using BET method, FTIR, and FESEM.

Kitchen and food wastes discarded from the food related premises contributes to the high proportion of organic waste that end up in its landfill. The methane gas released during the dumping of food waste at the landfills is unsafe because the gas is flammable, and it is also a strong greenhouse gas. To tackle this problem, efforts are necessary to reduce the kitchen waste generated and to manage the disposal of waste sustainably. However, for this initiative to be successful, the owners and workers in food sector play an important role. The main objective of this study was to evaluate the practice, knowledge, and attitude of the food premises owners towards managing the kitchen and food waste in the district of Bintulu, Sarawak. Thus, a survey was conducted among 130 owners of randomly selected food premises. The collected data showed that food waste has the largest portion (46.7%) produced in Bintulu compared to other MSW such as plastic, paper, glass, metal, etc. Most respondents prefer to dump the food and kitchen wastes into garbage bins (79.2%) rather than composting (6.2%), donate, reuse, and recycle. This result proved the importance of building a biogas plant for kitchen and food waste since the respondents preferred to throw away the leftover food rather than composting the food. It will also help to propose appropriate treatment technologies to support the National Solid Waste Management (SWM) Policy and National Green Technology Policy for waste-to-wealth projects.

The barium oxide impregnated iron(III) oxide (BaO/Fe2O3) adsorbent was synthesized by an ultrasonic-assisted method. The adsorbent was calcined at 200-500 °C and its adsorption capacity was measured. The ultrasonic-assisted synthesis generated well-dispersed of BaO on Fe2O3 by giving none of the BaO peaks were observed through the XRD pattern. The most efficient adsorbent of BaO/Fe2O3200 was calcined at 200 °C with adsorption capacity for physisorption and chemisorption of 5.01 and 88.81 mg/g respectively. Besides other carbonate species, it was believed the presence of the hydroxyl group could enhance the sorption by forming bicarbonate upon CO2 chemisorption. It is also possessed a lower desorption range compared to BaO and Fe2O3 alone. The experimental CO2 adsorption isotherm at 25 °C fit better with the Freundlich isotherm model. It implies a favorable adsorption process with multilayer adsorption occurs onto the heterogeneous surface.

The CO2 adsorption time for carbonate species and linear CO2 formation onto bimetallic CaO/Fe2O3 was investigated. The total basicity for CaO/Fe2O3was 52.85 cm3g-1 which is located at a medium basic site with maximum CO desorption temperature at 454 ℃. The CO2 adsorption was conducted by using a fluidized bed reactor at 4, 12, 24 and 36 h. The element distribution on the adsorbent showed carbonate formation through an increment of the C element when the CO2 adsorption time was longer. At 4 h of CO2 adsorption, the adsorbent is capable of generating bicarbonate, monodentate carbonate and bidentate carbonate species. The vibrational modes of the physisorbed linear CO2 for CO2 absorbed product at the absorption region of 2240-2402 cm-1 was identified after 36 h of CO2 adsorption. The absorption bands were assigned according to the adjacent CO2 molecule interactions giving formation of the core layer and second layer linear CO2 on the CaO/Fe2O3 surfaces. The results of the present work show that the addition of CaO on the Fe2O3 surfaces enhanced the basic site of the adsorbent which could generate several carbonate species and CO2 adsorbed products at ambient condition.

BACKGROUND Previous reported studies revealed that composite electrodes are effective and suitable for wastewater treatment applications owing to their high porosity and increased electrochemical active area. However, the critical challenges to the wider adoption of composite electrodes for environmental applications are the need to reduce the cost of electrode materials, and to improve both their long-term stability and electrocatalytic performance. This study aims to investigate the efficiency and stability of low-cost graphite/chitosan-polyvinyl chloride (C/Chi-PVC) composite electrodes for Reactive Red 4 (RR4) degradation. Toxicity of the treated RR4 wastewater also was investigated using a seed germination test. RESULTS A cyclic voltammetry study conducted revealed that C49/Chi21-PVC30 (49% C, 21% Chi, 30% PVC) showed better electrochemical behaviour for hypochlorous ion (OCl−) formation, which is responsible for RR4 degradation via indirect electrochemical reaction. Owing to the synergistic effect of both materials, high colour, total organic carbon (TOC) and chemical oxygen demand (COD) removals of 99.61%, 89.68% and 76.35%, respectively, were achieved with less electrode damage at optimum electrolysis parameters. The treated RR4 solution displayed low toxicity after 14 days of exposure to the water sample. The electrode stability in the aggressive OCl− solution was studied by characterization of fresh and used electrodes using field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX). This showed no significant difference in surface roughness and elemental composition; the reusability test confirmed that the electrode can be applied in repeated electrolysis. CONCLUSION Overall, the fabricated electrode in this study showed high efficiency with robust and durable characteristics for wastewater treatment applications

Solid sorbent from functionalized activated carbon (AC) could enhance the adsorption capacity in CO2 capture. This study emphasizes cyclic CO2 capture using NiO functionalized AC. Different loadings of NiO impregnated on AC were synthesized. This work showed that the most efficient adsorbent of 0.05NiO/AC exhibits an adsorption capacity of 55.464 mg/g at the adsorption temperature of 30 °C by using the temperature swing adsorption method. A slight loss of adsorption capacity at 0.28 % for a five cycles CO2 capture indicated consistency potential for large scales application. The adsorbent exhibited a slightly lower surface area compared to AC, but the presence of NiO improved the adsorption capacity by chemisorption phenomena. The NiO acts as the basic site for CO2 capture. Meanwhile, AC as support could increase the surface area of active sites and reduce the sintering effect of the NiO. It was found that various adsorption temperatures had a good correlation with the pseudo-second-order kinetic model. The magnitude of the sorption process was evaluated by the activation energy of 48.09 kJ/mol, which implies a chemisorption process at various adsorption temperatures. Thermodynamic studies explained the CO2 adsorption process for this study was found to be a spontaneous and endothermic process.

The reduction behaviour of cobalt doped with nickel oxide and undoped nickel oxide (NiO) by hydrogen (H2) in nitrogen (20%, v/v) and carbon monoxide (CO) in nitrogen (40%, v/v) atmospheres have been investigated by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Co doped and undoped nickel oxide in both reductants proceed in one step reduction (NiO → Ni) without intermediate. TPR results also suggested that by adding Co metal into NiO, the reduction to metallic Ni by both reductant gaseous give different intensity of the peak. The reduction process of Co and undoped NiO become faster when H2 was used as a reductant. Furthermore, in H2 atmosphere, Co-NiO give complete reduction to metallic Ni at 700 °C. Meanwhile, XRD analysis indicated that NiO without Co composed better crystallite phases of NiO with higher intensity.

Surface modification of Fe2O3 by adding BeO was synthesized and calcined at different temperatures of 200-600 °C. The adsorbents were characterized by using XRD, N2 adsorption-desorption isotherm prior to performing CO2 adsorption and desorption studies. The CO2 adsorption data were analyzed using adsorption isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich. BeO/Fe2O3-300 that calcined at 300 °C showed the most efficient adsorbent with physisorption and chemisorption were measured at 5.85 and 45.88 mg/g respectively. The CO2 adsorption notably best fitted with Freundlich isotherm with R2 = 0.9897 and calculated adsorption capacity closest to experimental data. This implies the CO2 adsorption process was governed by multilayer adsorption on the heterogeneous surface of the adsorbent. The mean free energy of adsorption (E=3.536 kJ/mol) from Dubinin-Radushkevich and heat of adsorption (bT=3.219 kJ/mol) from the Temkin model support that the adsorption process is physical phenomena.

Corrosion of metal is a serious issue across many industries and is considered costly. Acids used during the cleaning process in industries may contribute to metal erosion. Dithiocarbamate is a ligand that can act as a corrosion inhibitor due to the presence of sulfur and nitrogen as electronegative atoms. Zn(II) N-isopropylbenzyldithiocarbamate (Zn[N-isopbenzdtc]2) complex was synthesized through direct synthetic method of < 4 °C and characterized using Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR), Ultraviolet-Visible (UV-Vis), Nuclear Magnetic Resonance (NMR), X-ray crystallography study, molar conductivity, melting point, and gravimetric analysis. Corrosion inhibition of mild steel was studied for different corrosive media (1 M HCl and 1 M H2SO4). The synthesized inhibitor was studied at different concentrations of 1, 2, 3, 4, and 5 mM at 40 °C. As a conclusion, as the inhibitor concentration decreased, the efficiency of the corrosion inhibitor also decreased at a constant temperature. In this study, it showed that the corrosion activity of mild steel in 1 M H2SO4 was higher compared to 1 M HCl due to the higher concentration of H+, which makes H2SO4 more corrosive than HCl.

Bimetal adsorbent system of calcium oxide impregnated on iron (III) oxide were evaluated as a potential source of basic sites for CO2 capture. The adsorbents were prepared by impregnation method were calcined at 200 until 600 °C. Several characterizations were carried out using XRD, BET and CO2-TPD analysis. The CaO loading increased the basicity of the adsorbent significantly enhance the CO2 chemisorption. Furthermore, it drastically reduced the desorption temperature to 310-490 °C, which is important in chemisorption aspect. The CaO/Fe2O3200 which calcined at 200 °C was found to be most efficient. The CO2 chemisorption (81.29 mg CO2/g adsorbent) was contributed most compared to physisorption (4.64 mg CO2/g adsorbent).

Supported ionic liquid (IL) [bmim][CF3SO3] on SiO2 was prepared, characterized and its potential evaluated for CO2 capture via adsorption and desorption studies using gas adsorption analyzer. The physical and chemical properties were determined using N2 adsorption/desorption and CO2-TPD analysis. The increasing IL loading caused a drastic decrease in the surface area as well as pore volume due to the confinement of IL within the micropore and mesopore area. However, the increasing IL loading increased the basicity of the sorbent which significantly enhanced CO2 chemisorption. Supported [bmim][CF3SO3] on SiO2 revealed the physical and chemical adsorption of CO2 and resulted in a remarkable CO2 adsorption capacity at atmospheric pressure and room temperature (66.7 mg CO2/gadsorbent) which has great potential in industrial applications.

Carbon dioxide emissions generated from fossil fuel-based power plants and other industries has reached 400 ppm in atmosphere. This negatively impact the environment, infrastructures and wildlife in particular. A lot of efforts are needed to produce CO2 gas sorbent in order to reduce high CO2 concentration. Therefore, porous silica gel (SG) is modified with amine compound for carbon dioxide capture. Calcinated silica gel functionalized with tetradecylamine (TDA) using wet impregnation has been developed as a porous media. The prepared sorbents is characterized by N2 physisorption technique Brunauer-Emmet-Teller analysis (BET). Significant changes in physical properties of the sorbents further ascertained the dispersion of TDA on the internal channels and external surface of the SG. Reactivity of porous sorbent towards CO2 was evaluated using isothermal CO2 adsorption desorption technique. This study shows 65TDA/SG enable to adsorb CO2 in the highest capacity which is 23.22 cm3CO2per gram sorbent. Moreover, CO2 capture consists of two type sorption which are physisorption and chemisorption. 55TDA/SG is the best sorbent in capturing CO 2by chemisorption (19.62 cm3CO2per gram adsorbent).