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This study demonstrated the performance of the sugarcane bagasse ash (SCBA) impregnated with calcium oxide (CaO) as a novel heterogeneous basic catalyst in biodiesel production. The SCBA was prepared by calcination for 2 h at 500 to 800 °C and impregnated with CaO loadings (10 to 40 wt.%). The prepared SCBA/CaO catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature programmed desorption of carbon dioxide (TPD-CO2), thermal gravimetric analysis (TGA), X-ray fluorescence (XRF) and Brunauer-Emmett-Teller (BET) surface characteristics. A series of transesterification reactions were conducted to evaluate the performance of the catalysts. As a result, highest FAME yield of 93.8% was obtained by using SCBA600°C CaO(40%) catalyst at 20:1 methanol-to-oil molar ratio, reaction temperature of 65 °C, with 6 wt.% catalyst in 3 h. Besides, the catalyst can be reused up to 5 reaction cycles with biodiesel yield of 93.0% and 70.3% at first and fifth cycles, respectively. In this work, it was found that the natural SiO2 in the SCBA has a significant role to enhance the catalytic performance and reduce the catalyst's deactivation drawback by minimizing the leaching of active sites. [ABSTRACT FROM AUTHOR]

Organic pollutants such as dyes, antibiotics, analgesics, herbicides, pesticides, and stimulants become major sources of water pollution. Several treatments such as absorptions, coagulation, filtration, and oxidations were introduced and experimentally carried out to overcome these problems. Nowadays, an advanced technique by photocatalytic degradation attracts the attention of most researchers due to its interesting and promising mechanism that allows spontaneous and non-spontaneous reactions as they utilized light energy to initiate the reaction. However, only a few numbers of photocatalysts reported were able to completely degrade organic pollutants. In the past decade, the number of preparation techniques of photocatalyst such as doping, morphology manipulation, metal loading, and coupling heterojunction were studied and tested. Thus, in this paper, we reviewed details on the fundamentals, common photocatalyst preparation for coupling heterojunction, morphological effect, and photocatalyst's characterization techniques. The important variables such as catalyst dosage, pH, and initial concentration of sample pollution, irradiation time by light, temperature system, durability, and stability of the catalyst that potentially affect the efficiency of the process were also discussed. Overall, this paper offers an in-depth perspective of photocatalytic degradation of sample pollutions and its future direction. [ABSTRACT FROM AUTHOR]

• Highly active Na 2 O impregnated-CNTs nanocatalyst was prepared and synthesized. • Positive metal cations possess Lewis acidity that increases the catalytic activity. • Na 2 O impregnated-CNTs nanocatalyst gave above 97% of FAME yield. • Leaching of Na+ lower than 5 mg L−1 as required by EN14214 international standard. The present work demonstrated the preparation of sodium oxide impregnated on carbon nanotubes (CNTs) and its application as a heterogeneous catalyst for transesterification of waste cooking oil. The catalyst was prepared by impregnation of metal oxide such as sodium oxide, Na 2 O on the CNTs by calcination at 500 °C for 3 h. It was assumed that the positive metal ion which is Na+ (cations) possess Lewis acidity, whereby, high negativity of oxygen ions can acts as the Brønsted bases, which could enhance the activity of the catalyst. The characterization of synthesized Na 2 O impregnated-CNTs nanocatalyst was performed using Temperature-programmed desorption of carbon dioxide (TPD-CO 2), X-ray diffraction (XRD), infrared spectroscopy and Field emission scanning electron microscope (FESEM). Herein, the mechanism of the transesterification process assisted by the Lewis acidic metal oxide on carbon support was proposed and explained. Series of reactions were carried out to determine the performance of the catalyst. It was found that the prepared Na 2 O (20 wt%) /CNTs catalysts yielded above 97% of FAME yield at 65 °C assisted by 3 wt% of catalyst amount and 20:1 of methanol-to-oil molar ratio in 3 h of reaction time. Moreover, the results on catalyst's reusability indicated that the catalyst could last for 3 subsequent reaction cycles due to deactivation of the catalyst caused by leaching of metal oxides and poisioning effect on the active sites. It can be concluded that the prepared Lewis acidic carbon catalyst has a potential to catalyse the production of biodiesel from waste cooking oil (WCO). [ABSTRACT FROM AUTHOR]

This study proposed biodiesel production from refined, bleached, and deodorised palm oil via transesterification using black pepper seed-KOH catalyst. A heterogeneous industrial waste catalyst, notably black pepper seed-KOH, was proposed because it can offer sustainability in biodiesel production. While among first generation oil feedstocks, palm oil stands out due to its high productivity because more palm oil can be generated per land area than others. Despite the most common use of the pseudo-first-order kinetic model in biodiesel studies, limited attention has been given to the second-order and reversible kinetics studies. Therefore, catalyst characterization encompassed SEM, EDX, TGA, PSA, FTIR, and basicity tests were first performed. Then, transesterification was executed at different temperatures (50–70 °C), 240-minute reaction time, 6:1 methanol-to-oil ratio, 5 wt% catalyst loading, and 200 rpm to obtain the best fit kinetic model and thermodynamic data. The results displayed a pseudo-irreversible first-order kinetics. Activation energy and pre-exponential factor were determined as 61.5195 kJ mol−1 and 1.1367 × 107 min−1. While, thermodynamic value was calculated, ΔH = 58.7528 kJ mol−1, ΔS = − 0.0850 kJ mol−1 K−1 and ΔG = 86.2157 to 87.9162 kJ mol−1. Therefore, the transesterification was defined as an endothermic, endogenic, and non-spontaneous reaction. This study demonstrates the black pepper seed-KOH's efficacy in biodiesel production and enhances understanding of kinetic and thermodynamic parameters governing the transesterification process. [ABSTRACT FROM AUTHOR]

[Display omitted] The hydrothermal carbonization (HTC) technique is known for its advantages in producing hydrochar from biomass samples with high water content compared to conventional pyrolysis techniques. This study utilized HTC to produce an activated carbon catalyst from renewable mesocarp fiber derived from palm oil processing. The introduction of K 2 CO 3 and Cu(NO 3) 2 produced a bifunctional catalyst suitable for conversion of used cooking oil to biodiesel. The catalyst possessed a mesoporous structure with a BET surface area of 3909.33 m2/g. An optimum treatment ratio of 4:1 (K 2 CO 3 : Cu(NO 3) 2) provided elevated basic (5.52 mmol/g) and acidic (1.68 mmol/g) concentrations on the catalytic surface, which promoted esterification and transesterification reactions. Maximum yield (96.4%) of biodiesel was obtained at 70 °C for 2 h with 5 wt% catalyst and a 12:1 molar ratio of methanol to oil. The catalyst endured up to 5 reaction cycles while maintaining biodiesel yields of more than 80%. These findings indicated that HTC pretreatment yielded a high-quality bifunctional catalyst for conversion of low-quality used cooking oil for production of biodiesel. [ABSTRACT FROM AUTHOR]

Dye wastewater consists of high solids concentrations, heavy metals, minor contaminants, dissolved chemical oxygen demand, and microorganisms. Nanoflowers are nanoparticles that resemble flowers when viewed at a microscopic level. Inorganic metal oxide nanoflowers have been discovered to be a potential source for overcoming this situation. Their flower-like features give them a higher surface area to volume ratio and porosity structure, which can absorb a significant amount of dye. The metal oxide nanoflower synthesized from different synthesis methods is used to compare which one is cost-effective and capable of generating a large scale of nanoflower. This review has demonstrated outstanding dye removal efficiency by applying inorganic nanoflowers to dye removal. Since both adsorption and photocatalytic reactions enhance the dye degradation process, complete dye degradation could be achieved. Meanwhile, the inorganic metal oxide nanoflowers' exemplary reusability characteristics with negligible performance drop further prove that this approach is highly sustainable and may help to save costs. This review has proven the momentum of obtaining high dye removal efficiency in wastewater treatment to conclude that the metal oxide nanoflower study is worth researching. [ABSTRACT FROM AUTHOR]

Biodiesel is one of the ideal options, considering it is a renewable, biodegradable, non-toxic, environmentally friendly fuel with low pollutant emission. However, biodiesel encounters challenges, mostly connected to its high manufacturing costs, that hinder its continued development and advancement. Focusing on more affordable and environmentally friendly inputs, such as suitable and abundant feedstock and efficient catalysts, is crucial. This paper aims to summarize the literature on biodiesel production and life cycle assessment (LCA) studies, critically review the catalyst and oil feedstock employed, and the findings of the LCAs, focusing on spotting prospective low-cost feedstock sources. Furthermore, an overview of recent LCA-related works applied in various biodiesel processes incorporating various catalysts and oil feedstock was evaluated. The application of LCA and its environmental impacts in biodiesel production was discussed and summarised in table form. The importance of using a sustainable and favorable approach could result in cost-efficient biodiesel production. Additionally, the advantages and limitations of the LCA in biodiesel production have been discussed. Last, the status and challenges of LCA in biodiesel production are covered. The findings of using cheaper feedstock are expected to inspire future studies and help industry professionals develop sustainable biodiesel production. • A comprehensive review of LCA framework and biodiesel process technologies were covered. • LCA of biodiesel production using various catalysts and oil feedstock was reviewed. • Challenges and status were discussed for sustainable biodiesel production. [ABSTRACT FROM AUTHOR]

A highly mesoporous activated carbon derived from palm kernel shell was successfully prepared by hydrothermal-assisted carbonization (HTC) by improving the degradation of lignocellulosic composition and increase the porous texture of carbon structure. Additional NaOH treatment increased the surface area of the catalyst which enhanced the loading of the active site. Further impregnation of HTC based activated carbon with K 2 CO 3 and CuO via wet impregnation provided bifunctional characteristics suitable for simultaneous esterification and transesterification processes. The physicochemical properties of the prepared catalysts were conducted through the state-of-the-art techniques including N 2 adsorption-desorption analysis, functional group determination, surface morphology study, electron dispersive x-ray mapping, elemental distribution analysis, amount of basicity and acidity strength and thermal degradation behavior analysis. The investigation found that the chemical treatment with NaOH significantly increased the surface area from 3.57 to 3368.60 m2/g and impregnation with K 2 CO 3 and CuO offered higher amount of basicity of 5.73 mmol/g and acidity of 1.48 mmol/g, respectively. These properties enhanced the simultaneous esterification-transesterification of waste cooking oil to biodiesel. The catalytic study produced 95.36 ± 1.4% of biodiesel over 4 wt% of PKSHAC-K 2 CO 3(20%) CuO (5%) catalyst, 12:1 of methanol to oil molar ratio, reaction temperature of 70 °C for duration of 2 h. Meanwhile, the catalyst can be employed for five subsequent reaction cycles with FAME yield of 82.5 ± 2.5%. Thus, the synthesized bifunctional nanocatalyst supported on the HTC based activated carbon has been validated as an efficient catalyst for biodiesel production. Image 1 • Hydrothermal-assisted carbonization creates high surface area of 3368 m2/g. • Large surface area provides high surface for metal impregnation. • Amount of basicity and acidity was improved with high loading of active sites. • Reaction over PKSHAC-K 2 CO 3(20%) CuO (5%) produced 95.36 ± 1.4% biodiesel from WCO. • Catalyst can be reutilized for 5 cycles with <80% biodiesel. [ABSTRACT FROM AUTHOR]

The main purpose of this manuscript is to report the new usage of tea waste (TW) as a catalyst for efficient conversion of palm fatty acid distillate (PFAD) to biodiesel. In this work, we investigate the potential of tea waste char as a catalyst for biodiesel production before and after sulfonation. The activated sulfonated tea waste char catalyst was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), elemental composition (CHNS), nitrogen adsorption-desorption using Brunauer-Emmett-Teller (BET) and ammonia-temperature-programmed desorption (NH3-TPD). The activated tea waste char catalyst shows higher acid density of 31 μmol g−1 as compared to tea waste char of 16 μmol g−1 and higher surface area of 122 m2/g. The optimum fatty acid conversion conditions were found that 4 wt % of catalyst loading with 9:1 of methanol:PFAD for 90 min of reaction time at 65 °C gives 97% free fatty acid (FFA) conversion. In conclusion, the sulfonated tea waste (STW) catalyst showed an impressive catalytic activity towards the esterification of PFAD at optimum reaction conditions with significant recyclability in five successive cycles without any reactivation step. [ABSTRACT FROM AUTHOR]

The use of carbon-based catalysts has drawn so much interest in biodiesel production due to improved reaction performance. However, there was lack of comprehensive studies in term of its kinetic and thermodynamic perspective. Therefore, a methodical study is essential to uncover the influence of the carbon catalyst with respect to reaction rate and yield. This study represents kinetic and thermodynamic of heterogeneously K 3 PO 4 /AC-catalysed transesterification. It was done correspondingly via pseudo-first order mechanism and Eyring-Polanyi equation, whereby, under the optimal reaction temperature of 333.15 K, all data have fitted satisfactorily in both models with resulted R 2 of 0.99, respectively. Activation energy (E a ) and Gibbs free energy (ΔG) were calculated as 34.2 kJ mol −1 and −33.68 kJ mol −1 , indicating the reaction was exergonic and spontaneous at high temperature. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) photocatalysts are suitable for wastewater treatment via photocatalytic processes. However, they are hindered by fast e− and h+ recombination, a large bandgap, and the need for a high-energy light source for activation. Thus, this study was aimed to synthesize a photocatalyst that operates under a low-energy consumption. We introduced cadmium sulphide (CdS) heterojunction to ZnO photocatalyst, and successfully reducing their bandgap from 3.30 eV to 2.46 eV. This modification allows activation with a 21-Watt light-emitting diode (LED) visible light source. The surface structure characteristics of the ZnO/CdS photocatalyst was analyzed using XRD, HRTEM, FESEM, and N 2 adsorption-desorption isotherms. UV-NIR was used for bandgap analysis and the DFT simulation method to compute the atomic properties of the materials. Catalytic evaluation showed that the ZnO/CdS photocatalyst completely degraded the model dye solution (100%) using 0.5 g of Z 3 C 1 (3:1 M ratio) of 100 mg L−1 MB solution at pH 9 within only 90 min. A scavenger test confirmed that the hydroxyl OH• and superoxide •O 2 − radicals proved were the major active species responsible for degradation process. The reusability of Z 3 C 1 was demonstrated over 4 reaction cycles, proving that CdS significantly enhances visible light absorption by extending the photo-response range and promoting superior formation of e− and h+. This delays their recombination due to the Z-scheme type, making it highly potential for wastewater treatment. [Display omitted] • Excellent Z-scheme ZnO/CdS heterojunction photocatalyst was prepared successfully. • CdS enhances visible light absorption by reducing the bandgap from 3.30 eV.→ 2.46 eV. • The electronic DFT band structure of Z-scheme ZnO/CdS was successfully calculated. • OH.• and •O 2 − radicals serve as major active species responsible for photodegradation. • The ZnO/CdS photocatalyst successful degrades 100% dyes molecules within 90 min. [ABSTRACT FROM AUTHOR]

Fatty acid methyl esters (FAME) production from waste cooking oil was successfully carried out using a newly developed heterogeneous biomass-based catalyst. Activated carbon produced from oil palm biomass was calcined with potassium phosphate tri-basics (K 3 PO 4 ) in order to synthesize a high catalytic heterogeneous catalyst. As it is characterized with substantial surface area of 680 m 2 /g and basicity amount of 11.21 mmol/g, 98% of FAME yield was achieved under optimum reaction parameters of 5 wt% catalyst loading, 12:1 methanol to oil molar ratio at 60 °C for 4 h. The catalyst was shown to be reusable, with more than 76% FAME yield after 5 consecutive cycles. [ABSTRACT FROM AUTHOR]

To date, the development of renewable fuels has become a normal phenomenon to solve the problem of diesel fuel emissions and the scarcity of fossil fuels. Biodiesel production has some limitations, such as two-step processes requiring high free fatty acids (FFAs), oil feedstocks and gum formation. Hydrotreated vegetable oil (HVO) is a newly developed international renewable diesel that uses renewable feedstocks via the hydrotreatment process. Unlike FAME, FFAs percentage doesn't affect the HVO production and sustains a higher yield. The improved characteristics of HVO, such as a higher cetane value, better cold flow properties, lower emissions and excellent oxidation stability for storage, stand out from FAME biodiesel. Moreover, HVO is a hydrocarbon without oxygen content, but FAME is an ester with 11% oxygen content which makes it differ in oxidation stability. Waste sludge palm oil (SPO), an abundant non-edible industrial waste, was reused and selected as the feedstock for HVO production. Techno-economical and energy analyses were conducted for HVO production using Aspen HYSYS with a plant capacity of 25,000 kg/h. Alternatively, hydrogen has been recycled to reduce the hydrogen feed. With a capital investment of RM 65.86 million and an annual production cost of RM 332.56 million, the base case of the SPO-HVO production process was more desirable after consideration of all economic indicators and HVO purity. The base case of SPO-HVO production could achieve a return on investment (ROI) of 89.03% with a payback period (PBP) of 1.68 years. The SPO-HVO production in this study has observed a reduction in the primary greenhouse gas, carbon dioxide (CO 2) emission by up to 90% and the total annual production cost by nearly RM 450 million. Therefore, SPO-HVO production is a potential and alternative process to produce biobased diesel fuels with waste oil. • Waste palm oil is produced using a sustainable hydrotreated vegetable oil production technology. • Techno-economic and energy analysis was based on 25,000 kg/h plant capacity. • Cheap feedstock and sustainable process for hydrotreated vegetable oil production. • The case study demonstrated that recycling hydrogen is preferred for economic viability. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have been proposed and actively explored as innovative carriers for drug delivery applications. The functionalization of carbon nanotubes can improve substantially their dispersability and biocompatibility profile, thus offering the potential exploitation of carbon nanotubes in drug administration. In this study, the multiwalled carbon nanotubes (MWCNTs) were functionalized using concentrated nitric acid (68%) and sulfuric acid (98%) in the ratio of 3:1 volume per volume by sonication techniques and were characterized using various characterization instruments. The generation of carboxylic groups was proven by FT-IR spectroscopy. In addition, the loading of aspirin (ASA) drug onto functionalized MWCNTs was done by sonication technique at different concentration of ASA drug solutions and at different sonication time. The presence of ASA attached onto functionalized MWCNTs was determined by FT-IR spectroscopy. The results from UV-Vis Spectrophotometer gave the percentage of ASA loading onto functionalized MWCNTs with the amount of 77.64% (77.64 mg/ 100 mg) at 30 000 ppm for 5 hours sonication. From the release study of ASA in Simulated Body Fluid (SBF) at 37°C (human body temperature) and 39°C (fever temperature), the results show a fast release of ASA from ASA-f-MWCNTs composite for the first 5 hours compared to the commercialized aspirin tablets and followed by a controlled release at the following hours. It reveals that MWCNTs have the ability to improve the pharmacokinetics of ASA in the biomedical applications, thus it can be used to improve the drug delivery system. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) provides alternatives technique to produce a nanosize activated carbon from biomass with a high surface area. Herein, this study we prepared empty fruit bunch-based activated carbon (EFBHAC) using HTC technique. The activated carbon was then functionalized with K 2 CO 3 and Cu(NO 3) 2 to produce bifunctional nano-catalyst for simultaneous esterification-transesterification of waste cooking oil (WCO). The physicochemical properties were performed i.e. N 2 sorptions analysis, TPD-CO 2 /NH 3 , FESEM, EDX, FTIR and XRD analysis. The results revealed that produced EFBHAC possessed a BET surface area of 4056.17 m2 g−1, with pore volume of 0.827 cm3 g−1 and 5.42 nm of pore diameter resulting from hydrolysis, dehydration decarboxylation, aromatization and re-condensation during HTC process. Impregnation of EFBHAC with K 2 CO 3 and Cu(NO 3) 2 granted a high amount of basicity and acidity of 9.21 mmol g−1 and 31.41 mmol g−1, respectively, accountable to high biodiesel yield of 97.1%, produced at the optimum condition of 5 wt% of catalyst loading, 12:1 of methanol to oil molar ratio at 70 °C for 2 h. More than 80% of biodiesel was produced after the 5th cycle depicted the good reusability. The transformations from WCO to biodiesel was confirmed via 1H NMR, FTIR and TGA analysis. Fuel properties revealed kinematic viscosity of 3.3 mm2 s−1, cetane number of 51, flash point of 160.5 °C, cloud and pour point of 11 °C and −3 °C, respectively. These results show the excellent potential of waste materials to prepare bifunctional nano-catalysts to produce higher biodiesel yield which has potential to be commercialized. [Display omitted] • Empty fruit bunch was transformed into high quality activated carbon via HTC process. • Catalyst support help to reduce costs as the reaction occurs on the catalyst surface. • Bifunctional nano-catalyst overcome saponification problem through one-pot reaction. • Produced biodiesel is proven to have quality equivalent to international standards. [ABSTRACT FROM AUTHOR]

The global e-waste generation is projected to leap tremendously over the following years due to the fast urbanization and increasing population. Inadequate management and uncontrolled disposal may impact significantly to the health and environment. E-waste could become a significant source of precious metals at the end of e-waste life. The recovery of precious metals from e-waste provides a sustainable solution; however, conventional hydrometallurgical approach bears a greater fraction of environmental concerns and energy utilization. In this study, effort has been given to recover palladium (Pd(II)) from ceramic capacitor using solvent-ligand process with a focus on environmental sustainability. The use of 3–(((5–ethoxybenzenethiol)imino)methyl)–salicylic acid as a ligand to recover Pd(II) from ceramic capacitor was investigated. The effects of different variables such as, contact time and reaction temperature, leaching kinetics as well as the environmental assessment of synthesis process were examined. The high purity of Pd(II)was recovered from ceramic capacitor under optimized condition, as evident from XRD and XPS analysis. The formation of [Pd(II)-ligand]n+ complexes was attributed to the recovery of pure metallic Pd(II). The environmental assessment measured from Biwer and Heinzle Method (BHM) indicated that the solvent-legend approach for recovering Pd(II)is associated with the lower impact on the environment compared with the other process. The results open up a sustainable recovery of precious metals contributing to the circular economy. [Display omitted] • Palladium(II) separation & recovery from e-waste using solvent-legend approach was developed. • The high purity Pd(II) was recovered through the stable [Pd(II)-ligand]n+ complexation. • The environmental footprint of the extraction process was assessed. [ABSTRACT FROM AUTHOR]

A large amount of waste printed circuit boards (WPCBs) has been generated due to the tenacious scientific development and therefore, the improvement of expectations for everyday comforts. The unprecedented acceleration of electronic waste (e-waste) and informal disposal at end-of-life display the adverse impact of digitalization. Recently, home teleworking has increased a wide range of sectors and occupations which may eventually lead to increase the generation of e-waste. Effective management of e-waste is urgently required for protecting environment as well as human well-being's. In view of the precious metal content and rare earth elements, WPCBs could become a sustainable source of precious metals. Appropriate eco-friendly strategies to recover metals from WPCBs are therefore imperative and crucial for e-waste management. Recent progress in metal recovery through gravity, density, electrostatic and integrated approaches were investigated dependent on previous contribution to provide an overview of present recycling status. The mechanism and factors influencing the metal recovery efficiency in a countercurrent operation were critically reviewed. The application of biotechnological approach for metal recovery was discussed from the theoretical and experimental views. The hazardous impact on human health and environment due to the toxic substances released from e-waste were highlighted. Finally, the limitations and perspectives towards the sustainable process for recovery of metals from e-waste were discussed. [Display omitted] • Emerging trend of metal recovery from WPCBs was measured. • Integrated e-waste recycling process with environmental impact was considered. • Novel biotechnological approaches with genome reprograming strategy were emphasized. [ABSTRACT FROM AUTHOR]

In this work, the beads and powder potassium hydroxide (KOH) and potassium carbonate (K2CO3) supported on alumina oxide (Al2O3) were successfully prepared via incipient wetness impregnation technique. Herein, the perforated hydrophilic materials (PHM) made from low-density polyethylene (LDPE) was used as the catalyst reactor bed. The prepared catalysts were investigated using TGA, XRD, BET, SEM-EDX, TPD, FTIR while spent catalysts were analyzed using XRF and ICP-AES to study its deactivation mechanism. The catalytic performance of beads and powder KOH/Al2O3 and K2CO3/Al2O3 catalysts were evaluated via transesterification of waste cooking oil (WCO) to biodiesel. It was found that the optimum conditions for transesterification reaction were 1:12 of oil-to-methanol molar ratio and 5 wt.% of catalyst at 65 °C. As a result, the mesoporous size of beads KOH/Al2O3 and K2CO3/Al2O3 catalysts yielded 86.8% and 77.3% at 2 h' reaction time of fatty acids methyl ester (FAME), respectively. It was revealed that the utilization of PHM for beads K2CO3/Al2O3 increase the reusability of the catalyst up to 7 cycles. Furthermore, the FAME produced was confirmed by the gas chromatography-mass spectroscopic technique. From this finding, beads KOH/Al2O3 and K2CO3/Al2O3 catalysts showed a promising performance to convert WCO to FAME or known as biodiesel. [ABSTRACT FROM AUTHOR]

The contamination of groundwater by arsenic (As) in Bangladesh is the biggest impairing of a population, with a large number of peoples affected. Specifically, groundwater of Gangetic Delta is alarmingly contaminated with arsenic. Similar, perilous circumstances exist in many other countries and consequently, there is a dire need to develop cost-effective decentralized filtration unit utilizing low-cost adsorbents for eliminating arsenic from water. Morphological synthesis of carbon with unique spherical, nanorod, and massive nanostructures were achieved by solvothermal method. Owing to their intrinsic adsorption properties and different nanostructures, these nanostructures were employed as adsorption of arsenic in aqueous solution, with the purpose to better understanding the morphological effect in adsorption. It clearly demonstrated that carbon with nanorods morphology exhibited an excellent adsorption activity of arsenite (about 82%) at pH 3, remarkably superior to the two with solid sphere and massive microstructures, because of its larger specific surface area, enhanced acid strength and improved adsorption capacity. Furthermore, we discovered that iron hydroxide radicals and energy-induced contact point formation in nanorods are the responsible for the high adsorption of As in aqueous solution. Thus, our work provides insides into the microstructure-dependent capability of different carbon for As adsorption applications. [Display omitted] • Novel micro-structured carbon-based adsorbents were used to removal arsenic (As). • The adsorbents were able to remove As more effectively than spherical and massive structured carbon. • Surface radicals and energy-induced contact point were enhanced the electrostatic interaction with As. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, magnetic BiFeO 3 nanoparticles were successfully grown via biotemplated method utilizing complex polysaccharides, namely alginate (brown algae). The proportion impact of Bi:Fe molar ratio, weight percent of sodium alginate, pH, and calcination temperature on the phase structure, microstructure, and morphologies of the BiFeO 3 nanoparticles were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. XRD analysis confirmed the formation of a pure phase of BiFeO 3 nanoparticles with a rhombohedral structure in the presence of 0.5 wt. % of sodium alginate, Bi:Fe molar ratio of 1:2, at pH 8 and calcination temperature of 550 °C for 2 h. This work suggests that alginate provides a well-defined, chemically and thermally stable environment for the formation of nanoparticles. The biosynthesized BiFeO 3 nanoparticles were subsequently evaluated for the removal of methylene blue (cationic), neutral red (neutral), and methyl orange (anionic) dyes. However, they were effective for removing methylene blue and neutral red dyes, but had low efficiency in removing methyl orange dye. The facile and green route approach will render new opportunities for advanced nanomaterials as tremendous potential in environmental remediation for water treatment. [ABSTRACT FROM AUTHOR]

The water pollution problems severely affect the natural water resources due to the large disposal of dyes, heavy metals, antibiotics, and pesticides. Advanced oxidation processes (AOP) have been developed using semiconductor nanomaterials as photocatalysts for water treatment as an essential strategy to minimize environmental pollution. Significant research efforts have been dedicated over the past few years to enhancing the photocatalytic efficiencies of semiconductor nanomaterials. Graphene-based composites created by integrating reduced graphene oxide (rGO) into various semiconductor nanomaterials enable the unique characteristics of graphene, such as the extended range of light absorption, the separation of charges, and the high capacity of adsorption of pollutants. Therefore, rGO-based composites improve the overall visible-light photocatalytic efficiency and lead to a new pathway for high-performance photocatalysts' potential applications. This brief review illustrates the strategies of combining rGO with various semiconductor nanomaterials and focuses primarily on modification and efficiency towards environmental contaminants. [ABSTRACT FROM AUTHOR]

The present work investigated the biodiesel production from used cooking oil catalyzed by nano-bifunctional supermagnetic heterogeneous catalysts (RHC/K2O/Fe) derived from rice husk doped with K2O and Fe synthesized by the wet impregnation method. The synthesized catalysts (RHC/K2O/Fe) were characterized for crystallinity by X-ray diffraction spectroscopy (XRD), total acidity and basicity using CO2/NH3-TPD, textural properties through Brunauer-Emmett-Teller (BET), thermal stability via thermogravimetric analyzer (TGA), functional group determination by Fourier-transform infrared spectroscopy (FTIR), surface morphology through field emission scanning electron microscopy (FESEM), and magnetic properties by vibrating sample magnetometer (VSM). The VSM result demonstrated that the super-paramagnetic catalyst (RHC/K2O-20%/Fe-5%) could be simply separated and regained after the reaction using an external magnetic field. The operating conditions such as catalyst loading, methanol/oil molar ratio, temperature, and reaction duration were studied. The screened RHC/K2O-20%/Fe-5% catalyst was selected for further optimization and the optimum reaction parameters found were 4 wt % of catalyst, a molar ratio of methanol/oil of 12:1, 4 h reaction duration, and 75 °C reaction temperature with a maximal yield of 98.6%. The reusability study and reactivation results revealed that the nano-bifunctional magnetic catalyst (RHC/K2O-20%/Fe-5%) could be preserved by high catalytic activity even after being reused five times. [ABSTRACT FROM AUTHOR]