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The low cost and excellent catalytic properties of lipase for industrial processes are highly desirable. A promising new approach involves the support modification of lipase and spacer arm, which enables the enhancement of lipase properties. This study investigates the immobilization of crude lipase from Mucor miehei onto a Polyurethane Foam (PUF) surface using various coating techniques. The PUF matrix was obtained through isocyanate and polyol reactions. Subsequently, the PUF was coated by adsorbing lipase and adding edible support material. The immobilized lipase was then utilized in the hydrolysis of coconut oil to produce fatty acids. Furthermore, the immobilized enzyme was employed in the esterification of fatty acids to produce bio-flavors. The results demonstrate that the attachment reaction using support material, namely lecithin, gelatin, MgCl2, and Polyethylene glycol 6000 (PEG), all of which are simple and edible, was able to enhance the stability and reusability of lipase. This immobilization technique increased triglyceride hydrolysis into FFA by 422%. The successful edible support modification of immobilized lipase from M. miehei on PUF, coupled with significantly enhanced enzyme stability and catalytic activity, offers a promising, environmentally friendly solution for diverse applications in the food industry. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

This study compared free and immobilized cells with palm oil and hexanol as an extractant in a large volume ratio of extractant to the broth. Fermentation was conducted using TYA (Tryptone-Yeast-Acetate) media, glucose as the substrate and the palm oil, hexanol, and a mixture of hexanol and palm oil with a composition of 1:1 v/v as an extractant in the fermentation with a large volume ratio of extractant to broth of 5. The strain was inoculated as free-suspended cells of C. saccharoperbutylacetonicum N1-4 and immobilized cells in calcium alginate. The best extractant results for the acetone fermentation process in the ratio of extractive fermentation of free cells and immobilized cells were using palm oil as extractants. This extractant harvested acetone well, with the acetone concentration in the extractant at 18.41 g/L in free cell fermentation and 17.07 g/L in immobilized cell fermentation. The maximum total acetone concentration was up to 93.72 g/L broth. Using palm oil as an extractant in a large extractant volume combined with immobilization is an alternative to enhance bioacetone production by effectively reducing the toxicity effect of the products and minimizing nutrient requirements.

The application of the expanded polystyrene (EPS) waste to the functional material is still a challenge. The hydrophobic property of polystyrene has a potential to create a superhydrophobic surface. Here, we use expanded polystyrene waste to coat surfaces in two different ways—spray coating and dip coating—to produce superhydrophobic surfaces for food packaging. The ZnO was employed to make the surface rougher. However, the combination of ZnO and EPS waste produces only a hydrophobic surface. For spray coating and dip coating, the maximum water contact angle is 119° and 125° respectively. The scanning electron microscope (SEM) picture reveals many holes that increase the surface's roughness. The hydrophobic surface significantly cuts down on cleaning time. According to the food packaging parameter test mandated by the Indonesian Food and Drug Administration (BPOM) (BPOM regulation No. 20, 2019), the coating complies with heavy metals and ethanol stimulant migration testing requirements for food packaging. However, the migration condition in acetic acid stimulant surpasses the maximum standard. The total migration in 3% acetic acid stimulant (40°C for 10 days) is 22.95 mg/dm2 while the maximum value is 10 mg/dm2.

Biogas has been considered as a renewable alternative energy produced by anaerobic digestion of cow manure. A process of anaerobic digestion of cow manure was simulated by Aspen Plus software to analyze the cost of production. The simulated project used cow manure wastes as a feedstock. From the study, economic analysis includes Net Present Value (NPV), Internal Rate of Return (IRR), Payback period (PBP), and B/C Ratio. The resulting BEP value is 539.20, the NPV is 6,414,566,421.98, the IRR is 249.84%, and the B/C ratio is 1.66. These values can be said that the business of cow dung which is processed into biogas is feasible to run.

The main challenge with membrane bioreactors is fouling, which leads to decreased flux performance and a shortened membrane lifespan. This study aims to provide a solution for the flux recovery and removal of irreversible fouling on Polyvinylidene Fluoride (PVDF) membranes without damaging their structure using sulfate radicals. Sulfate radicals are formed via peroxodisulfate precursors that are activated by Fe2+. The membrane flux recovery and irreversible fouling ratio were 88.45-99.04% and 11.60-0.96%, respectively, at operating temperatures of 298-308 K. The PVDF membrane has been tested for microfiltration and washed up to 6 times per cycle. The mechanical properties, XRD, SEM-EDX, and ATR-FTIR characterization of the PVDF membrane after washing with PDS/Fe2+ did not show a negative effect on the PVDF structure. Additionally, the results of the kinetic and thermodynamic studies showed that washing with PDS/Fe2+ inhibited the formation of fouling particles on the membrane surface. Based on this study, sulfate radical oxidants with PDS precursors activated by Fe2+ can be applied as cleaning chemicals for PVDF membranes without damaging their structures.

Crude nyamplung Calophyllum inophyllum is a potential non-edible feedstock for biodiesel production. Calophyllum Inophyllum oil (CCIO) is a non-edible oil that has a high content of triglyceride (TG) and free fatty acid (FFA). This study aims to optimize microwave-assisted power and extraction time of triglyceride purification from C. inophyllum crude oil for biodiesel. This work deployed Artificial Intelligence (AI) algorithms consisting of eight Machine Learning (ML) algorithms and found the most accurate model, then optimized using the Particle Swarm Optimization (PSO) algorithm.The result of machine learning modelling Random Forest achieved higher accuracy in R-Square and lower Mean Square Error (MSE) than any other models. Overall, in R-Square average across all variables was 0.949 ± 0.026 and the MSE average of 0.097 ± 0.068. This result can be interpreted as a mean deviation between the predicted value and an accurate value of less than 0.1 for all variables. The optimum of the TG compound resulted in the power of 462.3 W and time of 39.12 min that equalled at 84.02% and FFA equalled at 6.92%. The TG have increased by 11% from the reference range, which states conventional methods from crude oil. Comparison with the MAE method has a minimum fitness value difference of 0.0006 but has a smaller accuracy of less than 1%. Implementing this prediction and optimization method can shorten the extraction time by 5.8 min and reduce energy consumption or system work by 130 kJ. This method can be used for input parameter model prediction and parameter optimization in purification for biodiesel feedstock. Further research can be carried out using other artificial intelligence methods to optimize biodiesel production.

The presence of oxide layers covering the surface of aluminum is known to impede the hydrogen production reaction. These oxide layers can be broken by adding catalysts and increasing the aluminum-water reaction temperature. Common catalysts used are alkaline catalysts that are capable of achieving high hydrogen production rates in a short time at lower temperatures, while intermediate temperatures of above 50 °C can accelerate the hydration reaction of the oxide layer. Herein, the mixture of NaOH and NaAlO2 catalysts was employed to attain a stable NaAlO2 solution and continuous reaction of NaOH and aluminum. This research analyzes the influence of temperature between 32 and 80 °C on the aluminum, 0.3 M NaOH and 0.001 M NaAlO2 catalysts solution at atmospheric pressure. All solutions produces a similar hydrogen yields and rate. Solutions containing NaAlO2 indicate reverse reaction that surpressing the Al(OH)3 precipitation. Residue from the reaction is investigated using X-ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscope (SEM). The volume of hydrogen produced is evaluated using a mathematical mass reduction and shrinking core model. The rate of hydrogen production depends largely on the aqueous solution's temperature, with an activation energy of 47.4 kJ/mol. Based on the findings, it is readily apparent that the reaction only produced gibbsite and bayerite, with gibbsite and bayerite being dominant at 32–70 °C and 80 °C, respectively. The mass reduction model fits well with the present results with only an average 5.1 mL deviation, whereas the shrinking core model generally tends to result in underestimated values with an average deviation of 23.9 mL. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Subcritical water hydrolysis of bagasse requires energy to convert lignocellulosic biomass into fermentation-ready sugars. Bagasse biomass has the potential to be used as raw material for the production of reducing sugar. This study evaluates the effectiveness of the hydrolysis process using an oven and autoclave through economic and energy analysis. The variables used were hydrolysis time of 20-60 minutes, oven temperature of 110-170°C, and autoclave temperature of 120-130°C. Reduced sugar concentration was obtained from analysis using the DNS (dinitro salicylic acid) method. The results of the analysis show that time and temperature have a significant effect on the yield of reducing sugar. The highest reduced sugar concentration from subcritical water hydrolysis using an oven was 27.4 g/L at 170°C operating conditions for 60 minutes with a total cost of Rp 351,744 and energy requirement of 480 W.h. In hydrolysis using an autoclave, it was obtained at 14.7 g/L at 125°C for 40 minutes with a total cost of IDR 923,079 and energy requirements of 1,936.67. Hydrolysis using an oven is more recommended than autoclaving because it is economical and has lower energy consumption.

Nature-inspired technology has been investigated widely. Anti biofouling properties of fish scale has inpired to improve membrane performance. Biofouling affects an oil-water separation membrane. The bacterial, coagulant, and hydrophobic oils attach to the membrane surface, demanding periodic cleaning. To overcome the problems, surface modification materials are introduced namely superoleophobic surface. The superoleophobic surface promises antifouling, high flux, and high separation efficiency. Superoleophobic surfaces are inspired by the scales on fish that form a hydrogel-like layer on their surface. The hydrogel repels oil and any organic materials, keeping the surface clean. The hydrogel of fish scales can be mimicked by cellulose-based materials. A dense layer of hydroxyl groups absorbs a lot of water and forms a hydrogel bond. The membrane with the cellulose hydrogel-like structure will perform a superoleophobic characteristic surface. The characteristic can be utilized as a functional membrane for oil-water separation. This article reviews the principle, mechanism, current development, and future challenges of bioinspired superoleophobic surfaces from cellulose-based materials for membrane applications.

The noodles in the market are dry noodles with 8-10% water content. Dried noodles have a longer shelf life because they are less prone to mold growth. Drying noodles with the help of the sun and tray dryers are currently an option because they are efficient and do not require a lot of energy. Reduction of water content is also optimized by soaking wet noodles in salt water. This study aims to determine the effect of soaking noodles in salt water and the flow rate to decrease the water content of noodles. The study began with soaking wet noodles in a salt solution with a variation of 50-150 g/L, then dried for 1 hour using a hybrid method and tray dryer with a flow rate variation of 1.2-3.3 m/s. Observations were made at intervals of 0-1 hour. The results showed that the time and speed of the flow rate can reduce the humidity in the drying chamber of the tray dryer. The lowest water content reduction of up to 11% was obtained when soaking wet noodles in 150 g/L salt solution and at the highest flow rate of 3.3 m/s. The ANOVA results show that the drying method with tray dryer is more optimal than hybrid drying. Thus, this method can be a solution to optimize the noodle drying process quickly and efficiently.

One of the critical problems in the sugar industry is the high number of reducing sugars due to the inversion of sucrose in sugarcane due to the presence of Leuconostoc sp. This study aims to determine the effect and the optimum conditions for adding chemical agents to the number of reducing sugars in the first milking juice (NPP). The chemical agents used were benzalkonium chloride, sodium metabisulfite, and calcium hypochlorite with variations of 1, 2, 3, and 4 g/L. Analysis of reducing sugar (%GR) using the Lane-Eynon test method. The results showed that the addition of chemical agents had an effect on decreasing %GR of NPP, but at low doses there was an increase in %GR. The optimum point was reached when the addition of 3g/L benzalkonium chloride + sodium metabisulfite (BKC+SMB) was able to reduce %GR up to 2.16%. This condition has the potential to provide a net profit of sugar production of ±Rp. 14,056,000.00 per day. The use of BKC+SMB is a solution to reduce the number of reducing sugars and increase the yield value of the sugar industry.

Membrane bioreactor (MBR) deteriorates due to fouling on the membrane pores, which can reduce the membrane performance. To reduce membrane fouling, the addition of inorganic filler can enhance the antifouling properties. This study investigates two different membrane preparation by thermally induced phase separation (TIPS) and dip coating methods to modify hollow fiber membrane with Silver Nanoparticles (AgNPs)-Zeolites used in MBR for industrial wastewater treatment. Performance was evaluated by analyzing the flux of water and wastewater, rejection, water content, and antifouling properties. Characterization result represented the synthesized silver nanoparticles had similar diffraction peak with commercial AgNPs, then the micrograph of AgNPs and zeolites addition membrane showed that the inorganic material had an octahedral shape representing zeolite crystal and irregular shape representing AgNPs. The addition of zeolites and AgNPs resulted in satisfying performance, increased flux, rejection, and antifouling properties.

The competitive reactions of lignocellulose hydrolysis and monosaccharide degradation in the subcritical water (SCW) hydrolysis of coconut husk were investigated to optimize the reducing sugar yield. Optimization analysis was performed by response surface methodology (RSM) and kinetics studies. Parameters of process optimization were varied at 130-170 °C for 15-45 min. The reducing sugars were measured using the Dinitro salicylic acid method. The sugar yield increased when the temperature increased from 130 °C to 170 °C. The highest reduction sugar yield of 4.946 g/L was obtained at 183.6 °C for 4.8 min and 23.4 liquid/solid ratio (LSR). Kinetics studies were carried out at temperature variations of 150, 170, and 190 °C and pressures of 60, 80, and 100 bar for 5 to 60 min. The yield of reducing sugar decreased with increasing temperature. The kinetic model 2B is the best method to explain the competitive reaction kinetics of coconut husk hydrolysis. This research is an innovation to increase the reducing sugar to make the process more commercially viable. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Previous reports showed that there has been a continuous increase in the annual production of onion in Indonesia, and it is inversely proportional to the market price. The price drop is often caused by the high water content, which makes it easy to rot. Preservation of onions through a tray dryer is a good preservation method because it is effective and does not require much energy. Therefore, this study aims to determine the effect of variations in time, material thickness, and air velocity on the drying rate of onions. The samples were sliced to a size of 2 - 5 mm, followed by drying for 60 min using a tray dryer with different air rates between 4 - 7 m/s, and the rate of the process was observed every 15 min. The results showed that the drying time reduced the humidity in the chamber. The highest rate of 0.525 g/min was obtained at the peak air rate of 7 m/s. ANOVA results revealed that variations in time, onion thickness, and flow rate have a significant effect on increasing the drying rate of onions. This indicates that the method can be an effective and efficient solution to optimize the drying of the commodity.

Beluntas (Pluchea Indica L.) which commonly used as astringent and antipyretic has a high potential for the feedstock of essential oil production. The objective of this work is to optimize solvent-free microwave extraction (SFME) of Beluntas leaves by using response surface methodology (RSM). Box-Behnken Design with the variations of extraction time (60-120 min), feed/distiller ratio (0.06-0.1 g/ml), and heating power (150-450 W) was utilized to optimize essential oil yield. The feed/distiller ratio factor had the highest significant effect on the essential oil yield (P

There are several challenges for ABE fermentation to be used in an industrial scale including the low of butanol yield, the high energy requirement for separation and purification, and the competeness of sugar with food demand as substrat. In this study, techno-economical aspects of ABE fermentation by using immobilized cells with large extractant volume were studied. Overall production process was designed using rice straw as raw material which is semi-hydrolyzed to produce cellobiose, glucose, xylose, and arabinose mixture. Concentrated sugar was then fed to extractive fed-batch fermentation using immobilized cells. Finally, extractant was recovered and products were purified by distillation column. By evaluating this process design for the small scale capacity of 238 kg-butanol and acetone/day, the energy requirement was 41.3 MJ/kg-butanol and acetone and the cost was 1.91 $/kg-butanol and acetone. Although the cost was higher than butanol produced by petrochemical process of 1.08 $/kg-butanol, it may reduce if the scale is increased.

PT. Industri Gula Glenmore (PT. IGG) setiap tahunnya memproduksi 14.300 ton abu ampas tebu (AAT) sebagai hasil samping pembakaran boiler yang belum dimanfaatkan secara maksimal. Menariknya, AAT memiliki kandungan silika tinggi yaitu 68,5% yang dapat ditingkatkan nilainya sebagai substitusi parsial semen dalam pembuatan bata beton. Oleh karena itu, pada penelitian ini komposisi dan ukuran partikel AAT dioptimalkan dalam pembuatan bata beton. Optimasi dilakukan dengan menggunakan Response Surface Methodology (RSM) untuk memahami perilaku faktor-faktor signifikan yang mempengaruhi kuat tekan bata beton. RSM ditentukan dengan menggunakan software Design-Expert V11. Bata beton dibuat dengan perbandingan semen dan pasir menggunakan perbandingan 1:6 dengan variasi AAT 5% sampai 25% dari berat normal semen. Hasil pengujian di Workshop menunjukkan bahwa penggunaan Fly Ash dan kapur sebagai bahan pengikat untuk menggantikan sebagian semen dengan variasi 23, 26, 28, 30, dan 33% menghasilkan kuat tekan berturut-turut sebesar 56, 52, 49, 40, dan 34 kg/cm2. Dengan demikian, bata beton pada penelitian ini termasuk dalam mutu tingkat 3 berdasarkan SNI 03-0349-1989. Inovasi ini merupakan solusi untuk meningkatkan nilai tambah AAT dan menjadi peluang bisnis baru bagi PT. IGG di masa depan PT. The Glenmore Sugar Industry (PT. IGG) annually produces 14,300 tons of Sugarcane Bagasse Ash (SCBA) as a by-product of boiler combustion that has not been fully utilized. Interestingly, SCBA has a high silica content of 68.5%, which can be valorized as a partial substitution of cement in the manufacture of concrete bricks. Therefore, in this study the composition and particle size of SCBA were optimized in the manufacture of concrete bricks. Optimization was carried out by using Response Surface Methodology (RSM) to understand the behavior of significant factors affecting the compressive strength of concrete bricks. RSM was determined using the Design-Expert V11 software. Concrete bricks were made with a ratio of cement and sand using a ratio of 1:6 with a variation of bagasse ash 5% to 25% of the normal weight of the cement. The test results showed that the use of fly ash and lime as a binder to replace some cement with variations of 23%, 26%, 28%, 30%, and 33% resulted in a compressive strength of 56 kg/cm2, 52 kg/cm2, 49 kg/cm2, 40 kg/cm2, and 34 kg/cm2, respectively. Thus the concrete brick in this study was included in the quality level 3 based on SNI 03-0349-1989. This innovation is a solution to increase SCBA's added value and a new business opportunity for PT. IGG in the future.

Biobutanol is a renewable fuel that can be used as a gasoline substitute and a chemical feedstock. Its production using the Clostridial bacterial strain involves three steps: refreshment from a stock, a preculture for bacterial propagation, and primary fermentation for butanol production. Refreshment is an important process to activate the bacteria and multiply the stock. This process uses potato glucose media for C. saccharoperbutylacetonicum N1-4, while the use of starch from other sources has not been studied. This study aimed to understand various carbon sources’ effects on this refreshment process as part of ABE (acetone-butanol-ethanol) fermentation. Starch was substituted in refreshment media with several types of potato, rice, sweet corn, and sweet potato at 15% w/v. After 24 hours of refreshment at an ambient temperature, fermentation was run for 48 hours in TYA (tryptone-yeast-acetate) glucose media. All the starch sources could be used in the refreshment process, resulting in butanol and total solvent concentration ranging from 7.58 to 8.76 g/L and 12.5 to 14.6 g/L, respectively. Among the samples, sweet corn provided the highest fermentation performance, with butanol of 8.76 g/L, total solvents of 14.6 g/L, average butanol productivity of 0.182 g/L/h, and a butanol yield per substrate of 0.481 C-mol/C-mol. All the starchy materials used in this experiment offered potential for ABE fermentation, while sweet corn performed remarkably—producing the highest final butanol concentration, productivity, and yield.

In this study, the optimization of microwave-assisted alkaline (MAA) pretreatment is performed to attain the optimal operating parameters for the delignification of cocoa pod husk (CPH). The MAA performance was examined by heating the CPH solid with different particle sizes (60–120 mesh) and NaOH solution with a different sample to a solvent (SS) ratio (0.02–0.05 g/L), for short irradiation time (1–4 min). Box-Behnken Design (BBD) was utilized to optimize the percentage of lignocellulose composition changes. The results show that by enlarging particle size, the content of lignin and cellulose decreased while hemicellulose increased. By prolong irradiation time, the content of lignin and hemicellulose decreased while cellulose elevated. On the other hand, increasing the SS ratio was not significant for hemicellulose content changes. From FTIR and SEM characterization, the MAA drove the removal of lignin and hemicellulose of CPH and increased cellulose slightly. Supported by kinetic study which conducted in this work, it was exhibited that MAA pretreatment technology is an effective delignification method of CPH which can tackle the bottleneck of its commercial biofuel production. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Preventing the further degradation of monomeric or oligomeric sugar into by-product during biomass conversion is one of the challenges for fermentable sugar production. In this study, the performance of subcritical water (SCW) and enzymatic hydrolysis of coconut husk toward reducing sugar production was investigated using a severity factor (SF) approach. Furthermore, the optimal condition of SCW was optimized using response surface methodology (RSM), where the composition changes of lignocellulose and sugar yield as responses. From the results, at low SF of SCW, sugar yield escalated as increasing SF value. In the enzymatic hydrolysis process, the effect of SCW pressure is a significant factor enhancing sugar yield. A maximum total sugar yield was attained on the mild SF condition of 2.86. From this work, it was known that the SF approach is sufficient parameter to evaluate the SCW and enzymatic hydrolysis of coconut husk. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Coconut husk (CCH) as an abundant agricultural waste in Indonesia has the potential to be utilized for sugar production, which is the intermediate product of biofuel. In this study, subcritical water (SCW) assisted by nitrogen (N2) was developed to enhance the enzymatic hydrolysis of CCH. SCW process was optimized by varying the operation condition: the pressure of 60-100 bar, the temperature of 150-190 °C, and the time of 20-60 min. The SCW-treated solid was subsequently hydrolyzed by utilizing a mixture of commercial cellulase and xylanase enzymes. The result shows that the optimum total sugar yield was obtained under the mild condition of SCW treatment, resulting in the sugar of 15.67 % and 10.31 % gained after SCW and enzymatic hydrolysis process, respectively. SEM and FTIR analysis of SCW-treated solid exhibited the deformation of lignin and solubilization of cellulose and hemicellulose, while XRD and TGA revealed an increase of the amount of crystalline part in the solid residue. The use of N2 in SCW treatment combined with enzymatic hydrolysis in this study suggested that the method can be considered economically for biofuel production from CCH waste in commercial scale. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Bio‐based fatty acids (FAs) produced through hydrolysis of natural oils and fats are promising chemical feedstocks for increasing the economic value of renewable raw materials. In this work, lecithin, gelatin, PEG, and MgCl2 were employed as the co-immobilized material of crude lipase Mucor miehei immobilization on the polyurethane foam (PUF) matrix for hydrolysis of coconut oil to Free Fatty Acid (FFA). The unconventional immobilized technique was used through cross-linking and covalent bond. Single factor analysis and response surface method were utilized to determine the optimum conditions of the hydrolysis reaction. After optimization, co-immobilized lipase was examined for storage stability at a temperature of 4°C and reusability performance. The optimum conditions for coconut oil hydrolysis were obtained on the co-immobilized-PUF ratio, water-oil ratio, and reaction time of 20.17 w/w, 4.45 w/w, and 20 h, respectively. Under these conditions, the acid value as lauric acid enhanced 573% to 3.21 mg KOH/g oil. Storage stability attained through remaining activity on free lipase, PUF-lipase, PUF-co-immobilized-lipase were 9.89%, 42.3%, and 91.88%, respectively. In this study, the application of PUF-co-immobilized lipase in hydrolysis reactions can be reused up to 5 times. Characteristics of the addition of co-immobilized lipase have been analyzed using Fourier Transform Infra Red (FTIR) and Scanning Electron Microscope (SEM), showing the presence of functional groups binding and the changes in the surface matrix structure.

Limestone is commonly used for wall painting, but it is easy to be dirty. In this study, a self-cleaning limestone paint was synthesized by modifying dispersant and TiO2 nanoparticles. The TiO2 that prepared by TiCl3 were functionalized with PEG6000 as a surface activating agent. The paint achieved highest impurity degradation of 83.11 % for the mass ratio of TiO2 and PEG6000 (MRTP) of 1: 6, in which TiO2 average size distribution was 75.81 µm2, the particle surface area of TiO2 was 2,544 µm2, and the smallest contact angle was 7°. It was found that the dispersant (PEG6000) significantly improved the self-cleaning ability of limestone paint. The surface tension reduction from PEG6000-modified prevented the agglomeration process of TiO2 and suggests that the limestone paint a good self-cleaning coating for wall painting.

The presence of oxide layers covering the surface of aluminum is known to impede the hydrogen production reaction. These oxide layers can be broken by adding catalysts and increasing the aluminum-water reaction temperature. Common catalysts used are alkaline catalysts that are capable of achieving high hydrogen production rates in a short time at lower temperatures, while intermediate temperatures of above 50 °C can accelerate the hydration reaction of the oxide layer. Herein, the mixture of NaOH and NaAlO2 catalysts was employed to attain a stable NaAlO2 solution and continuous reaction of NaOH and aluminum. This research analyzes the influence of temperature between 32 and 80 °C on the aluminum, 0.3 M NaOH and 0.001 M NaAlO2 catalysts solution at atmospheric pressure. All solutions produces a similar hydrogen yields and rate. Solutions containing NaAlO2 indicate reverse reaction that surpressing the Al(OH)3 precipitation. Residue from the reaction is investigated using X-ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscope (SEM). The volume of hydrogen produced is evaluated using a mathematical mass reduction and shrinking core model. The rate of hydrogen production depends largely on the aqueous solution's temperature, with an activation energy of 47.4 kJ/mol. Based on the findings, it is readily apparent that the reaction only produced gibbsite and bayerite, with gibbsite and bayerite being dominant at 32-70 °C and 80 °C, respectively. The mass reduction model fits well with the present results with only an average 5.1 ml deviation, whereas the shrinking core model generally tends to result in underestimated values with an average deviation of 23.9 ml. [ABSTRACT FROM AUTHOR]