Biodiesel has recently received much attention as an energy source with numerous benefits such as high degradability, negligible toxicity, and minimal emissions of carbon monoxide gases as well as particulates. Therefore, this research aims to compare, review, and summarize the conventional and advanced methods of biodiesel production. Currently, some emerging processes that were developed for advanced biodiesel production include microwave-assisted synthesis, ultrasonic-assisted synthesis, supercritical transesterification, and liquid phase plasma discharge technology. The types of feedstocks, catalysts, and operating conditions as the influential parameters in biodiesel synthesis are also discussed. Moreover, in the purification process, the effectiveness of purification depends on the type of catalyst applied in the synthesis process. This research also reviewed and compared several commonly used purification methods such as wet and dry washing, ion exchange and precipitation, complexation, and membrane-based separation that have shown significant results along with the impacts of biodiesel production on environmental and economic sectors

An effective method to prepare slow-release urea was developed with aminopropyl-functionalized mesoporous silica (MS) to achieve enhanced urea adsorption and slow-release properties. As a novel study, mesoporous silica was developed using treated geothermal silica as the silica source, cetyltrimethylammonium bromide (CTAB) as the surfactant, and 3-aminopropyl trimethoxy silane (APTMS) as the surface modification agent. Mesoporous silica with the most desirable properties of uniform micromorphology containing 38.55 wt % silica particles, 668.849 m 2 /g surface area, 149.33−353.28 mL/g adsorption−desorption range, and 0.26 mL/g adsorption pore volume was achieved using 0.05 mol of CTAB. The synthesized mesoporous silica showed type-IV hysteresis, which corresponds to mesoporous materials. Differential scanning calorimetry (DSC)−thermogravimetric analysis (TGA) thermograms showed that mesoporous silica is more reactive, with peaks at 82.3 and 159.5 °C, has good thermal stability, and undergoes only 17.61% weight loss until 124 °C. Scanning electron microscopy (SEM) showed that functionalization and urea adsorption to mesoporous silica resulted in no significant morphological changes. In the Fourier transform infrared (FTIR) spectra, MS/APTMS/U26.74 was observed to have higher intensities of CO, N−H, C−N, and C−H groups compared with other samples. The cumulative urea release during 7 days was 184.5 ppm (92.4%) for commercial urea and 124.6 ppm (64.4%) for MS/APTMS/U26.74. The Higuchi kinetic model yielded the best fit predicting MS/ APTMS/U26.74 release kinetics, with an R 2 of 0.9979 and a Higuchi constant of 24.4964%/day. Finally, MS/APTMS/U26.74 synthesized using geothermal silica, CTAB, and APTMS was noted to possess a potential composition for slow-release urea with enhanced efficiency.

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Scrubber is widely used in various products, such as cosmetics, facial cleansers, and soaps. The use of scrubber releasing 209.7 trillion microplastics would harm the environment due to lack of process in treatment facilities. Efforts to substitute plastic-based scrubbers with more environmentally friendly materials need to be made. In previous studies, substitution scrubber with grape seeds has been done but has a low viscosity. This problem may be solved by using bacterial cellulose (BC) in the manufacture of bio-scrubbers. Several methods are currently being investigated to produce bacterial cellulose microparticles, such as mechanical methods using high-pressure homogenizer (HPH), acid hydrolysis, microbial hydrolysis, hydrogel fiber cultivation, microfluidic process, and ultrasonication. This review recommends the manufacture of bacterial cellulose microparticles by ultrasonication method. The recommendation is based on the literature study that has been carried out. The ultrasonication method has more advantages than other methods. It does not use solvents that pollute the environment and increasing the number of bacterial cellulose microparticles. The synthesis of bio-scrubber from bacterial cellulose ends with the drying process of bacterial cellulose microparticles. This review recommends the ambient pressure drying method. The ambient pressure drying method can produce bio-scrubber with high crystallinity, high mechanical properties, and transparency.

The hydrophobic and antibacterial coatings derived from geothermal waste silica modified by APTES and AgNPs. The paper aims are to investigate contact angle (CA) and antibacterial test from the coating upon ethanol, sodium silicate, water, and APTES; to characterize silica raw by XRD, and coating product by SEM EDX. The research was conducted by sodium silicate preparation, AgNPs synthesis, silica-APTES on the glass, and AgNPs layer on the coated glass. The result showed that the CA attained in range of 20-50° with bacterial inhibition diameter of 10 mm and 12 mm for E.coli and S. aureus, respectively.

The trend of research and development of technological advancement in thermal insulators involves using renewable materials, selecting manufacturing processes that require the lowest possible energy, or using waste materials that may help subdue the reduction of petroleum reserves. This review discusses the potential substitution of petroleum by natural materials in thermal insulation manufacturing. This review presents an overview of the definition, properties, materials, and methods that can be used in the manufacture of thermal insulators based on results reported in the literature. Many materials are currently being investigated to produce thermal insulator such as cellulose. Cellulose fiber has a big potential to be used in the manufacture of thermal insulators because cellulose possesses many advantageous properties over petroleum-based polymers, i.e. biocompatibility, biodegradability, thermal stability, chemical stability, and low cost. Another material that may be used is silica, as it has high temperature resistance and low thermal expansion. Bagasse containing high cellulose and silica with the composition of 32-44% cellulose and 55.5%-70% silica. Therefore, bagasse proves appealing to be processed into thermal insulator. Aerogels are among the best thermal insulating materials known. This review proposes the impregnation method followed by the ambient pressure drying (APD) method to synthesize cellulose-silica aerogel. The impregnation of silica into cellulose aerogel will increase mechanical strength, flexibility, and the resulting silica-cellulose aerogel will be transparent with a very low thermal conductivity.

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