The separation of CO₂/CH₄ using porous carbon can be increased by the presence of a functional group of nitrogen on the carbon surface. This study explores the potential of porous carbon derived from the palm kernel shell (C-PKS) impregnated with a deep eutectic solvent (DES), which is one of the chemicals containing a nitrogen element. The DES was composed of a quaternary ammonium salt of choline chloride (ChCl) and a hydrogen bond donor of alcohol. Three alcohols of 1-butanol (-ol), ethylene glycol (-diol), and glycerol (-triol) were employed to study the effects of a number of hydroxyl groups in the separation performance. The research steps included (i) the preparation of DES-impregnated porous carbon synthesized from the palm kernel shell (DES/C-PKS), (ii) characterization of the material, and (ii) a separation test of CO₂/CH₄ with a breakthrough system. Materials were characterized using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), N₂-sorption analysis, and Fourier transform infrared (FTIR) spectroscopy. SEM images showed a significant morphological difference of pristine carbon and DES/C-PKS. There was a significant decrease in the range of 67–73% of a specific surface area with respect to pristine carbon, having initially 800 m²/g. However, the N element on the carbon surface increased after impregnation treatment, which was shown from the intensity of the FTIR graphs and EDX analysis. Adsorption isotherm revealed that DES/C-PKS could enhance up to 1.6 times the adsorption capacity of CO₂ at 1 atm and 30 °C while increasing the selectivity of CO₂/CH₄ up to 125%. The breakthrough experiment showed that all DES/C-PKS materials displayed a better performance for the separation of CO₂/CH₄, indicated by a longer breakthrough time and enhancement of CO₂ uptake. The best separation performance was achieved by DES/C-PKS using glycerol as a hydrogen bond donor with 15.4 mg/g of CO₂ uptake or equivalent to 95% enhancement of the uptake capacity compared to pristine porous carbon. Also, the cycling test revealed that DES/C-PKS can be used repetitively, which further highlights the efficiency of the material for the separation of CO₂/CH₄.

Hydrothemal treatment is a thermochemical process that converts biomass into a coal-like materials called hydrochar by applying elevated temperature to biomass in a suspension with water under saturated pressure for a certain time. With this conversion process, easy to handle fuel with well-defined properties can be created from biomass residues, even with high moisture content. In this research, the effects of temperature (200-330°C) and biomass to water ratio (5%-20%) at initial pressure of 1.0 MPa to hydrothermal treatment of biomass (in the form of sawdust) were examined. All samples were then characterized in terms of yield, proximate analysis, calorific value,and changes in functional groups by FTIR. Approximately 52-69% of the original material was recovered as hydrochar. The gross calorific value ranged from 5472-7032 cal/g compared 5180 cal/g in the raw material. Fixed carbon ranged from 26.035-wt% compared with 26.269 wt% in the raw material.

Currently, fossil fuels are still the primary fuel source and reducing agent in the steel industries. The utilization of fossil fuels is strongly associated with CO₂ emissions. Therefore, an alternative solution for green steel production is highly recommended, with the use of biomass as a source of fuel and a reducing agent. Biomass’s growth consumes carbon dioxide from the atmosphere, which may be stored for variable amounts of time (carbon dioxide removal, or CDR). The pellets used in this study were prepared from a mixture of low-grade iron ore and palm kernel shells (PKS). The reducing reactivity of the pellets was investigated by combining thermogravimetric analysis (TGA) and laboratory experiments. In the TGA, the heating changes stably from room temperature to 950 °C with 5–15 °C/min heating rate. The laboratory experiments’ temperature and heating rate variations were 600–900 °C and 10–20 °C/min, respectively. Additionally, the reduction mechanism was observed based on the X-ray diffraction analysis of the pellets and the composition of the reduced gas. The study results show that increasing the heating rate will enhance the reduction reactivity comprehensively and shorten the reduction time. The phase change of Fe₂O₃ → Fe₃O₄ → FeO → Fe increases sharply starting at 800 °C. The XRD intensities of Fe compounds at a heating rate of 20 °C/min are higher than at 10 °C/min. Analysis of the reduced gas exhibits that carbon gasification begins to enlarge at a temperature of 800 °C, thereby increasing the rate of iron ore reduction. The combination of several analyses carried out shows that the reduction reaction of the mixture iron ore-PKS pellets runs optimally at a heating rate of 20 °C/min. In this heating rate, the reduced gas contains much higher CO than at the heating rate of 10 °C/min at temperatures above 800 °C, which encourages a more significant reduction rate. In addition, the same reduction degree can be achieved in a shorter time and at a lower temperature for a heating rate of 20 °C/min compared to 10 °C/min.

The development of textile industry in Indonesia has been increasing rapidly. The vast and continuous development of the textile industry results in an evitable increase of wastewater. One of the wastewater ingredients that difficult to be treated is dye. Dye is a pollutant with complex aromatic structure that is difficult to degrade. There are many dyes could be used, however, methylene blue is mostly used. To treat MB, several treatment methods are available. Among the methods, adsorption has been widely applied, due to its simplicity and effectiveness. In this research, nano crystal cellulose (NCC), which has a large surface area dan better mechanical properties, was prepared from the oil palm trunk and it was proposed to adsorb the methylene blue. Briefly, the process of making NCC as a biosorbent consists of the raw material pretreatment, alkaline treatment, bleaching, hydrolysis, and sonication steps. Alkaline treatment plays an important role for extracting hemicellulose, lignin and other extractive substances, so that NCC is expected to have high cellulose purity. The alkaline treatment was conducted by extraction methode using NaOH at 80 °C for 2 hours. The result showed that the percent of removal of hemicellulose dan lignin were 50.0, 55.6, and 51.73 % for NaOH concentration of 3, 4, and 5 % (w/v) respectively. This result was also supported by the result of FTIR spectra analysis on each corresponding sample. Based on these data, it can be confirmed that the optimum NaOH concentration for alkaline treatment of oil palm trunk is 4 % (w/v). Furthermore, adsorption test of NCC using methylene blue solution gave percent removal of methylene blue in the range of 69.46-72.51%.