By breaking down harmful dye waste into harmless components under the right irradiation sources, photocatalysis is an unorthodox but promising technique that can reduce industrial wastewater pollution, particularly in the textile industry. Synthetic textile dyes called cationic dyes must be handled carefully because they are poisonous and challenging to breakdown. Photocatalytic oxidation is a useful technique for eliminating hazardous organic pigments. This investigation aims to synthesize and characterize ZnO/MnFe2O4 nanocomposites as well as investigate the effects of varying ZnO:MnFe2O4 ratios, pH levels, doses, and irradiation times on band gap reduction and photocatalytic applications tested with cationic dyes, specifically methylene blue, under the illumination of sunlight. the co-precipitation approach for the manufacture of nanocomposites with different mole ratios of ZnO:MnFe2O4 (1:0.1; 2:0.1; 3:0.1). The component comprising the nanocomposite is ZnO/MnFe2O4, according to the results of the characterisation using XRD, SEM-EDX, FTIR, and BET. UV-DRS measurements of the band gap revealed that as ZnO was reduced, the band gap of the nanocomposite likewise decreased, from 3.35 eV to 2.78 eV. The greatest degradation of 93.2% was achieved for the degradation of 50 mg/L methylene blue (MB) dye with a catalyst dosage of 20 mg at a ratio of 1:0.2 for 50 minutes of irradiation. Since the point of zero charges (pzc) was reached at a pH of 7.8, a photodegradation adsorption-friendly solution pH of 8 was created.
The valorisation fine coal waste is still very limited in creating energy, especially syngas. This study aims to convert fine coal waste into synthetic gas via gasification using catalyst. Fine coal gasification takes place at 350–750 °C in an updraft gasifier using catalyst of 12.5–25 wt% natural zeolite. The research results show that the addition of zeolite has synergy with increasing temperature. The syngas produced at 750 °C and 12.5 wt% zeolite consisted of 32 vol% H2, 30.1 vol% CO, 27.7 vol% CH4 and 5.1 vol% CO2. The carbon conversion efficiency and high heating value (HHV) of synthetic gas are 88.34% and 18.97 MJ/Nm3. Fine coal has the potential to be reused as an energy source in the future.
The utilisation of fine coal waste is still limited, even though its availability is very abundant in the mining industry. This study utilises fine coal by converting it into syngas through catalytic gasification. The gasification process was carried out at a temperature range of 350–550°C for 10–50 minutes using natural zeolite as a catalyst. The syngas composition and quality parameters were evaluated through the H2/CO ratio, heating value, and gasification efficiency. From the research results, fine coal contained high amounts of carbon and fixed carbon. Temperature is the variable that most influences the gasification process. The addition of zeolite actively increased the CO content in the syngas. The H2/CO ratio of syngas >1, the highest HHV and LHV 16.15 and 14.46 MJ/Nm3 with the highest carbon conversion efficiency value of 88.85%, made fine coal very suitable to be used as raw material for the gasification process to produce environmentally friendly syngas.
Heavy metal is a type of metal that has a high density and high toxicity when consumed by living things, especially humans. To prevent the impact of environmental pollution, optimal handling of wastewater containing heavy metals is required, including the wastewater from laboratories. This research aimed to study the effect of pH, catalyst dose, and irradiation time on the reduction of Copper (Cu), Iron (Fe), and Lead (Pb) heavy metals and their application to laboratory wastewater treatment. Among the Advanced Oxidation Processes (AOPs) methods, photocatalysis was chosen to reduce the level of Cu, Fe, and Pb heavy metals where zinc oxide (ZnO) is used as a photocatalyst and the sunlight as a light source. To determine the effect of pH, catalyst dose, and time on the reduction of heavy metal levels, firstly, this research used the synthetic wastewater containing Cu, Fe, or Pb heavy metals. On the basis of the experimental results, it is concluded that the pH value, catalyst dose, and time affect the photocatalytic process, decreasing the levels of Cu, Fe, and Pb metals. The optimum pH value obtained for Cu was at pH 7–8, for Fe it was at pH 6, and for Pb it was at pH 8; in turn, the metal removal percentages were 99.46, 99.91, and 99.70%, respectively. In the photocatalysis of synthetic wastewater, high removal percentage of more than 99% was achieved by using 0.1 g/L catalyst. The optimum decrease of metals occurred in the first 15 minutes of solar irradiation where the removal percentage was close to 100%. In this study, the application of ZnO photocatalyst under solar irradiation can reduce the heavy metals content in the laboratory wastewater by almost 100%, which meets the environmental quality standard for Cu, Fe, and Pb.
Modification of bentonite by the Al/Fe metal oxide pillarization process was carried out with metal oxides. The bentonite pillars were successfully characterized using an X-Ray Diffraction (XRD) spectrophotometer. The results of XRD characterization showed the peak diffraction angle (2θ) in metal-pillared bentonite was 26.84° at 698.98 cps. Meanwhile, in thermally and chemically activated bentonite, the peak angles were marked at 20.64° and 26.7°. There is a shift in the peak angle after activation and pillarization. XRD patterns showed dioctahedral smectite and quartz accessory minerals.
The presence of CO2 in the syngas is attracting more attention in terms of reducing the greenhouse gas emissions in its utilisation. The aim of this study was to purify syngas from the CO2 content of fine coal gasification. Fine coal is gasified with and without absorption using CaO, which is hydrated to Ca(OH) 2 in the modified updraft gasifier at 450–700 °C. Apart from investigating the CO2 absorption process, the gasification process also evaluates the influence of temperature in terms of its synergy with Ca(OH) 2. The best conditions for the gasification process are achieved at 700 °C. The content of CO2 was proven to be well absorbed, which is characterised by a decrease in the CO2 content and an increase in H2 in syngas. After the absorption process, the H2 content obtained increased from 42.6 mole% to 48.8 mole% of H2 at 700°C. The H2 ratio also increased after absorption to 2.57 from the previous value of 2.23. The highest absorption efficiency of CO2 by Ca(OH) 2 occurred at 700°C at 50.63%. With an increase in temperature in the gasification process with absorption, the CO2 content decreased dramatically from 16.9 mole% to 3.9%. Ca(OH) 2 has good absorption power at CO2 at high temperatures.
The rapid progress of the CPO industry in Indonesia is not in line with good waste management and utilization. Palm empty fruit bunch, as the first waste from the CPO production process in Indonesia, is mostly piled on the ground. Palm empty fruit bunch must be processed to reduce pollution and increase its use-value. This study aimed to convert oil palm empty fruit bunches solid waste through the gasification process using Indonesia’s natural zeolite into synthesis gas. Gasification takes place at 350–550°C by added 12.5% wt zeolite using a modified updraft gasifier. Good results were achieved at 550°C with a gas composition of 22.64% vol CH4, 29.22% vol CO, and 3.4% vol H2. The gasification efficiency is evaluated through carbon conversion efficiency (CCE) and cold gas efficiency (CGE). Both the highest CCE and CGE were found at 550°C by 95.74% and 81.65% respectively. The results showed that the gasification temperature has the greatest influence in driving higher carbon conversion to syngas and palm empty fruit bunches are very suitable for conversion into environmentally friendly syngas in the CPO industry.
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