Search

In this paper, we study the effects of Cu, Ni, and Zn doping in TiO2 layers on the performance of MAPbI3-based perovskite solar cells (PSCs) fabricated under ambient air with relative humidity between 60% and 70%. One of the factors limiting the efficiency of MAPbI3-based PSCs is the TiO2 electron transport layer properties. The efficiency of PSCs is the maximum power that can be produced by a PSC when illuminated by light with a specific energy. This study aims to enhance MAPbI3-based PSC efficiency by doping TiO2 with 2 mol.% Cu, Ni, and Zn. MAPbI3-based PSCs were then fabricated using spin coating with the structure ITO/TiO2/MAPbI3/graphite/ITO. X-ray diffraction and scanning electron microscopy (SEM) analyses revealed that doping reduced TiO2 crystal sizes from 19.34 nm (pure) to 18.96 nm (Cu-doped), 18.04 nm (Ni-doped), and 17.6 nm (Zn-doped), with corresponding average particle sizes of 225 nm, 107 nm, 79 nm, and 50.4 nm. Ultraviolet–visible (UV–Vis) spectroscopy indicated an increase in the bandgap from 3.0 eV (pure) to 3.1 eV (Cu-doped), 3.2 eV (Ni-doped), and 3.25 eV (Zn-doped). Current–voltage (I–V) electrical testing revealed improvement in efficiency from 5.7% (undoped) to 7.6% (Cu-doped), 6.9% (Ni-doped), and 8.01% (Zn-doped). These findings demonstrate that metal-doped TiO2 significantly enhances the efficiency of MAPbI3-based PSCs fabricated in open-air environments without the need for a glove box. [ABSTRACT FROM AUTHOR]

Indonesia is a strategic maritime country, especially in terms of trade and economy. The most vital defense is Indonesian waters in the form of shipping by the Indonesian Navy. The support is in the form of nautical chart paper which is strong and waterproof. Natural paper reinforcement needs to be added because synthetic materials contain monomer groups, can damage the environment and are difficult to grade. Examples of natural agents are carrageenan and bentonite which work to form hydrogen bonds with cellulose fibers, thereby increasing the strength of paper. The research aims to study the effect of carrageenan and bentonite on opacity, tearing, tensile, wet index, and Cobb. The highest opacity was 100.2% in carrageenan with a dose of 14%. The highest tearing was in the mixed agent, amounting to 745.87 mN at a dose of 14%. The highest tensile dose of 14% was 1.58 kgf/15mm. The highest wet index dose is 14%, which is 2.55% of the mixed agent. The best Cobb for mixed agents with a dose of 14% was 67.09 g/m2. In conclusion, carrageenan and bentonite have potential as wet strength agents in making nautical chart paper.

Non-communicable diseases have become the leading cause of death in Indonesia, accounting for approximately 69% of deaths in 2023. Various health disorders, such as cancer, neurodegenerative diseases, inflammation, hypertension, and heart disease, are linked to oxidative stress caused by reactive oxygen species (ROS). Chemical treatments often have side effects and high costs, prompting many to turn to natural remedies. One preventive measure against ROS is consuming natural foods rich in antioxidants, such as oil palm leaf extract. This study uses the roller slugging compaction method to transform oil palm leaf extract into effervescent tablets. Palm oil leaf extract has been prepared in 2 different sources ( 1st and 17th leaf) to assess percent inhibition. The experimental results showed that the 17th leaf extract had the highest antioxidant activity value (IC50 = 20.35). Then, the 17th palm oil leaf extract was used in effervescent tablet formulations. The results obtained indicate that formulation 1, consisting of 0.5 grams of oil palm leaf extract, 0.195 grams of citric acid, 0.2925 grams of tartaric acid, 0.4875 grams of NaHCO3, 0.975 grams of maltodextrin, and 0.05 grams of PVP, is the best formula for oil palm leaf extract effervescent tablets. This formulation demonstrated the highest antioxidant activity (IC50 = 30.22), consistent with its total phenolic content (394.451 mg GAE/mL).

Red mud, a residue of the bauxite industry, represents a secondary source of rare earth elements (REEs) with substantial commercial value and untapped potential. Bioleaching, an innovative, cost-effective, and environmentally friendly method, offers a means of extracting valuable metals from mining wastes. This study explored the bioleaching of Indonesian red mud using Bacillus nitratireducens strain SKC/L-2 to recover REEs. The experiments were carried out over three days at 25 °C with different concentrations of red mud (1.5, 3, and 6 g/L) and a 10% v/v bacterial inoculum in a specific bioleaching medium. The findings indicated a slight reduction in REEs extraction by the bacterium as the red mud concentration increased from 1.5 to 6 g/L in the direct bioleaching process. In the experiment using 1.5 g/L red mud, 16 REEs were successfully extracted, with high extraction levels for specific elements such as Lu (92.0%), Tb (80.61%), and Gd (67.42%). However, when the red mud concentration was increased to 6 g/L, the survival potential of Bacillus nitratireducens strain SKC/L-2 decreased, leading to reduced recovery of elements such as Lu (76.80%), Tb (70.30%), and Gd (55.83%). The study reveals the behaviour of Bacillus nitratireducens in interacting with red mud and enduring high alkalinity, resulting in REEs extraction. These findings enhance the understanding of microbial interactions with red mud and provide insights into potential resource recovery applications.

This study aims to investigate the effect of cow’s rumen and rice straw ratio on hydrolysis as well as sulfuric acid concentration, temperature, and time were also examined. The fermentation was also carried out, with the main focus on the effect of the yeast concentration. The more straw in the material, the higher the glucose. In the rumen and straw ratio of 40:60 and 80:20%, 0.3 M sulfuric acid, 90 oC, and 60 minutes, the glucose was 10.60 and 5.87 g/L. Hydrolysis at 90 was better than 80 oC. In the rumen and straw mixture of 40:60%, 0.6 M sulfuric acid, and 75 minutes, the glucose was 18.47 and 15.11 g/L. The catalyst concentration of 0.6 was also better than 0.3 M, in which the glucose could reach 17.32 and 8.46 g/L at a rumen and straw ratio of 0:100, 90 oC, and 45 minutes. Glucose in the hydrolysate could be fermented well. The higher the yeast concentration, the higher the ethanol content, respectively 1.22, 1.35, and 1.52% in 72 hours at yeast concentrations of 9, 15, and 20 g/L. Ethanol rose sharply within 24 hours and after 72 hours it continued to rise even though it started to slow down at 60 hours.

This study used solvent extraction to separate nickel and cobalt from nitrate leaching of mixed nickel-cobalt oxalate precipitate (MOP). Laterite ore was first leached using citric acid, and then leaching filtrate was mixed with oxalic acid to produce MOP. MOP was releached using nitric acid (1M) to prepare the aqueous phase as a feed for solvent extraction. Solvent extraction used the extractant trihexyltetradecylphosphonium bis (2,4,4-trimethyl pentyl) phosphate (Cyphos®IL 104) in kerosene. Solvent extraction experiments were conducted in the pH range of 6 to 7.6 (O/A ratio = 1 at 15 min). After separation, the concentration of the aqueous phase was analyzed using an ICP-Optical Emission Spectrometer (ICP-OES) to measure cobalt and nickel content. The results showed that the highest extraction efficiency of cobalt and nickel was obtained at pH 7.2, 99.97%, and 32.57%, respectively. At this optimum condition, the separation factor obtained for cobalt was 8008.66 and for nickel 0.0001, while cobalt was 3868.00 and nickel 0.48 for the ion distribution obtained. It indicates that at this condition, the extractant can extract cobalt to the organic phase, and nickel remains in the aqueous phase.

The mineralogical properties and distribution of information established in saprolite from Indonesia were investigated using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy energy dispersion spectroscopy (SEM--EDS) and differential thermal analysis (DTA) measurements. The findings suggest that laterite ore has a complex inner core. The percentages of nickel, iron, magnesium, aluminium and silicon in saprolite are 1.82 wt%, 30.47 wt%, 10--20 wt%, 4.86 wt% and 8.1 wt%. Saprolite has 53.1 wt% iron oxide/oxyhydroxide, 38.3 wt% lizardite and 8.7 wt% silicate. According to DTA, saprolite undergoes a phase shift from goethite to haematite at low temperatures (200--300°C). This is a suitable phase to optimise nickel diffusion in iron. Furthermore, the thermal upgrading approach was utilised for this saprolite. [ABSTRACT FROM AUTHOR]

Aceh Selatan is the oldest district in Aceh Province, located on the edge of the Banda Aceh - Medan west cross highway consisting of mountainous areas, lowlands, and water areas (Hindia Ocean). The problem at this time is that 54% of the people of South Aceh Regency do not have proper access to latrines and drainage channels, which are the target for receiving domestic wastewater. There is no public awareness of the importance of providing and maintaining domestic wastewater facilities and infrastructure. This research aims to sustainably carry out regional-scale domestic wastewater management based on Maqashid Syari'ah. The method used in the research is to determine the target of wastewater handling in South Aceh Regency until 2040 to determine the development model and strategy. Meanwhile, the zoning method was used to determine the planning area. Labuhan Tarok Village, Meukek District, South Aceh Regency, is one of the villages in urgent priority scale wastewater treatment with the An Aerobic Baffled Reactor (ABR) model. The reduction of BOD, COD, and TSS can be made with this treatment model in accordance with the Quality Standard of Peraturan Menteri Lingkungan Hidup dan Kehutanan No. 68 of 2014 and accordance with Permen PUPR No.4 of 2017, concerning the Implementation of Domestic Waste Water Management Systems. [ABSTRACT FROM AUTHOR]

Katingan River has been contaminated by mercury from ASGM activities since the early 2000s. This study aims to assess the risk of mercury exposure from Katingan fish consumption and analyze relationships between exposure variables. We proposed two risk assessment scenarios based on mercury analysis of 74 fish samples and fish consumption questionnaire. The risk assessment result revealed that estimated daily intakes (EDIs) of Scenario 2 were generally 3–4 times higher than Scenario 1. The statistical test results showed significant differences (p < 0.05) in EDI values between scenarios, indicating that variations in fish consumption influenced the mercury intake. Three different health reference-based values (HRVs) were applied in estimating the hazard quotient (HQ) and it influenced the HQ results (p < 0.05), for both scenarios. The relationship analysis between variables presented a strong non-linear correlation between EDI and hair mercury level for both scenarios, but a weak relationship between age and hair mercury level. [ABSTRACT FROM AUTHOR]