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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]

Worldwide, silicified woods are found in many geological formations. Significantly, the organic materials of wood are no longer dominant; almost all wood fossils have been mineralized into inorganic silica materials. These unique geological processes must be understood to develop better understanding on organic material fossilization, particularly in the micron scale. Therefore, our aim was to characterize the composition of silicified wood using comprehensive microanalysis. The methods utilized were XRF, ICP-MS, XRD, FTIR, and FE-EPMA. Specimens are from Jasinga, West Java, Indonesia. The results showed that wood silicification was controlled by the infiltration of silica from the host rock into the spaces of the wood structure. In Jasinga, they are controlled by Pliocene tuffaceous sedimentary rocks. The ratio of silica phases revealed a trend in the degree of silicification. Besides silica, the distribution of trace elements also demonstrates the geochemical interaction between the wood fossil and host rock. Wood fossils are affected by the gradual replacement of organic carbon-based materials with silica through silicification. Silica enrichment occurs in the internal of wood, facilitates permineralization and recrystallization. Silica replaces organic material and preserves the wood structures. The microanalytical approach provides comprehensive perspectives on wood petrification, leads to better insights for paleontological studies. [ABSTRACT FROM AUTHOR]

Halmahera Island in Indonesia holds great potential for nickel laterite due to its geological setting. As the product of chemical weathering, nickel laterite can be divided into saprolite and limonite. Despite containing invaluable elements like nickel and cobalt, limonite ore is seldom used in metal production. This study evaluates these two elements' leaching behavior and kinetics from the Halmahera deposit. Limonite ore was leached using 50 mL of 0.5 M sulfuric acid at an S/L ratio of 10% and 20%. The leaching process was conducted at 30°C, 50°C, and 80°C. The experimental results showed that the highest recovery for cobalt and nickel was 100% in the adequate presence of H+ ions. The result shows that sulfuric acid is more selective to cobalt than a nickel. The shrinking core ash diffusion model represents the leaching kinetics of cobalt, while nickel recovery follows the Kröger-Ziegler kinetics model. [ABSTRACT FROM AUTHOR]

Replacing metallurgical coke with greener material is a long-term challenge in pyrometallurgy. With the fact of biomass abundance in Indonesia, the usage of bio-char as a replacement for coke resulted from coal has been an intensive study. This study compared the performance between anthracite coal and coconut shell charcoal for nickel laterite reduction using the Equilibrium module on FactSage software simulation. The simulation was done by inputting a 4:4:1:20 weight ratio of nickel laterite ore, reductant (coal or coconut shell charcoal), lime and air, respectively. The temperature studied was 1300ᵒC to 1700ᵒC, and the pressure was atmospheric. The result shows that coconut shell charcoal has the potential to substitute anthracite coal as a reductant material in blast furnace processes. Anthracite coal consistently gives better results on the metal phase product with higher liquid metal yield and higher nickel and iron content. However, the coconut shell charcoal posseses the potential as a substitute material with temperatures above 1400°C regarding to the higher nickel concentration compared to anthracite coal. The resulting nickel and iron concentrations can reach above 2% and 96%, respectively, which is the required characteristics of a nickel pig iron product. [ABSTRACT FROM AUTHOR]

Natural polymer (cellulose)-based fabric was colored using an environmentally friendly natural dye extracted from Jalawe (Terminalia bellirica) in the preparation of Batik fabric, a cultural heritage of Indonesia that is recognized by United Nations Educational, Scientific and Cultural Organization (UNESCO). Despite the significant favorable properties in terms of functions, environmental, and cultural aspects, the combination between natural polymer-based fabric and natural dyes makes the Batik fabric an ideal medium for bacterial growth, leading to lower product quality. In the quest for a sustainable, environmentally friendly, rich-in-culture, yet durable textile, this study aimed at the functionalization of natural dye (ND)-colored Batik fabric with antibacterial ZnO nanoparticles (ZnO NPs) synthesized from Electric Arc Furnace Dust (EAFD) waste. An in situ immobilization process with a Chemical Bath Deposition (CBD) method was explored at a pH range from 6 to 11 at 50 °C. Characterization methods include XRD, XRF, FESEM, EDX, FT-IR, tensile strength measurement, agar diffusion testing, and a CIE L*a*b* scale measurement. The XRD and XRF results showed that pure (>98%) ZnO NPs were formed at pH 11 of the CBD process. FESEM results demonstrated that the pure ZnO NPs either precipitated at the CBD reactor or were immobilized on the cellulose fabric, exhibiting distinct morphology compared to the non-pure ZnO NPs. EDX elemental analysis before and after washing demonstrated the durability of the ZnO NPs attachment, in which 84% of the ZnO NPs remained on the fabric after two washing cycles (equal to 10 cycles of home laundering). The FT-IR spectra provided information on the chemical functional groups, demonstrating the success of the ZnO NPs immobilization on the cellulose fabric through Van der Waals or coordination bonding. Moreover, the in situ immobilization of ZnO NPs enhanced the Batik fabric's tensile strength but reduced its elongation. ZnO NP-functionalized Batik fabric that was treated at pH 10 and pH 11 showed antibacterial activity against Staphylococcus aureus. The CIE L*a*b* scale results showed that the immobilization process affects the color quality of the ND-colored Batik fabric. However, based on organoleptic observations, the color of the Batik fabric that was treated at pH 11 is still acceptable for Jalawe ND-colored Batik fabric. [ABSTRACT FROM AUTHOR]

A study on mineral characterization and nano titanium dioxide synthesis from ilmenite ore of Bangka Island, Indonesia, has been carried out using a caustic fusion method and hydrochloric acid leaching. Comprehensive mineral characterization was conducted using X-ray fluorescence spectroscopy (XRF) and X-ray diffraction (XRD) to depict each fractionated particle's elemental composition and mineralogy, i.e., +80, -80+100, -100+150, -150+200, -200+325, and -325 mesh. Other analyses performed are VSM to measure the magnetic properties and SEM to determine the distribution of elements at each particle size. Based on the characteristics of the ilmenite ore, magnetic separation was applied for the initial stage and analyzed gravimetrically. Later processing was the synthesis of nano titanium dioxide, conducted sequentially, including roasting and leaching. Roasting was run at 900°C with and without caustic soda, and then hydrochloric acid was applied. In reference to the elemental analysis, titanium (Ti) concentration is higher in smaller particle sizes and vice versa for iron (Fe) concentration, so the synthesis of nano titanium dioxide was carried out using a -100+150 mesh particle size. The optimum condition for nano titanium dioxide synthesis was 2:1 of NaOH and ilmenite weight ratio, 20% HCl concentration, and 4 hours of leaching time. The nano titanium dioxide (TiO2) obtained was then characterized using XRF, XRD, particle size analyzer (PSA), and transmission electron microscopy (TEM). Roasting with caustic soda showed better nano titanium dioxide purity with 96.04% of TiO2 with particle size in the range of 50–80 nanometers. [ABSTRACT FROM AUTHOR]