Indonesian Chimica Letters

Enhancing Water Quality: Application of Coconut Shell Activated Charcoal for Sulfide and Ammonia Removal from Tofu Industry Wastewater

Asnawati Asnawati — 2024-12-31

This study investigates the optimization of an adsorption process using activated coconut shell charcoal to reduce sulfide and ammonia levels in tofu industry wastewater. These pollutants pose significant environmental risks due to their biodegradable nature. Experimental parameters, including adsorbent particle size (50, 60, and 70 mesh), heating temperature (40, 80, 120 °C, and ambient), and contact time (15-60 minutes for sulfide, 20-100 minutes for ammonia), were systematically varied to determine optimal conditions. The initial sulfide and ammonia concentrations in the wastewater exceeded regulatory limits at 0.169 mg/L and 8.177 ppm, respectively. The results indicate that 70-mesh activated charcoal at ambient temperature achieved maximum pollutant removal: 93.46% for sulfide with a 30-minute contact time and 93.693% for ammonia with a 40-minute contact time. These findings offer a promising approach to mitigating the environmental impact of tofu industry wastewater.

Synthesis and Characterization of Glutaraldehyde-Crosslinked Chitosan for Urea Controlled Release

Bambang Piluharto — 2024-12-31

Urea exhibits high nitrogen content (∼46%), which is essential for plant growth. However, significant nitrogen losses occur through decomposition, leaching, denitrification, and volatilization. Employing controlled-release systems, such as chitosan membranes crosslinked with glutaraldehyde, can mitigate these losses and enhance fertilizer efficiency. Therefore, this study aimed to develop and characterize chitosan-glutaraldehyde membranes as controlled-release fertilizer systems for urea. Chitosan membranes were crosslinked with varying glutaraldehyde concentrations (0%, 0.4%, 0.9%, 1.3%, and 1.8%) and used to encapsulate urea. The membrane produced was characterized using FTIR and swelling degree assay. The potency of glutaraldehyde-crosslinked chitosan as a urea coating agent was also studied spectrophotometrically using the Nessler reagent. FTIR analysis revealed low intensity of the C=N stretching vibration, indicating limited crosslinking reaction. Additionally, both swelling degree and urea release increased proportionally with increasing glutaraldehyde concentration. These findings suggest limited crosslinking reactions occurred between glutaraldehyde and chitosan within the studied concentration range.

Effectiveness of Gold Extraction with Thiourea Solution from Gold Rocks in Mount Tumpang Pitu Pasanggaran Banyuwangi

Novita Andarini — 2024-12-31

This research aims to determine the effect of adding an oxidizing solution in the gold extraction process using thiourea solution. The oxidizing agent used in thiourea leaching solution is FeCl₃. Variations of additional volume of oxidizing solution are 0 mL, 10 mL, 20 mL, 30 mL, and 40 mL. Based on the results obtained, the addition of 30 mL oxidant FeCl₃ can get optimal results. The thiourea leaching solution can extract gold as much as 46.7%.

Isolation and Transformation of Tefrosin From The Seed of Tephrosia Vogelii With SelectfluorTM

Ana Yulvia — 2024-12-31

In this study, tefrosin (1), a known phenolic compound, was successfully isolated and identified from the seed extract of Tephrosia vogelii. The structure of this compound was determined based on 1D and 2D NMR spectroscopy. Furthermore, the isolated compound was transformed using 0.5 equivalent of selectfluor™ in acetonitrile solvent at 100 ^oC for 3 hours. The reaction product, namely dehydrotephrosine (2), is new reaction product from selectfluor™ reagent as a catalyst in tertiary alcohol dehydration in aromatic group. This finding highlights the effectiveness of selectfluor™ as a catalyst in dehydration reactions, demonstrating its potential to introduce new chemical properties to compounds. The study underscores the versatility of selectfluor™ and its ability to facilitate the generation of valuable derivatives from phenolic compounds. These results provide insights into the reactivity of tefrosin and offer a new approach for chemical transformations involving phenolic substrates.

The Effect of Substrate Concentration and Incubation Time on The Activity of The Uricase Enzyme From Goat Liver

Wuryanti Handayani — 2024-12-31

Uricase is an oxidoreductase enzyme that catalyzes the degradation of uric acid into allantoin, hydrogen peroxide, and carbon dioxide. Allantoin, the primary product of uric acid degradation, exhibits 5-10 times greater solubility in water compared to uric acid. This property underscores the importance of uricase in managing hyperuricemia, a condition characterized by elevated uric acid levels in the blood. Hyperuricemia is associated with diseases such as gout, kidney dysfunction, and hypertension. While humans and primates lack the uricase enzyme, it is naturally present in the liver of non-primate mammals, including goats. This study investigated the activity of uricase extracted from goat liver, focusing on the optimum concentration of uric acid as the substrate and incubation time necessary for achieving maximum enzymatic activity. Goat liver samples were processed using borate buffer (pH 8.5) ammonium sulfate fractionation and dialysis to isolate uricase. The enzymatic activity was evaluated at uric acid concentrations of 1.0, 1.5, 2.0, 2.5, and 3.0 mM and incubation times of 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0 hours. The results revealed that the optimum substrate concentration for uricase was 2 mM, yielding total enzyme activity of 0.6704 U/mL and specific activity of 0.0443 U/mg. Additionally, the optimum incubation time was determined to be 5 hours, resulting in total enzyme activity of 0.8421 U/mL and specific activity of 0.0556 U/mg. These findings provide valuable insights into enhancing uricase activity and optimizing its application in therapeutic strategies for hyperuricemia management. Further research is recommended to explore the potential of uricase in clinical and pharmaceutical contexts.