Henry Setiyanto

The increasing global demand for lithium and other critical elements has intensified the need for efficient and cost-effective exploration approaches. This study presents a preliminary hydrogeochemical assessment of lithium distribution in the Kulon Progo volcanic region, Southern Mountains of Java, Indonesia, using integrated ICP-OES, X-ray diffraction (XRD), and petrographic analyses. Surface water samples contain lithium concentrations ranging from 0.01 to 0.49 ppm, with the highest value recorded in Banyuasin well water. Associated trace elements, including strontium, boron, barium, magnesium, and cobalt, were also detected, reflecting complex water–rock geochemical interactions within the volcanic system. Volcanic rock samples contain 5–57 ppm Li, reflecting substantial spatial variability related to lithological differences across the study area. XRD and petrographic analyses provide mineralogical context for interpreting lithium distribution; however, specific lithium-hosting mineral phases could not be conclusively identified. The integrated geochemical and mineralogical data suggest that water–rock interaction is a key process controlling lithium mobilisation and distribution. This study provides the first baseline dataset on lithium distribution in the Kulon Progo volcanic region, identifies previously unrecognised lithium anomalies, and demonstrates the value of integrated hydrogeochemical approaches for preliminary lithium exploration in Indonesian volcanic terrain.

Mango peel extract was utilized for the fabrication of green zinc oxide nanoparticles (gZnO), exploited as a natural stabilizing and reducing agent. X-ray diffraction pattern confirmed the wurtzite crystalline phase with an average crystallite size of 12 nm. The scanning electron microscope observation revealed a spherical-like morphology of gZnO. The electrochemical behavior and EASA of bare and modified GCE were examined using cyclic voltammetry technique. The EASA of bare GCE increased from 0.118 cm2 to 0.182 cm2 after modification with gZnO. Measurement of uric acid (UA) using differential pulse voltammetry (DPV) in 0.1 M phosphate buffer pH 7.0, reveals a sharp oxidation peak at a potential of − 0.08 V (vs. Ag/AgCl). In addition, the UA peak current response was elevated 2.6-fold (from 3.7 µA to 9.75 µA) when analyzed at gZnO/GCE in comparison with bare GCE. The proposed electrode exhibits a narrow linear range at UA concentrations from 0.3 µM to 1.20 µM, with a low LOD value of 0.23 µM. These findings highlight the synergistic interaction between gZnO nanostructure and the conductive carbon matrix, enabling improved sensitivity and electron transfer kinetics. The gZnO/GCE platform offers a green, cost-effective, and non-enzymatic approach for UA detection in low-volume biological samples.

The increasing shrimp production and consumption in Indonesia generates significant amounts of shrimp shell waste, which has not been optimally utilized and often becomes an environmental problem. This waste is rich in chitin, which can be processed into chitosan—a multifunctional biopolymer with various applications in food, health, agriculture, and environmental fields. This literature review explores the synthesis process, characterization, and utilization of chitosan derived from shrimp shell waste, while highlighting the importance of integrating Islamic ethical values in the sustainable management of natural resources. The synthesis of chitosan involves demineralization, deproteinization, and deacetylation steps, with critical parameters such as temperature, time, and base concentration affecting the degree of deacetylation. The review shows that utilizing shrimp shell waste as a source of chitosan not only supports circular economy principles and waste reduction but also aligns with Islamic teachings on responsible environmental stewardship. The integration of science and Islamic ethics is expected to promote the development of high-value, sustainable, and environmentally friendly biomaterials.

Purification and functionalization of SWCNTs with HCl reduces impurities, and annealing Si/P-SWCNT/ZnO solar cells improves performance, achieving 18.6% efficiency with excellent photoresponse.