KOVALEN: Jurnal Riset Kimia

Formulation and Characterization of Soursop Leaf extract (Annona muricata L.) Nanoemulsion Using VCO and Tween 80

Ratih Dyah Puspitasari — 2025-12-29

Methanol extract of soursop leaves contains various bioactive compounds such as alkaloids, saponins, tannins, and flavonoids. To increase the absorption of these compounds, a nanoemulsion formulation of soursop leaf extract was carried out. Extraction was carried out using the maceration method using 96% methanol, followed by a thickening process using a rotary evaporator and freeze drying to obtain the dry extract. The nanoemulsion preparation was made from methanol extract of soursop leaves (Annona muricata L.) using Virgin Coconut Oil (VCO) as the oil phase and Tween 80 as a surfactant. The nanoemulsion was formulated using a high-energy method using an ultrasonicator. Two formulas were tested (F1 and F2) and evaluated through organoleptic tests, clarity (transmittance), physical stability (centrifugation), solubility, emulsion type, storage test (freeze-thaw), and measurement of droplet size and polydispersity index with a Particle Size Analyzer (PSA). The results showed that formula F1 had the most optimal characteristics, with a clarity of 80% indicating better droplet dispersion with an average droplet size of 13.96 nm and a polydispersity index of 0.216 indicating the successful formation of a stable and uniform nanoemulsion. Nanoemulsions showed good physical stability, were soluble in polar and semi-polar solvents, and were oil-in-water (O/W) type supporting increased solubility and availability of active compounds in air-based systems. These results indicate that F1 is the most potential formula to increase the bioavailability of active compounds in soursop leaves and can be further developed as a carrier system candidate in pharmaceutical preparations.

XRD-Based Structural and Crystallite Size Analysis of Nano-MgO Prepared via Sol–gel Method

Imas Masriah — 2025-12-29

Nano-MgO was synthesized via a nitrate–citrate sol–gel combustion method, in which magnesium nitrate acted as the oxidizing precursor and citric acid served simultaneously as the chelating agent and organic fuel. The formation of a homogeneous Mg–citrate coordination network enabled controlled gelation, while the auto-combustion process produced a porous MgO matrix composed of ultrafine crystallites. Calcination at 800 °C promoted phase consolidation, removal of organic residues, and enhanced long-range atomic ordering. X-ray diffraction confirmed the exclusive formation of the cubic periclase phase (fm3m), with no detectable hydroxide or carbonate impurities. Crystallite size analysis yielded an average size of 16.03 nm based on the Scherrer equation, whereas the Williamson–Hall method produced a larger value of 25.44 nm with a microstrain of 5.37 × 10^-4. indicating minimal lattice distortion. The discrepancy between the two size estimates reflects the contribution of microstrain effect not considered in the Scherrer approach. Overall, the synthesized nano-MgO exhibits high crystallinity, narrow crystallite size distribution, and excellent structural stability, highlighting its potential for catalytic, gas-sensing, and high-temperature functional applications. These results demonstrate that the sol–gel combustion method is an efficient and reliable strategy for producing nanocrystalline MgO with well-controlled structural characteristics.

Modification of Areca Nut (Areca catechu L.) Peel Hydrochar for Photodegradation of Methylene Blue

Eva Musifa — 2025-12-29

Synthetic dyes such as methylene blue (MB) are persistent pollutants that pose serious environmental risks due to their toxicity and resistance to biodegradation. This study investigates the development of sustainable photocatalysts derived from Areca catechu L. peel through hydrothermal carbonization, followed by activation, zeolite impregnation, and magnetic modification using Fe²⁺/Fe³⁺ ions. XRD and FTIR analyses confirmed the successful formation of Fe₃O₄, increased porosity, and the presence of functional groups that facilitate adsorption and photocatalytic activity. The results indicate that photodegradation is significantly more effective than adsorption, with magnetic hydrochar and hydrochar–zeolite composites achieving degradation efficiencies above 90%. Optimal performance was observed at a catalyst mass of 0.20 g and an irradiation time of 150 minutes. The high removal efficiency is attributed to synergistic interactions including pi-pi stacking, hydrogen bonding, and electrostatic attraction between MB molecules and the modified hydrochar surface. Overall, this study demonstrates that Areca catechu L. peel waste can be valorized into an efficient, low-cost, and magnetically recoverable photocatalyst for dye-contaminated wastewater treatment

Effect of Column Diameter on the Performance of an Ion Exchange System in Reducing Water Hardness

Widya Yeni Rawati — 2026-01-05

Ion exchange is an effective method for removing hardness ions such as Ca²⁺ and Mg²⁺ from water, and its performance is strongly influenced by column design parameters. This study aims to evaluate the effect of column diameter on the efficiency of a sequentially operated cation–anion ion exchange system at a constant flow rate of 10 L/h. Six column diameters (20, 25, 30, 35, 40, and 50 mm) were tested using synthetic solutions. The results showed that the 30 mm column achieved the highest ion-exchange performance, with a removal efficiency of 92.47%. This column also produced the most well-defined breakthrough curve, yielding an exchange capacity of 8.76 mg/g, equivalent to 0.437 meq/g for Ca²⁺ and 0.720 meq/g for Mg²⁺. These findings indicate that the 30 mm diameter provides an optimal balance between contact time and flow distribution, resulting in superior ion exchange efficiency.

Preconcentration of Cr (VI) Using Ca-Alginate-EDTA Microcapsules in a Column System for UV-Vis Spectrophotometric Analysis

Ika Yekti Lianasari — 2026-01-08

This study introduces optimized Ca-Alg-EDTA microcapsules specifically designed as a high-performance column filler for the preconcentration and sensitive detection of toxic Cr(VI) in aquatic systems. Monitoring Cr(VI) at trace levels is critical due to its high toxicity and environmental persistence. Unlike previous alginate-based sorbents, this work focuses on a synergistic EDTA integration within a column-switching framework to enhance retention efficiency (74.73 %) and capacity (0.3995 mg/g). Analytical validation using UV-Vis spectrophotometry demonstrated excellent linearity (R² = 0.9995) with a low detection limit of 0.014 mg/L, ensuring reliability for samples with minimal analyte concentrations. The method’s robustness was confirmed through Mahakam River water analysis, yielding a 93.05 % recovery in compliance with AOAC 2002 standards. This optimized microencapsulation approach provides a cost-effective and sustainable solution for routine environmental monitoring of heavy metal contamination.