Jurnal Kimia Unand

Analisis Potensi Produksi Enzim Amilase oleh Beberapa Species Bacillus serta Penentuan Aktivitasnya secara Kualitatif dan Kuantitatif

Geliz Luh Titisari — 2026-05-31

This study aimed to analyze the potential of several Bacillus species—Bacillus subtilis, Bacillus thuringiensis, and Bacillus cereus—in producing amylase enzymes and to determine their enzymatic activity both qualitatively and quantitatively. Screening was conducted using starch agar medium, where the formation of clear hydrolysis zones indicated amylase activity. Growth curve analysis was used to determine the optimal harvesting period based on the bacterial growth phase. Enzyme production was carried out in a nutrient medium containing starch, and the crude enzyme extract was tested for activity using the Somogyi–Nelson method. The results showed that all Bacillus species tested exhibited amylolytic activity, with B. subtilis showing the highest amylolytic index (1.97). However, B. cereus demonstrated the greatest enzymatic performance, with an enzyme activity of 0.219 U/mL and a specific activity of 8.193 U/mg protein. These findings indicate that B. cereus possesses strong physiological and genetic potential to produce high levels of extracellular amylase compared to B. subtilis and B. thuringiensis. Therefore, B. cereus can be considered a promising candidate for industrial amylase production, and further optimization of fermentation conditions is suggested to enhance enzyme yield and catalytic efficiency.

Isolasi dan Karakterisasi Senyawa Metabolit Sekunder Fraksi Etil Asetat Daun Sungkai (Peronema canascane Jack.)

Suryati — 2026-05-31

Peronema canescens Jack, locally known as Sungkai, is a medicinal plant widely found in Indonesia and traditionally used as an antipyretic, anthelmintic, antimalarial, and mouthwash. Due to its diverse pharmacological potential, Sungkai leaves represent a promising subject for research. This study aimed to isolate and characterize secondary metabolites from the ethyl acetate fraction of Sungkai leaves collected from Agam Regency. The isolation process was carried out using column chromatography followed by purification through trituration, yielding 4.2 mg of white solid. Purity analysis by thin- layer chromatography (TLC) showed a single purple spot after spraying with Liebermann–Burchard reagent, with a melting point in the range of 251–253 °C. UV–Vis spectrophotometry exhibited a maximum absorption at 284 nm, indicating the presence of a limited conjugated system. FTIR spectrum confirmed the presence of aliphatic C–H stretching (2919 cm⁻¹), C=C stretching (1635.41 cm⁻¹), geminal dimethyl group (1450.30 cm⁻¹), and C–O stretching (1028.88 cm⁻¹). Based on these results, the isolated compound was identified as a member of the triterpenoid class.

Degradasi Residu Pestisida Klorpirifos pada Buncis Menggunakan Katalis TiO2/Zeolit secara Fotolisis

Z. Zilfa — 2026-05-31

Pesticide residues such as chlorpyrifos in agricultural products are toxic to both human health and the environment. Titanium dioxide (TiO₂) is a widely used photocatalyst for pollutant removal; however, its efficiency is limited due to its relatively low surface a-rea. To enhance its photocatalytic performance, natural zeolit was employed to improve the effectiveness of TiO₂. Zeolit has a high surface area and strong adsorption capacity, and when combined with a photocatalyst, it can improve pollutant degradation efficiency through simultaneous adsorption and photocatalysis. This study aims to degrade chlorpyrifos pesticide residue on green beans using TiO₂ supported by zeolit through a photolysis process. The TiO₂/zeolit catalyst was synthesized through activation and saturation of zeolit, followed by combination with TiO₂. Chlorpyrifos residues on green bean samples were analyzed using a UV-Vis spectrophotometer, while catalyst characterization was conducted using FTIR and XRD. The study also looked at the effects of photolysis time and catalyst dosage on degradation efficiency. The results showed that the degradation percentage of chlorpyrifos under UV light reached 72.88% with TiO₂ and 30.17% with zeolit. The TiO₂/zeolit composite exhibited a significant improvement in degradation efficiency, reaching 98.82%, indicating an effective synergy between photolysis and adsorption. In the absence of UV irradiation, degradation was only 44.45%, confirming the essential role of UV light in activating TiO₂ as a photocatalyst and enhancing the degradation of chlorpyrifos. The degradation of chlorpyrifos using TiO₂/zeolit followed first-order kinetics, where the reaction rate is directly proportional to the remaining chlorpyrifos concentration. FTIR analysis of the samples indicated successful degradation through the reduction of characteristic peak intensities. Furthermore, FTIR and XRD characterizations of the catalyst showed that the TiO₂/zeolit catalyst maintained its structural stability after the degradation process, allowing for potential reuse. This study shows that TiO₂/zeolit is effective for photocatalytic pesticide removal and may be applied in agricultural waste treatment.

Synergistic Inhibition of Mild Steel Corrosion in Hydrochloric Acid by Kecapi (Sandoricum koetjape ) Leaf Extract and Iodide Ions

Emriadi — 2026-05-31

The corrosion inhibition performance of steel in hydrochloric acid solution using kecapi (Sandoricum koetjape (Burm.f.) Merr) leaf extract (KLE) and the synergistic effect of iodide ions was investigated using the weight loss method at temperatures ranging from 30 to 60 °C. The inhibition efficiency increased with increasing concentrations of both KLE and iodide ions, as well as with increasing temperature. A maximum inhibition efficiency of 86.61% was achieved at a KLE concentration of 6 g L⁻¹ in the absence of iodide ions, which further increased to 92.63% upon the addition of 0.5 g L⁻¹ iodide ions, indicating a pronounced synergistic effect. The adsorption behavior of KLE on the mild steel surface followed the Langmuir adsorption isotherm, suggesting monolayer adsorption. FTIR analysis revealed shifts in characteristic functional group bands, confirming interactions between extract constituents and the steel surface. SEM observations demonstrated significant improvement in surface morphology for mild steel specimens immersed in 1 N HCl containing KLE and iodide ions compared to the uninhibited solution. The synergistic effect between KLE and iodide ions was quantitatively evaluated using synergism parameters derived from inhibition efficiency values, confirming enhanced adsorption and corrosion protection.