Jurnal Teknik Kimia USU

Pengaruh Hydraulic Retention Time pada Proses Aklimatisasi Reaktor Nitrifikasi Biofilter dari Olahan Limbah Cair Industri Tahu

Fatimah — 2025-09-27

The characteristics of tofu wastewater in Polonia-Medan contain a high organic load and an acidity degree of between 4-5 so it needs to be treated appropriately. The initial processing technique has been carried out anaerobically, but the NH3-N content is still high so it is necessary to carry out a nitrification process. Biofilters are widely used as a medium for the growth of microorganisms in waste processing. Bio balls as a medium for the growth of microorganisms have been previously carried out in anaerobic processing of tofu wastewater. This bio ball biofilter is capable of providing optimal growth of microorganisms, so this research also uses bio balls as biofilter media. Aerobic process in the biofilter nitrification reactor with variations in hydraulic retention time (HRT) of 24, 12, 6 hours and substrate concentrations of 50% and 100% for the acclimatization process. Acclimatization shows that HRT influences the acclimatization process to variations in substrate concentration. The highest removal process results were at 24 hour HRT, 100% substrate concentration, which resulted in NH₃-N removal of 86.95%, COD 77.97% and nitrate production of 103.25 mg/L.

Solvent-Free Microwave Extraction: Analisis Fitokimia Minyak Atsiri Daun Ruku-Ruku (Ocimum tenuiflorum, L.) dan Aktivitas Antibakteri terhadap Escherichia coli

Yuni Susanti — 2025-09-27

Holy basil (Ocimum tenuiflorum, L.) is one of the aromatic herbs that grows in empty or abandoned areas. Previous studies used conventional methods, including maceration and hydrodistillation, to extract Ocimum tenuiflorum, L. Genetic variation, plant phenology, geographical conditions, and extraction techniques affect the yield and variability of essential oil phytochemical composition. Here in, we report essential oil extraction of Ocimum tenuiflorum green and purple using solvent-free microwave extraction. The yield calculation obtained from purple and green O. tenuiflorum essential oils was 2.25 and 2.17%, respectively. GCMS data shows that the phytochemical compounds in Ocimum tenuiflorum essential oils, purple and green leaves, are dominated by sesquiterpene and phenylpropene groups. In the essential oil of purple Ocimum tenuiflorum leaves, the major phytochemical compound components are methyl eugenol, β-Caryophyllene, and Germacrene-D. Antibacterial activity showed that Ocimum tenuiflorum purple essential oils a more preeminent effect against Escherichia coli than green.

Pengaruh Konsentrasi Methylene Blue dan NaClO pada Proses Degradasi Photocatalytic Fuel Cell Menggunakan Elektroda Cu-TiO2/ZnO

Cicilia Putri Meylani — 2025-09-27

The contamination of synthetic dyes such as methylene blue has become a serious issue in textile industry wastewater due to its resistance to natural degradation. Photocatalytic Fuel Cell (PFC) technology is an effective and environmentally friendly method for degrading toxic dyes in wastewater. In this study, a dual-chamber PFC was developed using a photoanode composed of a Cu-TiO₂/ZnO semiconductor composite synthesized via the sol-gel method. The objective was to develop an efficient composite electrode and evaluate the effect of methylene blue and sodium hypochlorite (NaClO) concentrations on degradation efficiency. The composite was prepared with 5 wt% Cu, calcined at 200 °C, and deposited onto a glass substrate. Characterization using Scanning Electron Microscopy (SEM) revealed that the resulting nanoparticles exhibited a spherical morphology with diameters ranging from 0.22 µm to 4.33 µm. UV-Vis Diffuse Reflectance Spectroscopy (DRS) analysis showed that the band gap energy decreased from 3.18 eV (TiO₂/ZnO) to 2.29 eV after Cu doping. The experimental results demonstrated that the addition of NaClO enhanced the photocatalytic activity of the Cu-TiO₂/ZnO composite for methylene blue degradation, achieving an optimal degradation rate of 78% after 120 minutes of operation.

Optimasi dan Sintesis Selulosa Dialdehid Berbasis Limbah Tandan Kosong Kelapa Sawit

Elvri Melliaty Sitinjak — 2025-09-27

Empty Fruit Bunches of Oil Palm (EFB) represent one of the most problematic biomass wastes in Indonesia due to their massive volume, inefficient management, and underutilization of their chemical potential, leading to significant environmental, economic, and technical impacts. The degradation or processing of such large-scale waste generally requires a long period of time. This study focuses on converting the cellulose content in EFB into dialdehyde cellulose (DAC), which can be applied as a wet strength agent. The aim is to reduce EFB waste by isolating cellulose from EFB biomass and subsequently converting it into DAC, which can be utilized as a wet strength additive in paper or tissue products. The oxidation of EFB cellulose into DAC was optimized using sodium periodate (NaIO₄) as the oxidizing agent, with varying reaction times of 3, 6, and 9 hours. The synthesized DAC was qualitatively analyzed using the Fehling’s test and solubility observations, followed by functional group identification via FTIR and morphological characterization using SEM. Among the samples, DAC-6 exhibited the most optimal characteristics, with a degree of oxidation reaching 82.1% and a carbonyl content of 52.8%. FTIR analysis confirmed the presence of carbonyl functional groups in all DAC samples, indicating successful oxidation of hydroxyl groups in cellulose. DAC-6 showed the most prominent carbonyl absorption peak at a wavenumber of 1748 cm⁻¹.

Pengaruh Penambahan Bio-filler Serbuk Pelepah Pisang pada Sifat Termal, Reologi, dan Mekanik Komposit Termoplastik Berbasis Polipropilena

Khadijah Sayyidatun Nisa — 2025-09-27

This study examines the effect of banana stem powder (SPP) addition on the thermal, rheological, and mechanical properties of polypropylene (PP) composites with the addition of stearic acid. The composites were made with variations of PP:SPP of 100:0%, 98:2%, 96:4%, and 94:6% by weight. Differential Scanning Calorimetry testing showed the highest melting temperature of 165.4°C at 4% SPP, while the highest crystallinity of 42.64% was obtained at 2% SPP. The highest flow rate was obtained at 2% SPP of 8.83 g/10 min, and there was a decrease in the flow rate at 4% and 6% SPP. The tensile strength test results showed a decrease, from 30.10 MPa in pure PP to 23.40 MPa at 2% SPP. The results indicate that SPP can improve the thermal and rheological properties of the composite within certain limits, but excessive addition decreases the mechanical strength.

Pemanfaatan Selulosa dari Ampas Tebu (Saccharum officinarum) pada Penyediaan Bioplastik Berbasis Pati Biji Durian (Durio zibethinus Murr) yang Bersifat Biodegradable

Febry Angelika Nababan — 2025-09-27

Biodegradable bioplastics are environmentally friendly plastics that can decompose into water, carbon dioxide, biomass or organic compounds, which can be made from biomass materials such as starch. Starch-based bioplastics were mixed with hydrophobic plasticizers like glycerol to prevent it from cracking and fillers like cellulose from sugarcane bagasse were added to make it stronger. This study aims to determine the effect of sugarcane bagasse cellulose on the characteristics and properties of bioplastics. In this study, the starch used was 5 g, cellulose concentrations were (0, 3, 6, 9, 12)%, and glycerol 30% of the total weight of bioplastics. Yield of durian seed starch and bagasse cellulose was 16.06% and 46.36%. The best bioplastic was obtained with 6% bagasse cellulose concentration, with tensile strength of 2.331 MPa, elongation of 8.193%, density of 0.933 g/mL, water absorption of 92.43%, and 100% degradation on the 21st day in the soil burial test method.

Pengaruh Perbandingan Komposisi Ampas Tebu dan Kulit Durian Terhadap Karakteristik Bio-oil

Iriany — 2025-09-27

The bio-oil from bagasse has poor physical characteristics, so it requires a combination with other materials, such as durian peel. This study aims to produce high-quality bio-oil from the best composition ratio of bagasse and durian peel. The study used variations of sugarcane bagasse and durian peel compositions (0:1; 1:0; 1:1; 2:1; 3:1) at a pyrolysis temperature of 400 °C for 5, 6, and 7 hours using an 83.1 L upright cylindrical reactor. The bio-oil with the best characteristics was found at a 1:1 ratio, with yields of 32.28%, 38.82%, and 40.8%, pH values of 2.7; 2.8; 2.9, and viscosities of 0.952 cSt, 0.928 cSt, and 0.908 cSt. The results show that adding durian peel improves the bio-oil characteristics.

Sintesis Nanohibrida Silika-urea Berbasis Abu Bagasse sebagai Pupuk Lepas Lambat Ramah Lingkungan

Siti Muslimah — 2025-09-27

The urea–silica nanohybrid is an innovative slow-release fertilizer designed to enhance nitrogen use efficiency in agriculture. This study synthesized the nanohybrid using silica sourced from bagasse ash via the sol-gel method. Silica was extracted by reacting the ash with sodium hydroxide to form sodium silicate, which was then converted into silicic acid through ion exchange using a cation resin. Ammonium hydroxide was added to adjust the pH to 5, forming a gel at room temperature. The gel was aged for 18 hours to strengthen its structure, then freeze-dried to produce hydrophilic silica aerogel. To form the nanohybrid, 1 g of silica aerogel was mixed with urea at varying concentrations, stirred for 24 hours, filtered, and dried at 40 °C. Characterization using Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of Si–O–Si and Si–OH groups, along with urea-specific bands (C=O and N–H), indicating successful integration of urea into the silica matrix.

Kuantifikasi Flavonoid dan Analisis Aktivitas Antioksidan Ekstrak Daun Nilam (Pogostemon cablin) Menggunakan Uji DPPH

Natasya Dila Putri Anggraini — 2025-09-27

Patchouli leaves (Pogostemon cablin) are known to contain flavonoid compounds with potential antioxidant properties. However, comparative data on flavonoid content and antioxidant activity across different extract fractions of patchouli leaves remain limited. To address this gap, the present study was conducted to analyze the total flavonoid content and evaluate the antioxidant activity of the ethanol extract and three solvent fractions—n-hexane, ethyl acetate, and wáter using the DPPH method as an indicator of free radical scavenging activity. The extraction was carried out through maceration, followed by fractionation. The determination of flavonoid content employed a colorimetric method based on the aluminum chloride reaction, while antioxidant activity was assessed using the DPPH assay. The results revealed that the ethyl acetate fraction contained the highest flavonoid concentration (1.615 ± 0.0591%) and exhibited very strong antioxidant activity, with an IC₅₀ value of 17.3909 ± 0.1327 μg/mL. These findings suggest that the ethyl acetate fraction holds significant potential as a natural antioxidant agent, with possible applications in the pharmaceutical field or nutraceutical-based health products.