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Konversi
Published by Universitas Lambung Mangkurat
ISSN : 23023686     EISSN : 25413481     DOI : -
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Articles 279 Documents
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Chitosan and modified chitosan for essential oils encapsulation: a review Serina Amka Putri; Azlan Kamari; Mierta Dwangga; Sunardi Sunardi
Konversi Vol 15, No 1 (2026): APRIL 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i1.23934

Abstract

This review discusses the role of chitosan and modified chitosan as encapsulation matrices for essential oils (EOs) to overcome the limitations of volatility, hydrophobicity, and instability that have historically hindered the application of EOs in the food, pharmaceutical, cosmetic, and agricultural fields. Thru a literature review, this article examines the composition and extraction methods of EO; the principles, wall materials, and encapsulation techniques; and chitosan modification strategies ranging from cross-linking (e.g., sodium tripolyphosphate/TPP, glutaraldehyde), grafting functional groups, sulfation, to composite formation with other polymers (alginate, pectin, gelatin, cellulose, PVA). Generally, chitosan enhances oxidative stability, protects against light/oxygen/heat, improves solubility and bioavailability, and enables controlled release while providing antimicrobial and antioxidant properties that synergize with EO. Performance evidence is demonstrated by high encapsulation efficiency (often >80–90%) and nano particle size (<100 nm) in a number of formulations. For example, chitosan–TPP/alginate nanoparticles for rosemary oil achieved >98% efficiency with a size <100 nm, while oregano oil in chitosan–TPP nanoparticles reached 92.90%. Highlighted applications include active food preservatives and smart packaging, drug/topical delivery, biopesticides and fungal control, and the inhibition of resistant pathogens (e.g., Klebsiella pneumoniae). Nevertheless, the challenges toward commercialization still include process scale, cost, material standardization, long-term release control, and safety evaluation. Overall, chitosan and its derivatives emerge as versatile and promising encapsulating agents for enhancing the effectiveness, stability, and added value of essential oils across various sectors.
Gas composition analysis of biogas produced through anaerobic fermentation using tofu wastewater and cow manure as substrates Ahmad Moh. Nur; Abdullah Azam; Eko Heryadi; Hairul Huda; Kartina Kartina
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.25571

Abstract

Analyzed gas composition of biogas produced through anaerobic fermentation using two substrate systems: mono-digestion of cow manure and co-digestion of cow manure with tofu wastewater. The experiment was conducted in a laboratory-scale batch reactor for seven days, evaluating biogas volume, pH variation, and gas composition, including methane (CH₄), carbon dioxide (CO₂), and hydrogen sulfide (H₂S). The results showed that mono-digestion of cow manure produced a higher total biogas volume (7.944 mL) compared to the co-digestion system (1.9459 mL). Methane concentration was significantly higher in the mono-digestion system (1700 ppm), while the co-digestion system produced only 2 ppm. The cow manure substrate maintained a pH closer to neutral (6.23), whereas the mixed substrate became more acidic (3.05), potentially inhibiting methanogenic activity. In addition, mono-digestion generated lower concentrations of CO₂ (80 ppm) and H₂S (12 ppm) compared to the co-digestion system (138 ppm and 100 ppm, respectively), indicating superior gas quality. These findings demonstrate that effective biogas production is characterized by high methane concentration, near-neutral pH conditions, and low CO₂ and H₂S levels. Under the evaluated conditions, mono-digestion of cow manure produced higher-quality biogas with greater methane yield and total gas production.
Waste-to-hydrogen conversion: A mini review of feedstocks, processes, and hydrogen production Farid Fadhillah; Fekri Abdulraqeb Ahmed Ali; Mohammod Hafizur Rahman
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27859

Abstract

Waste-to-hydrogen (WtH₂) technologies can address two persistent challenges simultaneously: the accumulation of heterogeneous wastes and the need for lower-emission hydrogen. However, route-centered reviews often compare gasification, pyrolysis–reforming, dark fermentation, or microbial electrolysis independently, obscuring the more fundamental question of how feedstock properties determine reaction pathways and achievable hydrogen performance. This review develops a feedstock–process framework that links moisture, ash, elemental composition, volatile matter, polymer chemistry, carbohydrate accessibility, and biodegradability to thermochemical and biological conversion routes. Dry, carbon-rich residues and plastics generally favor high-temperature gasification or staged pyrolysis–reforming, whereas wet, readily biodegradable wastes more naturally match dark fermentation and bioelectrochemical upgrading. Sewage sludge and heterogeneous municipal wastes occupy an intermediate region in which pretreatment, hydrothermal processing, co-conversion, or hybrid systems become particularly important. Across thermochemical routes, hydrogen formation is governed by devolatilization, cracking, steam reforming, char gasification, and water–gas shift reactions; catalyst stability, tar control, steam-to-carbon ratio, and heat integration are therefore decisive. In biological systems, hydrolysis, acidogenic metabolism, hydrogen partial pressure, pH, microbial ecology, and suppression of hydrogen-consuming pathways control net recovery. The analysis shows that hydrogen yield cannot be interpreted independently of feedstock basis, gas composition, carbon conversion, external energy input, and downstream purification. Hybrid concepts-such as dark fermentation followed by microbial electrolysis, or pyrolysis followed by catalytic steam reforming and water–gas shift- offer a pathway toward more complete carbon and energy recovery. The review proposes standardized reporting metrics and a route-selection matrix and identifies impurity-tolerant catalysts, wet-waste integration, carbon management, modular reactors, and harmonized techno-economic/life-cycle boundaries as priorities for scalable WtH₂ systems.
Effect of pyrolysis temperature on product yields and characteristics of bamboo-derived bio-oil and biochar Ari Susandy Sanjaya; Nurhaliza Nurhaliza; Riszca Rahmawati; Mohd Rosli Mohd Hasan
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27075

Abstract

Pyrolysis of bamboo (Gigantochloa apus) offers a route for converting lignocellulosic biomass into bio-oil and biochar. This study evaluated the effect of pyrolysis temperature on product yields and selected properties of bamboo-derived products. Dried bamboo powder (250 g) was pyrolyzed in a laboratory-scale fixed-bed reactor without inert-gas flow at 300, 400, 500, and 600 °C for 60 min. Bio-oil was evaluated by yield, pH, density, and viscosity, whereas biochar was analyzed by yield and Fourier transform infrared spectroscopy. The highest bio-oil yield was 18.80% at 400 °C, while biochar yield declined from 25.20% at 300 °C to 9.00% at 600 °C. Bio-oil exhibited weakly acidic pH (5–6), density of 0.8917–0.9168 g cm⁻³, and viscosity of 0.9322–1.2711 cP. FTIR indicated progressive carbonization with increasing pyrolysis temperature. SEM analysis showed that increasing pyrolysis temperature promoted micropore development, as evidenced by wider cavities and thinner cell walls in biochar at 600 °C compared to 300 °C. These results confirm that pyrolysis temperature strongly governs bamboo product distribution and biochar chemical structure.
From biogas to methanol: Recent advances in methanotrophic biocatalysis, enzyme immobilization, and reactor intensification Rowina Lestari
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27880

Abstract

Biogas is a renewable methane-containing feedstock that can be upgraded to methanol, linking waste treatment with the production of a transportable liquid chemical. Conventional methanol manufacture relies on reforming, syngas conditioning, elevated temperature, and pressure. Methanotrophic bacteria and methane monooxygenase (MMO) provide a different route: methane can be hydroxylated selectively under comparatively mild conditions. The difficulty is that biological methane-to-methanol conversion is still limited by the low solubility of methane and oxygen, rapid methanol oxidation by methanol dehydrogenase (MDH), redox and cofactor constraints, loss of biocatalyst activity, gas impurities, and modest volumetric productivity. This review examines recent progress through three closely connected engineering themes: methanotrophic biocatalysis, immobilization of cells or enzymes, and reactor intensification. Studies using chitosan, lignocellulosic carriers, alginate/silica matrices, banana leaves, and magnetic-particle-containing polymers show that immobilization can improve reuse and cumulative methanol production. At reactor scale, trickle beds, inverse membrane systems, airlift reactors, pressurized stirred tanks, fine-bubble spargers, silicone-oil mass-transfer vectors, and emerging nanobubble approaches have been explored to address gas-transfer limitations. Molecular developments, including engineered mini-sMMO and photo-biocatalytic activation of MMO, also offer routes that reduce dependence on native methanotrophic metabolism and costly NADH regeneration. On this basis, an integrated process is proposed in which anaerobic digestion, selective biogas conditioning, intensified gas delivery, stable biocatalysis, controlled MDH activity, and methanol recovery are designed as a single process. The main challenge is no longer demonstrating methane hydroxylation, but maintaining useful methanol productivity with realistic biogas under scalable mass-transfer conditions
Conversion of CO₂ to methane in the methanation process using Ni/Al₂O₃ catalyst Muhammad Fikri; Erika Dwi Oktaviani; Didiek Hari Nugroho
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27345

Abstract

Carbon dioxide (CO₂) is a major greenhouse gas, with global emissions reaching 37.8 billion tons in 2024. CO₂ methanation via the Sabatier reaction offers a promising route for converting CO₂ into methane (CH₄) as a synthetic fuel. This study investigates the effect of reactor temperature (180–300°C) and operating time (60–180 minutes) on CO₂ conversion using a Ni/Al₂O₃ catalyst with a Zn promoter in a fixed-bed reactor integrated with a NaOH absorption unit. The novelty lies in the dual integration of NaOH, which is fed directly into the reactor and circulated to the post-reactor absorber, combined with a tray system for uniform gas distribution. Catalyst activation was performed using 4 M NaOH at 110°C for 2 hours, followed by calcination at 600°C. The process was conducted at 1 bar with a CO₂ flow rate of 0.05 L/min. Results showed that 260°C provided the best conversion, while 300°C decreased conversion due to equilibrium shifting toward reactants and excessive Zn consumption. An operating time of 120 minutes was optimal, while longer times reduced conversion due to limited Zn reductant. The optimal condition was achieved at 260°C and 120 minutes, yielding the highest CO₂ conversion of 65.59%, with a CH₄ concentration of 63.22% and residual CO₂ of 34.41%.
Temperature effects on ultrasonic extraction yield and DPPH response of harumanis mango leaves Non Aeni Febriyanti; Vera Pangni Fahriani; Ghina Putri Nabila
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27644

Abstract

Harumanis mango leaves are a potential source of extractable antioxidant constituents, but the selection of extraction temperature requires a clear distinction between extract recovery and antioxidant potency. This study examines the apparent extract yield and recorded DPPH response associated with three extraction temperatures. Concentrated extract masses of 27, 31, and 39 g were reported at 40, 50, and 60 °C, respectively, corresponding to apparent mass recoveries of 54, 62, and 78% relative to the starting dried leaf material. The corresponding absorbance values were 0.2974, 0.2365, and 0.2042 against a reported control absorbance of 0.4517. Nominal DPPH inhibition calculated from these values was 34.16, 47.64, and 54.79%, respectively. The 60 °C condition therefore gave the highest recorded extract mass and nominal inhibition within the tested range. These observations remain preliminary because the records available for assessment do not establish independent extraction replication, extract concentration during the DPPH assay, matched control preparation, or drying of the concentrated extracts to constant mass. Accordingly, the results do not establish statistically supported differences in antioxidant potency or a process optimum. The findings identify 60 °C as a candidate for further validation using independently replicated extractions, dry-mass determination, and concentration-controlled antioxidant measurements. This distinction provides a clearer basis for subsequent development of mango leaf extraction processes.
The effect of cassava peel starch and chitosan ratio with pineapple leaf cellulose nanofibers as fillers on bioplastic characteristics Yuli Darni; Lia Lismeri; Simparmin Br Ginting; Audhea Yolandha Kania
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.24342

Abstract

This study aims to examine and determine the formulation of starch-chitosan and filler materials in bioplastic production in relation to the characteristics of the resulting bioplastic and the optimum conditions for bioplastic formulation, to obtain cellulose fibers from pineapple leaves with nanometer dimensions, and to obtain bioplastic from the application of nanoserats with mechanical and physical properties comparable to plastic in accordance with Indonesian National Standards (SNI). In this study, the starch-chitosan mass ratio used varied between 9:1, 8:2, and 7:3 (gram/gram), and the addition of corn stalk cellulose fiber filler varied between 0 grams, 0.5 grams, and 1 gram. The sieve size for starch and filler was 200 mesh. In the bioplastic manufacturing process, the glycerol concentration was set at 10% (weight percent), the stirring time was 35 minutes at a temperature of 75℃, and the stirring speed was 375 rpm. The cellulose fibers produced were still micro in size with a diameter of 1.078–1.224 µm. The results showed that the cassava peel starch chitosan bioplastic with pineapple leaf filler was close to the Indonesian National Standard (SNI) values. The analyses performed included mechanical properties (tensile strength, elongation percentage), physical properties (water absorption and biodegradation test, water vapor permeability), and functional group analysis using FTIR. This bioplastic has the best tensile strength value of 21.74 MPa, elongation of 105.70%, water absorption of 150%, biodegradation of 106.25%, and water vapor permeability of 2.62 g/m². 
Valorization of date palm waste: A review of thermochemical and biochemical conversion routes for sustainable biorefineries Mohammed A. Zeinelabdeen; Mohamed Saifeldin Mubarak Mohamed; Ahmed MohamedAlamen Alzain Mohamed; Muzamul MA Siddig; Abubakr Hassan Kheiri
Konversi Vol 15, No 2 (2026): OCTOBER 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i2.27840

Abstract

Date palm cultivation and date processing generate substantial quantities of agricultural and agro-industrial residues, including fronds, leaves, rachis, trunks, leaf sheaths, pedicels, empty fruit bunches, seeds, press cake, pomace, and rejected fruits. These materials are frequently burned, landfilled, or used in low-value applications despite containing cellulose, hemicellulose, lignin, fermentable sugars, lipids, proteins, minerals, and bioactive compounds that can support a diversified biorefinery. This review critically compares thermochemical and biochemical routes for date palm waste valorization, with emphasis on feedstock–process compatibility, product yields, pretreatment requirements, energy integration, scale-up, techno-economic performance, and environmental implications. Pyrolysis can generate biochar, bio-oil, and non-condensable gas from dry lignocellulosic residues; recent studies report biochar yields approaching 45% under slow pyrolysis and bio-oil yields around 26–33% for selected date palm fractions. Gasification offers syngas, hydrogen-rich gas, and methanol opportunities, whereas hydrothermal processing is an underexplored option for wetter residues. Biochemical conversion can recover ethanol, methane, volatile fatty acids, lactic acid, and other products. Recent biorefinery studies have shown that pretreatment followed by fermentation and anaerobic digestion can substantially increase overall energy recovery, while date seeds can support cascade schemes involving oil extraction, biodiesel synthesis, enzymatic hydrolysis, ethanol fermentation, and pyrolysis of the remaining solids. The evidence indicates that no single route maximizes resource efficiency across all date palm residues. Instead, integrated biorefineries that fractionate feedstocks and combine biochemical conversion of carbohydrate-rich fractions with thermochemical processing of lignin-rich residues provide the strongest pathway toward circularity. Key barriers remain feedstock seasonality, logistics, water use, pretreatment cost, product upgrading, catalyst and enzyme expense, tar and inhibitor management, and the scarcity of pilot-scale data. Future work should focus on region-specific feedstock inventories, low-water pretreatments, renewable heat integration, standardized mass and energy balances, and harmonized techno-economic and life-cycle assessments.

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