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2 Journal of Ecological Engineering

2 2024

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Bioethanol Fermentation from Banana Pseudostems Waste (Musa balbisiana) Pretreated with Potassium Hydroxide Microwave

100%

Uljanah D. , Melwita E. , Novia N.

Journal of Ecological Engineering

2024

tom Vol. 25, nr 9

1--13

Several nations are committed to developing an alternative energy source to achieve the net zero emissions (NZE) target. A typical alternative is bioethanol, which has been reported to be a renewable energy supporting the achievement of the target. Although banana pseudostem waste is often minimally utilized and discarded by the community, several studies have shown its potential to yield bioethanol due to the high cellulose content. Therefore, this study aimed to synthesize bioethanol from banana pseudostem waste (Musa balbisiana) pretreated with potassium hydroxide (KOH) microwave using hydrolysis and fermentation. The effect of yeast concentrations (8%, 10%, and 12%) and fermentation times (6, 7, 8, 12, and 13 days) on the pretreated sample was also analyzed. Fermentation was carried out using enzymatic kinetic modeling with Michaelis Menten’s equations to determine the reaction rate. The results showed that the sample with 12% yeast and fermentation time of 13 days produced the highest ethanol content (41.5%). In addition, the appropriate kinetic modeling results were similar to Hanes Woolf’s linearization modeling. The 10% yeast concentration led to KM values of 1.606×10-3g mL-1 and Vmax of 6.837×10-4g mL-1h.

Synthesis and Characterization of Zinc Oxide-Zeolite Photocatalyst Nanocomposite for Heavy Metals Degradation

75%

Agustina T. E. , Ramadhini T. K. , Melwita E. , Bahrin D. , Wijayanti M. S. , Gayatri R.

Journal of Ecological Engineering

2024

tom Vol. 25, nr 3

272--281

Heavy metals are the major contributors to pollution due to their enduring presence and poisonous characteristics. Wastewater that contains heavy metals is classified as harmful and has the potential to contaminate the environment. Large-scale disposal of heavy metal discharged into the environment causes significant environmental harm. Commonly seen heavy metals in water deposits include non-biodegradable metals such as cadmium (Cd), copper (Cu), lead (Pb) and iron (Fe). To mitigate the adverse effects of environmental contamination, it is necessary to handle wastewater containing heavy metals properly and optimally. Photocatalysis is a technology that involves the breakdown of pollutants with the use of light. This study aims to synthesize and characterize the nanocomposite of ZnO-Zeolite photocatalyst on the degradation of Cd, Cu, Fe, and Pb heavy metals. The ZnO-Zeolite nanocomposites were characterized by using SEM-EDX, XRD, and BET methods. The degradation caused by exposure to ultraviolet (UV) light occurs within the time of between 60 to 120 minutes, with a pH range of 6–8. The removal of heavy metals proceeds within a time frame of one hour and two hours, resulting in an optimal percentage removal of metals that approaches 100%. The composite showed a surface area of 19.436 m2/g, a pore size of 17.227 Å, and a total pore volume of 0.112 cm3/g. The heavy metals Cu, Fe, and Pb exhibited the highest rates of degradation, reaching their maximum percentages after 60 minutes when exposed to ultraviolet radiation under ideal conditions at varying pH levels (pH 6–8). More precisely, the degradation percentage of Cu metal was 95.4% at pH 7, Fe metal achieved 96.1% at pH 6, while Pb metal obtained 95.5% at pH 8. The Cd metal removal percentage was found to be 98.9% under the conditions of a pH of 8 and an irradiation time of 120 minutes, indicating high effectiveness.