An experiment on Fenton degradation of sugarcane vinasse was carried out to determine its effect on the wastewater characteristics. Vinasse, a by-product of distillation in the bioethanol industry, contains high organic matter, as the value of chemical oxygen demand (COD) is >100,000 mg/L and BOD₅ is 31,250 mg/L. The Fenton reaction is one of the advanced oxidation process (AOP) methods which has been widely applied for the treatment of wastewater containing organic pollutants and contaminants. This method utilizes hydroxyl radical (^•OH) produced from the catalyzing reaction between Fe²⁺ or Fe³⁺ and hydrogen peroxide. The effect of pH, the ratio of [H₂O₂] and [COD], and the ratio of [H₂O₂] to [Fe³⁺] were studied in this research to evaluate the Fenton reaction. Results from this experiment showed that treatment of vinasse using the Fenton reaction decreased the COD value to 48.10%, and its biodegradability enhanced almost two times at a pH value of 3.8, a ratio of [H₂O₂] to [COD] of 0.62, and a ratio of [H₂O₂] to [Fe³⁺] of 50 (g/g), which demonstrated that the Fenton treatment was effective to reduce organic matter of sugarcane vinasse. Three kinetic models (first order, second order, and Behnajad–Modirshahla–Ghanbery (BMG) kinetic model) were used to evaluate the degradation of the COD value. On the basis of the value of R² (coefficient of determination), we suggested that BMG represented the best kinetic model. This study finds that the Fenton treatment is able to mitigate the environmental impacts of sugarcane vinasse.

The distillery spent wash (DSW) from bioethanol industries has a very high chemical oxygen demand (COD). Hence, the goal of this study is to investigate the effect of currents (2.5, 3 and 3.5 A) and initial pHs (4.4, 5.0 and 7.0) on electrocoagulation (EC) to decrease the COD in DSW. The results showed that the EC at the current of 3.5 A enabled a higher COD removal efficiency (74.9%) than those at the currents of 2.5 (35.4%) and 3 A (60.9%). Furthermore, the initial pH of 7.0 resulted in a higher COD removal efficiency than the initial pHs of 4.4 and 5.0. The solution pH and temperature increased throughout the process. The working volume was not constant due to the reactions of water reduction, evaporation and flotation. Scum and sludge productions were also monitored during the process. Then, the measured data (COD, sludge and scum) were used in the modeling. The simple mechanistic models were successfully built and applied to simulate the data in mass units with two different routes of process. Route 1 assumed that the COD was converted to sludge and then the latter was converted to scum. Route 2 assumed that the COD was converted to the sludge and scum at the same time. When the EC was operated at the initial pH of 4.4, the COD removal process followed route 1, but that at the initial pHs of 5.0 and 7.0, the COD removal process followed route 2. The higher the current applied in the EC, the higher the kinetic constants of $k_a$ and $k_b$. Additionally, the higher the initial pH set, the higher the kinetic constants were. This showed that the formation rates of sludge and scum at the higher currents or initial pHs were faster than those at the lower values.

Beef bones contain a gelatin component that can be further extracted. This extraction process requires the right solvent to produce good yield and quality. Gelatin has multifunctional properties, namely biodegradable, biocompatible and non-toxic. This is because it is a natural ingredient that contains high amino acids. The most dominant amino acid content as a parameter for determining the quality of gelatin is proline, glycine, and hydroxyproline. The purpose of this study was to study the effect of the solvent used as a medium for soaking cow bones to be converted into gelatin. The solvent variations used include NaOH, HCl, H₂SO₄, CH₃COOH, and NaHCO₂. The concentration variations are 4, 5, 6, 7, 8 (%). This research method includes the preparation of cow bone samples, fat removal, mineral removal, soaking for 7 days, and extraction. The extraction process was carried out with variations times of 4 h and 6 h. The results of the study showed that the highest yield value was with 5% HCl solvent with 4 h extraction time of 26.5% with 8.67% water content, 0.9% ash content, pH 4.64, and viscosity 3.19 cP (p < 0.05). A good isoelectric point is produced when using an acidic solvent, which is between 5.3–5.8. The cross-linking of gelatin with chitosan, glutaraldehyde, and glucose was successfully carried out with the FTIR absorption indicator at a wavelength of 3200 cm⁻¹, which indicates the presence of hydrogen bonds, 1022 cm⁻¹, which indicates the breakdown of aldehyde bonds in glutaraldehyde compounds into C-O bonds. According to the microbial test, when gelatin is combined with chitosan, there will be an increase in the microbial inhibition zone. This shows that the development of gelatin materials is very prospective and promising.

The synthesis of hybrid fiber based on bovine bone gelatin combined with polyvinyl alcohol-chitosan-oxidized sucrose (PVACOS) has been successfully carried out using the coaxial electrospinning technique. The presence of oxidized sucrose can improve the diameter and the tensile strength of hybrid fibers due to the formation of new covalent bonds. The combination of gelatin with PVACOS material aims to increase the strength of the hybrid fiber so that it has better tensile strength characteristics and improves the diameter of the resulting hybrid fiber. The characterization of the resulting material was tested using FTIR, SEM, EDX, XRD, and TGA. Based on FTIR analysis, there is an increase in absorption intensity in the 2900 cm-1 – 3000 cm-1 band, which indicates the occurrence of covalent bond interactions so that it can increase the bond strength between materials with the performance of crystalline materials. Apart from that, the morphological structure of the hybrid fibers was also investigated using scanning electron microscopy (SEM), and the resulting fiber diameter for Ge-Ch, Ge-Ch-PVA, Ge-PVACOS 3%, and Ge-PVACOS 5%, respectively, was 0.4049 µm. 0.3735 µm, 0.3388 µm, and 0.3206 µm. The tensile strengths of hybrid fiber for Ge-PVACOS 3% and Ge-PVACOS 5%, respectively, are 39.91935 N/m2 and 76.12507 N/m2. Statistical tests show that the concentration of oxidized sucrose has a significant influence on hybrid fiber performance. The significance values for diameter and tensile strength are 0.0486 and 0.0325, respectively. According to this performance, the Ge-PVACOS hybrid fiber is recommended as a material for advanced medical textiles. Doi: 10.28991/ESJ-2024-08-02-022 Full Text: PDF

Textile industries produce a complex wastewater which is difficult to be treated. In this work, a catalytic degradation of wastewater effluent composed of sulphur black coloring agent discharged by industry was studied. UV lamp power, peroxide concentration, pH, and iron oxide catalyst were varied to determine the best conditions for oxidative treatment. Kinetic parameters were evaluated based on the reaction model proposed. In the absence of iron oxide catalyst, chemical oxygen demand (COD) and biological oxygen demand (BOD) degradation of up to 80% and 75%, respectively, were observed as resulting from using an H₂O₂ concentration of 0.61 moles/L, UV lamp power of 30 watts, and pH of 6. When using an iron oxide catalyst combined with UV light irradiation, the degradation rate could be increased significantly, while similar final COD and BOD degradation percentages resulted. It is found that the reaction rate order was shifted from first order to second order when using an H₂O₂/UV/Fe₂O₃ system. The results could be an alternative for treating textile industry wastewater, and the parameters obtained can be used for equipment scale-up.