A response surface methodology for the use of MIL‐101 as a catalyst for the one‐step synthesis of lactide

Lactide is a vital monomer for producing high molecular weight polylactic acid (PLA) through ring‐opening polymerization. This study synthesized crude lactide from L‐lactic acid with MIL‐101 as the catalyst. MIL‐101 is a metal‐based catalyst with organic ligands (MOF) that was prepared by reacting Cr(NO3)3.9H2O with terephthalic acid (BDC). The formation of MIL‐101 was confirmed from Fourier‐transform infrared (FTIR) analysis. The role of MIL‐101 and the effect of temperature, time, and MIL‐101 loading, as well as their interactions in the conversion of lactic acid to crude lactide, were then investigated using the response surface method (RSM). Crude lactide was analyzed using 1H‐nuclear magnetic resonance (NMR) spectroscopy to confirm the presence of lactide. The RSM results indicated that the highest conversion of 22.84% can be obtained using a temperature of 175 °C, 1.5% w/w MIL‐101 loading, and a reaction time of 5 h. The RSM model showed that the interaction of MIL‐101 loading and reaction time strongly affected the conversion of lactic acid to lactide, with a P‐value of 0.0021 and an F‐value of 50.45. In contrast, the interaction of catalyst loading and temperature did not significantly affect the conversion of lactic acid to lactide, with a P‐value of 0.2565 and an F‐value of 1.75

The Effect of Solvent Hydrophilicity on the Enzymatic Ring-Opening Polymerization of L-Lactide by Candida rugosa Lipase

Contradictions have been reported on the effect of organic solvents, especially toluene, on enzymatic ring-opening polymerization (eROP) of L-lactide. Studies have shown that log P, a common measure of hydrophilicity, affects enzyme activity. This study examines the effect of solvents with various log P values on the eROP of L-lactide, performed using Candida rugosa lipase (CRL). N,N-dimethylacetamide (DMA), 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, diphenyl ether, and dodecane were used as the organic solvents. The eROP in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) was also conducted to compare its performance with the organic solvents. The results show that BMIMPF6-mediated eROP gave better conversion and molecular weight than the organic solvent-mediated eROP. In this study, the effects of solvents hydrophilicity are discussed, including the possibility of hexafluorophosphate ion (PF6−) hydrolysis to occur. © 2022 by the authors

The Effect of Solvent Hydrophilicity on the Enzymatic Ring-Opening Polymerization of L-Lactide by Candida rugosa Lipase

Contradictions have been reported on the effect of organic solvents, especially toluene, on enzymatic ring-opening polymerization (eROP) of L-lactide. Studies have shown that log P, a common measure of hydrophilicity, affects enzyme activity. This study examines the effect of solvents with various log P values on the eROP of L-lactide, performed using Candida rugosa lipase (CRL). N,N-dimethylacetamide (DMA), 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, diphenyl ether, and dodecane were used as the organic solvents. The eROP in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) was also conducted to compare its performance with the organic solvents. The results show that [BMIM][PF6]-mediated eROP gave better conversion and molecular weight than the organic solvent-mediated eROP. In this study, the effects of solvents hydrophilicity are discussed, including the possibility of hexafluorophosphate ion ([PF6]−) hydrolysis to occur

Preliminary membrane screening and evaluation for the separation of bioethanol obtained from fermentation of oil palm empty fruit bunch (OPEFB)

This study evaluates the effectiveness of some commercial membranes (polytetrafluoroethylene [PTFE], polyvinylidene fluoride [PVDF], polyethersulfone [PES], and nitrocellulose [NC]) in concentrating a binary ethanol-water mixture under different conditions (volumes, temperatures, pressures, and concentrations). Then, the membrane was selected based on its performance for use in ethanol and by-product separation from OPEFB fermentation broth. The optimum result for the binary ethanol-water separation was found in the PVDF membrane with the highest separation factor of 3.03 and flux of 0.015 g.cm−2 s−1 under 10 ml permeate volume, 75 °C temperature, 60 psi pressure, and 20 % (v/v) ethanol concentration. Based on the membrane field emission-scanning electron microscope (FE-SEM) analysis, the PVDF membrane also had the lowest swelling degree. Utilization of the PVDF membrane to separate crude bioethanol resulting from OPEFB fermentation gave a separation factor of 3.66. The initial bioethanol concentration was 7.67 % (v/v), and the ethanol concentration in the permeate was 23.31 % (v/v). In addition, the separation factor of propanol from the crude mixture was 5.44, and the acetic acid rejection factor was 96.7 %. The S.cerevisiae suspension and the cellulase enzyme were also separated and recovered in the retentate phase. Hence, the PVDF membrane can be used to separate bioethanol from the yeast and enzyme suspension while pre-concentrating the bioethanol product. This could eventually help reduce the energy requirement to obtain industrial-grade bioethanol

Utilisation of gelatin as nitrogen source for N-doped carbon nanotubes and its performance for the oxygen reduction reaction

Gelatin is utilised as a nitrogen source to synthesise nitrogen (N)-doped carbon nanotubes (CNTs). The N-doped CNT was prepared by mixing gelatin and CNT, followed by calcination at 500 °C and 800 °C under N2 atmosphere. X-ray diffraction analysis shows that the higher gelatin weight ratio results in a decrease of the crystallisation. X-ray photoelectron spectroscopy deconvolution analysis confirms that pyridinic-N and pyrrolic-N have appeared at the surface of the samples. The higher calcination temperature affects the surface properties of N-doped CNT which tend to shift the pyrrolic-N to the pyridinic-N. Cyclic voltammetry analysis reveals that the presences of pyridinic-N and graphitic-N configuration have higher oxygen reduction reaction (ORR) activity compared to the N-pyrrolic structure. © 2022 Vietnam Academy of Science & Technology

Shelf life of indigenous tengkawang butter: Storage kinetic and effect of antioxidant to oxidation stability index

Tengkawang butter is an indigenous and traditional butter from Borneo that can be a lipid source for pharmaceutical and food applications. Studies found that Tengkawang butter is a cheaper cocoa butter substitution without compromising its quality. However, the current storage method is still very traditional, resulting in faster deterioration of Tengkawang butter. This study aims to calculate and evaluate the storage kinetics model with the Arrhenius model and the tengkawang butter oxidation stability index analysis. Storage conditions were carried out at temperatures of −5, 5, 24, and 60 °C to predict the tengkawang butter storage kinetics model. The addition of antioxidants such as ascorbic acid, tocopherol, and lignin to tengkawang butter help increase the oxidation stability index. The kinetics of the tengkawang butter acidity and peroxide models followed a zero-order reaction with activation energy values of 11.139 kJ mol−1 and 12.320 kJ mol−1, respectively. The prediction model for acidity is Acidity = 4.417–7.903t exp (−11,139/RT), and the model for peroxide is peroxide = 2.155–10.998t exp (−12,320/RT). The oxidation stability index values at 22 °C and the rate of oxidation when the temperature rises by ten degrees (Q10) of tengkawang butter, tengkawang butter with ascorbic acid, tengkawang butter with tocopherol, and tengkawang butter with lignin were 66,896 and 2.815; 224,680 and 1.993; 106,120 and 2.725; 81,658 and 2.961, respectively. The kinetic and oxidation stability index model data can be used as a reference for storage and preserving products made from tengkawang butter

Physicochemical and oxidative stability of indigenous traditional tengkawang butter as potential cocoa butter equivalent (CBE)

This study identified the quality, physicochemical properties, and oxidation stability of tengkawang butter (TB) from indigenous plants in various areas of Kalimantan, Indonesia. The fatty acid profile was dominated by palmitic acid, stearic acid, and oleic acid. Acidity ranged from 6.88 to 15.94%, while the peroxide number was 0.41 and 8.27 meq O2/kg. TB had a melting point of 36–37°C. The solid fat content (SFC) varied from 0.03 to 3%. The Oxidation Stability Index (OSI22) was more than 10,000 h. The composition and properties show the potential of TB to become a cocoa butter equivalent (CBE)