This study aims to investigate the adsorption of methylene blue (MB) over particulate durian peel waste, which is chemically-activated with hydrogen peroxide. The equilibrium data is well-described by the Freundlich isotherm model, which outlines where the MB adsorption takes place predominantly on multilayers and heterogeneous surfaces of the biosorbent. The Freundlich adsorption constants, KF and n, are 11.06 L/g and 2.94, respectively. Thermodynamic data suggests that the MB adsorption occurs spontaneously and exothermically. The enthalpy and entropy for the MB adsorption are obtained as 10.26 kJ/mol and 0.058 kJ/mol K, respectively, in the temperature range of 303–323 K. Based on the stepwise desorption method, the adsorption of MB is dominated by physical interactions, particularly hydrogen bonding.

In this study, the optimization of microwave-assisted alkaline (MAA) pretreatment is performed to attain the optimal operating parameters for the delignification of cocoa pod husk (CPH). The MAA performance was examined by heating the CPH solid with different particle sizes (60–120 mesh) and NaOH solution with a different sample to a solvent (SS) ratio (0.02–0.05 g/L), for short irradiation time (1–4 min). Box-Behnken Design (BBD) was utilized to optimize the percentage of lignocellulose composition changes. The results show that by enlarging particle size, the content of lignin and cellulose decreased while hemicellulose increased. By prolong irradiation time, the content of lignin and hemicellulose decreased while cellulose elevated. On the other hand, increasing the SS ratio was not significant for hemicellulose content changes. From FTIR and SEM characterization, the MAA drove the removal of lignin and hemicellulose of CPH and increased cellulose slightly. Supported by kinetic study which conducted in this work, it was exhibited that MAA pretreatment technology is an effective delignification method of CPH which can tackle the bottleneck of its commercial biofuel production. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA   License (https://creativecommons.org/licenses/by-sa/4.0).

<p><strong><em>Abstract: </em></strong><em>Pineapple skin is an agricultural waste that has a carbohydrate content of about 10:54% and the skin of pineapple juice glucose levels by 17% so it can be utilized to ethanol. Hydrolysis reaction is so slow that the reaction requires a catalyst. The catalyst used in this study were hydrochloric acid (HCl). This study aims to Learn how to use the skin of pineapple waste as alternative raw material manufacture bioethanol. The variables studied were the concentration of hydrochloric acid, the hydrolysis and fermentation time. Sorghum starch hydrolysis process using a three neck flask equipment, mercury stirrer, heating mantle, cooling behind and a thermometer to measure temperature. Sampling for glucose analysis performed when the temperature reaches 100^oC every 45 minutes to obtain optimum glucose levels. Glucose samples were analyzed by using the Lane-Eynon. Data analysis showed the longer the higher the hydrolysis of the resulting glucose levels, but there are times when the glucose level will drop over time for glucose resulting damage due to continuous heating. In the fermentation process is carried out with fermentation time of 24 hours, 48 hours, 72 hours, 96 hours, 120 hours fiber. The most optimum bacterial activity is a long fermentation for 96 hours. Distillation process carried out on the final results of ethanol fermentation and obtained the highest levels of 31.399%.</em></p><p><strong><em> </em></strong><strong><em>Keywords</em></strong><em> : Pineapple skin, hydrolysis, fermentation, distillation, ethanol.</em></p><p> </p>

<p>Abstract: Pineapple skin is an agricultural waste that has a carbohydrate content of about<br />10:54% and the skin of pineapple juice glucose levels by 17% so it can be utilized to ethanol.<br />Hydrolysis reaction is so slow that the reaction requires a catalyst. The catalyst used in this<br />study were hydrochloric acid (HCl). This study aims to Learn how to use the skin of pineapple<br />waste as alternative raw material manufacture bioethanol. The variables studied were the<br />concentration of hydrochloric acid, the hydrolysis and fermentation time. Sorghum starch<br />hydrolysis process using a three neck flask equipment, mercury stirrer, heating mantle, cooling<br />behind and a thermometer to measure temperature. Sampling for glucose analysis performed<br />when the temperature reaches 100 ºC every 45 minutes to obtain optimum glucose levels.<br />Glucose samples were analyzed by using the Lane-Eynon. Data analysis showed the longer the<br />higher the hydrolysis of the resulting glucose levels, but there are times when the glucose level<br />will drop over time for glucose resulting damage due to continuous heating. In the fermentation<br />process is carried out with fermentation time of 24 hours, 48jam, 72 hours, 96 hours, 120 hours<br />fiber. The most optimum bacterial activity is a long fermentation for 96 hours. Distillation process<br />carried out on the final results of ethanol fermentation and obtained the highest levels of<br />31.399%.<br />keyword : Pineapple skin, hydrolysis, fermentation, distillation, ethanol.</p>

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Biobutanol is well-known as a suitable substitute for gasoline which can be applied without enginemodification. Butanol toxicity to the producer strain causes difficulties to grow strain with more than 4 g/L dry cellweight and to produce butanol more than 20 g/L. Fermentation with high initial cell density was reported to enhancebutanol productivity. In addition, oleyl alcohol has been recognized to perform effective extraction for butanol because ofits selectivity and biocompatibility so that reducing toxicity effect. Butanol fermentation with high cell density and largeextractant volume has not been reported and is expected to improve butanol production in minimum medium volume.Clostridium saccharoperbutylacetonicum N1-4, C. beijerinckii NCIMB 8052 (8052), and C. acetobutylicum ATCC 824(824) were used in this study. Three kinds of media, TYA, TY, and TY-CaCO3, were used to investigate in conventionalextractive fermentation. Then, in situ extractive fermentations with Ve/Vb ratios at 0.1, 0.5, 1.0, and 10 were operated.Total butanol concentration was defined as the broth based total butanol, that is total amounts of butanol produced inbroth and extractant per the volume of broth. TYA medium resulted the highest total butanol concentrations by N1-4 (12g/L), 8052 (11 g/L), and 824 (15 g/L) and the highest partition coefficient (3.7) among the three media with Ve/Vb ratiosat 0.5. N1-4 yielded the highest increment of total butanol production (22 g/L) in the extractive fermentation with highcell density. Low butanol concentration of 0.8 g/L butanol in broth was maintained with the extractant to broth volumeratio (Ve/Vb), which was much lower than 4.4 g/L with the ratio of 0.5. Ve/Vb ratio of 10 provided 2-fold higher totalbutanol concentration (28 g/L) than that 11 g/L obtained with Ve/Vb ratio of 0.5. These results indicated that largervolume of extractant to broth improved total butanol concentration by reducing butanol toxicity and led to high mediumbasedbutanol yield in fermentation using high cell density.