Oil palm empty fruit bunches (OPEFB) as one of lignocellulosic biomass, consists of three main components: cellulose, lignin, and hemicelluloses. Cellulose may occur in a crystalline form in addition to amorphous form. Cellulose and hemicelluloses can be converted into fermentable sugar, i.e. glucose and xylose, by chemical or enzymatic hydrolysis. This sugars is usually used as a feedstock for bioethanol production. Lignin and high-crystallinity of cellulose inhibit the performance of enzymatic hydrolysis process. Therefore pretreatment is necessary to remove lignin, decrease the crystallinity and improve the yield of enzymatic hydrolysis. One of the developed pre-treatment processes is soaking with aqueous ammonia solution or called by SAA process. In this study, the advantage of SAA pre-treatment process was investigated using ammonium solution prior to the enzymatic hydrolysis. The pre-treatments were carried out in various ammonium concentrations (5%, 7.5%, and 10%) at mild conditions (25 o C and 1 atm) for 24 hrs, and with or without a following additional diluted-acid pre-treatment (92-98 o C and 1 atm for 1 hour). The pre-treated materials were then enzymatically hydrolyzed by cellulose and β-glycosidase for 96 hrs and anaerobically digested by inoculums microbial. The changes in cellulose crystallinity were analyzed by FTIR Spectroscopy. The OPEFB pre-treated by 10% ammonium solution without a following dilute-acid pre-treatment shows low crystallinity with a crystallinity index (CI) of 0.80 compared to that of the untreated material (2.11). The method could increase the yield of hydrolyzed glucose to 79% compared with that of untreated material (13 g/g glucan added). The results also show increasing the methane production from 0.18 Nm 3 /g volatile solid to 0.35 Nm 3 /g volatile solid via anaerobic digestion.
Design of the Proton Exchange Membrane (PEM) fuel cell system is still developed and improved to achieve performance and efficiency optimal. Improvement of PEM fuel cell performance can be achieved by knowing the effect of system parameters based on thermodynamics on voltage and current density. Many parameters affect the performance of PEM fuel cell, one of which is the relative humidity of the reactants that flow in on the anode and cathode sides. The results of this study show that the increase in relative humidity value on the cathode side (RHC) causes a significant increase in current density value when compared to the increase of relative humidity value on the anode side (RHA). The performance of single cells with high values is found in RHC is from 70% to 90%. The maximum current density generated at RHA is 70% and RHC is 90% with PEM operating temperature of 363 K and pressure of 1 atm
Secara umum konversi lignoselulosa menjadi bioetanol dilakukan dalam 4 (empat) proses, pengolahan awal, sakarifikasi, fermentasi, dan pemurnian (distilasi
A proton Exchange Membrane Fuel Cell (PEMFC) was developed as a potential solution in power supply applications. In this study, the parameter values such as the relative humidity, the temperature, the pressure, the stoichiometric ratio of hydrogen to oxygen and the mass of catalyst used were varied to determine their effects on the single cell performance of PEMFC. The investigation showed that an increase in the temperature from 353 to 363 K resulted in a modest improvement in the single-cell performance. The single cell performance was more affected by an increase in relative humidity at the cathode (RHC) in comparison with an increase in relative humidity at the anode (RHA).The best performance when the cell was operated at relative humidity values were 75% for the RHA and 90% for the RHC, the optimal operating temperature was 353 K, and the amount of Pt catalyst required was 0.2 mg.
A B S T R A K PENDAHULUANAir raksa atau merkuri termasuk salah satu logam berat, dengan berat molekul tinggi (http://www.jombangkab.go.id, 2017). Logam merkuri dilambangkan dengan Hg. Merkuri merupakan salah satu unsur logam transisi dengan golongan IIB dan memiliki nomer atom 80, memiliki bobot atom 200,59 adalah satu-satunya logam yang berbentuk cair. Banyak logam yang larut dalam merkuri membentuk komponen yang disebut amalgam (alloy). Uap merkuri di atmosfer dapat bertahan selama 3 bulan sampai 3 tahun, sedangkan bentuk yang melarut dalam air hanya bertahan beberapa minggu.Merkuri merupakan bahan yang memiliki tingkat toksisitas yang tinggi di bawah arsenik dan timbal (Rompalski, dkk., 2016). Sehingga merkuri menjadi masalah global terkait dengan resiko paparan merkuri pada kesehatan dan lingkungan. Dalam hal ini, badan dunia PBB mengadakan perjanjian yang ditandatangani oleh 128 perwakilan dari 25 pihak pada Minamata Konvensi tentang Merkuri (Nagpal, dkk., 2017). Di lain pihak, keberadaan atau pencemaran merkuri pada lapisan tanah dalam konsentrasi yang tinggi masih dapat ditolerir oleh Taxa dari Chthoniobacteraceae (bakteri) dan Trichosporon sp. (jamur) walaupun dalam jangka waktu yang panjang (Frossard, dkk., 2018). Penelitian lain menunjukan bahwa tanaman Oxalis corniculata merupakan jenis tanaman yang dapat memperbaiki tanah yang tercemar merkuri (Liu, dkk., 2017).
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