Ethanol Dehydration by Adsorption with Starchy and Cellulosic Materials

Abstract

Adsorption with starchy and cellulosic materials was evaluated as an energy efficient technology for ethanol dehydration. Corn (Zea mays), upright elephant ear (Alocasia macrorrhiza), cassava (Manihot esculenta), and sugar cane bagasse (Saccharum), were used as sources of starch and cellulosic fibers and further used as adsorbents for water removal. Enzymes (α-amylase and cellulase for starch and cellulose, respectively) were evaluated as modifying agents with the aim of increasing water adsorption capacity. Native and enzyme-treated materials were examined with SEM, XRD, and BET analysis to determine the hydrolysis influence on structure and superficial area. Partial hydrolysis was obtained under operation conditions evaluated, as was shown by the SEM micrographs. Crystallinity increased with the enzymatic hydrolysis for all materials. For all materials, superficial area was not increased with enzymatic hydrolysis but water adsorption capacity was improved reaching an anhydrous product with enzyme-treated materials. Water adsorption capacity ranges from 4 to 19 g/ 100 g adsorbent were found for evaluated materials. Corn starch had the highest water adsorption capacity (19 g/ 100 g ads) while upright elephant ear starch presented the lowest (4.2 g/ 100 g ads). Tested materials showed affinity with water for both native and enzyme-treated cases. This allowed water to adsorb from the feed for obtaining anhydrous ethanol. It was suggested that water adsorption capacity was increased because of the more exposed hydroxyl groups from the polymeric structures evaluated (starch and cellulose). Applicability of these materials was oriented to small scale ethanol production plants in developing countries where rural areas are the objective and small productions are expected.

Ethanol Dehydration in a Pressure Swing Adsorption Process Using Canola Meal

“…There are a number of adsorbents that can be employed to dry ethanol: zeolite (Jeong et al, 2009;Simo et al, 2009), silica gel, activated alumina, cassava (Boonfung and Rattanaphanee 2010;Liu et al, 2010;Quintero and Cardona 2009), cornmeal (Chang et al, 2006b;Hu and Xie 2001;Vareli et al, 1998), wood chips (Boonfung and Rattanaphanee 2010;Benson and George 2005), potato starch (Hu and Xie 2001), natural corncobs, natural and activated palm stone, oak (Al-Asheh et al, 2004). Among these adsorbents, 3A zeolite and corn grit are currently used in ethanol plants to dry ethanol (Kim et al, 2011;Simo et al, 2009).…”

“…Bio-adsorbents adsorb water due to the polar attraction between water molecules and the polar groups (such as hydroxyl and carboxyl) in the biomaterials (Quintero and Cardona 2009). Sun et al, (2007) used different adsorbents to study water and ethanol adsorption in liquid phase.…”

“…In addition, the adsorption on bioadsorbents was explained by the polar attraction between their polar groups (hydroxyl, carboxyl, and protein) and water or ethanol molecules. Since the polarity of water is higher than ethanol, water molecules are selectively adsorbed by bio-adsorbents (Quintero and Cardona 2009). This indicates that bio-adsorbents have a potential for industrial application in ethanol dehydration.…”

“…Bio-adsorbents that have been extensively studied for ethanol dehydration purposes, include cassava (Boonfung and Rattanaphanee 2010;Liu et al, 2010;Quintero and Cardona 2009), cornmeal (Chang et al, 2006b;Hu and Xie 2001;Vareli et al, 1998), wood chips (Boonfung and Rattanaphanee 2010;Benson and George 2005) natural corncobs, natural and activated palm stone and oak (Al-Asheh et al, 2004). However, other bio-based adsorbent such as canola meal have not been systematically investigated for this purpose.…”

Kinetics Modeling of The Column Adsorption for The Dehydration of Ethanol-Water Mixtures using Biomass Adsorbents

“…Figure 18 broad Figure 19 which is the X -RD patterns for the adsorbents. The strong X -ray diffractogram patterns of the corn starch noticed are; 14 [25,26] which indicated a typical A type diffraction pattern. The amorphous zone present in the diffractograms is mainly due to amylopectin as reported in the works of Ahmad et al [26].…”