Improving Biomethane Production and Mass Bioconversion of Corn Stover Anaerobic Digestion by Adding NaOH Pretreatment and Trace Elements

This research applied sodium hydroxide (NaOH) pretreatment and trace elements to improve biomethane production when using corn stover for anaerobic digestion. Full-factor experimental tests identified the best combination of trace elements with the NaOH pretreatment, indicating that the best combination was with 1.0, 0.4, and 0.4 mg⋅L −1 ⋅d −1 of elements Fe, Co, and Ni, respectively. The cumulative biomethane production adding NaOH pretreatment and trace elements was 11,367 mL; total solid bioconversion rate was 55.7%, which was 41.8%-62.2% higher than with NaOH-pretreatment alone and 22.2%-56.3% higher than with untreated corn stover. The best combination was obtained 5-9 days shorter than T 90 and maintained good system operation stability. Only a fraction of the trace elements in the best combination was present in the resulting solution; more than 85% of the total amounts added were transferred into the solid fraction. Adding 0.897 g of Fe, 0.389 g of Co, and 0.349 g of Ni satisfied anaerobic digestion needs and enhanced biological activity at the beginning of the operation. The results showed that NaOH pretreatment and adding trace elements improve corn stover biodegradability and enhance biomethane production

The Effect of Microwave-NaOH Pretreatment and Hydrolysis Enzyme Using Trichoderma reesei-Aspergillus niger on Rice Straw Bioethanol Production

The process of bioethanol production from rice straw consists of two steps: (1) conversion of cellulose into simple sugars which is conducted by using microwave-NaOH pretreatment and straw hydrolysis using mold catalyst T.reesei and A. niger; and (2) fermentation of simple sugars into ethanol. In a microwave-NaOH pretreatment process has been obtained the best value content of cellulose in straw size of 100 mesh and a long exposure of 40 minutes for 72.70+1:10%. Crude cellulase enzyme activity of T.reesei isolation, A.niger and it mixtures were optimum at temperature of 50°C. The addition of crude enzyme from A.niger and T.reesei on a comparison of 1: 2 (v/v) was able to increase the yield of the rice straw cellulose hydrolysis which is produces sugar at 12.89 mg/ml (1.29% w/v) or 0.15% (w/v) when converted into ethanol. The glucose yield from rice straw was 25.47% with 3% ethanol

Comparison of a solvent mixture assisted dilute acid and alkali pretreatment in sugar production from hybrid Pennisetum

Abstract(#br)The effects of an acetone-butanol-ethanol (ABE) mixture on dilute H 2 SO 4 and NaOH pretreatment for enzymatic saccharification of hybrid Pennisetum (HP) were investigated. The results showed that ABE assisted the removal of xylan and lignin during H 2 SO 4 and NaOH pretreatment, respectively. The glucose yield of HP increased from 33.6% to 52.9% with the assistance of a relatively higher concentration of ABE mixture (ABE4) during H 2 SO 4 pretreatment, and during NaOH pretreatment, a lower concentration of ABE (ABE2) increased the glucose yield from 64.6% to 80.2%. The hydrolysis yield increases were related to the compositional change and surface characteristics of the pretreated materials. As observed by X-ray photoelectron spectroscopy, ABE4 resulted in a greater lignin content on the surface of materials than that produced by ABE2 during NaOH pretreatment, which possibly increased the non-productive adsorption of cellulase, thus decreasing the hydrolysis yield. The results suggested that an ABE mixture could be used as an auxiliary agent for further increasing of the digestibility of acid- and alkali-pretreated lignocellulosic materials. However, the digestibility was different depending on the concentrations of ABE during acid and alkali pretreatments

Comparative evaluation of different pretreatment methods on biogas production from paddy straw

The present investigations observed the effect of chemical, enzymatic, biological and micro-wave pretreatment on paddy straw for enhancement of biogas production. Chopped and soaked paddy straw was subjected to chemicals Na2CO3 (1%) and NaOH (2%) concentrations, microwave irradiation (720 watt, 30 min), fungal (spawn impregnated, 7 days) and crude silicase (24 hrs) pretreatment. The proximate and chemical analysis showed 16.0% and 12.1% reduction in lignin and silica content in the case of Na2CO3 pretreated paddy straw whereas 23.0% and 46.8% reduction was observed in enzymatic pretreatment with 43.7% and 31.1% enhancement in biogas production respectively. This clearly indi-cates that Pleurotus ostreatus MTCC 142 is silicolytic as well as ligninolytic in nature. Enzymatic pre-treatment was also compared with, microwave (30 min) and fungal pretreatment which showed 31.2% and 32.8% reduction in silica content enhancing biogas production by 19.7% and 42.6% respectively. NaOH pretreatment showed a maximum increase in biogas production i.e. 49.7% as compared to 1% pretreated sample which showed 28.5% enhancement. The results indicated that the NaOH pretreatment was one of the potential methods to increase biogas production of paddy straw

Sodium hydroxide pretreatment as an effective approach to reduce the dye/holes recombination reaction in P-Type DSCs

We report the synthesis of a novel squaraine dye (VG21-C12) and investigate its behavior as p-type sensitizer for p-type Dye-Sensitized Solar Cells. The results are compared with O4-C12, a well-known sensitizer for p-DSC, and sodium hydroxide pretreatment is described as an effective approach to reduce the dye/holes recombination. Various variable investigation such as dipping time, dye loading, photocurrent, and resulting cell efficiency are also reported. Electrochemical impedance spectroscopy (EIS) was utilized for investigating charge transport properties of the different photoelectrodes and the recombination phenomena that occur at the (un)modified electrode/electrolyte interface

Influence of Different Pretreatments on the Structure and Hydrolysis Behavior of Bamboo: A Comparative Study

Article 2570201

Chemical Kinetics of Alkaline Pretreatment of Napier Grass (Pennisetum purpureum) Prior Enzymatic Hydrolysis

Background: Napier grass is a naturally abundant waste material that can be cultivated over a vast area of land which makes it a viable source for sugar and bioethanol production. Introduction: The presence of lignin in the biomass makes cellulose inaccessible for conversion to useful products, however, in order to provide for efficient utilization of the waste material, reagent and energy, a study on the kinetics of lignin removal from Napier grass was carried out in this work using 1 and 3 w/w % NaOH at temperatures between 80 and 120°C. Materials & Methods: Based on the investigation, there was increased lignin removal for increased NaOH concentration. Kinetic parameters were also determined and it was observed that, the reaction of lignin in Napier grass with NaOH obeys a pseudo-zero or pseudo-fractional order kinetics. Furthermore, the orders of the reaction for the pretreatment conditions of 3 w/w% NaOH at 100°C and those of 3 and 1 w/w NaOH at 120°C gave close reaction orders of 0.2, 0.22 and 0.24 respectively after 110 minutes, which implies that, for the three cases, the residual lignin in the extract was almost the same at the pretreatment conditions while slight differences are evident in their pseudo rate constants. Also, it was observed that, the activation energy of the reaction reduced significantly as the concentration of NaOH increased from 1w/w - 3 w/w%. Conclusion: Based on the AIL and the total lignin (i.e. AIL + ASL) in the Napier grass, the recorded delignification efficiencies at the optimum pretreatment time of 17.5 h are 90 and 76% respectively. In addition, the adopted Differential Technique (DT) combined with the Ostwald Method of Isolation (OMI) can be accurately used to study the kinetics of lignin removal from Napier grass

Pretreatment of Oil Palm Empty Fruit Fiber (OPEFB) with Aquaeous Ammonia for High Production of Sugar

AbstractCorncob Oil Palm Empty Fruit Bunch (OPEFB) is an agricultural residue that has the potential to become a good source for renewable feedstock for production of sugar. This work evaluated the effectiveness of aqueous ammonia as pretreatment at low (soaking, SAA) and elevated temperature (Pressurized Chamber) to deconstruct the lignocellulosic feedstock, prior to enzymatic hydrolysis. The ammonia pretreatments were compared against the standard NaOH method. The best tested Pressurized Chamber method conditions were at 100°C with 3 hour retention time, 12.5% Ammonium hydroxide and 1:30 solid loading. The digestibility of the feedstock is determined with enzymatic hydrolysis using Cellic Ctech2 and Cellic Htech2. The sugars produced by Pressurized Chamber method within 24 hour of enzyme hydrolysis are similar to that produced by NaOH method which is 439.90mg/ml and 351.61mg/ml, respectively. Compared with optimum SAA method (24 hour, 6.25% of ammonium hydroxide at room temperature), Pressurized Chamber method was capable of producing enhanced delignification and higher production of sugar upon hydrolysis. These findings were supported by the disappearance peak at 1732, 1512 and 1243 on Fourier Transform Infrared (FTIR spectrum) of treated OPEFB by Pressurized Chamber method. XRD determination showed reduced crystallinity of OPEFB (37.23%) after treatment by Pressurized Chamber, suggesting higher accessibility toward enzyme hydrolysis. The data obtained suggest that the Pressurized Chamber pre-treatment method are suitable for OPEFB deconstruction to produce high yield of sugar

Comparison of delignified coconuts waste and cactus for fuel-ethanol production by the simultaneous and semi-simultaneous saccharification and fermentation strategies

It is of the highest importance to study different alternatives/strategies as simultaneous (SSF) and semi-simultaneous (SSSF) saccharification and fermentation process, as well as the prospects of the utilization of lignocellulosic residues as raw materials for fuel-ethanol production. In the first part of this work, different raw materials (cactus (CAC), green coconut shell (GCS), mature coconut fibre (MCF) and mature coconut shell (MCS)) were pretreated by sequential alkaline hydrogen peroxide (Alk-H2O2)–sodium hydroxide (NaOH) process. The characterization of the obtained solids by FTIR, SEM, X-ray and crystallinity indexes confirmed the higher susceptibility of these pretreated materials to enzymatic action. These results were further confirmed by the corresponding glucose conversion yields – 68.44%, 70.20%, 76.21% and 74.50% for CAC, GCS, MCF and MCS, respectively. Subsequently, the comparison between SSF and SSSF using Saccharomyces cerevisiae, Pichia stipitis, Zymomonas mobilis and pretreated MCF (selected in the enzymatic hydrolysis step) was done, being shown that a short presaccharification step at 50 °C for 8 h in the SSSF had a positive effect on the overall ethanol yield, with an increase from 79.27–84.64% to 85.04–89.15%. In all the cases, the SSSF strategy allowed the obtention of higher ethanol concentrations than SSF.The authors gratefully acknowledge the Brazilian research funding agencies CNPq and CAPES for financial support

Evaluation of High Solids Alkaline Pretreatment of Rice Straw

Fresh-harvested, air-dried rice straw was pretreated at a water content of 5 g H2O/g straw using sodium hydroxide (NaOH) and compared to pretreatment at 10 g H2O/g straw by hydrated lime (Ca(OH)2). Full factorial experiments including parallel wash-only treatments were completed with both sources of alkali. The experiments were designed to measure the effects of alkaline loading and pretreatment time on delignification and sugar yield upon enzymatic hydrolysis. Reaction temperature was held constant at 95°C for lime pretreatment and 55°C for NaOH pretreatment. The range of delignification was 13.1% to 27.0% for lime pretreatments and was 8.6% to 23.1% for NaOH pretreatments. Both alkaline loading and reaction time had significant positive effects (p < 0.001) on delignification under the design conditions, but only alkaline loading had a significant positive effect on enzymatic hydrolysis. Treatment at higher temperature also improved delignification; delignification with water alone ranged from 9.9% to 14.5% for pretreatment at 95°C, but there was little effect observed at 55°C. Post-pretreatment washing of biomass was not necessary for subsequent enzymatic hydrolysis. Maximum glucose yields were 176.3 mg/g dried biomass (48.5% conversion efficiency of total glucose) in lime-pretreated and unwashed biomass and were 142.3 mg/g dried biomass (39.2% conversion efficiency of total glucose) in NaOH-pretreated and unwashed biomass