Volume 8 Issue 2

Acetic acid (HOAc) was selected as a bio-oil model compound for the steam reforming of bio-oil for hydrogen production. The influence of temperature and steam-to-carbon ratio (S/C) on the steam reforming of HOAc over hydrogen-type Zeolite Socony Mobil-5 (HZSM-5) and the catalyst with added Pd (Pd/HZSM-5) have been investigated in a fixed-bed reactor. Brunauer–Emmett–Teller surface area measurements, scanning electron microscopy, and transmission electron microscopy were performed to characterize the texture and structure of the catalysts. Upon addition of Pd to HZSM-5, the selectivity of the products was modified and the H2 yield was greatly increased. The hydrogen yield and potential hydrogen yield from the steam reforming of HOAc were as high as 60.2% and 87.5%, respectively, under optimized reaction conditions. Both the conversion of HOAc and the H2 yield over Pd/HZSM-5 were significantly enhanced with increasing S/C ratio and reaction temperature below 600 °C, whereas the H2 yield did not significantly increase at temperatures above 600 °C. The mechanism of HOAc decomposition on the Pd(111) surface was calculated via density functional theory. The optimal decomposition route was found to be CH3COOH* → CH3CO* → CH3* + CO*.

Corn cob (CC) was used as a filler in chitosan (CS) biopolymer films. The effect of glutaraldehyde (GLA) as a crosslinking agent was studied in an effort to improve the properties of CS/CC biocomposite films prepared via solvent casting. The tensile strength and elongation at break values decreased, but the modulus of elasticity increased with CC content. However, the tensile properties of CS/CC biocomposite films improved when modified with GLA. The Fourier transform infrared (FTIR) results indicated the presence of imine bonds (C=N) and ethylenic groups due to the cross-linking reaction between CS and GLA. The thermal stability of CS/CC biocomposite films reduced with increasing CC content. The modification of CS/CC with GLA enhanced the thermal stability of the biocomposite films. Moreover, the wettability and adhesion of the CC-CS system were enhanced by modification with GLA, as demonstrated by a morphological study. The crosslinking agent glutaraldehyde positively affected the tensile strength, modulus of elasticity, and thermal stability of the biocomposite films.

A unique approach was used in which polyoxometalate-based ionic liquids (POM-IL) were synthesized and employed for the one-pot dissolution and conversion of biomass. A library of four functional POM-IL compounds was synthesized using two cationic organic groups (1-butyl-3-methylimidazolim and 1-ethyl-3-methylimidazolium) and two anionic POMs (phosphotungstate and tungstosilicate). The POM-IL compound serves a dual-purpose. First, it dissolves approximately 30 wt% of cellulosic biomass in 2 h at 200 °C. Second, analysis using HPLC confirmed that the POM-ILs catalyze conversion of biomass into commodity monosaccharides such as glucose and xylose. All of the prepared POM-IL compounds demonstrated dynamic thermal stabilities exceeding 300 °C and were characterized using IR and thermogravimetric analysis.

The Raffia textilis fiber has a specific strength of 660 MPaŸcm3/g and scales and hollows on its surface. Thus, this fiber is a potential composite reinforcement. The objective of this study was to evaluate the effect of alkaline treatment at room temperature on its microstructure, structure, composition, thermal behavior, mechanical properties, and color. To this end, slack raw fibers were soaked in three NaOH solutions (2.5%, 5%, and 10% by weight) for 12 hours. SEM observations revealed that fibers got more and more clean and smooth when the solution concentration was increased. In comparison with the raw fiber, it was found that fiber treated with 5% NaOH solution exhibited enhanced tensile strength (129%) and strain to failure (175%), in addition to increased yellowness, redness, and thermal stability. Contrariwise, the Young modulus and lightness slightly decreased with the treatment. The Fourier transform infrared spectra and the XRD patterns suggested an incipient allotropic transformation of cellulose for 10% NaOH-treated fibers. These changes could be explained by the gradual dissolution of non-cellulosic components as revealed by the Fourier transform infrared attenuated total reflection spectra and thermal analysis.

Activated carbons (ACs) prepared from apple pulp and apple peel with phosphoric acid as an activation agent under microwave radiation were investigated. The effects of microwave radiation power and time on the adsorption capacities of the ACs were studied. The optimum AC preparation condition was identified by comparing the MB adsorption capacities of the produced ACs. The obtained results show that the microwave radiation power and time had strong effects on the adsorption capacities. Relative to conventional heating methods, microwave-prepared ACs showed higher BET surface areas and mesopore volumes after a shorter activation time due to differences in the type of heat transfer between these two methods. The N2 adsorption isotherms at −196°C and SEM and FTIR results were used to characterize the properties of the prepared ACs. The N2 adsorption results revealed BET surface areas of 1552 m2/g and 1103 m2/g for apple-peel and apple-pulp-based AC, respectively.

The kraft pulps produced from heartwood and sapwood of Eucalyptus globulus at 130 ºC, 150 ºC, and 170 ºC were characterized by wet chemistry (total lignin as sum of Klason and soluble lignin fractions) and pyrolysis (total lignin denoted as py-lignin). The total lignin content obtained with both methods was similar. In the course of delignification, the py-lignin values were higher (by 2 to 5%) compared to Klason values, which is in line with the importance of soluble lignin for total lignin determination. Pyrolysis analysis presents advantages over wet chemical procedures, and it can be applied to wood and pulps to determine lignin contents at different stages of the delignification process. The py-lignin values were used for kinetic modelling of delignification, with very high predictive value and results similar to those of modelling using wet chemical determinations.

Bio-oil and hydrochar were produced through the hydrothermal liquefaction (HTL) of Salix psammophila (SP) branch residues with recycled processing water, in order to address the lack of water in deserts or sandy lands and the difficulty of water treatment in a batch reactor. The results indicated that the recycling of the HTL processing water could significantly improve the yield of bio-oil from 30.3% to 46.9%. The gas chromatography and mass spectrometry analyses of the obtained bio-oil confirmed the presence of value-added chemicals, such as phenolics, acetic acid, and furans. The acetic acid in the processing water played a key role in the HTL. The heavy oil had a high content (maximum of 42.7 wt%) of the low boiling point fraction (<300 °C), indicating its potential for further applications. The higher heating value of the hydrochar was about 27 MJ/kg, equivalent to the heating value of medium-rank and high-rank coals. These results show that HTL using recycled processing water has great potential for utilization of desert biomass wastes.

Empty fruit bunch oil palm (EFBOP) fibres were surface modified by four different methods, propionylation, vinyltrimethoxy silanization, PPgMA dissolution modification, and PPgMA blending, and integrated into a polypropylene (PP) matrix. The designed biocomposites were subjected to an absorption process at different temperatures. Their water uptake behaviour was compared with the unmodified fibre biocomposites. An increased fibre content and temperature resulted in increased water uptake for all of the biocomposites. The biocomposites containing modified fibres showed a reduction in water uptake, rate of diffusion, sorption, and permeation in comparison with unmodified fibre composites. Comparing the 20 wt% fibre composites at ambient temperature, the performance in water absorption followed the sequence silanization < propionylation < PPgMA dissolution modification < PPgMA blending < no modification. Furthermore, the lowest water absorption was obtained from the silanized fibre/PP composite with 40% fibre content at ambient temperature. Dissolution or blending of PPgMA gave similar water uptake results. The reduction of diffusion, sorption, and permeation confirmed that the modification of fibres was potentially effective at resisting water penetration into the composites.

In the conversion process of lignocellulose into fuel ethanol, the enzymatic hydrolyzed or fermented lignocellulosic residues are produced as byproducts. In order to further recycle these byproducts, this study used the enzymatic hydrolyzed residues of sugarcane bagasse (EHR-SCB) as the media for culturing Lentinula edodes. The sugarcane bagasse (SCB), pretreated by liquid hot water (LHW), was hydrolyzed for 120 h with cellulase to obtain the EHR-SCB. The EHR-SCB was mixed with wheat bran and gypsum powder in a certain proportion to make six kinds of media. The media containing 50% and 60% EHR-SCB could cultivate Lentinula edodes, due to their rational ratio of carbon to nitrogen and mineral contents. Compared with Lentinula edodes sold in the market, the one cultured in the medium containing 50% EHR-SCB had a little higher content of amino acids except cysteine and proline, and mineral elements except zinc, while that cultured in the medium containing 60% EHR-SCB had a lower content of amino acids except serine, glutamic acid, glycine, methionine, tyrosine, and arginine, and mineral elements except selenium, copper, chromium, and manganese. After harvesting Lentinula edodes, the mushroom residues might be further used as media for obtaining value-added products or composting for manure.

Trace elements, at tolerable concentrations, are either part of the active site or act as an activity modulator of ligninolytic enzymes of white-rot mushrooms. They are usually in plant raw materials in a non-toxic amount or non-available and extractable forms. This study evaluated the effects of Fe, Zn, and Se on the activity of laccase and Mn-oxidizing peroxidases of P. ostreatus and P. pulmonarius during solid-state fermentation of grapevine sawdust. The studied species showed different levels of tolerance to the trace elements. A stimulatory effect of the microelements on laccase activity was demonstrated in P. ostreatus, while Fe and Zn were strong inhibitors of the activity of P. pulmonarius, which was contrary to Se, independent of the cultivation period. With the exception of SeO2, activity of Mn-oxidizing peroxidases in P. ostreatus was suppressed in various levels by the elements. However, in P. pulmonarius, activity against phenol red oxidation in the presence of external Mn2+ was stimulated by the elements on day 7, while on day 10, activity inhibition by Fe and Zn and stimulation by Se was noted. The effect on activity against phenol red oxidation in the absence of external Mn2+ was the opposite.