Volume 12 Issue 1

A non-destructive method for measurement of the modulus of elasticity (MOE) was compared with the static method on beams of Cupressus lusitanica and Populus x canadensis. The dynamic method is based on the principle of the resonance frequency, using longitudinal vibrations (Timber Grader MTG, accelerometer) and the static method for measurement of the flexural modulus of elasticity is according to EN 408 (2012). The differences between the ascertained dynamic and static MOE values were 1.1% to 2.4% for the Populus x canadensis sample and 12.7% to 15.5% for the Cupressus lusitanica sample. Furthermore, the correlation dependence of the applied methods was determined and the regression equations are shown. Experimental measurement showed the effect of the knot clusters, which appeared primarily in Cupressus lusitanica samples and considerably impacted the resultant values.

Acetylation of cellulose fiber extracted by methylbenzene/ethanol (2/1), sodium chlorite solution, and sodium hydroxide from raw wheat straw (RWS) was studied to examine its potential as an oil-spill adsorbent. Wheat straw cellulosic sorbent was produced by using acetic anhydride as an acetylating reagent and N-bromosuccinimide (NBS) as a catalyst. Effects of the volume ratio of acetic anhydride (from 6.25% to 57.5%), catalyst concentration (from 10 to 60 mM NBS), reaction temperature (from 50 to 120 °C), and reaction time (from 0.5 to 3 h) on oil-sorption properties were evaluated. The best oil absorbencies for diesel fuel, diesel oil slick, corn oil, and corn oil slick treatments were 24.21 ± 0.76, 22.39 ± 0.77, 25.61 ± 2.13, and 24.73 ± 1.19 g/g, respectively. Chemical composition and morphologic structure of RWS before and after acetylation were investigated and compared. Oil-absorption capacity, oil-retention ability, recyclability, and selectivity of RWS, pretreated wheat straw, and acetylated wheat straw were also discussed. The acetylated wheat straw demonstrated good potential for the utilization of agricultural residues as natural sorbents in oil cleanup.

The hydrolysis of cellulose using carbonaceous solid acid (CSA) in an ionic liquid was studied. The types and concentrations of products generated during the hydrolysis of the cellulose under different conditions, including temperature, reaction time, water addition, and recycle time, were investigated. The CSA prepared in the study contained 1.45 mmol/g of acidic groups, which was higher than the theoretical amount of sulfonic groups. The highest yields of total reducing sugars (TRS) and glucose were obtained at 5% water content, 6 h of reaction time, and 140 °C. The cellulose was hydrolyzed effectively via catalysis of CSA in [AMIM][Cl] with a low water content. Analysis of the products under different conditions in this work provides a strong basis for the full use of hydrolyzed cellulose.

A comparative study of single-stage fermentation (wet or dry) and two-stage (wet-dry and dry-wet) fermentation systems was carried out under medium temperature conditions. The effect of the length of the first wet or dry fermentation stage (5-, 10-, 15-, 20-, and 25-d) in the two-stage anaerobic fermentation was investigated. The results showed that the gas production of wet fermentation and two-stage wet-dry fermentation was better than that of the dry fermentation and two-stage dry-wet fermentation. The cumulative gas production increased gradually with increased stage conversion times for the two-stage wet-dry fermentation. The gas production for the 20-d experimental group of the two-stage wet-dry fermentation system was the best. The cumulative biogas production in the anaerobic fermentation of straw correlated significantly with the changes in the degradation rates of volatile solids, cellulose, and hemicellulose (P < 0.01). The kinetic fitting analysis showed that the Reaction Curve (RC) model was more suitable for data modeling of the single-stage wet fermentation and two-stage wet-dry fermentation with straw than the Modified Gompertz (GM) and Modified Logistic (LM) models. The results of this study provided a theoretical basis for choosing a fermentation process for large-scale biogas production with straw.

Cotton is a natural fiber that takes up carbon dioxide from the environment when grown; however, it requires various resources to be cultivated in a financially viable way. Resources such as fertilizer, pesticides, herbicides, and irrigation water can create environmental impacts as well as present significant costs to the grower. Understanding the efficacy of technologies and grower practices is an important aspect of developing best practices and guiding future research. To better understand the grower needs, practices, and resource use efficiency, a survey was conducted in 2015 with 925 U.S. cotton grower respondents. This survey gathered data on field performance, pest pressures, growing practices, and other parameters that were used to examine the resources used per pound of cotton lint as well as estimate the greenhouse gas emissions and energy use from cotton cultivation. In general, growers who used various precision agricultural technologies reported higher performing fields with higher resource use efficiencies than non-precision technology adopters.