Chemical Composition of Apricot Pit Shells and Effect of Hot-Water Extraction

Abstract

Abstract:Agricultural residues, such as corn stover, wheat straw, and nut shells show promise as feedstocks for lignocellulosic biorefinery due to their relatively high polysaccharide content and low or no nutritional value for human consumption. Apricot pit shells (APS) were studied in this work to assess their potential for use in a biorefinery. Hot water extraction (HWE; 160 °C, 2 h), proposed to remove easily accessible hemicelluloses, was performed to evaluate the susceptibility of APS to this mild pretreatment process. The chemical composition of APS before and after HWE (EAPS) was analyzed by standard methods and 1 H-NMR. A low yield of the remaining HW-extracted APS (~59%) indicated that APS are highly susceptible to this pretreatment method. activity (AOA) of APS extracts was also undertaken. AOA of organic APS extracts were shown to be more than 20 times higher than that of a synthetic antioxidizing agent.

Toward Complete Utilization of Miscanthus in a Hot-Water Extraction-Based Biorefinery

“…There is a reduction in absorption at this wavelength for EMS, which is in agreement with a noticed removal of Seifert cellulose of~6.4% across all extraction scales (Table 2), originating most probably from amorphous regions of cellulose. Similar results after hot water extraction have been observed previously [53,55]. A decrease in absorption bands at 1728 nm also confirmed results of carbohydrate analysis (Table 3) indicating a higher absorption for MS at this hemicellulose-associated wavelength compared to EMS [56].…”

“…Lignin recovery yields (1.9% (RecLMK) and 1.7% (RecLPilot) based on OD miscanthus) accounted for ~25% of the total dissolved lignin, which is higher than that for apricot shells (5%, [55]) but lower than that for sugar maple (47%, [39]). This indicates an extensive cleavage of lignin to hydrophilic, low molecular weight phenolic compounds, which remain soluble even after acidification of the Degree of crystallinity of cellulose was calculated for MS and EMS using NIR spectra and Equation (1) [53]:…”

“…After HWE, the HHV of miscanthus produced at three different scales increased 6.49 ± 1.6% in average, as expected due to a relative increase in cellulose and lignin contents and decrease in content of hemicellulose/xylan (energy of combustion lignin (~21 MJ/kg) > cellulose (~17 MJ/kg) > hemicelluloses (~16.63 MJ/kg)) [62]. Moreover, increase in HHV observed for miscanthus was higher than reported earlier for sugar maple (2.9%), wheat straw (3.0%) and apricot pit shell (4.1%) after HWE (Parr reactor; [55,63]). As expected, the higher heating value of RecL Pilot is higher than that of EMS Pilot and is comparable to that of coal (23.67 MJ/kg vs. 23-28 MJ/kg, [64]).…”

“…Carbohydrates: The carbohydrate content of native biomass (MS) and hot-water extracted biomass (EMS) was determined by a modified acid hydrolysis procedure [55]. 150 mg of extractive-free biomass was sonicated with 4.8 mL of 72% sulfuric acid for one h at room temperature, after which 6.3 mL deionized water was added to dilute the acid to 4%.…”

Chemical modification of apricot kernel shell waste and its effect on phenolic novolac epoxy composites

“…For the untreated AKShs, the percentage of cellulose was lower, while the percentage of lignin was higher than those of the treated AKShs. Typically, AKShs mainly consist of 27–34.31% lignin and 34.31–39.75% cellulose . In our study, the percentages of hemicellulose, cellulose, and lignin of the untreated AKShs were determined to be 19.5%, 37.8%, and 33.5%, respectively.…”