Assessment of pure, mixed and diluted deep eutectic solvents on Napier grass (Cenchrus purpureus): Compositional and characterization studies of cellulose, hemicellulose and lignin.

Pretreatment with pure, mixed, and diluted deep eutectic solvents (DESs) was evaluated for its effect on Napier grass through compositional and characterization studies. The morphological changes of biomass caused by pretreatment were analyzed by FTIR and XRD. The cellulose and hemicellulose content after pretreatment using mixed DES increased and decreased 1.29- and 4.25-fold, respectively, when compared to untreated Napier grass. The crystallinity index (CrI. %) of mixed DES sample increased due to the maximum removal of hemicellulose (76 %) and delignification of 62 %. The material costs of ChCl/FA and ChCl/LA for a single run are ≈2.16 USD and ≈1.65 USD, respectively. Pure DES showed that ChCl/LA pretreatment enhanced delignification efficiency and that ChCl/FA increased hemicellulose removal. It was estimated that a single run using ChCl/LA:ChCl/FA to achieve maximum hemicellulose and lignin removal would cost approximately ≈1.89 USD. Future work will evaluate the effect of DES mixture on enzyme digestibility and ethanol production from Napier grass. HYPOTHESES: Deep eutectic solvent (DES) pretreatment studies on the fractionation of lignocellulosic biomass have grown exponentially. The use of pure and diluted DES has been reported to improve saccharification efficiency, delignification, and cellulose retention (Gundupalli et al., 2022). These studies have reported maximum lignin removal but also a lower effect on hemicellulose removal from lignocellulosic biomass. It was hypothesized that mixing two pure DESs could result in maximum removal of hemicellulose and lignin after pretreatment. To our knowledge, no studies have been performed to investigate the efficiency of pretreatment using a DES mixture and compared the outcome with pure and diluted DESs. Furthermore, it was hypothesized that using two pure DESs in a mixed form could lower the material cost for each experimental run. Process efficiency was determined by compositional, XRD, and FTIR analysis. Avenues for future research include determining glucose and ethanol yields during the enzymatic saccharification and fermentation processes.

Interferences of Waxes on Enzymatic Saccharification and Ethanol Production from Lignocellulose Biomass.

Wax is an organic compound found on the surface of lignocellulose biomass to protect plants from physical and biological stresses in nature. With its small mass fraction in biomass, wax has been neglected from inclusion in the design of the biorefinery process. This study investigated the interfering effect of wax in three types of lignocellulosic biomass, including rice straw (RS), Napier grass (NG), and sugarcane bagasse (SB). In this study, although small fractions of wax were extracted from RS, NG, and SB at 0.57%, 0.61%, and 1.69%, respectively, dewaxing causes changes in the plant compositions and their functional groups and promotes dissociations of lignocellulose fibrils. Additionally, dewaxing of biomass samples increased reducing sugar by 1.17-, 1.04-, and 1.35-fold in RS, NG, and SB, respectively. The ethanol yield increased by 1.11-, 1.05-, and 1.23-fold after wax removal from RS, NG, and SB, respectively. The chemical composition profiles of the waxes obtained from RS, NG, and SB showed FAME, alcohol, and alkane as the major groups. According to the conversion rate of the dewaxing process and ethanol fermentation, the wax outputs of RS, NG, and SB are 5.64, 17.00, and 6.00 kg/ton, respectively. The current gasoline price is around USD 0.903 per liter, making ethanol more expensive than gasoline. Therefore, in order to reduce the cost of ethanol in the biorefinery industry, other valuable products (such as wax) should be considered for commercialization. The cost of natural wax ranges from USD 2 to 22 per kilogram, depending on the source of the extracted wax. The wax yields obtained from RS, SB, and NG have the potential to increase profits in the biorefining process and could provide an opportunity for application in a wider range of downstream industries than just biofuels.

Heterogeneous base catalysts: Synthesis and application for biodiesel production - A review.

Recently, much research has been carried out to find a suitable catalyst for the transesterification process during biodiesel production where heterogeneous catalysts play a crucial role. As homogenous catalysts present drawbacks such as slow reaction rate, high-cost due to the use of food grade oils, problems associated with separation process, and environmental pollution, heterogenous catalysts are more preferred. Animal shells and bones are the biowastes suitably calcined for the synthesis of heterogenous base catalyst. The catalysts synthesized using organic wastes are environmentally friendly, and cost-effective. The present review is dedicated to synthesis of heterogeneous basic catalysts from the natural resources or biowastes in biodiesel production through transesterification of oils. Use of calcined catalysts for converting potential feedstocks (vegetable oils and animal fat) into biodiesel/FAME is effective and safe, and the yield could be improved over 98%. There is a vast scope for biowaste-derived catalysts in green production of biofuel.

Nutrient Removal from Wastewater Using Microalgae: A Kinetic Evaluation and Lipid Analysis.

The objective of this study was to examine the performance of mixed microalgal bioreactors in treating three different types of wastewaters-kitchen wastewater (KWW), palm oil mill effluent (POME), and pharmaceutical wastewater (PWW) in semi-continuous mode and to analyze the lipid content in the harvested algal biomass. The reactors were monitored for total nitrogen and phosphate removal at eight solid retention times (SRTs): 2, 4, 6, 8, 10, 12, 14, and 16 days. The nutrient uptake kinetic parameters were quantified using linearized Michaelis-Menten and Monod models at steady-state conditions. The nutrient removal efficiency and lipid production were found to be higher in KWW when compared with the other wastewaters. Saturated fatty acids (C16:0, C18:0, and C18:1) accounted for more than 60% of the algal fatty acids for all the wastewaters. The lipid is, therefore, considered suitable for synthesizing biodiesel.