A Novel and Effective Recyclable BiOCl/BiOBr Photocatalysis for Lignin Removal from Pre-Hydrolysis Liquor

The presence of lignin hampers the utilization of hemicelluloses in the pre-hydrolysis liquor (PHL) from the kraft-based dissolving pulp production process. In this paper, a novel process for removing lignin from PHL was proposed by effectively recycling catalysts of BiOCl/BiOBr. During the whole process, BiOCl and BiOBr were not only adsorbents for removing lignin, but also photocatalysts for degrading lignin. The results showed that BiOCl and BiOBr treatments caused 36.3% and 33.9% lignin removal, respectively, at the optimized conditions, and the losses of hemicellulose-derived saccharides (HDS) were both 0.1%. The catalysts could be regenerated by simple photocatalytic treatment and obtain considerable CO and CO2. After 15 h of illumination, 49.9 μmol CO and 553.0 μmol CO2 were produced by BiOCl, and 38.7 μmol CO and 484.3 μmol CO2 were produced by BiOBr. Therefore, both BiOCl and BiOBr exhibit excellent adsorption and photocatalytic properties for lignin removal from pre-hydrolysis.

AGRO-FORESTRY RESIDUES VALORIZATION BY LIGNINOSOME OF GRIFOLA FRONDOSA

Grifola frondosa HAI 1232 was tested for ligninolytic enzyme activities and for lignin, cellulose and hemicellulose degradation during cultivation on eight common agro-forestry residues in Serbia. Wheat straw was favorable lignocellulosic for the production of Mn-dependent and Mn-independent peroxidases (2513.89 and 354.17 U L-1, respectively), while selected residues inhibited the synthesis of laccases. The highest lignin removal was observed during fermentation of blackberry sawdust (36.75%), while the highest selectivity index was recorded on oak sawdust (4.34). The dry matter loss varied between 8.17% in corn stalks and 14.16% in apple sawdust. According to the presented results, it can be concluded that G. frondosa HAI 1232 could be an important participant in various biotechnological processesdue to its high capacity to selectively degrade different agro-forestry residues.

Enzymatic Pretreatment with Laccases from Lentinus sajor-caju Induces Structural Modification in Lignin and Enhances the Digestibility of Tropical Forage Grass (Panicum maximum) Grown under Future Climate Conditions

Since laccase acts specifically in lignin, the major contributor to biomass recalcitrance, this biocatalyst represents an important alternative to the pretreatment of lignocellulosic biomass. Therefore, this study investigates the laccase pretreatment and climate change effects on the hydrolytic performance of Panicum maximum. Through a Trop-T-FACE system, P. maximum grew under current (Control (C)) and future climate conditions: elevated temperature (2 °C more than the ambient canopy temperature) combined with elevated atmospheric CO2 concentration(600 μmol mol−1), name as eT+eC. Pretreatment using a laccase-rich crude extract from Lentinus sajor caju was optimized through statistical strategies, resulting in an increase in the sugar yield of P. maximum biomass (up to 57%) comparing to non-treated biomass and enabling hydrolysis at higher solid loading, achieving up to 26 g L−1. These increments are related to lignin removal (up to 46%) and lignin hydrophilization catalyzed by laccase. Results from SEM, CLSM, FTIR, and GC-MS supported the laccase-catalyzed lignin removal. Moreover, laccase mitigates climate effects, and no significant differences in hydrolytic potential were found between C and eT+eC groups. This study shows that crude laccase pretreatment is a potential and sustainable method for biorefinery solutions and helped establish P. maximum as a promising energy crop.

Alkaline pre-treatment of rice hull and coconut hull using Response Surface Methodology

In this research, the rice hull and coconut hull from agriculture waste were investigated. The lignin content within the rice and coconut hull were determined before and after pre-treatment. Response Surface Methodology (RSM) used to predict the optimal condition for the treatments and Fourier Transform Infrared (FTIR) to identify the lignin content. The interaction of NaOH concentration, contact time (CT), and sample weight was investigated to optimize the lignin removal percentage (%). The correlation coefficient, R2 for a quadratic model of rice hull lignin removal was 0.8863 while for coconut hull lignin removal in the linear model was 0.7998, as well as the 2FI model was 0.8892. The optimum condition for rice hull lignin removal predicted by RSM were10 M NaOH concentration, 1-hour CT and 0.5 g sample produced 32.45% lignin removal. While for coconut hull lignin removal were 10 M NaOH concentration, 12 hours CT, 0.5 g sample produced 59.47% removal of lignin. Results show that alkaline pre-treated rice hull and coconut hull able to be used to remove higher percentage of lignin.

Solvothermal-Based Lignin Fractionation From Corn Stover: Process Optimization and Product Characteristics

Fractionation of lignocellulosic is a fundamental step in the production of value-added biobased products. This work proposes an initiative to efficiently extract lignin from the corn stover using a single-step solvothermal fractionation in the presence of an acid promoter (H2SO4). The organic solvent mixture used consists of ethyl acetate, ethanol, and water at a ratio of 30: 25:45 (v/v), respectively. H2SO4 was utilized as a promoter to improve the performance and selectivity of lignin removal from the solid phase and to increase the amount of recovered lignin in the organic phase. The optimal conditions for this extraction, based on response surface methodology (RSM), are a temperature of 180°C maintained for 49.1 min at an H2SO4 concentration of 0.08 M. The optimal conditions show an efficient reaction with 98.0% cellulose yield and 75.0% lignin removal corresponding to 72.9% lignin recovery. In addition, the extracted lignin fractions, chemical composition, and structural features were investigated using Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance spectroscopy (2D-HSQC NMR). The results indicate that the recovered lignin primarily contains a β-O-4 linking motif based on 2D-HSQC spectra. In addition, new C–C inter-unit linkages (i.e., β-β, and β-5) are not formed in the recovered lignin during H2SO4-catalyzed solvothermal pretreatment. This work facilitates effective valorization of lignin into value-added chemicals and fuels.

Mushroom-mediated delignification of agricultural wastes for bio-ethanol production

Biological pretreatment is a cost-effective method of delignifying lignocellulosic biomass, making it less recalcitrant to hydrolysis into fermentable sugars. In this study, selected agricultural wastes were pretreated with mushrooms (Lentinus squarrosulus and Pleurotus ostreatus) to delignify them for bioethanol production. The substrates were supplemented with 0.2 % CaCO3, inoculated with 12 % (w/w) L. squarrosulus and Pleurotus ostreatus spawns and incubated at 25 oC for 21 days. The highest lignin removal and highest bioethanol yield of 77.45 % and 13.98 % were obtained from bean husks pretreated with L. squarrosulus. Similarly, 64.29 % and 60.92 % lignin were removed from the Pleurotus ostreatus-pretreated banana leaves and sawdust, respectively, while 12.08 % and 13.05 % bio-ethanol yields were recorded, respectively. These findings demonstrate that affordable and straightforward mushroom delignification of abundant and cheap biomass can improve hydrolysis outcomes, thus easing bioethanol production.

Effect of Extraction Time and Temperature on Total Flavanoid Contents of Petai Belalang (Leucaena leucocephala) Seed Pretreated by Enzymatic Hydrolysis

The abundant availability of Leucaena leucocephala (petai belalang) in Malaysia was one of the contributing factors of this research. The phytochemicals obtained from this plant will contribute towards many fields mainly medicine and it becomes more favorable as compared to the modern medicines used these days. Diseases such as cancer, high blood pressure and diabetes are very crucial, and it occurs frequently among all ages of citizens in Malaysia. Therefore, phytochemicals in this plant can be a great substitute of modern medicines. However, lignin is known to interfere with the cell wall polysaccharides digestion, and hence considered as an anti-quality component in forages. To improve phytochemicals extraction, an effective degradation method of lignin is in demand. Thus, the goal of the present study was to investigate the feasibility of using enzymatic hydrolysis by laccase from Trametes versicolor (LTV) to breakdown lignin using mild reaction condition. To clarify the effect of enzymatic hydrolysis, a preliminary study on the percentage of lignin removal was conducted that taking the effect of LTV concentration, incubation temperature and time into consideration. The results were then used to analyze total flavonoid contents (TFC) of L.leucocephala seed after the extraction by using microwave-assisted hydrodistillation (MAHD) method. In view of this, extraction temperature and time were varied. TFC was estimated by UV-VIS spectrophotometer for quantification by using quercetin as standard. The result emerge from this study showed that the TFC was high in the extraction temperature of 60˚C in 12 min with an average of 1639 mgQE/g.d.w and the lowest TFC was recorded at 30˚C with 677 mgQE/g.d.w. Further analysis showed that enzymatic hydrolysis has assisted the extraction of flavonoids, thus, provided scientific method to extract flavonoid as an alternative therapy for various diseases.