Showing papers by "Sushil Adhikari published in 2021"

Influence of plasticizers on thermal and mechanical properties of biocomposite filaments made from lignin and polylactic acid for 3D printing

Abstract: Polylactic acid (PLA) and organosolv lignin were mixed at different ratios and extruded to obtain PLA-lignin composite filaments. PLA was replaced with lignin up to 20 wt%. Two plasticizers (polyethylene glycol (PEG) 2000 and struktol TR451) were added in varying concentrations to enhance the properties of PLA_L20 (20% lignin in PLA) composite filaments. The effect of lignin in PLA, and PEG, and struktol in PLA_L20 composites was investigated via tensile test, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy of the filaments, and dynamic mechanical analysis of 3D printed samples. A 2 wt% PEG was able to enhance both tensile stress and elongation at maximum load of PLA_L20 composite by 19% and 35%, respectively, whereas struktol TR451 was able to improve elongation at maximum load by 24%.

Biopolymers Fractionation and Synthesis of Nanocellulose/Silica Nanoparticles from Agricultural Byproducts

Abstract: Agricultural byproducts rich in lignocellulose are considered one of the most promising feedstocks to produce sustainable value-added materials with different industrial applications. However, fractionation into carbohydrates, lignin, and silica is a key challenge in the conversion of plant biomass into value-added products due to its complex structure. This study is designed to develop a novel method for sequential separation and collection of cellulose, hemicellulose, lignin, and silica from agricultural byproducts, peanut shell (PS), rice husk (RH), and sugar cane bagasse (SB), using an integrated approach under mild hydrolysis conditions. Silica and cellulose nanofibers (CNFs) were synthesized using an ultrasonic-assisted chemical method. Pure silica was obtained by further pyrolysis. The yield percent of cellulose was 35%, 39%, and 41% and hemicellulose and lignin combined was 30%, 18%, and 29% from PS, RH, and SB, respectively. The X-ray diffraction results demonstrated that CNFs were semicrystalline from all samples, and CNFs from SB had the highest crystallinity. Similarly, silica nanoparticles (SNPs) were amorphous in RH, while it was crystalline in both PS and SB. The surface morphologies of the CNFs and nanosized fibers were observed by field emission-scanning electron microscopy. It revealed that there were different morphological characteristics such as web-like, parallel, and tangled in PS, RH, and SB, respectively. The surface morphology of SNPs was also varied among the samples. In BET analysis, SNPs from RH had a larger specific surface area of 37.5 m²/g and total pore volume of 0.08 cc/g compared to SNPs from both PS and SB. The ascribed method could be a potential approach for comprehensive utilization of agricultural biomass through a relatively simple process, which can then be used for the biorefinery process or as a feedstock for the biomaterials industry. It is also suggested that the structural variations of CNFs/SNPs might be a vital factor to be considered for selecting optimal biomaterials.

Improving hydrocarbons and phenols in bio-oil through catalytic pyrolysis of pine sawdust

Abstract: The objective of this research was to develop low-cost metal-supported catalysts to improve the hydrocarbons, phenols, and phenolic compounds yield in the bio-oil. In this study, pyrolysis of pine sawdust was performed without a catalyst, with HZSM-5 catalyst and with Ni/HZSM-5 catalyst at temperatures of 400, 500, and 600 °C in a fixed bed reactor. The metal supported catalyst Ni/HZSM-5 was developed by wet impregnation method. The effects of temperatures and catalyst type on the yield and quality of the pyrolysis oil were investigated. The non-catalytic pyrolysis resulted in bio-oil yield of 37.4 wt% at 500 °C; however, HZSM-5 and Ni/HZSM-5 catalysts had a marginally lower yield of bio-oil (36.6 and 35.3 wt%, respectively) at 400 °C. The presence of catalysts improved the bio-oil viscosity by producing approximately more than 90% of light bio-oil while the remaining 10% was heavy bio-oil. Ni/HZSM-5 catalyst exhibited the best catalyst activity, with 80.2% and 49.7% yields of the desired compounds in heavy and light bio-oils respectively, while the bio-oil obtained without catalyst contained only 34.9% at 400 °C.

Effects of feeding varying levels of hempseed meal on dry matter intake, rumen fermentation, in vitro digestibility, blood metabolites, and growth performance of growing meat goats

Abstract: Objective The objective of this study was to evaluate the effect hempseed meal (HSM; a by-product of hemp oil production) supplementation has on DMI, rumen fermentation, in vitro true digestibility, blood metabolites, and growth performance of growing meat goats over a 60-d feeding trial. Materials and Methods Forty castrated Boer cross goats 4 to 5 mo of age with an average BW of 25.63 ± 0.33 kg were randomly assigned to 1 of 4 treatments (n = 10/treatment): control (0), 11%, 22%, and 33% HSM of the total diet on a DM basis. The forage to concentrate ratio was maintained at 50.2:49.8 on a DM basis, and timothy hay was used as a forage source. Diets were pelleted as TMR. Data were collected for DMI, rumen fermentation, blood metabolites, and growth performance for the 60-d feeding trial. Data were analyzed utilizing the GLM procedures of SAS (SAS Institute Inc.). Orthogonal contrasts for increasing HSM inclusion rates were used to determine linear and quadratic effects within the data. Results and Discussion The DMI was similar among treatments (P > 0.05). Total live weight gain (kg) decreased linearly (P Implications and Applications These findings provide new insights into the feeding value of HSM for meat goats; however, further research needs to be conducted to determine the optimal level of HSM supplementation.

Influence of Biomass Inorganics on the Functionality of H+ZSM-5 Catalyst during In-Situ Catalytic Fast Pyrolysis

Abstract: In this study, the contamination of H+ZSM-5 catalyst by calcium, potassium and sodium was investigated by deactivating the catalyst with various concentrations of these inorganics, and the subsequent changes in the properties of the catalyst are reported. Specific surface area analysis of the catalysts revealed a progressive reduction with increasing concentrations of the inorganics, which could be attributed to pore blocking and diffusion resistance. Chemisorption studies (NH3-TPD) showed that the Bronsted acid sites on the catalyst had reacted with potassium and sodium, resulting in a clear loss of active sites, whereas the presence of calcium did not appear to cause extensive chemical deactivation. Pyrolysis experiments revealed the progressive loss in catalytic activity, evident due the shift in selectivity from producing only aromatic hydrocarbons (benzene, toluene, xylene, naphthalenes and others) with the fresh catalyst to oxygenated compounds such as phenols, guaiacols, furans and ketones with increasing contamination by the inorganics. The carbon yield of aromatic hydrocarbons decreased from 22.3% with the fresh catalyst to 1.4% and 2.1% when deactivated by potassium and sodium at 2 wt %, respectively. However, calcium appears to only cause physical deactivation.

Friction and wear properties of biomass-derived oils via thermochemical conversion processes

Abstract: Tribological properties of biomass-derived oils (bio-oils) were experimentally investigated, and the properties were compared with that of standard mineral oils used for lubrication purposes. Bio-oils were obtained from fast pyrolysis (using poultry and pine), gasification (“gasitar” using pine) and hydrothermal liquefaction processes (using Scenedesmus and Nannocholoropsis). The friction and wear tests were conducted using a ball on the disk tribometer test. The results showed that the coefficient of friction (COF) were around 0.02 for both gasitar and Scenedesmus bio-oil; whereas, catalytic and non-catalytic pyrolysis oils had a COF around 0.1. The wear measurements showed that catalytic fast pyrolysis bio-oils had lower wear followed by non-catalytic bio-oil and “gasitar”. Nannocholoropsis bio-oil had the highest amount of wear, and algal bio-oils showed higher wear compared to other oils. The bio-oil chemical analysis indicated that catalytic and non-catalytic fast pyrolysis bio-oil had higher oxygen content, while algal bio-oil had higher nitrogenates. Gasitar had higher hydrocarbon content with lower oxygen and nitrogenates making it a favorable lubricating oil.