Jiby Kurian

Experimental Study on Calcium Hydroxide-Assisted Delignification of Hydrothermally Treated Sweet Sorghum Bagasse

The hydrothermally treated sweet sorghum bagasse (SSB) powder was treated using Ca(OH)2 to extract the lignin from it. Changes in chemical composition of SSB and the formation of sugars and hydrolytic products were studied. The optimum conditions of 10% (g/g substrate) Ca(OH)2 and 106.3 min of isothermal treatment residence time at 394 K resulted in 69.67 ± 1.26% of the lignin extracted from the hydrothermally treated SSB powder, producing a solid residue containing 68.29 ± 0.31% residual cellulose and 13.26 ± 0.32% residual lignin in it. The Ca(OH)2 concentration and isothermal treatment residence time were significant in the responses observed. Treatment using Ca(OH)2 is one of the potential processes for the on-farm processing of lignocellulosic materials.

Optimization of microwave-assisted fluidized-bed drying of carrot slices

ABSTRACT The drying of carrot slices in a microwave-assisted fluidized-bed drying (MWFBD) system was investigated. The drying conditions such as the initial microwave power density and the inlet air temperature were optimized. The effects of different pretreatment processes such as water blanching, osmotic drying with 20% sugar solution, and 1% citric acid solution on the drying of carrot slices were investigated under the optimized drying conditions. The drying kinetics and the physical properties of the dried carrot slices were analyzed. Different mathematical models of the drying process were explored and fitted to the drying of carrot slices in MWFBD. The pretreatment of the carrot slices reduced the drying time required and improved the qualities such as color and textural strength of the dried carrot slices.

Electro-osmotic dewatering of soaked hemp stems

ABSTRACT Hemp stems were immersed in water as a pretreatment to enhance the production of hemp fiber. To reduce the high moisture content, the soaked hemp stems were dewatered using a bench-type electro-osmotic roller press. Variables like applied voltage (12, 24, and 36 V), roller pressure (1000, 2000, and 3000 kPa), and duration of soaking of hemp stems (12, 24, and 36 h) were subjected to investigation and the percentage of total water expelled due to electro-osmotic dewatering (EOD) at various levels of experiments was recorded. Hemp stems soaked for 24 h treated at a roller pressure of 2,000 kPa at an applied voltage of 36 V showed the maximum water removal after EOD process. The water removal was found to be increasing with increase in applied voltage and roller pressure. Soaking time up to 32 h leads to an increase in water removal and then it started decreasing. The probable reason for that was the penetration of surface water into micropores and its adhesion to the lignocellulosic bonds. Electro-osmotic permeability of hemp stems at various levels of voltages, roller pressures, and soaking times was studied and the result proved that electro-osmotic permeability was inversely proportional to applied voltage and it was independent of the applied pressure.

Microwave-assisted lime treatment and recovery of lignin from hydrothermally treated sweet sorghum bagasse

Microwave (MW)-assisted lime treatment was applied for the extraction of lignin from sweet sorghum bagasse (SSB) which was previously subjected to a MW-assisted hydrothermal treatment for the extraction of hemicellulose. Under optimum conditions, lime dosage at a concentration of 10% by weight of the substrate and 78 min of treatment residence time resulted in 68.27 (± 1.19) % by weight of the lignin extracted from the substrate. The residual SSB was composed of 69.41 (± 1.83) % cellulose, 12.14 (± 0.71) % hemicellulose, 12.59 (± 0.31) % lignin and 4.03 (± 0.21) % ash in it. The bulk density of the two-step treated SSB was 3.6 times that of the untreated SSB. The yellow liquor was treated with CO2 and 60.26 (± 2.11) % by weight of the dissolved lignin was precipitated from it. The physicochemical properties of the treated-SSB and the lignin samples were analysed using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscope (SEM). The mass balance of the MW-assisted fractionation of SSB was conducted and the prospect of the process for on-farm fractionation of lignocellulosic materials was considered.

Comparative evaluation of steam-assisted treatments of biomass components and sweet sorghum bagasse

A process originally used for the fractionation of sweet sorghum bagasse powder was evaluated using biomass components such as cellulose, xylan and lignin. The autohydrolysis of the substrates was conducted at 121±0.5°C with isothermal treatment time of 90 min. The lime treatment of the autohydrolysed substrates was conducted at 121±0.5°C for 106 min with 0.1 g Ca(OH)2 dosage per gram of the substrates. The responses from the treatment of the biomass components were used to evaluate the responses observed during the treatment of the sweet sorghum bagasse. Carbon dioxide gas at a flow rate of 17 mL*min−1 was used for the precipitation of lignin and lime from the liquid obtained from the lime treatment process. The process responses were also compared and confirmed using the Fourier transform infrared spectrophotometry and the differential scanning calorimetry of the sweet sorghum bagasse and the treated and untreated biomass components.