Influence of Hydrothermal Pretreatment Temperature on the Hydration Properties and Direct Carbonation Efficiency of Al-Rich Ladle Furnace Refining Slag

The influence of hydrothermal pretreatment temperature on the hydration products and carbonation efficiency of Al-rich LF slag was investigated. The results showed that the carbonation efficiency was strongly dependent on the morphology of hydration products and the hydration extent of the raw slag. Hydrothermal pretreatment at 20 °C or 80 °C favored the formation of flake-shaped products with a higher specific surface area and therefore resulted in a higher CO2 uptake of 20 °C and 80 °C-pretreated slags (13.66 wt% and 10.82 wt%, respectively). However, hydrothermal pretreatment at 40 °C, 60 °C or 100 °C led to the rhombohedral-shaped calcite layer surrounding the unreacted core of the raw slag and the formation of fewer flake-shaped products, resulting in a lower CO2 uptake of 40 °C, 60 °C and 100 °C-pretreated slags (9.21 wt%, 9.83 wt%, and 6.84 wt%, respectively).

PRETREATMENT OF MILLET HUSK USING ALKALINE HYDROGEN PEROXIDE TO ENHANCE ENZYMATIC HYDROLYSIS FOR REDUCING SUGAR PRODUCTION

The effectiveness of alkaline hydrogen peroxide as a suitable choice of pretreatment for the conversion of millet husk to reducing sugars using cellulase enzyme for hydrolysis and subsequent ethanol production was determined. The effects of three variables on reducing sugar production from millet husk were determined using one factor at a time (OFAT) method namely; peroxide concentration, pretreatment time and pretreatment temperature. From the results, it was observed that a significant (P<0.05) amount of reducing sugars were lost during pretreatment of millet husk. The untreated group which was only physically pretreated (milled) however yielded a significantly higher (P<0.05) reducing sugar concentration of 10.67mg/ml after enzymatic hydrolysis while the highest reducing sugar concentration of 4.82mg/ml was obtained using 0.375%v/v peroxide concentration for 60minutes at 250C. Therefore, pretreatment of biomass with alkaline hydrogen peroxide may be more suitable for feedstock with high lignin contents than millet husk.

Microwave Pretreatment for the Extraction of Anthocyanins from Saffron Flowers: Assessment of Product Quality

The potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a feasible intensification step. The effectiveness of microwave pretreatment was assessed in terms of increased yield and improved quality of the final product. The operational variables studied were the pretreatment temperature (60–120 °C) and the solid–liquid ratio (0.30–0.50 g/mL). It was found that the addition of the microwave pretreatment to the conventional process allowed one to reduce extraction time by up to 12 times and to greatly improve the characteristics of the final product, using microwave energy densities as low as 0.16–0.54 kJ/mL. The extract quality was evaluated in terms of polyphenol richness (25% increase), product composition (80% of the anthocyanins was delphinidin), antioxidant capacity (boosted by the pretreatment) and color (variations in red and blue hue depending on conditions). To conclude, a microwave pretreatment in which the material is heated to a temperature of 65 °C with a solvent ratio of 0.30 g/mL was selected as the optimum to maximize process efficiency and product quality.

Pseudo-lignin retarded bioconversion of sugarcane bagasse holocellulose after liquid hot water and acid pretreatments

Pseudo-lignin derived from the condensation of carbohydrate degradation products can retard the bioconversion of lignocellulose. In this work, liquid hot water (150 to 190 °C) and 1% H2SO4 pretreatments (130 to 190 °C) were used on sugarcane bagasse holocellulose for 3 h to generate pseudo-lignin. The effects of pseudo-lignin generation on structural characteristics and bioconversion of substrates were evaluated. The results showed that the formation of pseudo-lignin increased the hydrophobicity of the substrates. After LHW pretreatments and acid pretreatments at low temperatures (<150 °C), most of the xylans were removed, yielding 2.1 to 5.4% pseudo-lignin. Increasing acid pretreatment temperature to 170 and 190 °C yielded 34.3% and 93.6% pseudo-lignin, respectively. After pretreatment, the accessibilities and bioconversions of substrates were enhanced by degradation of xylans, increasing glucose conversions and bioethanol productions of substrates from 53.2 to 85.3%, and 9.9 to 13.1 g/L, respectively. However, large amounts of pseudo-lignin were generated during acid pretreatments at 170 °C, reducing glucose conversion and bioethanol yield to 45.6% and 6.3 g/L, respectively.

Determining Optimal Temperature Combination for Effective Pretreatment and Anaerobic Digestion of Corn Stalk

Temperature is one of the important factors affecting both chemical pretreatment and anaerobic digestion (AD) process of corn stalk (CS). In this work, the combined ways between pretreatment temperature (40℃ and 60℃) and AD temperature (35℃ and 55℃) were selected to investigate the AD performance for sodium hydroxide (NaOH) pretreated CS. Three organic loading rates (OLRs) of 1.6, 1.8 and 2.0 g·L-1·d-1 were studied within 255 days using continuously stirred tank reactors (CSTR). The results revealed that temperature of 40°C was considered as an appropriate for pretreatment whether in mesophilic or thermophilic anaerobic digestion systems. On the other hand, temperature of 35°C and 55°C were chosen as the optimal AD temperatures for lower and higher OLRs, respectively. This study provides a significant insight for exploring the effects of temperatures on the pretreatment and AD of CS.

Multi-criteria optimization of beet juice obtaining process by press-diffusion method

Currently, the application of advanced technologies in sugar factories is relevant. These technologies are based on the use of a combination of physical and energy effects on the feedstock and provide a reduction in sucrose losses at the stage of diffusion juice obtaining. A method of press-diffusion production of juice from sugar beet which allows to increase the yield of sucrose from beet chips and to reduce losses at the stage of diffusion juice obtaining and production costs is suggested by us. The press-diffusion method of extracting juice from sugar beet with the methods of mathematical planning and statistical processing of the experimental results was studied in the work. Regression equations and suboptimal parameters providing the maximum yield of beet juice with minimum energy consumption for its implementation were received in experimental plants under the influence of technological parameters, which were the pressure applied to the beet mass at the pressing stage, the temperature at the diffusion stage, and the pretreatment temperature of beet chips before pressing and the frequency of ultrasonic vibrations of the emitter in the diffusion installation. These operating parameters were the following: pressing pressure 0.27–0.33 MPa, pretreatment temperature of beet chips 334.2–337.3 K, diffusion temperature 342.5–345.0 K and frequency of ultrasonic radiation 21.25–23.36 kHz. The engineering nomograms presented make it possible to determine the value of the specific energy consumption and the value of the liquid phase output from the technological parameters of the press-diffusion method for producing beet juice in a quick and qualitative way.