Bio-Crude Production from Protein-Extracted Grass Residue through Hydrothermal Liquefaction

In the present study, the protein-extracted grass residue (press cake) was processed through hydrothermal liquefaction under sub and supercritical temperatures (300, 350 and 400 °C) with and without using a potassium carbonate catalyst. The results revealed that bio-crude yield was influenced by both temperature and the catalyst. The catalyst was found to be effective at 350 °C (350 Cat) for enhancing the bio-crude yield, whereas supercritical state in both catalytic and non-catalytic conditions improved the quality of bio-crude with reasonable HHVs (33 to 36 MJ/kg). The thermal behaviour of bio-crude was analysed and higher volatile contents (more than 50% under the range of 350 °C) were found at supercritical conditions. The overall TOC values in the residual aqueous phase varied from 22 to 38 g/L. Higher carbon loss was noticed in the aqueous phase in supercritical conditions. Furthermore, GCMS analysis showed ketones, acids and ester, aromatics and hydrocarbon with negligible nitrogen-containing compounds in bio-crude. In conclusion, the catalytic conversion of grass residue under subcritical conditions (350 Cat) is favourable in terms of high bio-crude yield, however, supercritical conditions promote the deoxygenation of oxygen-containing compounds in biomass and thus improve HHVs of bio-crude.

Removal of Volatile Toluene Using K2CO3-Activated Carbon Adsorbents Prepared from Buckwheat Hull

Carbon adsorbents for use in the removal of gaseous toluene from the air were prepared from buckwheat (Fagopyrum esculentum Moench) hull. A chemically-activated adsorbent was prepared via the impregnation of raw hull powder with potassium carbonate, followed by thermal decomposition. The chemically-activated adsorbent exhibited improved adsorption capacity for toluene compared to the adsorbent prepared without chemical activation. Toluene concentration in the air decreased from 220 ppm to 160 ppm during 24 h of adsorption using unactivated adsorbent. Only a trace amount of toluene remained after the adsorption under the same conditions using K2CO3-activated adsorbent. This improvement was explained based on experimental results, specifically, iodine adsorption tests, methylene blue adsorption tests, and microscopic observations. Chemical activation dramatically increased the specific surface area of the adsorbent and created mesopores capable of adsorbing toluene. This study revealed that a mesoporous adsorbent for use in volatile toluene removal can be prepared from waste biomass (buckwheat hull) by chemical activation using potassium carbonate.

Potassium–carbonate co-substituted hydroxyapatite compositions: maximising the level of carbonate uptake for potential CO2 utilisation options

CO2 utilisation is a rapidly growing area of interest aimed at reducing the magnitude of anthropogenic greenhouse gas emissions.

Rheological characterization of potassium carbonate deep eutectic solvent (DES) based drilling mud

Different additives are added in the drilling mud to increase its efficiency in terms of its rheology and filtration properties. Recently, the application of ionic liquids (ILs) has been exploited by various investigators as a drilling additive for improving the mud rheology. The more recent studies have shown that imidazolium-based ionic liquids (the most used class of ionic liquids in drilling fluids) are toxic. Moreover, the advancement in green chemistry has put a big question mark on the greener nature of ionic liquids because they are non-biodegradable and generally very expensive. Deep eutectic solvents (DES) are the non-toxic and cheaper alternative of ionic liquids possessing the same qualities as of ILs. In our previous work, we used potassium carbonate and glycerol-based DES as a drilling fluid additive. We found that DES has successfully improved the mud rheology and filtration properties of the mud. In this current study, various characterizations have been conducted to understand the underlying mechanism behind DES as a rheology modifier. The characterization shows the improvement in rheology is due to the intercalation of DES between alumino-silicate layers and interaction of DES with clay which alters edge to face orientation of sodium bentonite and ultimately its dispersion behaviour. The addition of DES decreases average grain size and disperses the clay particles in mud slurry which reduce the overall permeability and porosity of the filter cake thus improving the filtration behaviour of the mud. Moreover, the behaviour of DES based mud is modelled at 25 °C and 100 °C which shows DES-based mud follows Herschel–Buckley model and exhibits shear thinning behaviour even at elevated temperature.

Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysis

Is it possible to improve CO2 solubility in potassium carbonate (K2CO3)-based transition temperature mixtures (TTMs)? To assess this possibility, a ternary transition-temperature mixture (TTTM) was prepared by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform infrared spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliphatic functional groups in the prepared solvents. From thermogravimetric analysis (TGA), it was found that the addition of AMPD to the binary mixture can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temperature. In addition, Eyring’s absolute rate theory was used to compute the activation parameters (∆G*, ∆H*, and ∆S*). The CO2 solubility in liquids was measured at a temperature of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO2 solubility of TTTM was improved by the addition of AMPD. At the pressure of about 1.8 MPa, the CO2 mole fractions of TTM and TTTM were 0.1697 and 0.2022, respectively. To confirm the experimental data, density functional theory (DFT) was employed. From the DFT analysis, it was found that the TTTM + CO2 system has higher interaction energy (|∆E|) than the TTM + CO2 system indicating the higher CO2 affinity of the former system. This study might help scientists to better understand and to improve CO2 solubility in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD.