Thermal dehydration kinetics and characterization of synthesized potassium borates

Investigation on thermal degradation kinetics and mechanisms of chicken manure, lignite, and their blends by TGA

In this study, thermogravimetric analysis (TGA) was performed under the air environment for four different heating rates (10, 20, 30, and 40 °C min^-1) in order to find out thermal degradation and mechanisms of the chicken manure, a Turkish lignite, and their blends (25 lignite + 75 manure, 50 lignite + 50 manure, and 75 lignite + 25 manure). To calculate thermal kinetics and responsible solid-state mechanisms of the samples, the Flynn-Wall-Ozawa and Coats-Redfern methods were applied. Significant differences between Turkish lignite and chicken manure samples were observed in terms of thermal kinetics and mechanisms. D1 and D4 mechanisms were found to be the responsible mechanisms for the main oxidation region of the lignite and chicken manure/blends, respectively. A similar decreasing trend for the calculated activation energies and pre-exponential constants was observed with increasing biomass content in the manure blends from 25 to 75% by both Flynn-Wall-Ozawa and Coats-Redfern methods. Furthermore, biomass content has an effect on the mechanisms of chicken manure blends during the combustion. D3 was found to be the responsible solid-state mechanism for the third regions (pre-combustion of the manure) of the chicken manure samples. However, D1 and D2 mechanisms were found to be responsible mechanisms for the blends.

KB3H8: an environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols

Selective reduction of aldehydes and ketones to their corresponding alcohols with KB₃H₈, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB₃H₈ over NaBH₄ for the reduction of 4-acetylbenzaldehyde and aromatic keto esters.

A new rapid synthesis of potassium borates by microwave irradiation

Potassium borates are one of the minor groups of boron minerals with its distinct non-linear optical properties. In this study, potassium borate compound of santite (KB5O8·4H2O) are synthesized using potassium carbonate (K2CO3) and boric acid (H3BO3) with a new and rapid method of microwave irradiation. The synthesized minerals are characterized by various analysis techniques of X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). Three parameters of “microwave power level”, “reaction times” and “reaction stoichiometric constants (elemental potassium to boron ratios)” are determined for the optimum synthesis of potassium borate within the four step. At the end of the step 4, optimum products are obtained as santite type potassium borate. Synthesized potassium borates Raman bands are in mutual agreement with the boron compounds and the overall reaction yields to potassium borates are very high compared with the lower reaction times.