Effects Of Inorganic Impurities Research Articles

ВЛИЯНИЕ НЕОРГАНИЧЕСКИХ ПРИМЕСЕЙ НА ПРОЦЕСС КРИСТАЛЛИЗАЦИИ СУЛЬФАМИНОВОЙ КИСЛОТЫ

ВЛИЯНИЕ НЕОРГАНИЧЕСКИХ ПРИМЕСЕЙ НА ПРОЦЕСС КРИСТАЛЛИЗАЦИИ СУЛЬФАМИНОВОЙ КИСЛОТЫ

Catalytic conversion of cellulosic biomass to ethylene glycol: Effects of inorganic impurities in biomass

The effects of typical inorganic impurities on the catalytic conversion of cellulose to ethylene glycol (EG) were investigated, and the mechanism of catalyst deactivation by certain impurities were clarified. It was found that most impurities did not affect the EG yield, but some non-neutral impurities or Ca and Fe ions greatly decreased the EG yield. Conditional experiments and catalyst characterization showed that some impurities changed the pH of the reaction solution and affected the cellulose hydrolysis rate; Ca and Fe cations reacted with tungstate ions and suppressed the retro-aldol condensation. To obtain a high EG yield, the pH of the reaction solution and the concentration of tungstate ions should be respectively adjusted to 5.0–6.0 and higher than 187ppm. For raw biomass conversion, negative effects were eliminated by suitable pretreatments, and high EG yields comparable to those from pure cellulose were obtained.

Influence of Impurities on Crystallization Kinetics of Calcium Sulfate Dihydrate and Hemihydrate in Strong HCl-CaCl2 Solutions

The effects of inorganic impurities on the crystallization of calcium sulfates in strong HCl (6.3 mol L–1)-CaCl2 (1.8 mol L–1) solutions were investigated. The impurities considered relate to hydrochloric acid leaching of apatite-type ores for the extraction of rare earth elements. The impurities investigated were K+, Mg2+, Sr2+, Ba2+, Al3+, Fe2+, Fe3+, La3+, Y3+, F– (fluoride), and PO43– (phosphate). The investigation was done in the context of a continuous steady-state crystallization process. Therefore, temperature-controlled, semibatch crystal growth experiments with regulated reagent addition, to ensure nearly constant supersaturation, were performed. The experiments were conducted at 40 and 80 °C corresponding, respectively, to crystallization of calcium sulfate dihydrate (DH) and calcium sulfate hemihydrate (HH). Among all impurities investigated, phosphate and strontium were found to have the most significant effects, with La3+ and Y3+ having some modest effects. Phosphate (added as phosphoric aci...

Neural network modelling of the effects of inorganic impurities on calcium aluminate cement setting

Neural network analysis was used to construct models of setting time as a function of mix composition and addition concentration using existing data for calcium aluminate cements. The models were able to represent the non-linear temperature dependency of setting times and generalised from the literature data to find exponential relationships between setting time and addition concentration. An induction time estimated from the results of different types of setting measurements was used in modelling to determine the following ranking of induction times: Ba > Ca ≥ Sr ≥ Mg ≥ K ≈ Na ≥ control ≫ Li and citrate ≥ Br−≫ [Formula: see text] > C1−> control ≈ [Formula: see text] ≥ OH−> [Formula: see text] ≈ [Formula: see text] > [Formula: see text] High variability of the results reported in the literature resulted in a root-mean-square error of 174% for the best model, which may provide a method-independent estimate of the interlaboratory reproducibility for setting time measurement.

Effects of inorganic impurities on the mode of combustion of carbon

Effects of inorganic impurities on the mode of combustion of carbon