SOUTHERN JOURNAL OF SCIENCES

Background: The recovery of any valuable component from dolomite as a double carbonate mineral depends on its dissolution efficiency. Aim: This study aimed to optimize and provide a simplified novel approach to the kinetics of dolomite dissolution in sulphuric acid solution using the Box-Behnken experimental design. Methods: The dolomite sample was dissolved in a sulphuric acid solution at seventeen different experimental conditions. The residue containing impurities was removed via filtration, while precipitation was carried out at the optimum conditions. Results and Discussion: The relationship between the independent and dependent variables best fits into the two-factor interaction model with a coefficient of determination of 0.9492, adjusted R² of 0.9187, and predicted R² of 0.7514. The total residual sum of 3x10^-13 and adequate precision of 18.769 show that the predicted dissolution efficiency is much closer to the experimental values. The analysis of variance revealed that the individual effect of acid concentration, temperature, and dissolution time all positively contribute to the dissolution. The interactive effect of acid concentration with temperature and the interactive effect of temperature with dissolution time also positively influences the dissolution efficiency. Following the dissolution of dolomite in sulphuric acid, a white precipitate was formed at room temperature, which dissolved back at a temperature of 70 oC, agitation speed of 900 revolutions per minute, and within 10 minutes. A predictive approach using a two-factor interactive model was applied to generate the kinetic data. Conclusions: The established model equation is suitable for predicting dolomite dissolution in sulphuric acid. The application of the shrinking core model to the generated data shows that the reaction between dolomite and sulphuric acid is film diffusion control with a first-order reaction (0.6587) and activation energy of 27.5 KJmol-1k-1.

Editorial note.

Background: Recently, research has been carried out to improve the efficiency of electronic devices in general. With the commercial search for consolidated materials and the growth in demand with monitoring of costs, research has sought to minimize these effects with the replacement or functionalization of other substances, which may be applied at lower costs without compromising operating yields already achieved. Objective: This work aimed to obtain molecular modeling and reactivity parameters of -caprolactam and o-phenanthroline to evaluate the interaction capacity in the formation of molecular systems. Conductance measurements were taken to observe the electrolytic behavior. Infrared and UV-visible spectra were recorded to characterize vibrational transitions and evaluate spectrochemical properties. Methods: The WebLab program was used to obtain structural data and calculate reactivity parameters. Conductance was obtained in QUIMIS Q-405 equipment. IR spectra were recorded on PERKIN ELMER FRONTIER equipment. UV-vis spectra were recorded in a SHIMADZU equipment 200 – 1000 nm range to record the main transitions. Results and Discussions: Electron donor atoms are centered mainly on oxygen and nitrogen, respectively, which are sterically more favorable. The behavior was non-electrolyte. Groups with vibrational transitions sensitive to chemical interactions are comprised of C=N, C-N, and C=O bonds. The  parameter indicates transitions in the 190 – 300 nm region and the near-infrared, and the oscillator strength is typical of molecules used as dyes and sensitizers in optical light-emitting systems or light-to-electricity converters. Conclusions: We observed that these ligands have a donor capacity for the formation of complex systems that meet the need for electron transfer in optical pumping devices for the intensification of transitions or radiation converters, which can also be applied in radiation-to-electricity converter systems.