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This study analyzes the photocinetic environmental persistence of Polyhexamethylene Biguanide Hydrochloride (PHMB) using the pySiRC artificial intelligence model. PHMB is a cationic polymer with sanitizing properties. The objective of the study was to determine the kinetic constants of photochemical degradation of PHMB in an aquatic environment, using •OH and SO4•− radicals. The results show that the degradation of PHMB against •OH attacks is efficient, indicating low persistence in the environment. However, in relation to SO4•−, the degradation is less efficient. The half-life times vary between 2 and 1,715 days, depending on the concentrations of •OH in the environment. These data contribute to the understanding of the environmental persistence of PHMB. [Extracted from the article]

The mineral industry generates large amounts of tailings, and because of many accidents that have occurred with conventional dams, studies focus on tailings dewatering before their disposal. This study evaluates the properties of the red mud to determine their rheological behavior and stability for disposal in dams. For this, the red mud was flocculated with commercial cationic polymer and thickened. The thickened tailing was submitted to rheological tests with the vane rotor and slump test, in order to obtain information about yield stress and slump height of the tailings. The results show a strong influence of the initial solids concentration in particle aggregation, which could be noticed by the increase in particle cohesion and yield stress of thickened tailings; besides reduction of the slump height with the increase of initial solids concentration. It was possible to produce thickened tailings, reaching τ0 = 160 Pa, very close to the value specified for mineral paste, besides up to 90% water recover. [ABSTRACT FROM AUTHOR]

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