Thermodynamic and Kinetic Controls on Haidingerite Dissolution: Implications for Arsenic Mobilization

Description

This dataset contains the experimental and derived data supporting the study “Thermodynamics, Kinetics, and Mechanisms of Haidingerite Dissolution.” The data were generated from dissolution experiments using phase-pure synthetic haidingerite (CaHAsO₄·H₂O) at 25, 35, and 50 °C. The dataset includes: (1) aqueous Ca and As concentration data from long-term dissolution experiments used to determine equilibrium solubility; (2) short-term dissolution data used to determine initial dissolution rates; (3) equilibrium concentrations, aqueous-species activities, and calculated solubility products (Ksp) at different temperatures; (4) temperature-dependent thermodynamic parameters derived from the solubility data; (5) kinetic data used for Arrhenius and Eyring analyses, including the calculation of apparent activation energy and apparent activation enthalpy; and (6) surface-area-normalized dissolution rates and corresponding Gibbs free energy changes (ΔG) used to evaluate the nonlinear rate–affinity relationship and Burch–Hellmann-type kinetic behavior. The results show that haidingerite solubility decreases with increasing temperature, with logKsp values of −4.54, −4.75, and −4.87 at 25, 35, and 50 °C, respectively. The dissolution kinetics exhibit relatively weak temperature dependence and a strongly nonlinear, sigmoidal relationship between dissolution rate and reaction affinity. These data provide quantitative constraints on the thermodynamic stability and dissolution kinetics of haidingerite, as well as on the influence of thermodynamic driving force on dissolution behavior, and provide a data basis for evaluating arsenic release from haidingerite in Ca-rich environments. The deposited files include consolidated numerical datasets together with the corresponding Origin project files used for data processing, fitting, and figure preparation. Variable definitions and units are provided in the accompanying data workbook.

Steps to reproduce

Haidingerite (CaHAsO4·H2O) powder was synthesized and characterized before dissolution experiments. Dissolution experiments were conducted at different temperatures (25, 35, and 50 °C) under controlled pH conditions. A known amount of mineral powder was reacted with aqueous solution at a fixed solid-to-liquid ratio. Aliquots were collected at selected time intervals, filtered, and analyzed for dissolved Ca and As concentrations using inductively coupled plasma optical emission spectrometry (ICP-OES). The dissolution rate constants were obtained by fitting the concentration–time data using kinetic models. The activation energy was calculated using the Arrhenius equation, and thermodynamic parameters were derived using transition state theory. Equilibrium concentrations and solubility products were calculated using PHREEQC with appropriate thermodynamic databases.

Institutions

• Changzhou University

  Jiangsu, Changzhou
• Tianjin University

  Tianjin, Tianjin

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