Removal of Pb from Water: The Effectiveness of Gypsum and Calcite Mixtures

Anthropogenic lead pollution is an environmental problem that threatens the quality of soils and waters endangers living organisms in numerous surface subsurface habitats. Lead coprecipitation on mineral surfaces through dissolution-recrystallization processes has long-term effects bioavailability. Gypsum calcite are among most abundant reactive rock forming minerals present geological settings. In this work, we studied interaction slightly acidic (pHi = 5.5) Pb-bearing aqueous solutions ([Pb]i 1 10 mM) with crystals gypsum and/or under atmospheric conditions. This resulted a reduction concentration liquid phase due to precipitation newly formed solid phases. The extent Pb removal mainly depended nature primary involved interaction. Thus, when was only initially system, liquid-gypsum removals 98–99.8% range, regardless [Pb]i. contrast, took place calcite, strongly It reached 99% [Pb]i mM, while it much more modest (~13%) mM. Interestingly, Pb-removal maximized for both (99.9% mM 99.7% Pb-polluted simultaneously interacted crystals. Despite large found cases studied, final ([Pb]f) always well above maximum permitted drinking water (0.01 ppm), minimum ([Pb]f 0.7 ppm) being obtained after their mixtures result suggests integrating use gypsum-calcite might help develop efficient strategies in-situ decontaminating processes.