Dissolution Kinetics of Silicate Minerals in Aqueous Catechol Solutions

Abstract

Fine particle samples of silicate minerals and of gibbsite were shaken with solutions of pyrocatechol, 4-nitro-pyrocatechol or 3,4-dihydroxybenzoic acid at pH 9-3-97 and 25 "C. In 63 days, from 1.4 per cent (illite) to 17.9 per cent (nepheline) of the silica present was dissolved. Except for kaolinite in solutions of the two substituted catechols, the aluminosilicates dissolved incongruently, leaving residues enriched with aluminium.When accumulated amounts of elements (Si, Al, Na, K) dissolved from nepheline were plotted against time on log-log paper straight lines were obtained. For quartz, kaolinite, and in some cases gibbsite similar plots could be approximated by two straight-line segments. The plots for microcline and oligoclase may be described by a combination of three-line segments. Several possible reaction mechanisms are discussed but a mechanism which explains the similar rate profiles has not yet been formulated. P (1931). These complexes have been investigated by preparative (Rosenheim et al., 193 I ;Weiss et al., 1961 ; Barnum et al., 1970 Barnum et al., , 1972 I In this paper 'catechol' means any compound containing a benzene ring with two hydroxyls in the ortho-position, the simplest being pyrocatechol, I ,z-dihydroxybenzene.

Reactions Controlling Heavy Metal Solubility in Soils

“…Organic molecules with the capability to complex with metals can potentially increase concentrations of these metals in soil solution by dissolution reactions at mineral surfaces (Jorgensen, 1976;Manley and Evans, 1986;Pohlman and McColl, 1986). Generally, the metal-complexing ability of the organic within the range of soil pH is a good indicator of its ability to adsorb to metal oxides and enhance mineral dissolution.…”

Climate engineering by mimicking natural dust climate control: the iron salt aerosol method

“…In the reduced conditions, HA is characterized by catechol and other polyphenolic functions, which allows HA to complex with silicon (Belton et al, 2010;Demadis et al, 2011;Jorgensen, 1976) (Kastner, 1999) are formed by in situ microbial precipitation from sediment pore water, squeezed out to the seafloor on the sediment layer (Nayak et al, 2011;Wu et al, 2013). The main components of the nodules are the phytoplankton fertilizer components SiO 2 , Fe oxides and Mn oxides (Nayak et al, 2011).…”

Climate engineering by mimicking the natural dust climate control: the Iron Salt Aerosols method

“…Silicon is mobilized too, from the dissolution of silicates and SiO 2 in methanogenic conditions by complexation with reduced humic acid (HA) (Vorhies and Gaines, 2009;Wallmann et al, 2008). In the reduced conditions, HA is characterized by catechol and other polyphenolic functions, which allows HA to complex with silicon (Belton et al, 2010;Demadis et al, 2011;Jorgensen, 1976) (PO 4 ) 2 ) and within its suboxic surface (BaSO 4 ) and at its oxic surface (SiO 2 , Fe(III)OOH, Mn(IV)O 2 , clay minerals). The authigenically formed ferromanganese nodules (Kastner, 1999) are formed by in situ microbial precipitation from sediment pore water, squeezed out to the seafloor on the sediment layer (Nayak et al, 2011;Wu et al, 2013).…”