rates of feldspar dissolution at pH 3–7 with 0–8 m M oxalic acid

Stillings, Lisa L.; Drever, James I.; Brantley, Susan L.; Sun, Yan-Ting; Oxburgh, Rachael

doi:10.1016/s0009-2541(96)00043-5

Cited by 175 publications

(100 citation statements)

References 20 publications

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“…Then, the dissolution rate of kaolinite under steady-state conditions was calculated through the volume of suspension and total surface of kaolinite. Because the uncertainty of the surface increases during the dissolution of kaolinite, the methods used by other researchers [18][19][20] were followed, i.e., normalizing dissolution rates to the initial surface area. The results are given in Table 1, which demonstrates that organic acids possessed different abilities to promote the steady-state dissolution of kaolinite.…”

Section: Resultsmentioning

confidence: 99%

Dissolution of kaolinite induced by citric, oxalic, and malic acids

Wang

Hu³

et al. 2005

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

Dissolution of kaolinite induced by citric, oxalic, and malic acids

Wang

Hu³

et al. 2005

Journal of Colloid and Interface Science

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“…Experimental studies using relatively dilute solutions of compounds such as oxalic acid, citric acid, pyruvate, ␣-ketoglutarate, acetate, propionate, lactate, etc. have shown rate enhancements for silicate dissolution of up to one order of magnitude (96)(97)(98)(99)(100)(101). The effect is somewhat similar to that of acid production because organic ligands affect silicate mineral dissolution stoichiometry by complexing with, and increasing the solubility of, less soluble major ions such as Al and Fe (96,102,103).…”

Section: Application Of Insights From the Lichen-mineral Interface Tomentioning

confidence: 95%

Biological impact on mineral dissolution: Application of the lichen model to understanding mineral weathering in the rhizosphere

Banfield

Barker

Welch

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

514

282

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Microorganisms modify rates and mechanisms of chemical and physical weathering and clay growth, thus playing fundamental roles in soil and sediment formation. Because processes in soils are inherently complex and difficult to study, we employ a model based on the lichenmineral system to identify the fundamental interactions. Fixed carbon released by the photosynthetic symbiont stimulates growth of fungi and other microorganisms. These microorganisms directly or indirectly induce mineral disaggregation, hydration, dissolution, and secondary mineral formation. Model polysaccharides were used to investigate direct mediation of mineral surface reactions by extracellular polymers. Polysaccharides can suppress or enhance rates of chemical weathering by up to three orders of magnitude, depending on the pH, mineral surface structure and composition, and organic functional groups. Mg, Mn, Fe, Al, and Si are redistributed into clays that strongly adsorb ions. Microbes contribute to dissolution of insoluble secondary phosphates, possibly via release of organic acids. These reactions significantly impact soil fertility. Below fungi-mineral interfaces, mineral surfaces are exposed to dissolved metabolic byproducts. Through this indirect process, microorganisms can accelerate mineral dissolution, leading to enhanced porosity and permeability and colonization by microbial communities.

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“…Papers on laboratory experiments include: synthesis of H-exchanged sanidine (11)(12); infrared spectroscopy of H-feldspar (13); polarized infrared spectros-copy of molecular water in Eifel sanidine (14); various dissolution experiments in the laboratory (15)(16)(17)(18)(19)(20)(21)(22); adsorption of protons on adularia (23); adsorption of polyacrylamine (24); interaction of aquated Pb, Cd, and Cu cations with perthite (25); stationary and mobile H defects in K feldspar (26); formation of a nanometer-scale, silica-rich amorphous layer on acid-treated feldspars (27)(28)(29)(30); demonstration that a plagioclase͞K feldspar mineral isolate from a weathered granodiorite loses silica at the same rate as in the arid Southern California climate after 4 years of comparable leaching in the laboratory (31); and description of de Saussure's (1794-1795) demonstration that mineral weathering was faster when heating was combined with periodic wetting, as for rocks in Nature (32).…”

mentioning

confidence: 99%

Atmospheric weathering and silica-coated feldspar: Analogy with zeolite molecular sieves, granite weathering, soil formation, ornamental slabs, and ceramics

Smith

1998

Proc. Natl. Acad. Sci. U.S.A.

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Feldspar surfaces respond to chemical, biological, and mechanical weathering. The simplest termination is hydroxyl (OH), which interacts with any adsorption layer. Acid leaching of alkalis and aluminum generated a silica-rich, nanometers-thick skin on certain feldspars. Natural K, Nafeldspars develop fragile surfaces as etch pits expand into micrometer honeycombs, possibly colonized by lichens. Most crystals have various irregular coats. Based on surfacecatalytic processes in molecular sieve zeolites, I proposed that some natural feldspars lose weakly bonded Al-OH (aluminol) to yield surfaces terminated by strongly bonded Si-OH (silanol). This might explain why some old feldspar-bearing rocks weather slower than predicted from brief laboratory dissolution. Lack of an Al-OH infrared frequency from a feldspar surface is consistent with such a silanol-dominated surface. Raman spectra of altered patches on acid-leached albite correspond with amorphous silica rather than hydroxylated silica-feldspar, but natural feldspar may respond differently. The crystal structure of H-exchanged feldspar provides atomic positions for computer modeling of complex ideas for silica-terminated feldspar surfaces. Natural weathering also depends on swings of temperature and hydration, plus transport of particles, molecules, and ionic complexes by rain and wind. Soil formation might be enhanced by crushing granitic outcrops to generate new Al-rich surfaces favorable for chemical and biological weathering. Ornamental slabs used by architects and monumental masons might last longer by minimizing mechanical abrasion during sawing and polishing and by silicifying the surface. Silica-terminated feldspar might be a promising ceramic surface.Chemical and physical changes in minerals underlie many aspects of human welfare. Agriculture depends on the interaction of soils with water, ionic and molecular species, and biological organisms. The weathering of feldspar minerals (1-4) from bedrock into clays is important for the production of food. Many laboratory experiments have measured the dissolution rate of feldspar minerals by water containing a wide range of ionic and molecular species, including organic acids relevant to biological weathering. Data are available for the range of feldspar chemistry from strongly acid to alkaline conditions (2, 3). Electron and chemical microscopy of feldspar surfaces is revealing a wealth of information on chemical and physical changes, including pitting, honeycombing, and selective dissolution (5). Only scattered data are available for the rate of weathering of feldspars in natural watersheds, but they indicate that natural atmospheric weathering of many rocks is slower than for short term laboratory experiments of crushed samples (2, 3). Casual examination of granite slabs in cemeteries and city buildings indicates that the alkali feldspars are weathering slowly unless mechanical spalling is occurring.

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rates of feldspar dissolution at pH 3–7 with 0–8 m M oxalic acid

Cited by 175 publications

References 20 publications

Dissolution of kaolinite induced by citric, oxalic, and malic acids

Dissolution of kaolinite induced by citric, oxalic, and malic acids

Biological impact on mineral dissolution: Application of the lichen model to understanding mineral weathering in the rhizosphere

Atmospheric weathering and silica-coated feldspar: Analogy with zeolite molecular sieves, granite weathering, soil formation, ornamental slabs, and ceramics

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