Acid buffering a high pH soil for zinc diffusion

Journal Article · Sat Mar 01 04:00:00 EST 1997 · Journal of Geotechnical Engineering

DOI:https://doi.org/10.1061/(ASCE)1090-0241(1997)123:3(260)· OSTI ID:455421

Shackelford, C D; Cotten, T E; Rohal, K M; Strauss, S H ^[1]

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1. Colorado State Univ., Fort Collins, CO (United States)

The effective use of an aqueous buffer solution of acetic acid and sodium acetate (1.0 M HOAc/1.4 M NaOAc, pH = 4.8) to lower the pH of a sand-attapulgite clay mixture from 9.4 to 4.8 is demonstrated. Soil buffering is necessary to prevent precipitation of Zn{sup 2+} as Zn(OH){sub 2(s)} during zinc diffusion tests. The choice of the acetic acid/sodium acetate buffer solution is based on results of batch-type tests and permeation tests performed to evaluate the soil-mixture pH lowering and buffering capacity of dilute solutions of HNO{sub 3} (a strong acid), 0.057 M HOAc (a weak acid), potassium hydrogen phthalate (a pH {approximately} 4 buffer), and the 1.0 M HOAc/1.4 MNaOAc buffer solution. Measured values of effective diffusion coefficients D* for zinc on unconfined, compacted test specimens of the buffered soil mixture ranged from 0.54 {times} 10{sup {minus}6} cm{sup 2}/s to 6.5 {times} 10{sup {minus}6} cm{sup 2}/s. This range of D*-values is within the range of D*-values reported for most reactive inorganic solutes in saturated clay soils and at the lower end of the range of D*-values for zinc in saturated clay soils.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States)
• OSTI ID: 455421
• Journal Information: Journal of Geotechnical Engineering, Journal Name: Journal of Geotechnical Engineering Journal Issue: 3 Vol. 123; ISSN 0733-9410; ISSN JGENDZ
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BUFFERS
CLAYS
DIFFUSION
ENVIRONMENTAL TRANSPORT
LINERS
SANITARY LANDFILLS
SOIL CHEMISTRY
ZINC