The present study couples the
acid/basis titration and the ICP analysis in order to monitor the
concentrations of nitric and hydrofluoric acids, and presents into baths used to pickle alloys of titanium or stainless steel,
largely employed in the aeronautic industry. The pickling of the alloys releases various metallic cations able to react with HF in order to lead to
metal-fluoride complexes and free H+, the last being able to react
with the basis. In this study,it was determined: the most significant correlations providing the number of
the protons released by the complexation of the metallic cation by the
fluoride. The proposed method based on: 1) these
correlations;2) the titration pH=f(VKOH) curves; and 3) the
content of metallic cations determined by ICP, enables the monitoring of the
content of HNO3 and HF into the pickling bath. Assuming that one
bath was used for one type of alloy (alloys of Titanium for example, or alloys
of stainless steel), then the proposed method appears providing reliable
concentration values of both acids as well as metallic cations.
References
[1]
Bahadori, A. (2015) Essentials of Coating, Painting, and Lining for the Oil, Gas and Petrochemical Industries. In: Surface Preparation for Coating, Painting, and Lining, Chapter 1, Elsevier, Amsterdam, 1-105.
[2]
Kladnig, W.F. (2008) New Development of Acid Regeneration in Steel Pickling Plants. Journal of Iron and Steel Research International, 15, 1-6.
https://doi.org/10.1016/S1006-706X(08)60134-X
[3]
Sutter, E.M.M. and Goetz-Grandmont, G.J. (1990) The Behavior of Titanium in Nitric-Hydrofluoric Acid Solutions. Corrosion Science, 30, 461-476.
https://doi.org/10.1016/0010-938X(90)90051-6
[4]
Say, W.C. and Tsai, Y.Y. (2004) Surface Characterization of Cast Ti-6Al-4V in Hydrofluoric-Nitric Pickling Solutions. Surface and Coatings Technology, 176, 337-343. https://doi.org/10.1016/S0257-8972(03)00747-3
[5]
Schneiker, T. and Forsberg, K. (2014) Process Chemistry and Acid Management in Titanium Pickling Processes. Conference on Titanium Europe, Sorrento, 19-21 May 2014.
[6]
Steinert, M., Acker, J., Oswald, S. and Wetzig, K. (2007) Study on the Mechanism of Silicon Etching in HNO3-Rich HF/HNO3 Mixtures. The Journal of Physical Chemistry C, 111, 2133-2140. https://doi.org/10.1021/jp066348j
[7]
Tongwen, X. and Weihua, Y. (2003) Industrial Recovery of Mixed Acid (HF + HNO3) from the Titanium Spent Leaching Solutions by Diffusion Dialysis with a New Series of Anion Exchange Membranes. Journal of Membrane Science, 220, 89-95. https://doi.org/10.1016/S0376-7388(03)00218-7
[8]
Cros, C. and Bares, P. (2012) Procédé de régénération d’une solution de décapage ou d’usinage chimique de titane. French Patent, EP2438210A1.
[9]
Hermoso, J., Dufour, J., Gálvez, J.L., Negro, C. and López-Mateos, F. (2005) Nickel Hydroxide Recovery from Stainless Steel Pickling Liquors by Selective Precipitation. Industrial & Engineering Chemistry Research, 44, 5750-5756.
https://doi.org/10.1021/ie050422n
[10]
Gálvez, J.L., Dufour, J., Negro, C. and López-Mateos (2006) Fluoride Speciation in Stainless Steel Pickling Liquor. ISIJ International, 46, 281-286.
https://doi.org/10.2355/isijinternational.46.281
[11]
Gumin, K., Kwangchil, L., Haesung, P., Jinho, L., Youngjean, J., Kyoungsik, K., Boongho, S. and Hyoungkuk, P. (2010) Quantitative Analysis of Mixed Hydrofluoric and Nitric Acids using Raman Spectroscopy with Partial Least Squares Regression. Talanta, 81, 1413-1417. https://doi.org/10.1016/j.talanta.2010.02.045
[12]
Gumin, K., Kwangchil, L., Haesung, P., Jinho, L., Youngjean, J. and Kyoungsik, K. (2010) Optical Measurement for the Concentrations of the Pickling Acid with Near Infrared Spectroscopy in Steel Making Industry. SPIE Proceedings, 7792, 77920G.
[13]
Lindroos, K. (1987) Determination of Free Hydrofluoric and Nitric Acids in Pickling Bath Liquors using a Fluoride-Selective Electrode and Alkalimetric Titration. Analyst, 112, 71-73. https://doi.org/10.1039/an9871200071
[14]
Gálvez, J.L., Dufour, J., Negro, C. and López-Mateos, F. (2009) Routine to Estimate Composition of Concentrated Metal-Nitric-Hydrofluoric Acid Pickle Liquors. Hydrometallurgy, 96, 88-94. https://doi.org/10.1016/j.hydromet.2008.08.007
[15]
Gong, W.X., Qu, J.-H., Liu, R.-P. and Lan, H.-C. (2012) Effect of Aluminum Fluoride Complexation on Fluoride Removal by Coagulation. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 395, 88-93.
https://doi.org/10.1016/j.colsurfa.2011.12.010
[16]
Gálvez, J.L., Dufour, J., Negro, C. and López-Mateos, F. (2008) Determination of Iron and Chromium Fluorides Solubility for the Treatment of Wastes from Stainless Steel Mills. Chemical Engineering Journal, 136, 116-125.
https://doi.org/10.1016/j.cej.2007.03.014
[17]
Seigneur, C. and Constantinou, E. (1995) Chemical Kinetic Mechanism for Atmospheric Chromium. Environmental Science Technology, 29, 222-231.
https://doi.org/10.1021/es00001a029
[18]
Regel-Rosocka, M. (2010) A Review on Methods of Regeneration of Spent Pickling Solutions from Steel Processing. Journal of Hazardous Materials, 177, 57-69.
https://doi.org/10.1016/j.jhazmat.2009.12.043
[19]
Ghare, N.Y., Wani, K.S. and Patil, V.S. (2013) A Review on Methods of Recovery of Acid(s) from Spent Pickle Liquor of Steel Industry. Journal of Environmental Science & Engineering, 55, 253-266.
