Patent ID: 6339222
Filing Date: 2002-01-15
Classification: D21C,G01N

Abstract:
A method for determining the concentration of hydrogen ion, organic anionic species and anionic species selected from the group consisting of OHâˆ’, CO3&boxH;, HSâˆ’, ClO3âˆ’, SO4&boxH;, S2O3&boxH;, polysulphide and peroxide to a level of precision of about Â±1 g/L species concentration in a sample pulp mill process liquor containing at least OHâˆ’, CO3&boxH; and HSâˆ’, and further containing one or more components selected from the group consisting of suspended solids, suspended fibers, gaseous bubbles, lignin, hemicellulose and cellulose degradation products, fatty acids and resinous acids, said method comprising subjecting said liquor to near infrared radiation at a wavelength region of wave numbers selected from about 7,000 to 14,000 cmâˆ’1 through a liquor path length of at least 3 mm to obtain spectral data for said liquor; obtaining comparative spectral data for said anionic species at known concentrations in aqueous solutions; and correlating by multivariate calibration the relationships between said spectral data of said sample liquor and said comparative spectral data to determine said concentration of said anionic species in said sample liquor.