Application of Partial Least Squares-Kernel Calibration in Competitive Adsorption Studies Using an Effective Chemically-Activated Biochar

In this work, chemically activated pine wood was used to prepare biochar, which was used to study the competitive adsorption behavior of four colorants (allura red (AR), brilliant black (BB), tartrazine (TT), and sunset yellow (SY)). Dye concentrations in mixed solutions were simultaneously estimated by using partial least squares Kernel calibration. The analytical recovery of food dyes was 96.7-103.4% and prediction error was 1.4-9.4%. Adsorption isotherms of dyes (at pH 2 and 25°C) from multi-solute solutions were measured and the maximum adsorption capacities (according to the Jovanovich's model) were 68.4, 40.0, 29.6, and 23.4mg/g for SY, AR, TT, and BB, respectively. The biochar had a combined retention capacity of 186.9mg/g for dyes. The effects of dosage of adsorbent, pH and number of competing solutes on %Removal-retention capacity were studied. The extent of competition between dyes toward the surface was assessed from the magnitudes of competition factors. The competition factors were 0.69, 0.70, 0.75, and 0.76 for AR, TT, BB, and SY, respectively. During adsorption of mixtures from solution, SY manifested stable performance while allura red negatively competed with the rest of the dyes. Partial least squares Kernel calibration was usefully applied for studying competitive adsorption behavior of four food-dyes with minimum experimental setup.