Studying competitive sorption behavior of methylene blue and malachite green using multivariate calibration

Abstract Sorption of methylene blue MB and malachite green MG (with 96.4% spectral overlap) from bi-solute solution by natural kaolinitic-clay and philipsite-rich-zeolite tuff was addressed where solutes simply quantified using multivariate calibration MVC. For simultaneous quantification of dyes in solution, partial least squares PLS1 (a powerful MVC tool) was found satisfactory with high recovery (98.7–103.2%) and precision (RSD 9.2–11.7%). In MVC, the spectral range 409–700 nm is used and 43 spectral points where taken for each sample. Natural clay (80% kaolinite) and zeolite tuff (95% philipsite) showed a high uptake for dyes with maximum capacities of 0.77 mmol MB/g clay and 0.64 mmol MG/g clay , 0.66 mmol MB/g zeolite and 1.22 mmol MG/g zeolite reported at 1.0 g/L, particle diameter