Spectrophotometric determination of trace amount of malachite green from water with novel magnetic silica nanoparticles

A nano-hybrid based on polystyrene derivatives and magnetite was introduced as a new sorbent for pretreatment and determine the trace amount of malachite green from aqueous solution by spectrophotometry after preconcentration by solid phase extraction (SPE). UV–Vis spectrophotometer was used for determination of MG concentration after desorption of the dye by hydrochloric acid solution in the solutions. Different variables‌‌ affecting the separation/pre-concentration conditions, including pH of the sample solution, amount of the sorbent, extraction and desorption times, sample volume, and elution conditions were obtained in the range of 1–2000 ng/mL dye, with the correlation coefficient of 0.998. The enrichment factor of 133 was achieved. The limit of detection was 0.2 ng·mL−1 and the relative standard deviation for the determination of malachite was 1.4 % (n=6(. Langmuir, Freundlich, adsorption isotherm models were studied and the experimental results were addressed by Freundlich isotherm model. The maximum sorption capacity of the adsorbent for malachite green was 148.6 mg. g-1,  indicating high potential of MSMA in the adsorption of malachite green. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order  models. The method was successfully applied to determine malachite green in natural waters and satisfactory recoveries were obtained >98 %.from this.