Effect of variable magnetic fields on chromium (VI) removal capacity from water by watercress (Nasturtium officinale): a model proposed

This study presents the effect of a variable magnetic field on chromium (VI) absorption typical of a hydroponic system for Phytoabsorption using watercress (Nasturtium officinale) plants in a batch system. The experimentation was carried out applying magnetic fields of 12 and 44 mT and comparing it with the system without field; the field was generated by arrangement of coils and specific conditions for each system, for this work solutions with concentrations of 1, 10, and 20 ppm of chromium (VI) were used during a four-week process with the objective of evaluating the effect of the magnetic field in bioaccumulation in the system. The results indicate that the absorption of chromium increased per week, having that in most of the study cases (0 mT, 12 mT, 44 mT) the highest absorption was achieved in week 4, having that for all cases between week 3 and 4 the difference is minimal, likewise the results indicate that when implementing a magnetic field bioaccumulation is favored showing similar results for both magnetic fields studied in this work. The highest removal efficiency for the study cases corresponding to 1 ppm and 10 ppm was achieved when a field of 12 mT was applied, reporting values of 0.83 and 0.85 respectively, with respect to the case of 20 ppm, the highest efficiency was 0.83 applying a field of 44 mT. Statistical correlation models were found using multiple linear regression model finding significant variables (the magnetic field, concentration of chromium (VI), exposure time). With the interaction model we found significant interactions (concentration*week and field*concentration), and with the model of quadratic terms and interactions (non-significant field*week), which presented adequate adjustments description of the phenomenon, r<^>2=0.965 using coefficient analysis.