The effect of magnetic field on ion hydration and sulfate scale formation

• Treating cations with MF led to sulfate scales smaller than the conventional ones.
• Memory effects of magnetically treated cations last 2 days, but heating destroy them.
• The crystallinity of sulfate scales was weakly affected by MF treatment.
• MF treated divalent cations are more hydrated than the untreated counterparts.
• Divalent cations are more affected by MF than monovalent cations.

Scale is one of the most common and costly problems in industrial water treatment and petroleum industry. In this study, 0.5 M Ba(NO3)2, 0.5 M Sr(NO3)2, 0.5 M Ca(NO3)2, 0.5 M AgNO3, 0.5 M Na2(SO4) and 0.5 M NaCl solutions flowed with a flow rate of 25 L/h under magnetic flux of 1.0 T. After magnetic treatment, BaSO4, SrSO4, CaSO4 and AgCl salts were precipitated using equivalent volumes of cation and anion scalant. The colloidal dispersions were characterized by means of sedimentation rate measurements and low angle laser light scattering (LALLS). The effect of the magnetic treatment was more evident in the case of SrSO4, scales, which led to considerably smaller particles and more stable dispersions. This effect remained for two days after treating the pristine solutions. The “memory” effect was destroyed upon heating at 60 °C for 20 min. The crystallinity of insoluble particles was weakly affected by the external magnetic field. The kinematic viscosity values of 0.5 M Ba(NO3)2, 0.5 M Sr(NO3)2 and 0.5 M Ca(NO3)2 solutions treated with a magnetic field were larger than those of untreated solutions. However, no effects could be observed for 0.5 M AgNO3, 0.5 M Na2(SO4) and 0.5 M NaCl solutions treated with magnetic field. A model based on the effect of magnetic field on the ion hydration and orientation at air/water interface was proposed to explain the experimental observations.

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