Removal of arsenic (V) using natural zeolite: Fixed bed column tests

Abstract

Water pollution with arsenic has received special attention due to its health implications for the population. Therefore, its removal from groundwater is of vital importance. The main objective of this work was to investigate the removal performance of dissolved arsenic in multi-ionic solutions using a low-cost mineral material and, in parallel, to be able to compare its sorption capacity from its nature as a chemically modified form. To do this, fixed bed columns packed with natural zeolites (ZN) and chemically modified (ZMQ) with 1 M H₂SO₄ were implemented. Sorption studies showed that chemical conditioning improved the maximum sorption capacity (q_e), the breakthrough time, the exhaustion time and the effluent volume with a concentration equal to or less than 10 μg/L, correspondingly by 150, 45, 88 and 281 %, concerning the ZN. The breakthrough curves for the removal of As (V) were fitted with various mathematical models, being the Thomas nonlinear model the one that best reproduced the kinetics of sorption under the implemented operating conditions. The X-ray diffraction concluded that there is no structural change in the zeolite after the chemical modification, therefore, the increase in the sorption capacity of the ZMQ was attributed to the morphological and elemental chemical composition changes on their surface. These results show that the ZMQ can be used as a viable alternative, from the point of view of purifying efficiency, concerning its non-acidified form, for the removal of As (V).