Eliminating heavy metals from water with filters packed with natural zeolite of varying sizes

Abstract

The zeolite has been used effectively to adsorb harmful ions in contaminated water. The objective was to evaluate the removal of heavy metals from water using a filter packed with natural zeolites of different particle sizes. Four treatments were evaluated: 70 mm (T1-large), 30 mm (T2-medium), 500 μm (T3-small), and a combination (T4-mixed). The zeolite was characterized at the laboratory of the Mexican Geological Service (MGS). Concentrations of Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mo, Na, Ni, P, Pb, Sb, Se, Sn, Sr, Tu, Ti, Tl, V, W, and Zn were quantified from influent water (IW) and used for decontamination. In addition, the parameters of pH, EC, and TDS were estimated. The IW was filtered three times with two replicates. The statistical analysis was performed using a factorial arrangement of treatments 4×3; where Factor A was particle size (T1, T2, T3, and T4) and Factor B was several times through the filters (once, twice, and three). The zeolite was a heulandite type (CaAl2Si7O18•6H2O) with 61.43 % purity. The IW contained concentrations of As (0.189 mg l-1); B (1.339 mg l-1); Ca (23.90 mg l-1); Li (0.408 mg l-1); K (20.09 mg l-1); Mg (18.17 mg l-1), and Na (452.18 mg l-1). The four treatments were effective in removing heavy metals, but the T3-small (As = 48 %; B = 73 %; Li = 82 %; Na = 36 %) and T4-mixed Ca = 21 %; Li = 84 %; Na = 65 %; Mg = 86 %) treatments were more effective. We concluded that zeolite can be effective to remove metals in water.

Keywords

• water decontamination
• mineral
• metals
• filtration
• natural zeolites