Adsorptivity of heavy metals CuII, CdII, and PbII on woodchip-mixed porous mortar

Here, we developed a woodchip-mixed porous mortar (WPM) by mixing wood chips obtained from thinned Japanese cedar wood with porous mortar aggregates and evaluated the adsorption properties of the heavy metal ions CuII, CdII, and PbII on the WPM. The cation-exchange capacity (CEC) of cup-shaped WPM was approximately twice as large as that for wood chips. The saturation adsorption capacity of WPM for the heavy metal ions CuII, CdII, and PbII, determined by passing an aqueous solution of heavy metal ions, was 6, 23, and 7 times as much, respectively, as wood chips alone. Furthermore, the elution behavior of heavy metal ions adsorbed by WPM was studied by fractionation, wherein the metal speciation was divided into five classes by a sequential extraction method. The leached percentage of Fractions 1 and 2 combined, corresponding to the more easily eluted species of CdII, was higher than those of CuII and PbII. Finally, we found that the immersion of flat WPM in pure water and 3% sodium chloride for 1 year did not degrade the sample, which maintained its high adsorption capacity for heavy metal ions.

• Woodchip-mixed porous mortar (WPM) was developed.
• Cation exchange capacity of WPM is twice as large as that of wood chips.
• WPM can adsorb 23 times the amount of CdII as can wood chips.
• Speciation of Cu, Cd, and Pb adsorbed to WPM allows control of elution behavior.
• WPM maintains high adsorptivity for Cu, Cd, and Pb even after immersion for 1 year.