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2 Ars Separatoria Acta

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Effect of a chelating agent on the synthesis of zeolitic materials from waste sandstone cake using alkali fusion

Wajima T., Ikegami Y.

Ars Separatoria Acta

2007

No. 5

76-87

During quarrying, waste stone cake is discharged as industrial waste, and in Japan the amount of cake amounts annually to 50 millions tons. To promote waste recycling, we attempted to convert waste sandstone cake into zeolitic material using alkali fusion. However, calcium causes the synthesis of an undesirable zeolite by interfering in the synthesis of a high functional zeolite. As a means to inhibit this Ca-interference, we studied the effect of adding a chelating agent, EDTA (Ethylenediaminetetraacetic acid disodium dihydrate), on the synthesis of zeolitic material from sandstone cake using alkali fusion. Hydroxysodalite, zeolite-X and zeolite-P can be synthesized from sandstone cake using alkali fusion. With the addition of EDTA, calcium ions in solution were trapped by chelation, and the amount of zeolite-X and zeolite-P increased. A product with a high CEC, which has a high content of zeolite-X, can be obtained. The chelating agent can inhibit Cainterference for zeolite synthesis by Ca-masking, and the product with high content of zeolite-X can be obtained from waste sandstone cake using alkali fusion.

Zeolitic adsorbent synthesized from powdered waste porcelain, and its capacity for heavy metal removal

Wajima T., Ikegami Y.

Ars Separatoria Acta

2006

No. 4

86-95

A zeolitic adsorbent was synthesized from powdered waste porcelain kept at 80 °C for 24 h. The product contained the zeolite phases Na-P1 and hydroxysodalite. The product with the highest cation exchange capacity (CEC) was synthesized using 4 M NaOH and the sample weight / volume of alkali solution ratio was 1/4. The highest CEC obtained for the product was almost 1900 mmol/kg, which is the same as that of natural zeolite. The product with the highest CEC was tested for its ability to remove heavy metals (Fe, Cu, Ni, Zn, Pb, Cd, Mn, Cr, Al, B, Mo) from an acidic solution (pH 2). The product can neutralize the acidic solution to almost pH 7, and the capacity of the product for the removal of heavy metals is higher than that of the natural zeolite, except for Mo and B.