水銀およびメチル水銀のZnSによる除去

抄録

The removal of Hg²⁺ and CH₃Hg⁺ ions from waste water was studied by utilizing the exchage reaction between ZnS and heavy metal ions. The findings obtained are summarized as follows;
1) Hg²⁺ ion (10ppm) can be reduced to a trace amount over the wide pH range (2 to 11) by adding an adequate amount of artificial ZnS or natural sphalerite.
2) CH₃Hg⁺ ion (13ppm) can also be reduced to the same level as Hg²⁺ ion in the pH range less than 5, though the larger amount of ZnS is necessary as compared with the case of the removal of Hg²⁺ ion.
3) The reaction products formed on artificial ZnS (cubic) by the uptake of Hg²⁺ or CH3Hg+ions were identified to metacinnabar (hexagonal) by means of X-ray analysis, indicating that the reaction proceeds to produce well developed crystalline. The ratio of mercury uptaken by ZnS to Zn²⁺ emitted was found to be 1: 1 for Hg²⁺ ion and 2: 1 for CH₃Hg⁺ ion, respectively.
4) The removal of Cu²⁺, Pb²⁺ and Cd²⁺ ions was also examined by use of the same procedure. Cu²⁺ ion can be reduced to 0.05ppm by ZnS, whereas no removal of Pb²⁺ and Cd²⁺ ions is obtained, suggesting the possibility of selective removal of Hg²⁺ ion from waste water which contains coexisting metal ions having less adsorbability to ZnS.