Synthetic transformed demercuric acid

Isn’t it absorbed using activated carbon? This is the method used by most PVC manufacturers.

Precipitation method: Sodium sulfide is added to mercury-containing wastewater; due to the strong affinity between Hg2+ and S2-, mercury sulfide with a low solubility product is formed, thereby removing it from the solution. Therefore, the sulfide precipitation method is the most commonly reported precipitation treatment method. The precipitation method can be combined with separation processes such as flocculation, gravitational sedimentation, filtration, or air flotation. These subsequent operations can enhance the removal of mercury sulfide precipitates, but they do not improve the precipitation efficiency of dissolved mercury itself. When the initial mercury concentration is high, the sulfide precipitation method can achieve a removal rate of over 99.9%. However, even after advanced treatment with filtration or activated carbon, the minimum concentration of mercury in the effluent remains at 10–20 µg/L. The precipitation effect is best within a neutral pH range without increasing the amount of sulfides; when pH > 9, the precipitation efficiency drops sharply. In addition to the drawback of being unable to reduce the mercury content to below 10µg/L, this method has other shortcomings: (1) Soluble mercury sulfide complexes are formed when there is an excess of sulfides; (2) It is difficult to monitor the degree of sulfide excess; (3) The residual sulfur in the treated wastewater can cause pollution problems. Raw and auxiliary materials used in wastewater treatment: (1) NaHS (sodium hydrosulfide): purity ≥70% (by mass), Na2S

Those who pay close attention will notice that the information mentioned above is available to everyone; I have merely done some organizing of it, in the hope that it will be helpful to all!