ABSTRACT
Sulfide occurs in groundwater, hot springs, and wastewater. It is also formed from the bacterial reduction of sulfate. Sulfide salts in solid waste in contact with an acid can produce hydrogen sulfide, which is highly toxic. The sulfide remaining after the removal of suspended solids is termed the dissolved sulfide. Copper and silver sulfides are insoluble even under acidic conditions. Therefore, these two sulfides are not determined in the following tests. In a nonaqueous sample, such as soil, sediment, or hazardous waste, the sample is vigorously shaken with acidified water to leach out the sulfide. Sulfide in aqueous samples or leachates may be analyzed by one of the following methods: iodometric method, methylene blue colorimetric method and silver–silver sulfide electrode method. The first two methods are commonly used in environmental analysis. The third method uses a silver electrode to indicate the end point of the potentiometric titration of dissolved sulfide with standard AgNO3. The electrode response is slow.
