Restrictive requirements for maximum concentrations of metals introduced into the environment lead to search for effective methods of their removal. Chemical precipitation using hydroxides or sulfides is one of the most commonly used methods for removing metals from water and wastewater. The process is simple and inexpensive. However, during metal hydroxide precipitation, large amounts of solids are formed. As a result, metal hydroxide is getting amphoteric and it can go back into the solution. On the other hand, use of sulfides is characterized by lower solubility compared with that of metal hydroxides, so a higher degree of metal reduction can be achieved in a shorter time. Disadvantages of that process are very low solubility of metal sulfides, highly sensitive process to the dosing of the precipitation agent, and the risks of emission of toxic hydrogen sulfide. All these restrictions forced to search for new and effective precipitants. Potassium/sodium thiocarbonate (STC) and 2,4,6-trimercaptotiazine (TMT) are widely used. Dithiocarbamate (DTC) compounds are also used, e.g., sodium dimethyldithiocarbamate (SDTC), and ligands for permanent metal binding, e.g., 1,3-benzenediamidoethanethiol (BDETH₂), 2,6-pyridinediamidoethanethiol (PyDET), a pyridine-based thiol ligand (DTPY) or ligands with open chains containing many sulfur atoms, using of a tetrahedral bonding arrangement around a central metal atom. The possibility of improving the efficiency of metal precipitation is obtained by using a higher dose of precipitating agent. However, toxic byproducts are often produced. It is required that the precipitation agents not only effectively remove metal ions from the solution but also effectively bind with dyes or metal complexes.

对引入到环境中的最大浓度金属的限制要求导致寻求有效的去除方法。使用氢氧化物或硫化物进行化学沉淀是从水和废水中去除金属的最常用方法之一。该过程简单且廉价。然而，在金属氢氧化物沉淀期间，形成大量的固体。结果，金属氢氧化物变成两性的，并且可以回到溶液中。另一方面，与金属氢氧化物相比，使用硫化物的特征在于溶解度较低，因此可以在更短的时间内实现较高程度的金属还原。该方法的缺点是金属硫化物的溶解度非常低，对沉淀剂的计量高度敏感，以及排放有毒硫化氢的风险。所有这些限制迫使人们寻找新的有效沉淀剂。硫代碳酸钾/钠（STC）和2,4,6-三巯基噻嗪（TMT）被广泛使用。也可以使用二硫代氨基甲酸酯（DTC）化合物，例如二甲基二硫代氨基甲酸钠（SDTC），以及用于永久金属结合的配体，例如1,3-苯二氨基乙硫醇（BDETH）₂），2，6-吡啶二氨基乙硫醇（PyDET），吡啶基硫醇配体（DTPY）或具有围绕许多金属硫原子的开链的配体，使用围绕中心金属原子的四面体键排列。通过使用更高剂量的沉淀剂可以获得提高金属沉淀效率的可能性。但是，通常会产生有毒的副产物。要求沉淀剂不仅有效地从溶液中除去金属离子，而且有效地与染料或金属络合物结合。