Chemical removal of contaminants may be accomplished with which of the following?

Chemical removal of contaminants is commonly achieved using surfactants or solvents. Surfactants lower the surface tension between two substances, such as water and oil, which allows contaminants to be dispersed and removed more easily. They help to break down and solubilize contaminants, making it easier to wash them away or bind them to other substances for removal.

Solvents, on the other hand, can dissolve various types of contaminants, allowing for their extraction from solid or liquid matrices. This process is vital in environmental remediation and hazardous waste management, as it allows for the effective treatment of contaminated materials, ensuring safer and cleaner environments.

The other methods listed, while effective in certain contexts, do not primarily focus on the chemical removal of contaminants. Heat or pressure can change the state or phase of a substance but does not chemically alter or remove contaminants in the way that surfactants or solvents do. Vacuum or filtration are mechanical methods of separation rather than chemical and may not effectively address all types of contaminants. Mixing or dilution can reduce concentration but does not involve a chemical process for breaking down or removing harmful substances.