This book reviews principles, techniques and applications of metal, metal oxides, metal sulfides and metal-organic frameworks for removal and degradation of pollutants. Natural materials are often much more advanced than synthetic materials in terms of circularity and are functional, often biodegradable, recyclable and generate little waste. They are, therefore, a source of inspiration for new synthetic materials. In particular, recent research has focused on various types of functional materials such as organic, inorganic, nanostructured and composites for the remediation of environmental pollution.