Recent progress on corn (Zea mays L.)-based materials as raw, chemically modified, carbonaceous, and composite adsorbents for aquatic pollutants: A review

Adsorption is a low-cost, efficient and flexible method that can be applied to decontaminate polluted (waste) water. Among other materials, agricultural biomass/waste can be satisfactorily used in raw or modified form as adsorbent for the aforementioned purpose. Corn (Zea mays L.) is the most significant grain crop worldwide after wheat and rice. It is widely cultivated and consumed as food, feed, and industrial raw material, along with the release of a large quantity of corn wastes. Such abundant, renewable, and cheap wastes with unique chemical compositions can be efficiently converted into adsorbents for various aquatic contaminants thus supporting the concept of circular economy and green chemistry. This article represents an extensive review on the use of corn biomass/waste to produce adsorbents (raw, chemically modified, carbonaceous, and composites) for the elimi-nation of metal ions, dyes, pharmaceuticals, pesticides, inorganic ions, phenols and other contaminants. The maximum adsorption capacities for most studied pollutants were 227.27 and 158.7 mg/g for chromium and cadmium, 1301.10 and 512.80 mg/g for methylene blue and malachite green, and 612.38, 201.56, 102.041, and 221.89 mg/g for tetracycline, atrazine, nitrate, and phosphate, respectively. The adsorption behavior, mecha-nism, and regeneration of the studied adsorbate/adsorbent systems are identified. Special emphasis is also given to other adsorption parameters (pH, adsorbent dose, initial concentration, temperature, etc.). Isotherm, kinetic and thermodynamic studies are also discussed in detail. Important findings and future ideas are finally mentioned.