Water purification is considered one of the most essential issues in our lives. Therefore, the contamination of water surfaces owing to the hasty upsurge in industrialization has received great global attention because of its potential danger to human health and the eco-system. Particularly, the discharge of various non-biodegradable contaminants into the water body—heavy metal ions, organic dyes, pharmaceutical antibiotics, pesticides, and oils—causes these contaminants to accumulate on the water's surface and have harmful impacts on humans and the environment. Several conventional methods can be applied to solve this problem, including chemical oxidation, precipitation, coagulation, and so on. However, they suffer from serious limitations: high cost, limited functionality, prolonged and heavy energy use, and poor separation efficiency. Conversely, the adsorption technique has recently attracted a lot of attention for wastewater treatment thanks to its remarkable benefits of being a simple, highly selective, and low-cost technique. Recently, natural polysaccharides (especially starch)-based adsorbents have received great interest in water purification owing to their outstanding properties, including being easily available, non-toxic, low-cost, biodegradable, and biocompatible. However, it possesses notable drawbacks that prevent it from being used alone as an adsorbent for wastewater treatment, including low thermal stability, slight water solubility, and rapid degradability in water. Therefore, this review highlights a comprehensive presentation about various starch modifications: starch-based grafts, hydrogels, aerogels, beads, nanofibers, and nanocomposite formulations to remove several toxic contaminants, including toxic heavy metal ions, organic dyes, pharmaceutical antibiotics, pesticides, and oils.
