Remediation of contaminants from wastewater using algal nanoparticles via green chemistry approach: an organized review

Bio-nanotechnology is one of the new and sound techniques that have various advantages over conventional methods of wastewater treatment. The utilization of nanomaterials like nanoparticles for wastewater treatment is emerging field of research. Both physical and chemical methods can be used for nanoparticle synthesis, but synthesis based on algae (biological method) has numerous advantages over others as it is environmentally friendly and sustainable. Top-down and bottom-up are the two approaches used for nanoparticle synthesis, generally, bio-reduction (bottom-up approach) is used to synthesize nanoparticles. Nanoparticles can be synthesized inside the cell of algae called intracellular synthesis and outside on the surface of the cell called extracellular synthesis. Temperature, pH, and reaction time are some of the factors that can influence the synthesis, size, and properties of nanoparticles. Characterization of nanoparticles is carried out with the help of the techniques like UV-visible spectroscopy (UV-vis), x-ray diffraction, Fourier transfer infrared spectroscopy, etc. Algal nanoparticles are highly efficient in the remediation of contaminants like heavy metals and dyes from wastewater. In the present review, the utilization of algal nanoparticles for wastewater treatment containing contaminants like heavy metals, and dye, and various methods of synthesis of nanoparticles from algae are discussed. Moreover, the challenges and opportunities present in this field are also highlighted. As this field is in its initial stage, therefore, a lot of research gaps are present, which can only be filled by further new research.