Heavy metal is released from many industries into water. Before the industrial wastewater is discharged, the contamination level should be reduced to meet the recommended level as prescribed by the local laws of a country. They may be poisonous or cancerous in origin. Their presence does not only damage people, but also animals and vegetation because of their mobility, toxicity, and non-biodegradability into aquatic ecosystems. The review comprehensively discusses the progress made by various adsorbents such as natural materials, synthetic, agricultural, biopolymers, and commercial for extraction of the metal ions such as Ni2+, Cu2+, Pb2+, Cd2+, As2+ and Zn2+ along with their adsorption mechanisms. The adsorption isotherm indicates the relation between the amount adsorbed by the adsorbent and the concentration. The Freundlich isotherm explains the effective physical adsorption of the solute particle from the solution on the adsorbent and Langmuir isotherm gives an idea about the effect of various factors on the adsorption process. The adsorption kinetics data provide valuable insights into the reaction pathways, the mechanism of the sorption reaction, and solute uptake. The pseudo-first-order and pseudo-second-order models were applied to describe the sorption kinetics. The presented information can be used for the development of bio-based water treatment strategies.

Centro de Nanociencia y Nanotecnologia Universidad de las Fuerzas Armadas ESPE Av Gral Rumiñahui s n Sangolqui 171103 Ecuador

Department of Chemistry DAV College Sector 10 Chandigarh 160011 India

Department of Chemistry MCM DAV College for Women Sector 36 Chandigarh 160036 India

Department of Physics National Institute of Technology Srinagar Srinagar 190006 India

Department of Production Engineering Warsaw University of Life Sciences 02 787 Warsaw Poland

Faculty of Business and Economics Mendel University in Brno 61300 Brno Czech Republic

Institute of Forensic Science and Criminology Panjab University Chandigarh 160014 India

Post Graduate Department of Chemistry TATA College Jharkhand Chaibasa 833202 India

Smart Society Research Team Faculty of Business and Economics Mendel University in Brno 61300 Brno Czech Republic

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