Water pollution is one of the global challenges that society must address in the 21st century aiming to improve water quality and reduce human and ecosystem health impacts. Industrialization, climate change, and expansion of urban areas produce a variety of water pollutants. In this work, we discuss some of the most recent and relevant findings related to the release of heavy metals, the possible risks for the environment and human health, the materials and technologies available for their removal. Anthropogenic activities are identified as the main source of the increasing amounts of heavy metals found in aquatic environments. Some of the health hazards derived from repeated exposure to traces of heavy metals, including lead, cadmium, mercury, and arsenic, are outlined. We also give some perspectives about several techniques used to detect heavy metals, as well as about the factors that could affect the contaminant removal. The advantages and drawbacks of conventional and non-conventional heavy metal removal methods are critically discussed, given particular attention to those related to adsorption, nanostructured materials and plant-mediated remediation. Some of the commercial products currently used to eliminate heavy metals from water are also listed. Finally, we point out some the requirements and opportunities linked to developing efficient methods for heavy metal removal, such as the ones that exploit nanotechnologies.

Heavy metal water pollution: A fresh look about hazards, novel and conventional remediation methods

Heavy metal contamination has been a serious threat to environment and human health Carbon-based materials, from biochar/activated carbon to modified materials (ie carbon nanotubes-based materials, and graphene-based materials), have been widely studied as efficient adsorbents for the heavy metal removal from aqueous solutions This review discussed the recent achievements in adsorption isotherms, adsorption kinetics and adsorption mechanism according to the existing forms of heavy metals in water The effect of process conditions, such as temperature, pH value, and coexisting ions, on adsorption performance are combed, and the universal guidance law is obtained The physical adsorption, electrostatic interaction, ion exchange, surface complexation, and precipitation/coprecipitation play important roles in heavy metals adsorption process In addition to the common activated carbon(AC), biochar(BC) and the emerging carbon nanotubes(CNTs) and graphene(GN) adsorbent show good development potentials Meanwhile, though the modified carbonaceous materials can achieve high adsorption capacity and removal efficiency of heavy metals, the modification operation is complex, especially chemical modification Acid and alkali solution are often used to regenerate spent materials in desorption, however, further studies of other desorption reagent are really needed This review highlights the removal of heavy metal ions from aqueous solution using carbon-based materials as adsorbents, and discusses the existing deficiencies and suggestions on further study

Removal of heavy metals from aqueous solution using carbon-based adsorbents: A review

Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development.

Removal of metal ions using a new magnetic chitosan nano-bio-adsorbent; A powerful approach in water treatment.

In this study, a magnetic chitosan/Al2O3/Fe3O4 (M-Cs) nanocomposite was developed by ethylenediaminetetraacetic acid (EDTA) functionalization to enhance its adsorption behavior for the removal of Cd(II), Cu(II) and Zn(II) metal ions from aqueous solution. The results revealed that the EDTA functionalization of M-Cs increased its adsorption capacity ~9.1, ~5.6 and ~14.3 times toward Cu, Cd and Zn ions. The maximum adsorption capacity followed the order of Cd(II) > Cu(II) > Zn(II) and the maximum adsorption efficiency was achieved at pH of 5.3 with the removal percentage of 99.98, 93.69 and 83.81 %, respectively, for the removal of Cu, Cd and Zn ions. The metal ions adsorption kinetic obeyed pseudo-second-order equation and the Langmuir isothermal was found the most fitted model for their adsorption isothermal experimental data. In addition, the thermodynamic study illustrated that the adsorption process was exothermic and spontaneous in nature. 

Xiaomin Li

Papers

Removal of chelated heavy metals from aqueous solution: A review of current methods and mechanisms

Denitrification performance and microbial community of bioreactor packed with PHBV/PLA/rice hulls composite.