A Comprehensive Approach to Heavy Metal Removal by Adsorption: A Review

In the years, the existence and accumulation of heavy metal in water has become a general problem. Owing to the fact that these heavy metals tend to pose health hazard to human and aquatic live if their concentration exceeds the maximum contaminant level. This study seeks to review the use of chitin- and chitosan-based material in comparison with some other adsorptive materials such as activated carbon, zeolite and peat that have been used in the past for heavy metal ion removal. Their merits and shortcomings in application are also discussed. The maximum adsorption capacities obtained by these adsorbents from Langmuir isotherm model and the conditions such as temperature, equilibrium time, initial concentration range and pH at which these adsorption capacities were obtained are presented. The characteristics of physical and chemical adsorption and factors affecting adsorption of metal ions were presented and discussed. Consequently, the desorption of these ions from metal-loaded adsorbent is also highlighted, as they provide important information of the re-use of the adsorbent.