Opportunities and constraints of using the innovative adsorbents for the removal of cobalt(II) from wastewater: A review

The presence of cobalt(II) in wastewater is an emergent concern because of its toxicity at elevated concentration. Co(II) is a non-biodegradable, carcinogenic and mutagenic pollutant released from natural, industrial and manmade sources. In recent years, the control of water that has been polluted with Co(II) has been an emergent issue. The release of Co(II) into waterways is undesirable because ingestion of high levels of Co(II) may cause severe health issues including cancer. The current review discusses the different adsorbents such as carbonaceous and activated carbon materials, nanosized metal oxides, low-cost natural materials, clay minerals and nanocomposites employed by researchers to treat Co(II)-polluted water. The systems used have been assessed in terms of overall Co(II) sorption capacity. Special emphasis has been given to the environmental conditions such as contact time, solution pH, initial Co(II) concentration, temperature, and mineral dosage. Moreover, empirical and surface complexation modeling (SCM) of the sorption systems is summarized. Natural materials, agricultural waste materials, and bio sorbents exhibited outstanding Co(II) sorption performance. The current investigation provides an overview of the state of the Co(II) removal studies performed by using various adsorbents.