Abstract
The possible use of leaching residue from leaching deep-sea nodules in SO2/H2SO4/H2O medium as a low-cost adsorbent of heavy metals (Pb(II), Cd(II), Cu(II), Ni(II), Co(II), As(V)) was studied. The leaching residue was found to be an effective adsorbent for all of the tested elements; however, it was inactive in the solution containing As(V). The chemical activation of adsorbent in 10 vol. % HCl resulted in the greatest improvement of adsorption properties, while the activation in 10 vol. % HNO3 and heat treatment at 250 °C did not significantly affect the sorption characteristics of treated adsorbents compared with the original leaching residue. After HCl activation, the maximal adsorption capacities for lead (12.0 mg/g at pH 5.0 after 1 h), nickel (3.1 mg/g at pH 5.5 after 4 h) and cobalt (2.0 mg/g at pH 5.0 after 2 h) were achieved. Additional mechanical treatment connected with HCl activation provided the highest adsorption capacities for cadmium (11.5 mg/g at pH 4.0) and copper (5.7 mg/g at pH 4.5). Coprecipitation of Fe/Al-based particles on the surface of the leaching residue increased As(V) removal of the adsorbent. Surface coating based on AlIII was extremely effective, causing the increase of the adsorption capacity from 0 with the original leaching residue, to 28.1 mg/g (pH 7.0, 24 min). Kinetics studies showed the rapid progress of adsorption for Pb(II), Cd(II), and As(V) in tens of minutes, while the adsorption of Cu(II), Ni(II) and Co(II) approached a steady state after 2 h.
Highlights
Deep-sea manganese polymetallic nodules are sedimentary formations covering the bottom of many global seas and oceans
The residues generated by NH3 -SO2 leaching of manganese nodules were successfully used as an adsorbent of Ni2+, Cr6+, Cu2+, Cd2+ and Pb2+ [4,5,16,17,18], with removal efficiency strongly dependent on pH, temperature and usually initial metal ion concentration in the solution
Researches show that effective composite adsorbents can be synthesized by forming an oxide surface coating on another supporting material, and that these composite adsorbents can be separated from the aqueous solution after an adsorption process
Summary
Deep-sea manganese polymetallic nodules are sedimentary formations covering the bottom of many global seas and oceans. Studies on adsorption of heavy metals on deep-sea nodule leach residues have been carried out mainly in India. The residues generated by NH3 -SO2 leaching of manganese nodules were successfully used as an adsorbent of Ni2+ , Cr6+ , Cu2+ , Cd2+ and Pb2+ [4,5,16,17,18], with removal efficiency strongly dependent on pH, temperature and usually initial metal ion concentration in the solution. Researches show that effective composite adsorbents can be synthesized by forming an oxide surface coating on another supporting material, and that these composite adsorbents can be separated from the aqueous solution after an adsorption process. The objective of this research was to prepare, characterize and describe the adsorption potential of materials based on leaching residues obtained from deep-sea nodule leaching in SO2 -H2 SO4 -H2 O medium. The preparation of new nanocoated adsorbents based on the leaching residues, and the efficiency of their subsequent use for As(V) removal, was studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
