Chitosan-transition metal ions complexes for selective arsenic(V) preconcentration

Area of Science:

• Environmental Science
• Materials Science
• Analytical Chemistry

Background:

• Chitosan, a natural biopolymer, exhibits a strong affinity for transition metal ions.
• Chitosan-metal ion complexes can effectively adsorb inorganic arsenic anions from aqueous solutions.
• Arsenic contamination in water poses significant environmental and health risks.

Purpose of the Study:

• To investigate the efficacy of chitosan complexed with various transition metal ions for arsenic(V) sorption.
• To evaluate the performance of iron(III)-chitosan as a sorbent for arsenic(V) removal from different water matrices.
• To develop and characterize novel Fe(III)-chitosan based sorbent materials for arsenic preconcentration.

Main Methods:

• Synthesis and characterization of chitosan-metal ion complexes, including Fe(III)-chitosan.
• Arsenic(V) sorption studies using a (74)As radiotracer across a range of pH conditions.
• Preparation of self-supported membranes and fibrous matrix-supported Fe(III)-chitosan sorbents.
• Material characterization using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Fluorescence (EDXRF).
• Quantification of preconcentrated arsenic using Instrumental Neutron Activation Analysis (INAA).

Main Results:

• Fe(III)-chitosan and La(III)-chitosan complexes demonstrated high As(V) sorption (95 ± 2%) in the pH range of 3-9.
• Fe(III)-chitosan exhibited superior As(V) sorption efficiency (91 ± 2%) from seawater compared to La(III)-chitosan (80 ± 2%).
• Experimental sorption capacities for Fe(III)-chitosan were 51 mg g(-1) for fibrous sorbents and 109 mg g(-1) for self-supported membranes.
• The developed Fe(III)-chitosan materials were successfully used for preconcentration of As(V) from tap water, groundwater, and seawater.

Conclusions:

• Fe(III)-chitosan is a highly effective sorbent for removing arsenic(V) from various aqueous media, including challenging matrices like seawater.
• The developed self-supported membrane and fibrous matrix-supported Fe(III)-chitosan sorbents offer efficient preconcentration of arsenic.
• This study presents a promising chitosan-based material for practical arsenic remediation and preconcentration applications.