Porous alginate aerogel beads for effective and rapid heavy metal sorption from aqueous solutions: Effect of porosity in Cu2+ and Cd2+ ion sorption

Abstract Calcium alginate porous aerogel beads were prepared by sc-CO 2 drying, characterized and for the first time evaluated for their performance on metal ion sorption in comparison with their non-porous xerogel analogues. The aerogels were mainly mesoporous, also containing micropores and macropores with BET surface area of 419 m 2  g −1 . The material exhibited enhanced sorption capacity with 20% higher degree of active site saturation after sorption compared to the xerogel beads and sorption values reaching 126.82 mg g −1 for Cu 2+ and 244.55 mg g −1 for Cd 2+ . The sorption kinetics exhibited a significant decrease in sorption time, with 99% removal achieved 600–800 min earlier than for xerogel beads. This behaviour indicates increased functional groups accessibility combined with increased flexibility due to the effect of porosity, facilitating chain rearrangement during ion exchange. A multistage mechanism for heavy metal sorption kinetics was suggested by the results of both Weber–Morris and film diffusion models.

[1]  Kinam Park,et al.  Drug loading and release properties of ion-exchange resin complexes as a drug delivery matrix. , 2008, International journal of pharmaceutics.

[2]  F. Quignard,et al.  From natural polysaccharides to materials for catalysis, adsorption, and remediation. , 2010, Topics in current chemistry.

[3]  G. Malash,et al.  Piecewise linear regression: A statistical method for the analysis of experimental adsorption data by the intraparticle-diffusion models , 2010 .

[4]  F. Renzo,et al.  Methods to Analyse the Texture of Alginate Aerogel Microspheres , 2005 .

[5]  S. L. Eastman,et al.  SORPTION EQUILIBRIUM OF COPPER BY PARTIALLY-COAGULATED CALCIUM ALGINATE GEL , 1990 .

[6]  D. Reichenberg.  Properties of Ion-Exchange Resins in Relation to their Structure. III. Kinetics of Exchange , 1953 .

[7]  F. Renzo,et al.  Supercritically‐Dried Alginate Aerogels Retain the Fibrillar Structure of the Hydrogels , 2008 .

[8]  Gordon McKay,et al.  The kinetics of sorption of divalent metal ions onto sphagnum moss peat , 2000 .

[9]  Yuh-Shan Ho,et al.  Citation review of Lagergren kinetic rate equation on adsorption reactions , 2004, Scientometrics.

[10]  E. Barrett,et al.  (CONTRIBUTION FROM THE MULTIPLE FELLOWSHIP OF BAUGH AND SONS COMPANY, MELLOX INSTITUTE) The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms , 1951 .

[11]  G. Mckay,et al.  Intraparticle diffusion processes during acid dye adsorption onto chitosan. , 2007, Bioresource technology.

[12]  S. Saito,et al.  Sol–gel transition of alginate solution by the addition of various divalent cations: 13C‐nmr spectroscopic study , 1993 .

[13]  E. Favvas,et al.  Metal-carboxylate interactions in metal-alginate complexes studied with FTIR spectroscopy. , 2010, Carbohydrate research.

[14]  F. Renzo,et al.  Natural materials with high surface area. Physisorption methods for the characterization of the texture and surface of polysaccharide aerogels , 2011 .

[15]  Wojciech Plazinski,et al.  On the applicability of the pseudo-second order equation to represent the kinetics of adsorption at solid/solution interfaces: a theoretical analysis based on the statistical rate theory , 2009 .

[16]  A. Neimark,et al.  Unified Approach to Pore Size Characterization of Microporous Carbonaceous Materials from N2, Ar, and CO2 Adsorption Isotherms† , 2000 .

[17]  R. Lagoa,et al.  Kinetic analysis of metal uptake by dry and gel alginate particles , 2009 .

[18]  W. Weber,et al.  Kinetics of Adsorption on Carbon from Solution , 1963 .

[19]  A. Adamson,et al.  The exchange adsorption of ions from aqueous solutions by organic zeolites; kinetics. , 1947, Journal of the American Chemical Society.

[20]  N. Kanellopoulos,et al.  Development of hybrid alginate/ceramic membranes for Cd2+ removal , 2009 .

[21]  S. Saito,et al.  A small‐angle x‐ray scattering study of alginate solution and its Sol–Gel transition by addition of divalent cations , 1995 .

[22]  E. Favvas,et al.  Alginate fibers as photocatalyst immobilizing agents applied in hybrid photocatalytic/ultrafiltration water treatment processes. , 2012, Water research.

[23]  E. Kouvelos,et al.  Calcium alginate beads from Laminaria digitata for the removal of Cu+2 and Cd+2 from dilute aqueous metal solutions , 2008 .

[24]  E. Morris,et al.  Biological interactions between polysaccharides and divalent cations: The egg‐box model , 1973 .

[25]  Christophe Daniel,et al.  Aerogels with a Microporous Crystalline Host Phase , 2005 .

[26]  E. Kouvelos,et al.  Prediction of binary adsorption isotherms of Cu(2+), Cd(2+) and Pb(2+) on calcium alginate beads from single adsorption data. , 2009, Journal of hazardous materials.

[27]  F. Renzo,et al.  Aerogel materials from marine polysaccharides , 2008 .

[28]  S. Allen,et al.  Intraparticle diffusion of a basic dye during adsorption onto sphagnum peat. , 1989, Environmental pollution.

[29]  Yu Liu.  New insights into pseudo-second-order kinetic equation for adsorption , 2008 .

[30]  J. Nolan,et al.  Heavy metal sorption by calcium alginate beads from Laminaria digitata. , 2006, Journal of hazardous materials.

[31]  F. Quignard,et al.  Structural regime identification in ionotropic alginate gels: influence of the cation nature and alginate structure. , 2012, Biomacromolecules.

[32]  F. Renzo,et al.  Nitrogen sorption as a tool for the characterisation of polysaccharide aerogels , 2011 .

[33]  J. Boer,et al.  Thet-curve of multimolecular N2-adsorption , 1966 .

[34]  Ivar Storrø,et al.  Alginate as immobilization material: III. Diffusional properties , 1992, Biotechnology and bioengineering.

[35]  K. Bhattacharyya,et al.  Azadirachta indica leaf powder as an effective biosorbent for dyes: a case study with aqueous Congo Red solutions. , 2004, Journal of environmental management.

[36]  F. Quignard,et al.  From hydrocolloids to high specific surface area porous supports for catalysis. , 2005, Biomacromolecules.