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Publications in September and October 2013

In September and October 2013, 290 publications about chitosan and its diverse derivatives have been released. They present novel formulations of chitosan-based nanoparticles and pharmaceutical preparations and performed animal and human studies. The leading nations in chitosan research are China (75 articles), India (37) and USA (27).

Top Journals Publications
Carbohydrate polymers 36
International journal of biological macromolecules 25
International journal of pharmaceutics 16
Colloids and surfaces. B, Biointerfaces 12
Materials science & engineering. C, Materials for biological applications    36 10

Table: List of scientific journals, which published the highest number of chitosan-related articles in September and October 2013.
Source: GoPubMed

The accumulation of heavy metals in industrial wastewater becomes an increasing problem for the environment and human health. For this reason, novel materials are constantly developed to eliminate metals such as lead, cadmium, chromium, copper or mercury from aqueous solutions. These materials should be most effective and at the same time low in cost. Some biomaterials, including chitosan, possess a high adsorption capacity for different metal ions and moreover, they are biodegradable, renewable and economical. Below, we introduce two publications that analysed and compared chitosan and other biomaterials in terms of their metal sorption potential.

Heavy metals removal from aqueous solutions and wastewaters by using various byproducts.

Shaheen S.M., Eissa F.I., Ghanem K.M. et al.; Journal of Environmental Management. Vol.:128:514-21. Oktober 2013

The objective of this study was to examine the sorption capacity of different low cost sorbents like chitosan, sugar beet factory lime, humate potassium and egg shells. Chitosan is obtained from chitin, a polymer that is highly abundant in nature. Sugar beet factory lime is a byproduct during the purification process of sugar beet juice. Egg shells mainly consist of calcium carbonate and humate potassium is the potassium salt of humic acid and is produced by alkaline extraction of brown coal. All biomaterials possess good adsorption properties for metal ions and might be suitable to remediate contaminated soils and waters.

The metal removal efficiency of all four materials was tested by contaminating aqueous solutions with divalent heavy metal ions: cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). The experiments were performed in mono-metal or competitive sorption systems.

Results:

  • Affinity for metal ions: chitosan > sugar beet factory lime > egg shell > humate potassium
  • Adsorption capacity: Pb2+ > Cu2+ > Zn2+ > Cd2+
  • 100% metal ion removal at low metal concentrations
  • Sorption efficiency decreased with increasing metal concentration

Conclusion: Among the four tested biomaterials, chitosan proved to be the strongest adsorbent for heavy metals in aqueous solutions. The sorption capacity of chitosan is mainly affected by its degree of acetylation, crystallinity and molecular weight. Metal ions interact with functional groups of chitosan polymers and induce chelation. The largest sorption efficiency of chitosan was achieved at neutral and alkaline pH values.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23831673

Selective adsorption of Pb(II), Cd(II), and Ni(II) ions from aqueous solution using chitosan-MAA nanoparticles.

Heidari A., Younesi H., Mehraban Z., Heikkinen H. International journal of biological macromolecules. Vol.: 61:251-63. October 2013

The present study examined the sorption capacity of chitosan-based nanoparticles for heavy metal ions like lead (Pb2+), cadmium (Cd2+) and nickel (Ni2+). Chitosan is an excellent metal sorbent; however, data about nanoparticles for metal adsorbtion is rare.

Thus, chitosan-based nanoparticles (CS) modified with methacrylic acid (MAA) were generated. The CS-MAA nanoparticles were prepared with different weight ratios (CS:MAA) and their sorption efficiency was tested and compared. In addition, the influence of the pH, initial metal concentration and dosage of the adsorbent have been analysed.

Results for CS-MAA nanoparticles:

  • weight ratio 2:1 (CS to MAA) provides best particle size distribution and low agglomeration
  • Adsorption capacity: Pb2+ > Cd2+ > Ni2+
  • pH ≥ 5.0:  improved metal ion adsorption
  • Accelerated uptake rate (120 min) compared to raw chitosan (24 h)
  • Maximum adsorbtion capacity: Pb2+ (11.30 mg/g), Cd2+ (1.84 mg/g), Ni2+ (0.87 mg/g)

Conclusion: The adsorption performance of CS-MAA nanoparticles for heavy metals in aqueous solutions was superior to raw chitosan. Since raw chitosan has a low porosity and crystallinity, the diffusion of solutions is largely restricted. The increased surface ratio of CS-MAA nanoparticles allows the unimpeded diffusion of solutions. Due to the enhanced amount of free amino and carboxyl groups there are more sorption sites for metal ions available.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23817093

chitosan, nanoparticles, Heavy metals, metal sorption potential

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