Gold and Silver Uptake and Nanoprecipitation on Calcium Alginate Beads

Abstract

Calcium alginate beads were investigated for their biosorption performance in the removal of gold and silver from aqueous solutions. It was found that uptake capacities were significantly affected by the solution pH, with optimum pH values of 2 and 4 for gold and silver, respectively. Kinetic and isotherm experiments were carried out at the optimum pH. The maximum uptake capacities were 290 mg/g for Au and 52 mg/g for Ag. FTIR analysis indicated that both carboxylic and hydroxylic functional groups in alginate beads are involved in the metal binding and later reduction of gold (+3) and silver (+1) to gold (0) and silver (0). SEM and X-ray diffraction confirmed the formation of gold and silver nanoparticles.

Investigation of the electro-spinnability of alginate solutions containing gold precursor HAuCl 4

“…The voltage was of 20 kV, with slight variation until a stable Taylor cone has been formed. All experiments were carried out at room temperature (22)(23)(24)(25)(26) o C) and with relative humidity 45-55%. The procedure to prepare solutions containing SA/PEO/PF127 (4.0/1.5/1.0 %w/v) was: SA, PEO and PF127 were dissolved into 9 mL of water by stirring for two days, then 1mL of water was added and the final solution was stirred vigorous for 2 min.…”

“…With the aim to investigate how the degree of complexation of SA chains with gold anions [14], [24][25][26][27] affects the electrospinning process, we prepared SA/PEO/PF127 solutions containing different concentrations of gold precursor (HAuCl 4 ): Au/SA mass ratio of 0.0025 (sample A1), 0.0050 (sample A2), 0.0075 (sample A3), and 0.0150 (sample A4). Table 1 summarizes the experimental parameters and the physicochemical properties of the solutions.…”

“…Table 1 summarizes the experimental parameters and the physicochemical properties of the solutions. The interactions between SA and PEO were monitored by FT-IR spectroscopy [28], [29], which is a powerful tool in this case due to the different chemical structure of the three polymers used (SA is rich in carboxylic groups, and its FT-IR spectrum is characterized by the bands assigned to ); this peak is specific for ionic binding proving the new Au-carboxylate bonding [24], [26]. In addition the ν(OH) peak becomes narrower and of higher intensity [28].…”

Generation of alginate gel particles with AuNPs layers by polydimethylsiloxan template

“…7 Alginate has been used as stabilizer, 8,9 but there were few report on biopolymer used as immobilization matrix for the metal ions such as Au 3+ . 1,10 The biopolymer matrix for the synthesis of gold nanoparticles shows great potential in biomedical applications. Alginate acid is a kind of biopolymer, which containing 1,4-linkeda-D-mannuronic and L-guluronic acid residues arranged randomly along the chain.…”

Chemically Cross-Linking Effects on the Sorption of Heavy Metal Ions to Hydrogels of Cyanobacterial Megamolecules, Sacran

“…For instance, recovery technologies for Pb or other divalent heavy and noble metal ions with alginate gels have been reported [1][2][3][4]. On the other hand, cyanobacteria produce and secrete polysaccharides that give photosynthesis an edge by adsorbing and precipitating particles such as clay in water, or remove cytotoxity by adsorbing heavy metal ions in the environment where they live [5].…”