Spray-dried chitosan microspheres containing 8-hydroxyquinoline -5 sulphonic acid as a new adsorbent for Cd(II) and Zn(II) ions

Thermodynamics and kinetics of Zn(II) adsorption on crosslinked starch phosphates

“…It means that chemisorption is the determining step of the adsorption process rather than mass transfer in solution [28]. The similar results were obtained to adsorb Zn(II) ions from aqueous solution using adsorbents with active groups [29,30].…”

Sensor-containing microspheres of chitosan crosslinked with 8-hydroxyquinoline-5-sulphonic acid for determination of Cu(II) in instant coffee

“…The chitosan crosslinked with the chelating agent 8-hydroxyquinoline-5-sulphonic acid and glutaraldehyde and the microspheres were obtained according to a procedure described in the literature (Vitali et al, 2008). The sensor was constructed as follows: 30 mg (15% w/w) of chitosan microspheres and 130 mg (65% w/w) of graphite powder were mixed in a small mortar for 20 min to form a homogeneous mixture and 40 mg (20% w/w) of Nujol was then added followed by mixing for another 20 min.…”

“…For other ratios and other potential interferents, the change in the anodic current of the stripping voltammogram of Cu(II) was less than 12%. Although microspheres of chitosan crosslinked with 8-hydroxyquinoline-5-sulphonic acid can act as an adsorbent for several metallic ions (Vitali et al, 2008), the interference was greatly minimised by the application of the pre-concentration potential. At À0.4 V, the potential chosen to pre-concentrate Cu(II), the metallic ions with a reduction potential more negative than À0.4 V are not reduced (pre-concentrated) at the electrode surface.…”

“…The atomization of the biopolymer chitosan by this technique is generally used in pharmacological processes, especially in controlled-drug delivery systems, and produces good results. Recently, the spray drying technique has been employed to obtain microspheres of chitosan crosslinked with 8-hydroxyquinoline-5-sulphonic acid and glutaraldehyde, as a new adsorbent for metallic ions (Vitali, Laranjeira, Gonçalves, & Favere, 2008). This new adsorbent showed a maximum adsorption capacity for Cd(II) and Zn(II) ions higher than that of chitosan microspheres crosslinked with glutaraldehyde without the chelating agent 8-hydroxyquinoline-5-sulphonic acid.…”

“…Experimental conditions affecting the pre-concentration step, including the solution pH, potential and time of pre-concentration, were evaluated. Although the proposed sensor can be used to determine other heavy metals, since microspheres of chitosan crosslinked with 8-hydroxyquinoline-5-sulphonic acid can act as an adsorbent for several metallic ions (Vitali et al, 2008), the performance of the proposed sensor was examined using optimised operating parameters for Cu(II) determination in instant coffee samples. Copper was chosen as the test element because it has been found to be best suited to identifying the geographical growing origin of coffee, together with manganese and cobalt (Oleszczuk et al, 2007).…”