Chitosan has been proposed as a "natural" coagulating agent to solve
wastewater problems. The main hindrance in this commercial chitosan application has
been its low cost effectiveness. The hypothesis in our research is that chitosan
complexes with natural polyanions is more effective than chitosan alone, particularly
in recovering low concentration proteins from food processing wastewater.
Chitosan (Chi) was reacted with alginate (Alg), pectin (Pec) and carrageenan
(Car) ex-situ to obtain chitosan-polyanion complexes (Chi-Pol). Analysis by Fourier
Transform Infrared (FTER) spectroscopy confirmed electrostatic interactions as the
mechanism for complex formation. Scanning electron microscopy revealed a tight,
non-porous structure except for the porous Chi-Car complex. Tests with a bovine
serum albumin solution revealed low adsorption rates with slightly higher values for
Chi-Car suggesting the need for an improved complexation method.
Chi-Pol complexes prepared in-situ at different monomeric weight ratios (MR)
were evaluated using pH 6 adjusted Cheddar cheese whey and surimi wastewater
(SWW). Complexes used at 30 mg complex/L whey showed higher turbidity
reductions than at 10 mg/L. MR had no significant effect on turbidity reduction except for Chi-Alg at 30 mg/L; the value (72 %) at MR = 0.2 was higher than for MR = 0.8.
UV-Vis spectroscopy confirmed in-situ complex formation with a preference for the
adsorption of specific whey protein fractions.
Complexes formed at 0.2 and 0.8 MR were evaluated at two concentrations for
the treatment of SWW. Tests at 50 mg/L showed a turbidity reduction of up to 97 %
at 24 h with a 81-90 % recovery of SWW proteins. At 150 mg/L, similar efficacy was
achieved in only 1 h with turbidity reductions ranging 94-99 % and 78-94 % protein
recovery. FTIR analyses confirmed the adsorption of proteins as indicated by
similarities in the three amide bands for Chi-Alg recovered solids and untreated SWW.
Differential scanning calorimetry (DSC) was employed to study interactions
of SWW proteins and Chi-Alg complexes. Untreated and complex bound SWW
proteins revealed single exothermic peaks at 23.3 and 38.0°C, respectively. This
suggested Chi-Alg and SWW protein interactions increased the thermal stability of
SWW proteins. However, further thermal analysis studies are needed to confirm this
finding. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26560 |
| Date | 10 April 2001 |
| Creators | Savant, Vivek |
| Contributors | Torres, J. Antonio |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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