Their thesis focuses on development of simple and cost-effective methods for fabrication of high-performance composite adsorbents. For this, acid-stable polyvinyl chloride was selected as a support material, and ionic polymer able to provide binding sites for cations and anions were adopted. The develop adsorbents were need for recovery of precious metals and removal of heavy metals from solution phases. As model composites, polyethyleneimine-polyvinyl chloride (PEI-PVC) and polyacrylic acid-polyvinyl chloride (PAA-PVC) composite fibers were prepared via phase inversion processes by spinning PEI or PAA and PVC solution mixtures into mixed solutions of methanol and water (1:1 ratio). For each study, different weights of PEI or PAA with a constant weight of PVC were prepared and the optimum PEI: PVC or PAA: PVC ratios for the best performances were established through batch adsorption studies.
In the case of PEI-PVC composite adsorbent fibers the thickness of the fibers affected the sorbent performance. The fiber with the smallest size (0.18 mm) exhibited the best Pt(IV) adsorption capacity and kinetics. The maximum Pt(IV) uptake by this fiber was estimated to be 410.53 mg/g by the Langmuir isotherm model. The PEI-PVC fibers showed good acid-tolerance and were applicable in treating real industrial wastewater containing Pt(IV) in the presence of other ions. The PEI-PVC composite fibers could also be regenerated and reused over several adsorption-desorption cycles with high efficiencies.
For the case of PAA-PVC composite adsorbents, their shapes were able to be controlled, including fiber, film and granule. Among the different shapes, the fiber type adsorbents displayed the best performances and were thus selected for detailed studies. The as-prepared PAA-PVC composite fiber adsorbents were characterized by SEM, EDX, XRD, and FTIR, and their adsorption performances were evaluated. Through adsorption isotherm experiments, the maximum equilibrium Cd(II) uptake was estimated to be 331.59 mg/g.
Considering the simplicity and inexpensiveness of the methods suggested in this thesis, the results may pave ways for preparing cost-effective polyvinyl chloride-ionic polymer composite adsorbents for the recovery of precious metals or removal of heavy metals.