Renewable Starch Carriers with Switchable Adsorption Properties

This Research Article describes a systematic study on the structure and sorption properties of Carnation-based starch-particles (SPs) by various techniques. Structural characterization of the SPs utilized spectroscopy ( 1 H NMR and FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The sorption properties of the SPs were characterized by solvent swelling and uptake isotherms with cationic adsorbates at equilibrium and kinetic conditions. The surface area (SA; ∼3–588 m 2 /g) of the SPs was estimated using nitrogen gas and dye adsorption isotherm methods, where the range in SA was related to solvent swelling effects on the textural properties. The SPs contain lipid constituents according to results obtained by 1 H NMR spectroscopy, DSC, and confocal laser microscopy (CLM) with iodine staining. The unique solvent swelling properties of the SPs reveal greater swelling in water over ethanol. SPs display preferential equilibrium uptake of methylene blue (MB; Q m ≈ 716 mg/g) over cetylpyridinium bromide (CPB; Q m ≈ 292 mg/g). The uptake of MB was reduced by an order of magnitude ( Q m ≈ 67 mg/g) when the SPs were doped with CPB, further revealing the role of competitive adsorption and similar binding modes for MB and CPB. The doping of SPs with CPB provide a facile approach for alteration of the surface functional properties such as the hydrophile–lipophile character, surface charge, and hydration properties of the SPs. Evidence of monolayer and multilayer adsorption of CPB onto SPs lead to switchable adsorption properties where such amphiphile surface patterning can be harnessed to yield materials with unique controlled-release properties for diverse chemical systems according to tunable surface charge using self-assembly.