Removal of crystal violet by clay/PNIPAm nanocomposite hydrogels with various clay contents

Abstract The clay/poly( N -isopropylacrylamide) (PNIPAm) nanocomposite (CPN) hydrogels, using lithium magnesium silicate hydrate (LMSH) as a clay mineral physical cross-linker, with the mass ratio of NIPAm/LMSH ranging from 5 to 30 wt.% were prepared to remove crystal violet (CV) from aqueous solution. Morphology and temperature-sensitivity of hydrogels were investigated by SEM and DSC. Adsorption capacity and kinetic under different times, pH values and concentrations were evaluated by using UV/vis spectroscopy. The pore sizes of CPN hydrogels range from 30 to 50 μm, and volume phase transition temperature (VPTT) were 33–36 °C. The adsorption capacity (Q t ) of CV onto CPN hydrogels at 25 °C increased quickly at initial 12 h, with a maximum value of 4.71 mg/g. At 37 °C, the Q t values are not more than 2 mg/g. The Q t values of CPN hydrogels increase 2–4 times when CV concentration was added from 10 to 30 mg/L, and increase 1–1.5 times as pH value increases from 3.0 to 8.9.