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

• The clay/PNIPAm nanocomposite hydrogels (CPN) were synthesized.
• The CPN nanocomposite hydrogels were efficient adsorbent for crystal violet (CV).
• The CPN nanocomposite hydrogels could absorb high concentrated CV solution.

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 (Qt) 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 Qt values are not more than 2 mg/g. The Qt 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.

The clay/poly(N-isopropylacrylamide) (PNIPAm) nanocomposite hydrogels (CPN) with various nanoclay contents were successfully prepared, and can serve as an excellent dye adsorbent like crystal violet.Figure optionsDownload as PowerPoint slide