Preparation of polyhedral oligomeric silsesquioxane based cross-linked inorganic-organic nanohybrid as adsorbent for selective removal of acidic dyes from aqueous solution

Abstract

A cross-linked polyhedral oligomeric silsesquioxane (POSS) nanohybrid is synthesized through Schiff base chemistry by using octa-amino POSS as building blocks and glutaraldehyde as dual functional reagent. The obtained nanohybrid is characterized by FT-IR, solid-state Si NMR, SEM, TEM, TGA and N adsorption-desorption isotherm, and the results demonstrate the successful cross-linkage between POSS molecules, forming block-like irregular nanoparticles with a specific surface area of 42.8mg. As a novel solid-phase adsorbent, cross-linked POSS nanohybrid exhibits selective adsorption properties for acidic dyes, i.e., methyl orange (MO) in the present case. The strong electrostatic interactions between MO species and the nanohybrid are the main driving forces for MO adsorption. The kinetic data are well described by the pseudo-second-order kinetic model. The adsorption isotherm studies demonstrate that the data are well fit with Langmuir model at 293K and a maximum adsorption capacity of 237.5mgg is obtained. Thermodynamic studies indicate that the adsorption of MO is spontaneous and exothermal, along with reduced randomness. The adsorbed MO species could be effectively recovered by using methanol/NaOH (9/1, v/v, 0.1molL NaOH) as eluent. The practical application for textile wastewater treatment demonstrates that cross-linked POSS nanohybrid appears to be a promising material in dye removal field.

Regenerated Silk Nanofibers for Robust and Cyclic Adsorption–Desorption on Anionic Dyes

“…Figure a shows that the experiments taken under optimized conditions (5 mL of 50 mg·L –1 acid blue 117 containing 100 mg·L –1 electrolytes) indicated that there is no such negative impact on the adsorption potential of silk nanofibers in the presence of electrolytes either cations or anions, suggesting its consistent behavior in the electrolyte dye effluent mixture. The addition of electrolytes can cause to decline in dye solubility by increasing electric double layers between the adsorbent and the aqueous medium . Generally, it is anticipated that addition of electrolytes can encourage hydrophobic interfaces.…”

“…The addition of electrolytes can cause to decline in dye solubility by increasing electric double layers between the adsorbent and the aqueous medium. 37 Generally, it is anticipated that addition of electrolytes can encourage hydrophobic interfaces. Therefore, improved hydrophobic interactions in the existence of these ions can also be a source of complete dye removal.…”