Nanosilica‐Cross‐Linked Poly( <i>N</i> ‐(2‐Hydroxyethyl) Acrylamide)Hybrid Hydrogel for Remediation of Cr(VI) Ions and Methylene Blue Contaminated Water

ABSTRACT This investigation presents an effective method for purifying contaminated water containing toxic metal ions and dye to address the increasing demand for clean and safe water. The hybrid hydrogel was decorated using the reactive copolymer poly( N ‐(2‐hydroxyethyl) acrylamide‐ co ‐3‐methacryloxypropyl trimethoxysilane), which was cross‐linked with silica nanoparticles (SiNPs), which act as inorganic cross‐linkers to reinforce the polymer network. The resulting hydrogel was used as an efficient material for hexavalent chromium (Cr(VI)) ions and methylene blue (MB) dye remediation. Key parameters influencing the adsorption of Cr(VI) and MB onto the hydrogel such as initial contaminant concentration, adsorbent dosage, adsorption time, and temperature, were systematically investigated. At pH 3, maximum Cr(VI) adsorption was achieved within 180 min. The hybrid hydrogel selectively absorbed MB from a binary solution containing both the methyl orange and MB dyes. The adsorption behavior of Cr (VI) and MB were well described by the pseudo‐second‐order kinetic model and aligned well with Langmuir isotherm model. Additionally, the hydrogel displayed excellent reusability, as it could be desorbed and reused over multiple adsorption and desorption cycle for both Cr (VI) and dye removal. Thus, hybrid hydrogels with excellent selective adsorption properties are promising materials for effective and sustainable water remediation.