A novel cotton cellulose/poly(acrylic acid)@laponite hydrogel for fast and highly efficient removal of cationic dyes from wastewater: Performance and mechanism.
Efficient adsorbents with versatility, stability, and superadsorption are crucial for wastewater treatment. Here, a cotton cellulose/poly(acrylic acid)@laponite (CA@Lap) hydrogel for treating multiple cationic dyes is developed by a cooperative optimization strategy. Incorporating cotton cellulose dissolution system and cooperative crosslinking of laponite in reticular frameworks of polymer significantly enhances morphology, mechanical strength, and adsorption capabilities of CA@Lap. The hydrogel can adsorb crystal violet (CV), methylene blue (MB), and malachite green (MG) over a wide pH range (2-11), achieving about 95 % adsorption within 5 min. The adsorption capacities (qe,CV = 2245.7 mg/g, qe,MB = 3840.8 mg/g, qe,MG = 12,160.9 mg/g) surpass those of previous adsorbents. Mechanisms show that CV and MB adsorption is monolayer chemisorption, while MG adsorption involves multilayer chemisorption or physisorption. Changes in FT-IR and XPS spectra confirm hydrogen bonding and electrostatic interaction between the functional groups and dye molecules, supported by DFT calculations. The excellent mechanical properties (4.07 MPa) and strong interactions ensure adsorption stability after 5 cycles, maintaining high adsorption capacity and removal efficiency (above 90 %) in real wastewater and fixed bed experiments. Such efficient CA@Lap adsorbents prepared by cooperative optimization strategy can provide valuable insights to address the limitations of cellulose-based hydrogels for water treatments.