Covalently cross-linked cellulose-chitosan copper (II) Schiff base using citric acid for the efficient adsorptive removal of methyl orange.

An efficient and novel citric acid cross-linked cellulose-chitosan copper (II) Schiff base (CA@CL/CS-CuSB) composite was developed, and its efficiency in removing methyl orange (MO) dye from aqueous solution was assessed. The synthesized adsorbent showed a maximum adsorption performance of 96.7 % removal at solution pH 4, MO concentration 70 mg/L, 110 min contact time, and 0.02 g adsorbent dose, indicating its strong adsorption ability towards MO dye. The MO adsorption kinetic and isotherm were in agreement with the pseudo-second-order (PSO) and monolayer Langmuir models, respectively with maximum adsorption capacity of 666.66 mg/g. Thermodynamic results predicted that the MO adsorption is an endothermic and spontaneous process. According to the results, the MO adsorption involves hydrogen bonding, n-π, π-π and electrostatic attractions with the adsorbent surface. Characterization of as-prepared adsorbent after 6 reusable cycles using FT-IR, XRD and SEM techniques predicted that the reused CA@CL/CS-CuSB was mechanically stable, chemically and morphologically intact after MO adsorption. These results findings predicted that the as-prepared CA@CL/CS-CuSB is an effective and efficient and reusable adsorbent for removing MO anionic dye from aqueous solution.