Functionalized microcrystalline cellulose crosslinked via diisocyanate-derived urethane bonds for wastewater treatment.

Copper is a common water pollutant due to its toxicity and widespread presence in various water streams. Various adsorbents have been utilized to remove heavy metal contaminants from water; however, these methods often show limited efficiency and can incur significant costs. This work highlights the synthesis, characterization, and performance evaluation of new crosslinked cellulosic polymers in foam form functionalized with alkylsulfonate moiety for use as efficient adsorbents for copper and other metal ions. Cellulose was first reacted with butane sultone and subsequently crosslinked using p-phenylene diisocyanate and hexamethylene diisocyanate to produce Cell-S-PPF and Cell-S-HMF, respectively. The capacities of Cell-S-PPF and Cell-S-HMF for extracting metal ions from wastewater, along with their optimal adsorption conditions, were evaluated. The Qe values for both polymers were determined to be 19.2 mg/g and 20.0 mg/g for Cell-S-HMF and Cell-F-PPF, respectively. Adsorption proceeded spontaneously at ambient temperature as evidenced by negative Gibbs free energy values. Both polymers showed the ability to quantitatively remove more than 25 metal ions present in a sewage sample, including uranium. Recycling performance shows that Cell-S-PPF and Cell-S-HMF can be recycled by sequential washing with diluted acid and then base, without observable performance loss over at least five adsorption-desorption cycles. The adsorption process obeys the Langmuir isotherm model with a second-order rate. The findings suggest a promising avenue for the commercialization of these materials in wastewater treatment applications. Monte Carlo (MC), DFT, and Dynamic (MD) simulations indicated strong bonding between copper (II) ions and the coordination sites of cellulosic polymers. Since high adsorption negative energy was obtained.