Recyclable CMC/PVA/MIL-101 aerogels with tailored network and affinity sites for efficient heavy metal ions capture

A novel CMC/PVA/MIL-101(Cr) aerogel bead (CPMB) was prepared by the green polymer matrix of CMC and PVA and nanofiller of MIL-101(Cr) through the simple complexing with the ionic crosslinking agent, which could be an adsorptive platform for effectively capturing of Co(II) and Ni(II) ions in wastewater. The morphology, surface chemistry, and textural characteristics were investigated by varied characterization methods to reveal behind mechanisms for the dissimilarity in adsorption performance. The optimal modifying dosage of MIL-101(Cr) nanoparticles was determined to form an optimal tailored network with abundant MIL-101 clusters and hydroxyl/carboxyl groups inside the network that greatly achieved the most accessible heavy metals to CPMB-1. Meanwhile, the influences of temperature, adsorption dosage, pH, and interfering cations on the capacity of CPMB-1 were investigated, while adsorption behaviors of adsorbents were also explored. Analytic results indicated that the capture of two targeted ions by CPMB-1 could favorably comply with the Pseudo-second-order kinetic model and Freundlich isothermal adsorption model. The maximum adsorption capacities of two targeted ions calculated by data were 180.3 mg/g and 261.9 mg/g, respectively. According to the results of XPS and FTIR analysis, the electrostatic attraction and chelating effect could be the main mechanisms for improved performance, and contributing groups were the hydroxyl and carboxylic acid introduced into CPMB-1. Moreover, the as-designed CPMB-1 exhibited excellent recyclability and stability in eight cycles. The encouraging results exhibited by CPMB-1 might bring a new idea for integrating multiple functionalities of MOFs and biomass components for designing functional composites for efficient remediations of wastewater.