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A novel CMC/PVA/MIL-101(Cr) bead (CPMB) with tailored network and affinity sites 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 for efficient capture of heavy metal ions in wastewater. [Display omitted] • Intermolecular H-bonds of CMC/PVA matrix enhanced stable properties of adsorbents. • Adding MIL-101 to the matrix improved specific surface areas and offered active sites. • Synthesis of CMC/PVA/MIL-101(Cr) beads with increased the affinity for targeted ions. • High recycling adsorption performance even after eight cycles at testing conditions. 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. [ABSTRACT FROM AUTHOR]

This paper reports the preparation of zein nanoribbons and their application in the removal of Pb(II) from polluted water. A modified coaxial electrospinning process was conducted permitting the smooth and continuous generation of zein nanoribbons. The process utilized sodium lauryl sulfate ethanol aqueous solution as the sheath fluid to overcome protein–metal interactions and the corresponding spinneret clogging. Scanning electron microscopic images demonstrated that the zein nanoribbons created using the modified processes had a flatter and narrower morphology than the analogous materials from a single-fluid process. By exploiting the favorable interactions between metal and protein, these zein nanoribbon mats were used to treat Pb(II)-polluted water. Adsorption results indicated that equilibrium was obtained in 60 min for Pb(II) solutions with initial concentrations of 100, 150 and 200 mg/L. The process can be described using the pseudo-second-order model. Isotherm data fitted well to the Langmuir isotherm model, with a maximum adsorption of 89.37 mg/g. Desorption results showed that the adsorption capacity can remain up to 82.3% even after 5 cycles of re-use. Mechanisms underlying both the preparation and application of the zein nanoribbons were proposed. [ABSTRACT FROM AUTHOR]

• The latest progresses in the application of zeolite-based composites are summarized. • Pollutant adsorption and photocatalysis by zeolite-based photocatalysts are analyzed. • The effects of the characteristics of the zeolite-based composites are discussed. • The perspectives for the research of the zeolite-based composites are presented. Aluminosilicate zeolites have been found to be effective supports of semiconductor photocatalysts for the removal of organic compounds in wastewater and air. In this review, we summarize the progress in the application of zeolite materials such as Y, ZSM-5, mordenite, beta and clinoptilolite for improving the performance of semiconductor photocatalysts in degradation of environmental pollutants. The main synthesis strategies and the mechanisms of organic compounds adsorption and photocatalysis by zeolite-based photocatalysts are explicated in detail. Meanwhile, various types of zeolite-based photocatalytic composites are also thoroughly summarized. The more reliable zeolite-based photocatalysts with high photocatalytic activity under visible or sunlight irradiation should be extensively investigated. Additionally, we highlight the advancements for improving performance of different zeolite-based composites in photocatalytic degradation organic contaminants in wastewater and air. The achieved progress demonstrates that the photocatalytic enhancement of zeolite-based composites is predominantly dependent on the enhanced adsorption performance, as well as the high separation and transfer efficiency of photogenerated charge carriers. Hence, the characteristics of the zeolite-based composites (surface area, pHpzc value, hydrophobic, band gap and band edge), the nature of organic contaminants and other experiment factors need to be taken into account in applying to photodegradation process involving this catalyst. Finally, the current challenges and perspectives for the future research of these photocatalysts are presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new adsorbent was synthesized by modifying Zr-MOF with Ni 0.6 Fe 2.4 O 4 and PEI. • The adsorbent showed sufficiently magnetic strength, good thermal and acid-base stability. • The theoretical adsorption capacities of Pb(II) and Cr(IV) were 273.2 mg/g at pH 4.0 and 428.6 mg/g at pH 3.0. • The adsorbent was renewable and selective. A novel magnetic Zr-MOF named Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI was synthesized by modifying UiO-66-NH 2 with Ni 0.6 Fe 2.4 O 4 and polyethyleneimine and its sorption characteristics for two representing heavy metals Pb(II) and Cr(VI) in water were examined. This material showed good thermal stability and was sufficiently magnetic to allow effective solid-liquid separation. The material had a maximum adsorption capacity of 273.2 mg/g for Pb(II) at pH 4.0 and 428.6 mg/g for Cr(VI) at pH 3.0, as obtained from the model fitting by the Hill equation. The sorption kinetics for both heavy metals on the material was fast, with adsorption equilibrium established in 60 min and 30 min for Pb(II) and Cr(VI), respectively. Model fitting of the kinetic data showed that Pb(II) and Cr(VI) sorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI followed the pseudo-second-order model. This material had good selectivity for competing ions, and still hold fairly good binding capacities after 5 times of regeneration. Adsorption mechanisms for Pb(II) and Cr(VI) by Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI were proposed by analyzing FTIR, XPS and the electrokinetic property of the material. Specifically, Pb(II) adsorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be attributed to chelation of Pb(II) with the imine/amine functional groups in the material's matrix, while Cr(VI) adsorption might stem from a combination of electrostatic attraction, chelation and redox reaction. It seems that Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be used as a green and environmental-friendly material for heavy metals removal, particularly from acidic water streams. [ABSTRACT FROM AUTHOR]