Etched ZIF-8 as a Filler in Mixed-Matrix Membranes for Enhanced CO2 /N2 Separation.

Zeolite ZIF-8 has been etched with acid to form microporous ZIF-8-E crystals. These were then introduced into a polyethersulfone (PES) membrane matrix to enhance its CO2 /N2 separation performance. Open through pores of size about 100 nm formed in the ZIF-8 crystals allow the ingrowth of polyethersulfone chains, ensuring a reduction in the number of nonselective voids, thereby achieving better interaction between ZIF-8-E and PES. As a result, the CO2 /N2 separation performance of the ZIF-8-E/PES membrane increased significantly, showing a CO2 permeability of 15.7 Barrer and a CO2 /N2 ideal selectivity of 6.5.

Sustainable and scalable in-situ synthesis of hydrochar-wrapped Ti3AlC2-derived nanofibers as adsorbents to remove heavy metals.

To ensure a sustainable future, it is imperative to efficiently utilize abundant biomass to produce such as platform chemicals, transport fuels, and other raw materials; hydrochar is one of the promising candidates derived by hydrothermal carbonization of biomass in pressurized hot water. The synthesis of "hydrochar-wrapped Ti3AlC2-derived nanofibers" was successfully achieved by a facile one-pot hydrothermal reaction using glucose as the hydrochar precursor. Meanwhile, cellulose and pinewood sawdust as raw materials were also investigated. Products were characterized by XRD, N2 adsorption-desorption isotherms, SEM, TEM and FT-IR to investigate their crystal structures, textural properties, morphologies, and surface species. In the adsorption test to remove Cd(II) and Cu(II) in aqueous solution, hydrochar-wrapped nanofibers outperformed pure nanofibers derived from Ti3AlC2, hydrothermal carbon derived from glucose and commercial activated carbon. Finally, the regeneration, sorption kinetics, and possible adsorption mechanism were also explored.

Noble metal nanoparticle-functionalized Zr-metal organic frameworks with excellent photocatalytic performance.

Noble metal nanoparticles (NPs) functionalized MOFs are attractive materials for photocatalytic reactions, and outstanding catalytic performances can be expected, especially when they have intrinsically matched crystal faces between metals and MOFs. This study discovered that the photocatalytic oxidation of aromatic alcohols to aldehydes was enhanced over Au/UiO-66-NH2 or Au/UiO-66 but suppressed over Pt loaded counterparts, whereas the reduction of Cr(VI) was boosted over both two catalysts. In reactions, the conversion of benzyl alcohol was 17.1% over UiO-66-NH2 and 7.6% over UiO-66, and an enhanced conversion was obtained over Au/UiO-66-NH2 (30.5%) and Au/UiO-66 (24.1%). However, the conversion was decreased over Pt/UiO-66-NH2 (9.3%) and Pt/UiO-66 (<1%). Experimental results revealed strong correlations between Zr-MOFs and loaded metal NPs, as Zr centers promoted the formation of Pt(200) planes that suppressed the production of ·O2- intermediates to oxidize aromatic alcohols, whereas Pt(200) exhibited no effect on the Cr(VI) reduction triggered by photo-induced electrons. The findings in this study on constructing noble metal NPs functionalized Zr-MOFs catalysts with specially-matched crystal structures and on distinguishing photocatalytic mechanisms on oxidation of alcohols and reduction of Cr(VI) would provide valuable information for designer (photo)catalysts based on MOFs and their applications in such as catalysis and environmental remediation.

Acid-promoted synthesis of UiO-66 for highly selective adsorption of anionic dyes: Adsorption performance and mechanisms.

UiO-66 was modulated by addition of acetic acid or HCl in the precursor solution. The resulting acetic acid-promoted UiO-66has more regular octahedral structures and high surface areas of 892-1090m2/g. Anionic dyes (methyl orange (MO) and Congo red (CR)) and cationic dyes (methylene blue (MB) and rhodamine B (RhB)) were examined for the selective dye adsorption on various UiO-66. The acid-promoted UiO-66 exhibits an excellent selective adsorption to anionic dyes, where the adsorption capacities of MO and MB are 84.8 and 13.2mg/g, respectively. However, UiO-66 prepared without acid shows similar adsorption to both anionic dye MO (70.4mg/g) and cationic dye MB (67.5mg/g). Mixed dyes (MO/MB and MO/RhB) adsorption on acid-promoted UiO-66 further proves the selective adsorption to anionic dyes. The adsorption mechanism was studied by testing the Zeta potential of acid-promoted UiO-66, and more positive Zeta potential (hydrogen ions) of UiO-66 is beneficial to the anionic dye adsorption.