Yang Shen,Fatoye Sawyerr,Lunbo Xu,Shusu Shen,Xiaoji Zhou
The preparation of modified membranes utilizing the UiO-66 framework for wastewater filtration is regarded as one of the most promising approaches to wastewater treatment, owing to its high efficiency and cost-effectiveness. In this study, a post-modified MOF, UiO-66-RSA, was synthesized via the condensation reaction of UiO-66-NH 2 and 2,4-dihydroxybenzaldehyde. PVDF mixed matrix membranes (MMMs) were fabricated for the first time by mixing UiO-66-RSA into PVDF using the non-solvent induced phase separation (NIPS) method. Compared to pure PVDF membranes, the newly developed membrane, M4, demonstrated enhanced compatibility and superior mechanical strength. In dyeing wastewater treatment applications, M4 showed excellent separation efficiency for dye and heavy metal mixed wastewater, achieving rejection rates exceeding 90 %. Additionally, it maintained a high flux recovery rate (FRR > 90 %) and rejection rate (Rejection > 90 %) after six filtration cycles of dye-containing wastewater, indicating strong recyclability. These findings suggest that MMMs embedded with UiO-66-RSA hold significant promise for dyeing wastewater treatment.
A new metal organic framework UiO-66-RSA (UiO-66 with hydroxyl) was prepared by the post-modification of UiO-66-NH 2 (UiO-66 with amino) with resorcyl aldehyde and was employed for the efficient and selective separation and removal of Pb(II) in aqueous media . The maximum adsorption amount of UiO-66-RSA was 189.8 mg/g at an optimal pH of 4. The adsorption isotherm and kinetic were well described by Langmuir/Dubinin-Radushkevich and pseudo-second-order models respectively. Adsorption process was monolayer chemisorption . UiO-66-RSA was regenerated by thiourea/nitric acid and the removal rate was only decreased by 3.7% after five successive cycles. The analysis of X-ray photoelectron spectroscopy suggested the adsorption mechanism lay on the complexation reaction between hydroxyl/nitrogen-containing groups and Pb(II). The UiO-66-RSA bound Pb(II) by forming double/quadri coordinated complexes. Compared with a multitude of usual metal ions , viz., Zn(II), Co(IV), Ni(II), Mg(II), Cd(II), Cu(II) and Ca(II), the Pb(II) could be absorbed selectively by UiO-66-RSA. The results indicated that the UiO-66-RSA sorbent could be of great potential in the removal of Pb(II) from aqueous solutions.
Fang-Fei Shi,Ling-Xin Kong,Wei-Zhun Dong,De-Zhong Cao,Gang-Jin,Ying Liang,Kun-Shan Yang
Post-modification of metal-organic framework (MOF) materials is an effective means to enhance their efficient and selective adsorption for heavy metal ions . In this article, we presented a reflection-type optical fiber surface plasmon resonance (SPR) sensor based on dual core fiber (DCF) coated with UiO-66-RSA (UiO-66-NH 2 post-modified with resorcinol aldehyde) film for the specific detection of Pb(II) in aqueous media . The composite material UiO-66-RSA exhibits stronger affinity and specificity for Pb(II) than UiO-66-NH 2 . The adsorption of Pb(II) can change the equivalent refractive index (RI) of UiO-66-RSA film, causing a regular shift in SPR spectra. Experiments have shown that the limit of detection (LOD) of the SPR Pb(II) sensor can reach 0.1 nM. Meanwhile, research has found that the SPR sensor is accompanied by temperature crosstalk of 0.356 nm/°C. Therefore, we constructed a Michelson temperature interferometer using polymer micro tips on the end face of the fiber core to achieve temperature compensation. Based on the above two sensing channels, dual parameter demodulation of Pb(II) concentration and temperature can be achieved with an error rate of less than 0.5 %. This article has potential research value in exploring the application of post modification techniques of MOF in fiber optic lead ion detection.
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