# Scalable Hollow Fiber Adsorbents for Metal Ion Recovery via Selective In‐Pore MOF‐808 Growth under Aqueous Conditions

## TL;DR

This paper presents a scalable method to grow MOF-808 inside hollow fibers for efficient metal ion recovery from water.

## Contribution

A binding-assisted strategy for selective in-pore MOF-808 growth under mild aqueous conditions is introduced.

## Key findings

- MOF-808 in-pore growth achieved with 34 wt.% loading and >99% retention after ultrasonication.
- EDTA-functionalized composite shows 2.5-fold faster Pb2+ adsorption kinetics.
- A 105 cm fiber unit effectively treats 1 L of mixed-metal solution, demonstrating scalability.

## Abstract

Selective in situ growth of metal–organic frameworks (MOFs) within polymeric supports under mild, aqueous conditions remains a synthetic challenge due to interfacial instability, uncontrolled crystallization, and MOF leaching. Here, this study reports a binding‐assisted strategy for the selective in‐pore growth of MOF‐808 within polyacrylonitrile (PAN)/polyvinyl pyrrolidone (PVP) hollow fibers at 30 °C. Alkaline hydrolysis of PAN introduces anchoring sites for zirconium clusters, while ethanol‐assisted solvation promotes MOF crystallization under ambient conditions. The spatial distribution and surface charge of hydrolyzed PVP suppress MOF nucleation on the outer surface, enabling uniform in‐pore growth with 34 wt.% loading and > 99% retention after ultrasonication. Post‐synthetic functionalization with ethylenediaminetetraacetic acid (EDTA) imparts a strong affinity for Pb2+, Ni2+, and Co2+ ions. The EDTA‐modified composite exhibits a 2.5‐fold increase in Pb2+ adsorption kinetics compared to physically blended counterparts. A modularized 105 cm fiber unit effectively treats 1 L of a mixed‐metal solution (10 ppm each), underscoring the scalability and process compatibility of this approach. This work demonstrates a mild, scalable, and leaching‐resistant route for fabricating MOF‐polymer hybrid sorbents through spatially controlled in‐pore crystallization, offering a robust platform for water treatment and metal recovery applications.

Ethanol‐assisted solvation enables in situ crystalization of MOF‐808 within PAN/ PVP hollow fibers under mild aqueous conditions, while the spatial distribution of hydrolyzed PVP directs selective in‐pore growth. The resulting EDTA‐functionalized composite offers excellent structural stability and metal ion uptake, providing a scalable, leaching‐resistant architecture for MOF‐polymer hybrid sorbents.