# Effect of Hopcalite Modification on the Pore Textural and HCl Adsorption Properties of Activated Carbon Fibers

## TL;DR

This study shows how modifying activated carbon fibers with hopcalite improves their ability to capture hydrogen chloride gas from industrial air pollution.

## Contribution

The novel contribution is optimizing hopcalite modification to enhance HCl adsorption without significantly reducing the fiber's pore structure.

## Key findings

- Moderate CuMnOx loading (Cu 0.04) achieved 83.6% HCl removal and high adsorption capacity.
- Higher Cu loadings reduced microporosity and lowered HCl removal efficiency.
- Optimal modification combines physical and catalytic chemisorption for effective HCl capture.

## Abstract

Industrial air pollution, particularly acidic gases such as hydrogen chloride (HCl), poses serious environmental and health hazards. Here, hopcalite catalysts were introduced into activated carbon fibers via the impregnation process to enhance HCl capture. The Cu/Mn molar ratio was fixed at 1:1 while the Cu precursor loading was varied with the weight of Cu (Cu 0.04–0.1). Structural and surface modifications were examined using scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometer, and Brunauer–Emmett–Teller analyses. Progressive CuMnOx deposition increased Cu and Mn contents up to 4 at.% and 3.7 at.%, respectively, but decreased the specific surface area from 1565.1 to 1342.7 m2/g owing to pore blocking. Fixed-bed breakthrough tests (50 ppm HCl, 1000 mL/min) showed that moderate catalyst addition (Cu 0.04) yielded the highest total removal (83.6%) and adsorption capacity (12,354.6 mg/g), benefiting from combined physical and catalytic chemisorption. Higher loadings (Cu 0.06–0.1) further reduced microporosity and led to lower removal efficiencies. These results demonstrate that an optimal CuMnOx level effectively promotes chemical adsorption without compromising the intrinsic microporous network of ACFs.