Amine-functionalized porous aromatic frameworks for chlorine and chloramine removal in water treatment

Overview

This solution addresses the removal of free chlorine and chloramine from water using amine-functionalized porous aromatic frameworks (PAFs). Conventional water treatment relies on granular activated carbon (GAC) or ion exchange (IX) resins, which require large form factors and frequent replacement. PAFs offer extremely high surface area and chemical versatility, enabling a significantly smaller system footprint while maintaining or improving removal performance. A complementary polymer indicator layer changes color when the adsorbent approaches capacity, giving users a clear visual cue for replacement without specialized instrumentation.

Technical specifications

• High-surface-area adsorbent: PAFs provide approximately 5,600 m²/g of surface area, enabling high contaminant loading in a compact volume.
• Dual-mode quenching chemistry: The aromatic backbone interacts with chloramine while amine functional groups fix free chlorine on the PAF surface, addressing both common disinfectants in a single material.
• Tunable performance: Degree of functionalization and pore engineering can be adjusted to optimize capacity and selectivity for target contaminants.
• Granular form factor: Agglomeration methods are being developed to produce PAFs in granular shapes suitable for packed-bed filter columns.
• Visual endpoint indicator: A dye-loaded polymer layer placed at the end of the filter bed reacts with residual chlorine and chloramine, producing a color change that signals breakthrough is approaching.
• Reduced material requirements: Higher adsorption capacity per unit mass reduces the amount of adsorbent needed compared to GAC or IX resin systems.

Technology readiness level

The technology is at an early stage of development. Preliminary work in the lab has demonstrated that Lewis-acid-functionalized PAFs can selectively adsorb specific water pollutants, and that functionalization and pore engineering significantly tune adsorbent properties. Phase I (Year 1) will focus on batch-mode measurement of chlorine and chloramine quenching capacity for PAFs and amine-PAFs, granular form development, small-scale column testing, and polymer indicator sensitivity evaluation. Phase II (Year 2) will build on these results to plan pilot-scale testing and integrate the polymer indicator into a complete system. The research team has prior experience developing novel adsorbents for water treatment, including commercial products.