Zwitterionic poly (amino acid methacrylate) brushes functionalized dendritic mesoporous silica nanoparticles in layer-by-layer assembled membranes for selective Ion separation

Heavy metal contamination necessitates efficient water purification technologies that balance water permeability and selective ion removal. This study introduces dendritic mesoporous silica nanoparticles (DMSNs) decorated with zwitterionic polymeric brushes, engineered for high-performance ion separation. The polymer, cysteine methacrylate, was covalently attached to DMSNs using atom transfer radical polymerization (ATRP), generating ~162 nm-sized particles.

SEM, TEM, FT-IR, TGA, and DLS analyses confirmed the successful functionalization. In adsorption experiments, DMSNs-PCysMA exhibited superior Pb²⁺ and Cd²⁺ uptake compared to bare DMSNs, particularly at elevated concentrations. Composite membranes incorporating chitosan-modified DMSNs and the polymer-functionalized particles in a polysulfone matrix were synthesized and characterized for their water permeability and salt rejection properties.

The DMSNs-PCysMA@CHIT membrane displayed exceptional water flux while maintaining high salt rejection rates. Under cross-flow filtration, the assembled membranes effectively removed heavy metals such as Cr³⁺, Cu²⁺, Cd²⁺, and Pb²⁺, achieving removal efficiencies from 85% to 99%. This research, supported by King Saud University's Ongoing Research Funding Program, exemplifies a promising approach for enhancing heavy metal removal in water purification membranes.