Heavy metal removal using structured sorbents 3D printed from carbon nanotube-enriched polymer solutions

Sorbents with structures tailored at the molecular through device scales are needed to meet the demand for separations that can isolate trace analytes from complex mixtures. Here, direct-ink-writing three-dimensional (3D) printing is combined with a surface-segregation and vapor-induced phase separation (SVIPS) process to create hierarchically structured sorbents that satisfy this criterion. Composite inks containing polysulfone, polystyrene-blockpoly(acrylic acid) (PS-PAA), and carbon nanotubes (CNTs) were formulated to allow these processes to proceed simultaneously. Enriching the inks with CNTs modulated their rheological characteristics such that microstructured sorbents with permeabilities of similar to 105 L m(-2) h(-1) bar(-1) could be printed. The SVIPS process generated an interconnected network of PAA-lined nanopores whose chemistry was tailored to produce sorbents that recovered Co2+ selectively from mixtures of Co2+ and Li+ and efficiently treated sub-parts per million feed solutions under dynamic flow conditions. The versatile combination of 3D printing and SVIPS provides new strategies for manufacturing next-generation sorbents with structures controlled across multiple length scales.

Automated summary

In this study, direct-ink-writing 3D printing was combined with surface segregation and vapor-induced phase separation (SVIPS) to create hierarchically structured sorbents. These sorbents can effectively separate trace analytes from complex mixtures and treat solutions under dynamic flow conditions.