Nanocomposite carbon-PDMS membranes for gas separation

Polydimethylsiloxane (PDMS) composites containing variable weight amounts of carbon black (CB) have been synthesized as membranes to evaluate the effect of CB concentration on gas selectivity and separation. The membranes were used in conjunction with a commercial semiconducting methane (CH4) gas sensor that had a strong cross-talk with hydrogen (H2) gas. The selectivity of the CB-PDMS composite membranes for gas separation was tested using CH4 and H2. It was found that at 6 wt% of CB in PDMS, the permeability of CH4 was significantly and selectively attenuated through the composite membrane. This work demonstrates that CB is an effective additive for tuning H2/CH4 gas selectivity of the composite membranes. The selectivity is attributed to a chemical transition occurring with increasing CB doping, which was observed by vibrational spectroscopy measurements.