CNF/modified ZSM-5: Composite Sensors for Ammonia and Ethanol detection

This work deals with development of fiber reinforced nanocomposites and their gas sensing performances for ammonia and ethanol target gases. Effect of cellulose nanofibers (CNF) on gas sensing ability of newly developed composite sensors, wherein modified ZSM-5 forms work as matrices and CNF as a dispersing material, has been demonstrated. Modified forms of nano NaZSM- 5, synthesized in laboratory, are obtained via dealumination and ion exchange processes. CNF/Modified nano-ZSM-5 composite film sensors are developed by solution casting method and are characterized by XRD, FTIR, SEM, TGA and BET techniques. These films are tested for detection of ammonia and ethanol gases. Various gas sensing parameters like gas response, response /recovery time and saturation limit are determined. It is observed that the composite sensors have ability to detect ammonia and ethanol gases in low temperature range(30–35°C). Gas adsorption data indicates that sensing selectivity for ammonia over ethanol can be significantly improved by such modification. CNF/Cu-ZSM-5 (C80) CNF/Fe-ZSM-5(Fe80) composite sensors show higher affinity towards ammonia and ethanol gases respectively. It is remarkable to note that blending of CNF with various modified ZSM-5 forms results in low operating temperatures (30–35°C) compared to that for ZSM-5 (135°C) for ethanol. The developed sensors can detect both gases with a concentration as low as 1ppm. Incorporation of CNF results in reduction in response and recovery times than pure ZSM-5 sensor. These sensors have potential to be used selectively as ammonia sensors.