Modification of nanoclinoptilolite zeolite with hexadecyltrimethylammonium surfactant as an active ingredient of chromate-selective membrane electrode

A novel chromate selective pvc membrane electrode was constructed using a hexadecyltrimethylammonium-surfactant modified zeolite (smz). nano particles of an iranian clinoptilolite zeolite were prepared by a ball-mill mechanical method and characterized by ft-ir,sem and xrd. best performance was exhibited at the membrane composition of smz: pvc: dioctyl phthalate (dop) in the ratio of 4: 32: 64. this membrane worked well over a wide concentration range from 5×10-6 to 1.0×10-2 mol l-1 of cro42- with a nernstian slope of -29.38±0.29 mv per decade of cro42- concentration with detection limit of 2×10-6 mol l-1 in a wide ph range of 6.8-10.7. the response time of the sensor is 5-10 s over a period of 2 months with good reproducibility. the selectivity coefficients of the proposed electrode towards various interfering ions were determined by fim and ssm methods. the sensor was successfully used as indicator electrode in the potentiometric titration of cro42- against pb(ii) and determination of chromium in an electroplating wastewater sample. © 2013 alireza nezamzadeh-ejhieh and gholamhosein raja.