Efficient use of novel hybrid materials in the ultra-trace determination of arsenic from aqueous solutions: an electrochemical study

Hybrid material precursor to a natural bentonite is prepared. Bentonite is modified with hexadecyltrimethyl ammonium bromide (HDTMA) by simple wet cation exchange process as to obtain the organo-modified bentonite (BH). The material is characterized with the X-ray diffraction and IR analytical methods. Moreover, the surface morphology of these solids is discussed with the help of scanning electron microscopic images. Bentonite (B) and hybrid material (BH) is introduced with the carbon powder as to modify the carbon paste electrode (MCPE). The MCPE with reference to B and BH-modified electrodes are then utilized to study the electrochemical behavior of arsenic(III) from aqueous solutions. Characteristic reversible behavior of arsenic(III) is obtained by the cyclic voltammetric measurements. An enhanced cathodic or anodic current is obtained using the BH-modified electrode comparing to the B-modified electrode. Further, the study is extended with a wide range of scan rate (80–200 mV/min) and the effect of pH (2.5–8.5). The concentration dependence study clearly reveals that reasonably a good linearity of cathodic current is obtained for the As(III) concentration ranging from 1.0 to 40.0 μg/L using BH-modified electrode. Moreover, the limit of detection and limit of quantification (LOQ) is obtained for arsenic(III) detection using the calibration equation. The study is further extended for the detection of arsenic(III) in presence of several cations viz., Cu(II), Mn(II), Pb(II), Cd(II), and Fe(III) and anions phosphate, glycine and EDTA independently using the BH-modified electrodes.