Determination of mercury(II) by single-walled carbon nanotubes paste electrode modified with zincaluminium layered double hydroxide-3(4-methoxyphenyl) propionate nanocomposite

This study aimed to develop a mercury(II) sensor and to identify its ability in mercury(II) determination. A mercury(II) sensor was developed by using singlewalled carbon nanotubes (SWCNTs) paste electrode modified with ZnIAl layered double hydroxide-3(4-methoxyphenyl)propionate nanocomposite (ZnIAI-LDH-MPP). Determination of optimum conditions for the detector was done by voltammetry method and subsequently confirmed by the double potential-step chronocoulometry. The results show that the optimum conditions were observed at electrode composition 2.5% (w/w) of ZnIAI-LDH-MPP/SWCNTs, OA M potassium chloride, pH 4.0, and scan rate of 100 mV S-I. The sensor exhibited wide linear range from 1.0 x l O" M to 1.0 x1O-3 M mercury(II) and 1.0 xl O" M to 1.0 xlO-7M mercury(II), with a detection limit of 1.0 xlO-lO M mercury(II). The high sensitivity of the proposed electrode towards mercury(II) was confirmed by double potential-step chronocoulometry which indicated these values; diffusion coefficient: 1.5445 x 10-9 cm2 S-I, surface charge: 524.5 IlC s-Yz and surface coverage: 4.41 x 10-2 mol cm-2• The presence of 25-fold concentration of most metal ions had no influence on the anodic peak current. The analysis of real samples were also compared with those obtained by the proposed electrode and the mercury analyzer, which shows no significant difference between the results obtained by the two methods based on a r-test (at 95% confidence level). Thus, it can be concluded that the paste electrode modified with ZnIA1layered double hydroxide-3(4-methoxyphenyl)propionate nanocomposite (ZnlAI-LDH-MPP) is able to detect mercury(II). With characteristics such as high sensitivity, selectivity and repeatability, the electrode is proposed as the appropriate alternative for the determination of mercury(II).