Surfactant-Mediated Electrochemical Precipitation of ZnO Nanospheres for Adsorption of Eosin Yellow & Rhodamine B Dyes

Abstract

A simple electrochemical technique was used to synthesise zinc oxide (ZO) nanospheres and their in-situ modification by a two-step route of electrochemical precipitation with subsequent calcination. The ZO sample has been employed as an adsorbent for the removal of toxic dyes from their solutions. The electrochemical precipitation of zinc hydroxide (ZH) was carried out in a zinc nitrate bath at similar to pH 4. The optimised concentration of 40 g dm(-3) is used for the synthesis of modified zinc oxide (MZO) in the presence of the surfactant TEAB. XRD analysis confirms the formation of the heterostructure ZO. The field-emission scanning electron microscopy (FESEM) images support the formation of hierarchical nanostructures with interconnected nanospheres in the presence of surfactant TEAB, which was confirmed by a high-resolution transmission electron microscopy (HRTEM) study. The porous nature of ZO and MZO was established by the N-2 adsorption-desorption studies. The MZO sample showed similar to 99 % adsorption efficiency at an optimum dose of 0.09 g/20 mL of the 100 mg dm(-3) Eosin Yellow dye solution within 120 min. However, the same sample showed 96 % adsorption efficiency at an optimum dose of 0.05 g/20 mL of the 100 mg dm(-3) Rhodamine-B dye solution within 120 min.