Application of ZnO Nano Rods for the Batch Adsorption of Cr(VI): A Study of Kinetics and Isotherms

Abstract

The present study reports the synthesis of nano Zinc Oxide (ZnO) and its adsorption behaviour. The ZnO obtained by precipitation method were found to be well-defined nano rods arranged like flower. The shape, size and structure of ZnO were characterized from X-Ray Diffraction (XRD), Energy Dispersive X-ray (EDX) and Scanning Electron Microscope (SEM) analysis. These nano rods were utilized for the adsorption of hexavalent chromium ions [Cr(VI)] from their aqueous solution by using batch adsorption technique. Different physico-chemical parameters such as metal ion concentration, pH, dosage level and equilibrium contact time were studied during adsorption. The amount of chromium adsorption increases with increase in adsorbent dosage, whereas the adsorption was maximum in the first 40 min with optimum value of pH 3. The kinetic of adsorption was best fitted by the pseudo-second-order rate equation. Similarly, the equilibrium adsorption data were fitted well by both Temkin and Freundlich adsorption isotherm models in comparison to Langmuir adsorption model. The adsorption of chromium was supported by EDX and SEM analysis. Moreover, the change in the SEM morphology of ZnO nano rods into nano sheets after adsorption is an interesting observation of the present investigation.

Adsorptive potential of ZnO/SiO2 nanorods prepared via the sol–gel method for the removal of Pb(II) and Cd(II) from petroleum refinery wastewater

“…This corresponds to the hexagonal wurtzite phase (JCPDS 36-1541). The XRD pattern also shows intense and sharp diffraction peaks at 2⊔ values of 20 101), ( 110), (012), ( 111), ( 200), (021), ( 112), ( 202), ( 103), (211), ( 212) and (301), respectively. This matched well to crystalline SiO 2 nanoparticles with JCP2_83-0539 of the ⊍-quartz phase of silica.…”

“…The removal values for Hg(II), Pb(II), Bi(III) and Cd(II) reported were 86.8%, 97.1%, 61.2% and 80.9%, respectively. Kamath et al 20 successfully synthesized ZnO nanorods for Cr(VI) removal. Those authors reported 0.00165 mg g −1 to be the highest adsorption capacity.…”

Synthesis and Characterization of Zinc Oxide Nanoparticle Anchored Carbon as Hybrid Adsorbent Materials for Effective Heavy Metals Uptake from Wastewater

“…; the demand for zinc oxide is always rising [28,29]. In addition, zinc oxide nanoparticles have been investigated for water treatment by adsorption various heavy metal such as Cu(II), Cr(VI), Cd(II) and Pb(II) [30][31][32][33].…”

Green Zinc Oxide (ZnO) Nanoparticle Synthesis Using Mangrove Leaf Extract from Avicenna marina: Properties and Application for the Removal of Toxic Metal Ions (Cd2+ and Pb2+)

“…Angelin et al (2015) [16] employed spherical ZnO-NPs (8 nm), manufactured by the sol-gel technique, as an adsorbent for Hg(II), Cd(II), Bi(III), and Pb(II) elimination under the reaction parameters of duration (60 min), temperature (30 • C), dosage (0.250 g), and [M n+ ] (0.01 mol L −1 ) The reported elimination values for Cd(II), Pb(II), Bi(III), and Hg(II), were 61.2%, 97.1%, 80.9%, and 86.8%, respectively. Kamath et al (2019) [17] produced a ZnO nanosphere to effectively remove Cr 6+ , and the authors reported that the q e was 0.00165 mgg −1 . In contrast, the instability of zinc oxide nanoparticles in an aqueous matrix is a disadvantage.…”