The role of kaolin and kaolin/ZnO nanoadsorbents in adsorption studies for tannery wastewater treatment

Abstract

In the present study, comparative studies of kaolin and kaolin/ZnO nanocomposites for the adsorption of Cr(VI), Fe(III), COD, BOD, and chloride from tannery wastewater were investigated. ZnO nanoparticles and kaolin/ZnO nanocomposites were prepared by sol-gel followed by wetimpregnation methods. The prepared adsorbents were characterized using different analytical tools such as X-ray diffraction, Fourier transforms infrared, high-resolution transmission electron microscopy, energy dispersive spectroscopy, selective area electron diffraction and Brunauer Emmett-Teller (BET) and X-ray Photoelectron Spectroscopy (XPS). The HRSEM/EDS/XPS analysis confirmed successful immobilization of clay structural network on the lattice layers of zincite hexagonal structure of ZnO nanoparticles. BET measurement showed an increase in the surface area of kaolin/ ZnO nanocomposites (31.8 m 2 /g) when compared to kaolin (17 m 2 /g). Batch adsorption studies were carried out by varying the parameters such as contact time, adsorbent dosage and temperature. The maximum removal of Cr(VI) (100%), Fe(III) (98%), COD (95%), BOD (94%) and Chloride (78%) was obtained at 15 min by kaolin/ZnO composites. While 78% Cr(VI), 91% Fe(III), 91% COD, 89% BOD and 73% Chloride were removed by kaolin under the same conditions. The kaolin/ZnO nanocomposites exhibited better adsorption performance than kaolin due to higher surface area of the former than the latter. It was found that the Jovanovic isotherm model fitted the adsorption experimental data most with the highest correlation (R 2 > 0.99) for both nanoadsorbents and indicate the occurrence of adsorption on monolayer and heterogeneous surfaces. The mechanism for the adsorption of metal ions in tannery wastewater onto the nano-adsorbents was examined using Weber Morris intra-particle diffusion model and Boyd plot which showed that the adsorption process was both intra-particle and film diffusion controlled. The thermodynamic parameters such as enthalpy change showed that that adsorption of metal ions and other parameters was feasible, spontaneous and endothermic. The ZnO/ clay nanocomposites exhibited excellent recyclable and re-useable properties even after six repeated applications and can, therefore, be applied in wastewater treatment for removal of heavy metals and other physicochemical parameters. Environmental contamination via natural and anthropogenic activities have been recognized as one of the major global problems confronting the human race and aquatic species. Industrial manufacturing processes utilize a high amount of clean water during operations and at the same time generate and discharge a large volume of untreated wastewater into water bodies. Specifically, industrial tanning process which transforms animal hides and skins into leather generate highly turbid, coloured and foul-smelling wastewater containing different organic

Facile preparation of amine -functionalized corn husk derived activated carbon for effective removal of selected heavy metals from battery recycling wastewater

“…Pb (II) ions have the highest percentage removal due to their high electronegativity of 2.33, followed by Ni ions with 1.91 and Cu with 1.90. The higher the electronegativity, the faster the diffusion and removal efficiency ( Egbosiuba et al., 2020 ; Mustapha et al., 2020 ). Finally, the optimal AF-CHAC dosage for the removal of Pb(II), Cu(II), and Ni(II) ions was 4 g/L.…”

“…The maximum percentage removal for Pb(II), Cu(II), and Ni(II) ions was 99.66, 96.01, and 92.36 %, respectively and this was observed at an equilibrium time of 60 min. Furthermore, increasing the contact time beyond this point resulted in a percentage removal decrease due to blockage or saturation of the adsorbent active sites and the weakening of the binding force as the sorbate concentration decreases ( Mustapha et al., 2020 ). Similar observation was reported by Fatehi et al.…”

Optimization, Structural Characterization, Thermal Properties, and Bactericidal Activity of Novel Alginate/Kaolin/Ag Bionanocomposite against Streptococcus Mutans Biofilm

“…Kaolin is a mineral of layered phyllosilicate clay and a common compound in soils and sediments [20,21]. Due to its cheapness, availability, and unique chemical and physical properties, this clay has been used in many healthrelated matters such as the food industry, wastewater treatment, and bleeding control [22][23][24]. Even though clay particles have no antibacterial properties, the intercalation of Ag particles on them can kill adsorbed bacteria [25].…”

An In Situ Incorporation of Acrylic Acid and ZnO Nanoparticles into Polyamide Thin Film Composite Membranes for Their Effect on Membrane pH Responsive Behavior

“…Furthermore, these inorganic nanoparticles have been extensively applied as nano-adsorbents in order to remove heavy metal ions from wastewater. This is because of their high surface area, high activity, and enhanced structural stability [14][15][16][17][18][19][20]. For instance, Al-Hobaib et al reported that ZnO nanoparticles enhanced hydrophilic properties of reverse osmosis (RO) PA-TFC membranes.…”