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Present work described the synthesis of Al-Fe-Zn oxide nanocomposite and surface properties determinations by spectrophotometric method. Homogeneous mixing of metals, size range 9–13 nm, and rough surface determined from TEM and FESEM images are discussed. The specific surface area (121.3 m2/g), crystalline nature and elemental composition were deduced from XRD and EDAX analysis. The presence of surface hydroxyl group as identified by FTIR was found responsible for complex formation with chromate ion. The batch adsorption of chromium at different experimental variables revealed an optimised condition for chromium adsorption. Adsorption data followed second-order kinetics, Langmuir, and Freundlich isotherms. The pore diffusion and complex formation for chromium adsorption mechanism were predicted on the basis of kinetic and isotherm studies. The statistical data reveal that the double-layer model best explains the adsorption behaviour and mechanism. The unique surface properties, excellent reuse efficiency signify the application of nanocomposite. [ABSTRACT FROM AUTHOR]

Pb(II) doped zinc oxide nanoparticles (Pb-ZnONPs) was synthesised using the co-precipitation method. The average size distribution of the Pb-ZnONPs is 42.8 nm and further used as an adsorbent to remove Erichrome Black T (EBT) from wastewater. The adsorption of EBT onto the Pb-ZnONPs was best fitted for pseudo-second-order kinetics model, indicating that the adsorption phenomena depend on EBT and Pb-ZnONPs, showing chemisorption phenomenon. The maximum adsorption potential of Pb-ZnONPs (qmax = 200 mgg−1) for EBT is far better than that of the already available adsorbents. The high regression coefficient of freundlich shows that the adsorption can be shown by multi-layer process. The value of ΔG° is negative and temperature increases with an increase in the absolute value increases, suggesting the adsorption of dye onto the Pb-ZnONPs is spontaneous. The decrease in the concentration of adsorbed monolayer (Q0 = nNM) from 411 to 43.55 mg/g with the change in temperature revealed that the adsorption process is exothermic in nature. The Pb-ZnONPs have exhibited a variation of about 7–8% of adsorption compared to the fresh sample after 5th regeneration. [ABSTRACT FROM AUTHOR]