Abstract
A lignocellulose@ activated clay (Ln@AC) nanocomposite with a hierarchical nanostructure was successfully synthesized by the chemical intercalation reaction and applied in the removal of Zn(II) from an aqueous solution. Ln@AC was characterized by N2 adsorption/desorption isotherms and X-Ray Diffraction (XRD), scanning Electron Microscope (SEM), transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis, and the results indicate that an intercalated–exfoliated hierarchical nanostructure was formed. The effects of different adsorption parameters on the Zn(II) removal rate (weight ratio of Ln to AC, Ln@AC dosage, initial Zn(II) concentration, pH value, adsorption temperature, and time) were investigated in detail. The equilibrium adsorption capacity reached 315.9 mg/g under optimal conditions (i.e., the weight ratio of Ln to AC of 3:1, Ln@AC dosage of 1 g/L, initial Zn(II) concentration of 600 mg/L, pH value of 6.8, adsorption temperature of 65 °C, and adsorption time of 50 min). The adsorption process was described by the pseudo-second-order kinetic model, Langmuir isotherm model, and the Elovich model. Moreover, Zn(II) could be easily eluted by HCl, and the effects of HCl concentration, desorption temperature, and ultrasonic desorption time on desorbed amount were tested. Desorption studies revealed that with an HCl concentration of 0.25 mol/L, desorption temperature of 70 °C, and ultrasonic desorption time of 20 min, the maximum desorption capacity and efficiency were achieved at 202.5 mg/g and 64.10%, respectively. Regeneration experimental results indicated that the Ln@AC exhibited a certain recyclable regeneration performance. Due to such outstanding features, the novel Ln@AC nanocomposite proved to have great adsorption potential for Zn(II) removal from wastewater, and exhibited an extremely significant amount of adsorbed Zn(II) when compared to conventional adsorbents.
Highlights
Heavy metal contamination of water is a widespread environmental issue in recent years
The results indicate that compared to the activated clay (AC), the porous structure of the lignocellulose@ activated clay (Ln@AC) was well developed, the V meso highly increased, and the V mac decreased after Ln was intercalated into the interlayer space of the AC
The structure of Ln@AC was found to be loose, with many mesopores and micropores generated on its surface, and the mesopore structure can be supported by its average pore diameter (Dp = 54.09 nm)
Summary
Heavy metal contamination of water is a widespread environmental issue in recent years. The applicability of various methods has been assessed for the removal of Zn(II) from effluents including ion exchange, precipitation, filtration, reverse osmosis, electrolysis, and so on [6,7,8]. Natural layered silicates or activated clay (AC) are commonly accepted as appropriate low-cost adsorbents for their high surface area, high cation-exchange capacity, fine hierarchical structure, and expandable interlayers. AC adsorbs heavy metal ions only on external residual broken bonds on its surface in small amounts and has little or no affinity with organic polymers. Among the many kinds of polymer/layered silicate composites, the lignocellulose@ activated clay (Ln@AC) nanocomposite has rarely been covered with regard to the adsorption of Zn(II) from wastewater. The adsorption kinetics and isotherms with respect to Ln@AC were studied and the mechanism of Zn(II) adsorption is discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
