Abstract
Two novel adsorbents of CaAl-LDHs and sodium dodecyl benzene sulfonate (SDBS) intercalated CaAl-LDHs (SDBS-CaAl-LDHs) were successfully prepared by co-precipitation. The main composition and physical properties of two samples were characterized by XRD, XPS, FT-IR, TG, and SEM. Batch adsorption experiments were conducted to study the effect of pH, adsorption time, and initial concentration of Pb2+. The results showed that the prime adsorption conditions obtained were pH of 5.2 after 60min with the initial concentration of 300mgg-1 for CaAl-LDHs and 350mgg-1 for SDBS-CaAl-LDHs. At 303K, the adsorption capacities and removal rates of CaAl-LDHs and SDBS-CaAl-LDHs were found to be 456.05mgg-1, 91.21% and 682.26mgg-1, 97.47%, respectively. For CaAl-LDHs, the kinetic data for Pb2+ was best fitted with pseudo-2nd-order model, and the adsorption isotherms followed Langmuir and Freundlich isotherm model. The adsorption data of SDBS-CaAl-LDHs can be best described by the pseudo-second-order kinetic and Langmuir model. The Pb2+ adsorption mechanism on SDBS-CaAl-LDHs was explored by XRD, XPS, and SEM, and the important roles of the electrostatic attraction, precipitation, complexation, and ion exchange were demonstrated. The Langmuir adsorption capacities for SDBS-CaAl-LDHs were 797.63, 828.76, and 854.29mgg-1 at 293k, 303k, and 313k, respectively. Thus, SDBS-CaAl-LDHs may be a highly economical adsorbent for the treatment of contaminated water.
Highlights
Lead ion in the aquatic environment arouse serious threat to human health because of their bioaccumulation, toxicity, and potential biomagnifications (Kumar et al 2017)
We describe the preparation of sodium dodecyl benzene sulfonate (SDBS)-intercalated CaAl-Layered double hydroxides (LDHs) (SDBS-CaAl-LDHs), and the study of the lead ions removal process for wastewaters, and its adsorption effect is compared to that of CaAl-LDHs used as sorbent
Two bands located at 2982 and 2873 cm-1 were due to the C-H stretching vibration bands of dodecylsulfate ions in SDBS-CaAl-LDHs (b)
Summary
Lead ion in the aquatic environment arouse serious threat to human health because of their bioaccumulation, toxicity, and potential biomagnifications (Kumar et al 2017). Adsorption of Pb(II) using cost-efficient adsorbents has been studied in the last few years, such as bentonite (Niu et al 2020), activated carbon (Liu et al 2019), fly ash (Huang et al 2020), clay (Abukhadra et al 2019), zeolite (Han et al 2020) and so on. These adsorbents have a slow adsorption kinetics and low adsorption capacities for adsorbing heavy metal ions from wastewater (Gupta et al 2010). We describe the preparation of SDBS-intercalated CaAl-LDHs (SDBS-CaAl-LDHs), and the study of the lead ions removal process for wastewaters, and its adsorption effect is compared to that of CaAl-LDHs used as sorbent
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