In Situ Coprecipitation Formed Highly Water-Dispersible Magnetic Chitosan Nanopowder for Removal of Heavy Metals and Its Adsorption Mechanism

Abstract

The requirement for enhanced, less expensive, and eco-friendly nanocomposites as an adsorbent is highly preferred for removal of heavy metals and in the major applications of environmental remediation. For widespread application prospects, a simple and cost-effective method for highly effective nanoadsorbent preparation is mainly studied. In this study, by using natural polymer chitosan (CS) and different iron ion precursors, a facile in situ one-step coprecipitation synthetic approach is used to develop water-dispersible chitosan/Fe3O4 nanocomposites. The physical and chemical properties of the synthesized magnetic chitosan nanopowder (MCNP) before and after adsorption were studied using FTIR, SEM, TEM, XRD, BET, and TGA instrumental methods. The adsorption efficiency was specifically studied by varying initial metal ion concentration, pH of the solution, and MCNP dosage for Pb­(II) and Cu­(II) as a model pollutant. The experimental data obtained are fitted by three adsorption isotherms and reaction kinetics models. The adsorption of Pb­(II) and Cu­(II) onto MCNP (1 g/L) followed a Langmuir adsorption isotherm with the highest adsorption capacity of 113.38 and 92.34 mg/g at pH = 5.5 and temperature 25 °C, respectively. The results of thermodynamic analysis show that the adsorption of Cu­(II) on MCNP is endothermic, while the Pb ions are exothermic. MCNP nanocomposite is regenerated by the EDTA-2Na-washing method and exhibited greater stability with reusability over usage of five times. Overall, the synthesized water-dispersible MCNP presented regeneration capability and stability toward the aqueous phase and is an excellent adsorbent for heavy metals removal processes.

Effects of EDTA on adsorption of Cd(II) and Pb(II) by low-permeability soil minerals and on their microscopic characteristics

“…Additionally, the calculated value of q e from the pseudo-second order kinetic model was closer to the adsorption capacity obtained from experiments than other models. Namely, the behaviors of HM adsorption onto SMs with and without the effects of EDTA were both conform to the pseudo-second order kinetic model, and the adsorption sites on SMs might be the rate-limiting step [4]. When EDTA was added, it would block the adsorption sites on SM surfaces and affect the electron transfer between adsorbents, so that the adsorption process was controlled; this still related to chemisorption rate-limiting step and obeyed the pseudo-second order kinetic model.…”

“…Hence, the adsorption behaviors of both SM1 and SM2 for Cd and Pb ions suggested a monomolecular layer adsorption [4], and the surfaces of quartz sands and mineral mixtures were structurally homogenous; there was no interaction taking place between Cd or Pb ions. By contrast, with the effects of EDTA, correlation coefficients of both isotherm models for HM adsorption on SMs mostly decreased; and it seems that the experimental data was not well in line with both isotherm models.…”

“…Sanitary wastewater, agricultural and industrial discharges from increasing human activities has made heavy metal pollution become a ubiquitous environmental problem, especially in soil and groundwater system [1][2][3][4]. Enriched heavy metals (HMs) in the environment seriously threaten the ecological system and human health due to high toxicity, the nonbiodegradable nature and the ability of retention [4][5][6]. Toxic metals such as lead (Pb(II)), chromium (Cr(VI)), nickel (Ni(II)) and cadmium (Cd(II)) can cause many severe health effects including bone fractures, organ disorders and brain damage [7].…”

Adsorption of Congo red from solution using chitosan modified carbon nanotubes

“…CS and CS-MWCNTs possessed main peaks at 2920 cm −1 due to the bending vibrations of -CH 2 . The absorption peak at 1644 cm −1 was a characteristic absorption peak of C−N vibration [30]. The absorption at 1000 to 1200 cm −1 comes from the vibration of the C−O.…”

Coadsorption behaviors and mechanisms of Pb(ii) and methylene blue onto a biodegradable multi-functional adsorbent with temperature-tunable selectivity

“…A comparison of adsorption capacity for MB and Pb(II) between SLS and various adsorbents was listed in Table 2. [22][23][24][25][26][27][28][29] According to Table 2, some adsorbents are synthesized from chemical reagents, which may bring secondary pollution due to the exhausted adsorbents. The adsorbent of SLS is biodegradable and eco-friendly deriving from natural-polymerbased materials, though its adsorption capacity is not the highest.…”