Preparation of new diatomite–chitosan composite materials and their adsorption properties and mechanism of Hg(II)

Abstract

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet–visible (UV–Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g−1.

Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

“…CS has outstanding removal capacity with regard to many mercury ions especially the Hg(II) ion, which is attributed to amine and hydroxyl groups with chelating metal properties. However, CS can be dissolved in acidic solutions, resulting in agglomeration and formation of a gel, which makes CS difficult to disperse and hinders many hydroxyl and amino groups from chelating metal ions [ 24 ]. To improve the acid resistance and further increase the adsorption capacity, natural CS is modified by some physical or chemical approaches [ 25 , 26 ].…”

Fabrication of Green Diatomite/Chitosan-Based Hybrid Foams with Dye Sorption Capacity

“…The density and porosity of PDC60 were also evaluated to verify the effect of chitosan on the physical properties of the foams. As shown in Table 1 , the presence of chitosan into the matrix did not affect significantly the density and the porosity of the structure with respect to the pristine PD [ 27 , 42 ]. Moreover, the water absorption (that is directly correlated to the presence of open pores) and the high value of open porosity suggested that the PDC60 is suitable to be applied as an adsorbent for removing toxic compounds from aqueous media, such as the anionic dye Indigo Carmine [ 44 ].…”

“…Its value is higher with respect to that of pristine C, probably due to a synergistic contribution of functional groups of C and to a larger specific area available in presence of diatomite. In addition, the removal efficiency of IC dye increased with the amount of C. This is likely due to the effect either of the presence of micropores on the diatomite surface [ 42 , 45 ] and of the chitosan [ 27 ] that, in the DCs hybrid, is embedded on the surface of D and, thus, shows a higher specific surface area available to interact with IC with respect to the raw powders.…”

“…Among these applications, chitosan has received great interest as adsorbents for wastewater treatment [ 18 , 19 , 20 , 21 ]. On the other hand, in the recent literature, some papers deal with the combined use of both diatomite and chitosan to produce adsorbents for environmental pollutant removal, with the aim to evaluate their synergistic adsorption properties [ 22 , 23 , 24 , 25 , 26 , 27 ]. Herein, a chitosan-modified diatomite was synthesized with the aim to produce a novel, broad spectrum hybrid adsorbent.…”

Preparation of cellulose/diatomite composite material and its adsorption characteristics and kinetics

“…In Fig. 6(a), the peak at 26.4° belonged to the typical SiO2 diffraction peak (Fu et al 2017). Compared to raw diatomite, the diffraction peak at 2θ = 26.4 ° (α-quartz crystal phase) of the CDAs appeared to be weaker.…”