Functionalized diatom silica microparticles for removal of mercury ions

Abstract

Diatom silica microparticles were chemically modified with self-assembled monolayers of 3-mercaptopropyl-trimethoxysilane (MPTMS), 3-aminopropyl-trimethoxysilane (APTES) and n-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AEAPTMS), and their application for the adsorption of mercury ions (Hg(II)) is demonstrated. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses revealed that the functional groups (-SH or -NH 2 ) were successfully grafted onto the diatom silica surface. The kinetics and efficiency of Hg(II) adsorption were markedly improved by the chemical functionalization of diatom microparticles. The relationship among the type of functional groups, pH and adsorption efficiency of mercury ions was established. The Hg(II) adsorption reached equilibrium within 60 min with maximum adsorption capacities of 185.2, 131.7 and 169.5 mg g −1 for particles functionalized with MPTMS, APTES and AEAPTMS, respectively. The adsorption behavior followed a pseudo-second-order reaction model and Langmuirian isotherm. These results show that mercapto-or amino-functionalized diatom microparticles are promising natural, cost-effective and environmentally benign adsorbents suitable for the removal of mercury ions from aqueous solutions.

Polyethyleneimine functionalized mesoporous diatomite particles for selective copper recovery from aqueous media

“…The chemical compositions of the as received (pristine) and acid treated DE particles are shown in Table 2 Powder X-ray diffraction analysis of the particles before and after acid leaching indicated them to substantially amorphous in structure, consistent with previous studies [17,18].…”

“…As an alternative, naturally occurring and cheaper mesoporous materials such as DE particles, which display high metal ion sorption capacity similar to that of the more expensive synthetic adsorbents, are attracting significance attention [17][18][19][20]. As fossilized remains of diatoms, DE particles' unique and intricate structural, chemical and mechanical properties (e.g., hierarchical pore structure, high specific surface area, robustness, metal ion sorption capacity, non-toxic and chemical inertness etc.…”

Functionalization of the living diatom Thalassiosira weissflogii with thiol moieties

“…The incorporation of MPTMS into the frustule was confirmed by SEM-EDX, XPS, Si-NMR, and TEM-EDX analyses. The thiol moiety has a functional role and has been used in studies to demonstrate removal of heavy metals from water samples 26,27 . The possibility of using the living diatom following modification of the chemistry of the frustule is an exciting area of research.…”

Eco-friendly and cost-effective superabsorbent sodium polyacrylate composites for environmental remediation

“…5 b, c), and the regression coefficients (R 2 ) data in Table 2 indicate that the Langmuir model (R 2 = 0.999) described the Cu(II) adsorption process onto the PAANa sample much better than the Freundlich model (R 2 = 0.951). Thus, a Langmuir adsorption isotherm can be used for the best description of the observed adsorption equilibrium behavior of Cu(II) ions onto PAANa adsorbent and the adsorption may be assumed to be a monolayer coverage of adsorbate at homogeneous binding sites on the adsorbents [21,34,42].…”