| New materials such as biosorbent materials. carbonaceous adsorbent materials and magnetic adsorbent materials have been successfully applied in the removal of variety contaminates in aqueous water. Heavy metal pollution is a serious threat to pubilc health and ecosystem, which has been one of the focuses of the world. With the development of nanotechnology. the adverse impact caused by nanoparticles on biological health and the environment has also attracted tremendous attention. We investigate the adsorpiton properties of thiol functionalized eggshell membrane (TESM) toward multifold heavy metal ions such as Cr(VI). Hg(II), Cu(II). Pb(II), Cd(II) and Ag(I) from aqueous water, the adsorption of nanoparticles onto multiwall carbon nanotubes(MWCNTs) and the adsorbability of poly (diallyldimethylammonium chloride)(PDDA)-modified iron oxide toward silver nanoparticles (Ag NPs).1. TESM was successfully synthesized based on the reduction reaction of disulfide bonds in eggshell membrane (ESM) by ammonium thioglycolate. The as-prepared TESM was characterized, and its application as adsorbent for the removal of multifold toxic heavy metal ions Cr(VI), Hg(II), Cu(II), Pb(II), Cd(II) and Ag(I) from aqueous water has been investigated. The experiment results revealed that the prepared biosorbent TESM has a good affinity to various heavy metal ions. Kinetics of the removal of these ions was found to follow the pseudo-second-order rate equation and the adsorption process was fit well with the Langmuir adsorption isotherm. The maximum adsorption capacity toward Cr(VI), Hg(II), Cu(II), Pb(II), Cd(II) and Ag(I) were113.64,138.89,46.73,32.47,23.70and129.87mg/g. Compared with the ESM control, the adsorption capacities of these six ions increased1.6-,5.5-,7.7-,12.4-,12.7-and21.1-fold. Raman spectroscopy and X-ray photoelectron spectroscopic analysis (XPS) were employed to study the adsorption mechanism. The results demonstrated that TESM could realize not only the removal of heavy metal ions, but also the detoxification of Cr (VI) to Cr (Ⅲ). The effect of solution pH, coexisting substances and natural water matrices were studied. TESM can be used as column packing to fabricate a column for real industrial wastewater purification. The developed biosorbent material promises high adsorption performance, low cost and environmental friendliness, thus may become a promising adsorbent for water treatment.2. We employed carbonaceous materials MWCNTs as adsorbents for the adsorption study of metal nanoparticles such as Citrate-Ag NPs, PVP-Ag NPs, Citrate-Au NPs and PVP-Au NPs from water solution. The influences of dimensions and carboxyl surface modification of MWCNTs on the adsorption properties have been investigated. The experimental results revealed that the adsorbabilities increased with the increasing diameter of MWCNTs and the surface carboxyl of MWCNTs was not favorable for the adsorption of negative nanoparticles. We also explored the effect of nanoparticles coatings and environmental factors such as solution pH, ionic strength and concentration of humic acid on the adsorption behavior. Kinetics of nanoparticles adsorption was found to follow the pseudo-second-order rate equation and the adsorption process was fit well with the Langmuir adsorption isotherm. The maximum adsorption capacities of MWCNTs towards Citrate-Ag NPs, PVP-Ag NPs, Citrate-Au NPs and PVP-Au NPs can reach up to476.19mg/g,64.10mg/g,666.67mg/g and99.01mg/g. Given the good adsorption performance, MWCNTs may become a promising adsorbent for nanoparticles treatment.3. This study presents a facile, simple and rapid approach to functionalize Fe3O4with a low cost and environment friendly cationic polyelectrolyte PDDA when Fe3O4was prepared by the coprecipitation method. PDDA-Fe3O4was characterized by TEM, FT-IR, XRD, VSM and zeta potential, and its application as an adsorbent for Ag NPs adsorption from water solution has been investigated. We studied the effect of solution pH, concentration of humic acid and the coatings of nanoparticles on adsorption behavior. Kinetics of Ag NPs adsorption was found to follow the pseudo-second-order rate equation and the adsorption process was fit well with the Langmuir adsorption isotherm. The maximum adsorption capacities of PDDA-Fe3O4-0.1. PDDA-Fe3O4-0.5, PDDA-Fe3O4-1and PDDA-Fe3O4-2with different concentrations of PDDA towards Citrate-Ag NPs can reach up to357.14,500.00,526.32and588,24mg/g, which are much higher than that of the original Fe3O4with14.49mg/g as the maximum adsorption capacity. PDDA-Fe3O4could be easily seperated under external magnetic field due to its excellent magnetic property and served as a cheap, green and efficient adsorbent for the adsorption of Ag NPs from water solution. |
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