Dendrimer-like Polyamidoamine Research Articles

Removal of Fe(III) from ethanol solution by silica-gel supported dendrimer-like polyamidoamine polymers

The adsorption properties of silica-gel supported hyperbranched polyamidoamine dendrimers (SiO2-G1.0, SiO2-G2.0 and SiO2-G3.0) for the removal of Fe(III) from ethanol solution have been investigated. The effect of adsorbent mass, contact time, initial Fe(III) ion concentration, and temperature have been demonstrated. The adsorption kinetics of the three adsorbents was well described by the pseudo-second-order model. Langmuir isotherm model was more suitable to describe the equilibrium data, and suggested the monolayer adsorption. The mean free energy calculated from D-R isotherm model demonstrated the adsorption processes of was preceded by physical adsorption or chemical adsorption for different generation product in different temperatures. Thermodynamic parameters demonstrated that the adsorption process was exothermic, spontaneous, and random increasing process with the increase of temperature. The adsorption mechanics for Fe(III) is was greatly affected by the solvent. Furthermore, the desorption rate of the SiO2-G1.0 maintained more than 90%, and reflected excellent reusability.

Development of hyperbranched polymer encapsulated magnetic adsorbent (Fe3O4@SiO2–NH2-PAA) and its application for decontamination of heavy metal ions

The water dispersible magnetic adsorbent was fabricated by functionalization of magnetic nanoparticles (MNPs) with 3-aminopropyl trimethoxysilane (APTMS) and dendrimer-like polyamidoamine; the sorbent is named as Fe3O4@SiO2–NH2-PAA. The amine rich Fe3O4@SiO2–NH2-PAA adsorbent was further used in retrieval of heavy metal ions such as Cd(II), Co(II), Zn(II), Pb(II) and Cu(II) from the aqueous medium. Fabrication of Fe3O4@SiO2–NH2-PAA involves a two-step process: (i) surface initiation of MNPs by ligand exchange reaction and condensation of APTMS (Fe3O4@SiO2-NH2), (ii) surface functionalization of MNPs by controlled/living polymerization. Surface functional groups, crystallization characteristics, surface morphologies and magnetic properties of the adsorbent were analyzed by FT-IR, XRD, SEM, TEM, and VSM. The characterization outcomes showed that functionalization improved the oxygen and nitrogen atomic percentages of adsorbent resulting enriched adsorption. Sorption isotherm and kinetic models illustrated that sorption data better fitted to Langmuir isotherm model and pseudo-second order kinetic model. These results suggest that sorption process is monolayer and is chemical in nature. The order of sorption capacities (mgg−1) based on Langmuir isotherm model are: Pb(II) (108.82)>Cd(II) (100.81)>Co(II) (95.40)>Zn(II) (89.62)> Cu(II)(87.82). These findings suggest that as developed magnetic sorbent can be replaceable for traditional adsorbents due its high sorption performance, rapid kinetics, and magnetic separation characteristics.

Syntheses, characterization and adsorption properties for Pb2+ of silica-gel functionalized by dendrimer-like polyamidoamine and 5-sulfosalicylic acid

Silica-gel adsorbents PAMAM-n.0SSASG (n=1–4) with dendrimer-like polyamidoamine (PAMAM) and 5-sulfosalicylic acid as functional groups were prepared and characterized with FTIR, SEM, TG, elemental analysis and porous structure analysis. Micro-column enrichment and measurement of Pb2+ with graphite furnace atomic absorption spectroscopy (GFAAS) was studied with PAMAM-n.0SSASG (n=1–4) as adsorbent. It was emphasized to investigate the relationship between dynamic adsorption/desorption rates, adsorption capacities, and grafting percentage of PAMAM onto silica-gel surface. Experiments showed that the generation increase of grafted PAMAM changed the pore diameter distribution of adsorbent and obviously improved adsorption/desorption property for Pb2+. Adsorption capacity of PAMAM-n.0SSASG (n=1–4) was 14.04, 17.43, 20.07 and 25.05mgg−1 for Pb2+ respectively. An enrichment factor of 200 was obtained with PAMAM-4.0SSASG as adsorbent and with 2000mL Pb2+ solution (1.0ngmL−1). The priority of adsorption property of PAMAM-4.0SSASG was explained by steric hindrance effect of PAMAM on adsorption/desorption, and selective adsorption of 5-sulfosalicylic acid with Pb2+. With PAMAM-4.0SSASG as adsorbent, GFAAS method for analysis of Pb2+ combined with micro-column enrichment was proposed and applied to the determination of Pb2+ of standard reference sample and sea water sample.

Adsorption kinetics and equilibrium of copper from ethanol fuel on silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine polymers

The adsorption kinetics and equilibrium of silica-gel functionalized with amino-terminated dendrimer-like polyamidoamine (PAMAM) polymers SiO2-G1.0, SiO2-G2.0 and SiO2-G3.0 for Cu2+ in ethanol fuel were investigated by using batch method. The results indicated that the all the adsorptions of the three adsorbents followed well the pseudo second-order model. The adsorption isotherms were fitted by Langmuir model, Freundlich model and Dubinin–Radushkevich (D–R) model. The results showed that Langmuir model was more suitable to describe the equilibrium data than the Freundlich model. From the D–R isotherm model, the mean free energy E calculated of the three adsorbents showed that the adsorptions were taken place by physical processes. Thermodynamic parameters, ΔG0, ΔH0 and ΔS0 indicated the Cu2+ adsorption to be endothermic and spontaneous with decreased randomness at the solid-solution interface, resulting in their higher adsorption capacities at higher temperature. The effect of generation number of PAMAM polymers loaded on silica-gel, contact time, initial concentration and temperatures on the adsorption capabilities were studied in detail. Moreover, the adsorption mechanism of copper from ethanol fuel was also presumed.

Removal of Mercury Ions from Ethanol Solution Using Silica Gel Functionalized with Amino-Terminated Dendrimer-Like Polyamidoamine Polymers: Kinetics and Equilibrium Studies

The potential use of silica gel functionalized with dendrimer-like, amino-terminated polyamidoamine polymers (PAMAM) as adsorbents for the removal of mercury ions from ethanol solution was evaluated. The adsorption isotherm and adsorption kinetics were investigated by using the batch method. The adsorption capacity was found to depend on the generation number of PAMAM loaded, contact time, initial concentration, and temperature. The experimental data were fitted to pseudofirst-order and pseudosecond-order kinetic models. The results indicated that all of the adsorption data fitted well with the second-order kinetic model. A stepped fitting method was adopted to determine whether intraparticle diffusion or external diffusion was the rate-limiting step. The adsorption isotherms were fitted by the Langmuir model, Freundlich model, and Dubinin–Radushkevich (D-R) model. The results showed that the Langmuir model defined the equilibrium data better than the Freundlich model. From the D-R isotherm model, the cal...

Adsorption and desorption behaviors of Pd(II) on silica-gel functionalized with ester- and amino-terminated dendrimer-like polyamidoamine polymers

The dynamic adsorption and desorption properties of ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) functionalized silica-gels (SiO 2-G0 ∼ SiO 2-G4.0) for Pd(II) were investigated. The effect of solution acidity on adsorption was studied. The experimental result indicated that the optimum adsorption pH of above-mentioned functionalized silica-gels for Pd(II) was −0.30 when hydrochloric acid was used as medium. Adsorption kinetics suggested that the adsorption was controlled by film diffusion. The adsorption processes of SiO 2-G0 and SiO 2-G0.5 followed a pseudo-second-order model, and those of SiO 2-G1.0 ∼ SiO 2-G4.0 could be described by pseudo-first-order model. The solution of 5% thiourea in 0.2 mol l −1 HCl was employed as the eluent to assess the reusability of SiO 2-G0 ∼ SiO 2-G4.0. The results showed that ester-terminated products possessed higher desorption percentage than their corresponding amino-terminated ones. Due to the stronger encapsulation effects of interior cavities, the desorption percentages of higher generation products were lower than those of the low generation ones.

Preparation and metal-binding behaviour of chitosan functionalized by ester- and amino-terminated hyperbranched polyamidoamine polymers

A series of insoluble chitosan (CTS) derivatives were prepared by grafting ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) into CTS using a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups, and (2) amidation of the resulting esters with ethylenediamine (EDA). Their structures were characterized by infrared spectra (IR) and wide-angle X-ray diffraction (WAXD). The adsorption capabilities of the products for Au 3+, Pd 2+, Pt 4+, Ag +, Cu 2+, Zn 2+, Hg 2+, Ni 2+, and Cd 2+ were studied. The results showed that the products exhibited better adsorption capabilities for Au 3+ and Hg 2+ than for other metal ions, and the adsorption capabilities of amino-terminated products were higher than those of ester-terminated ones. Also it was observed that a high percentage of grafting of PAMAM into CTS does not ensure a high adsorption capacity.

Syntheses, characterization, and adsorption properties for metal ions of silica-gel functionalized by ester- and amino-terminated dendrimer-like polyamidoamine polymer

A series of ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) grafted silica-gel (SiO 2-G0–SiO 2-G4.0) was prepared with a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups; and (2) amidation of the resulting esters with ethylenediamine (EDA) from γ-aminopropyl silica gel core. Their structures were characterized by FTIR, XRD, TG, porous analysis, and SEM. FTIR method was employed to monitor amidation reaction in order to judge the optimum reaction time. The results indicated it needed at least 5, 7, 8, and 9 days for SiO 2-G0.5, SiO 2-G1.5, SiO 2-G2.5, and SiO 2-G3.5 to be converted into SiO 2-G1.0, SiO 2-G2.0, SiO 2-G3.0 and SiO 2-G4.0, respectively at 25 °C. The porous structure analysis showed the BET surface area, BJH desorption average pore diameter and BJH desorption cumulative volume of pores for the products decreased after the series of grafting reactions. Au 3+, Pd 2+, Pt 4+, Ag +, Cu 2+, Zn 2+, Hg 2+, and Cd 2+ were chosen as representatives to investigate the relationship between adsorption capacities and percentage of grafting of polymer onto the surface of silica-gel. The experiments showed that both ester- and amino-terminated dendrimer-like polyamidoamine (PAMAM) grafted silica-gel exhibited better adsorption capabilities for Au 3+ and Pd 2+ than for base metal ions Cu 2+, Zn 2+, Hg 2+, and Cd 2+ and noble metal ions Pt 4+ and Ag +. One interesting conclusion could be drawn from the above investigation, that is, a high percentage of grafting of polymer onto the surface of silica-gel did not mean a high adsorption capacity.

Preparation of dendrimer-like polyamidoamine immobilized silica gel and its application to online preconcentration and separation palladium prior to FAAS determination

A amino-terminated G 4.0 dendrimer-like polyamidoamine (PAMAM) immobilized silica gel (PAMAMSG) was prepared with a divergent method by repeating two processes: (1) Michael addition of methyl acrylate (MA) to surface amino groups; and (2) amidation of the resulting esters with ethylenediamine (EDA) from γ-aiminopropyl silica gel (APSG) core. It was then used for the first time as microcolumn packing for the flame atomic absorption spectrometry (FAAS) determination of trace or ultra trace Pd(II), after flow injection (FI) online preconcentration and separation process. A limit of detection (LOD) of 3.9 ng ml −1 was achieved when 0.200 μg ml −1 Pd(II) was preconcentrated in 0.2 mol l −1 HCl medium with a sampling flow rate of 6.0 ml min −1 for 60 s and the relative standard deviation (R.S.D.) was 1.7%. The proposed method was successfully used for the determination of Pd in two metallurgical samples.