Yaochi Liu

Phosphorus-modified poly(styrene-co-divinylbenzene)-PAMAM chelating resin for the adsorption of uranium(VI) in aqueous.

Polyamidoamine (PAMAM) modified poly(styrene-co-divinylbenzene) absorbents carrying phosphorus functional groups (PS-PAMAM-PPA) were prepared and used as adsorbents for the adsorption of uranium(VI) from aqueous solution. Different generations of PAMAM were used for obtaining different chelating resins, PS-PPA, PS-1.0G PAMAM-PPA, PS-2.0G PAMAM-PPA, PS-3.0G PAMAM-PPA and PS-4.0G PAMAM-PPA. The synthesized resins were characterized by FTIR and XPS. The effects of many physio-chemical properties on metal ion adsorption to adsorbent phase, such as solution pH, kinetic studies, initial uranium concentration, temperature, were investigated using batch method. The results showed that the maximum adsorption capacity (99.89 mg/g) was observed at the pH 5.0 and 25°C with initial U(VI) concentration 100mg/L and adsorbent dose 1g/L. PS-1.0G PAMAM-PPA had the largest adsorption capacity for U(VI) compared with other prepared adsorbents. The adsorption kinetics of U(VI) onto PS-1.0G PAMAM-PPA followed the mechanism of the pseudo-second-order equation, indicating that the chemical adsorption was a rate-limiting step. The calculated thermodynamic parameters (ΔG, ΔH, ΔS) stated that the adsorption of U(VI) onto PS-1.0G PAMAM-PPA were spontaneous, endothermic and feasible. The adsorption isotherms obeyed the Langmuir isotherm models. The desorption studies showed that PS-1.0G PAMAM-PPA could be used repeatedly and adsorption and desorption percentage did not have any noticeable loss after 27 cycles in a fixed bed.

Removal of mercury ions from aqueous solution by thiourea-functionalized magnetic biosorbent: Preparation and mechanism study

A novel magnetic bio-material (MCIT) was synthesized via coupling reaction and functional modification after load of Fe3O4 nano-particle on the puckered surface of cyclosorus interruptus (CI). The synthesized material was characterized by fourier transform infrared (FTIR), field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffractometer (XRD). The influence factors like pH, temperatures, contact time, initial concentration and cycle times on the adsorption of Hg (II) in aqueous solution were studied. Adsorption isotherm, kinetics, selectivity and mechanism were investigated. The results indicated that the isotherm model well agreed with monolayer adsorption model. The adsorption process could be divided into three steps, which included a fast step controlled by chemical adsorption, a slow step limited by intraparticle diffusion and an equilibrium stage. The maximum adsorption capacity of Hg (II) was 385.3mg/g at 318K. MCIT possessed high reusability (retained 93% after five successive cycles) and sharply magnetic nature (9.5emu/g), which endowed it easy and efficient separation from aqueous solution.

The effect of Ce doped in Ti/SnO2-Sb2O3/SnO2-Sb2O3-CeO2 electrode and its electro-catalytic performance in caprolactam wastewater

Ti/SnO(2)-Sb(2)O(3)/SnO(2)-Sb(2)O(3)-CeO(2) anodes were prepared by brush coating with high temperature oxidation. The anodes were characterized by X-ray diffractometer (XRD), scanning electron microscope and cyclic voltammetry. The surface of the electrode shows more compact and exist shallower mud cracks than the others by coating with 1% Ce to the surface of Ti/SnO(2)-Sb(2)O(3) electrode. The XRD patterns show that as-prepared electrodes are SnO(2) and TiO(2). The electrode with 1% Ce dopant shows the highest efficiency in the electrolysis of caprolactam wastewater. The oxygen evolution potential is about 1.75 V, the removal rate of chemical oxygen demand is 50%, and the biochemical oxygen demand is 353 mg/L for 5 h at a current of 0.12 A.

MODIFICATION OF POLYAMIDE 6 WITH POLYAMINOAMIDE-g-POLY(ETHYLENE GLYCOL) VIA HYDROLYTIC POLYMERIZATION

To enhance the impact strength of polyamide 6, hydrolytic polymerization modification by the polyaminoamide-g-poly(ethylene glycol) (PAAEG) derivatives with poly(ethylene glycol) (PEG) molecular weight of 400–10000 was studied. Amide groups of polyaminoamide segments were postulated to form hydrogen bonding with polyamide 6, and hydroxy groups of PAAEG units were expected to react with carboxylic acid groups of polyamide 6 forming copolymers during the polymerization. The improved compatibility in amorphous regions of blends has been confirmed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) of fracture surfaces. The effects of PAAEG on the water absorption and notch sensitivity of blends were investigated, using water uptake measurement and mechanical testings, respectively. For comparison, pure polyamide 6 and the blend of PEG/polyamide 6 were also investigated. The addition of PAAEG retarded the crystallization of polyamide 6, but did not make remarkable influences on its crystalline structure. As a consequence of the strong interactions between the dispersed phases and polyamide 6 matrices, PAAEG was a more suitable additive for improving the notched impact strength of polyamide 6 than PEG.

Preparation of bio-based magnetic adsorbent and application for efficient removal of Cd(II) from water

A novel magnetic bio-adsorbent (MCIA) was developed, characterized and tested for its Cd(II) removal from aqueous solution. MCIA could be easily separated from the solution after equilibrium adsorption due to its super-paramagnetic property. The functional and magnetic bio-material was an attractive adsorbent for the removal of Cd(II) from aqueous solution owing to the abundant adsorption sites, amino-group and oxygen-containing groups on the surface of Cyclosorus interruptus. The experimental results indicated that the MCIA exhibited excellent adsorption ability and the adsorption process was spontaneous and endothermic. The adsorption isotherm was consistent with the Langmuir model. The adsorption kinetic fitted the pseudo-second-order model very well. The maximum adsorption capacity of Cd(II) onto MCIA was 40.8, 49.4, 54.6 and 56.6 mg/g at 293, 303, 313 and 323 K, respectively. And the MCIA exhibited an excellent reusability and impressive regeneration. Therefore, MCIA could serve as a sustainable, efficient and low-cost magnetic adsorbent for Cd(II) removal from aqueous solution.

Highly efficient removal of Cu(II), Cd(II) and Pb(II) by carboxyl-modified multi-porous biochar

ABSTRACT The carboxyl-modified biochar derived from palm fiber was prepared through pyrolysis and oxidation. The adsorption behavior for Pb(II), Cu(II) and Cd(II) on the carboxyl-modified biochar was systematically investigated. The experimental results demonstrated that the carboxyl-modified biochar exhibited impressive adsorption performance owing to its multi-porous structure and abundant adsorption sites on the surface. The maximum adsorption capacities for Pb(II), Cu(II) and Cd(II) reached 218.5, 132.1 and 79.9 mg/g, respectively. The adsorption kinetics and isotherm could be well described by the pseudo-second-order model and the Langmuir isotherm model, respectively. After five successive adsorption/desorption cycles, the removal efficiency was still more than 90%, 86% and 83% for Pb(II), Cu(II) and Cd(II), respectively.

Adsorption of endocrine disrupting ethylparaben from aqueous solution by chemically activated biochar developed from oil palm fibre

ABSTRACT The activated biochar (ABC) was prepared, characterized and examined the feasibility of removing ethylparaben (EP) from aqueous solution. The characterization results showed that ABC possessed multi-porous structure and high surface area. The adsorption isotherm was well fitted the Langmuir isotherm and the adsorption kinetic followed the pseudo-second-order model. The maximum adsorption capacity of EP onto ABC was 349.65 mg/g at 298 K. The adsorption capacity maintained 90.82% after five successive adsorption/desorption cycles. ABC possessed high adsorption capacity, usability and stability, which indicating that ABC has great potential to be a promising adsorbent for removal of EP from aqueous solution.

Preparation of magnetic biochar derived from cyclosorus interruptus for the removal of phenolic compounds: Characterization and mechanism

ABSTRACT A novel magnetic biochar was prepared via pyrolysis method and modification. The influence factors of contact time, initial concentration, temperature, and pH on the adsorption were investigated. The experimental results exhibited that the adsorption ability of methyl salicylate onto biochar was higher than that of phenol and para-chlorophenol under the same condition, which may be owing to the effect of hydrogen bonding, hydrophobicity, and π–π interaction. The maximum adsorption capacities of phenol, para-chlorophenol and methyl salicylate were 62.6, 131.6, and 169.7 mg/g at 298 K, respectively. This magnetic biochar exhibited high reusability (retained 82.1% after five cycles) and sharply magnetic performance (21.4emu/g).