The aging of polyethylene mulch films in the presence of cadmium.

To determine the fates of the persistent pollutants cadmium (Cd) and micro-plastics in agricultural soils, an in-depth understanding of the interactions between Cd and mulching film is required. In the present work, pot experiments are conducted under natural conditions to study the influence of various Cd concentrations on the aging process of polyethylene mulching film in soil collected from Changzhi, Shanxi Province. The results indicate that during 150 days, the aging degree of the mulch film increases gradually as the increased Cd concentration in the soil. Further, the results of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometry and X-ray photoelectron spectroscopy (XPS) demonstrate that the average vinyl index (VI) of the aging mulch film increases from 1.29 to 1.82, while the oxygen-to-carbon (O/C) ratio of the mulch film decreases significantly from 0.344 to 0.045, as the Cd concentration is increased from 0 to 10 mg kg-1. When the aging time exceeds 90 days, the oxygen-containing functional groups (C-O and CO) generated consumed by the adsorbed Cd. In addition, electron paramagnetic resonance (EPR) measurements indicate that Cd both enhances the formation of hydroxyl radical (·OH) on the surface of the mulch film and prevents the combination of ·OH and electrons, thereby accelerating the aging of the mulch. Hence, the present study indicates that the presence of Cd will hasten the decomposition of mulch, which will inevitably result in the faster release of micro-plastics from the mulch into the soil environment.

Effect of double carbon chains on enhanced removal of phenol from wastewater by amphoteric-gemini complex-modified bentonite.

A novle amphoteric-gemini complex-modified bentonite was prepared with a gemini surfactant ethylene bis (tetradecyl dimethyl ammonium chloride) (EB) on the basis of the bentonite modified by amphoteric modifier dodecyldimethyl betaine (BS). The surface and structural characteristics of modified bentonite were characterized by X-ray diffraction (XRD), specific surface area (SBET), scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), total carbon (TC) and total nitrogen (TN). In addition to studying the enhanced effect of gemini surfactants on phenol adsorption by kinetics and equilibrium adsorption, the influences of modification ratio, pH, temperature and ionic strength were investigated. Results showed that BS + EB complex modification increased the interlayer spacing (IS), TC and TN of bentonite (BT), and SBET decreased with the increase in its total modification ratio. The adsorption of phenol on modified bentonite reached equilibrium in 20 min, and the adsorption capacities were in the order of BS+50 EB (BS+50% CEC EB)>BS+100 EB > BS+150 EB > BS+25 EB > BS > BT. The adsorption capacities of phenol on BS + EB complex modified bentonite (CMB) increased by 9.98-15.96 and 1.19-3.35 times compared with those on BT and BS single modified bentonite (SMB), respectively. The phenol adsorption capacities decreased with the increases in temperature and pH, while it increased with the augment in ionic strength. This study revealed that double carbon chains increased the organic carbon content more effectively than single carbon chains at low complex modification ratios, thus promoting the adsorption of phenol by hydrophobic partitioning on the bentonite surface.

Insights into the interaction between cadmium/tetracycline and nano-TiO2 on a zeolite surface.

Titanium dioxide (TiO2) nanoparticles interact with organic-inorganic pollutants in the environment, and these interactions affect their environmental behavior. The mechanisms of the interaction between TiO2 and organic-inorganic pollutants on the surface of clay minerals are still unclear. In this work, isotherm adsorption was studied to explore the interactions between Cd2+/tetracycline (TC), TiO2 nanoparticles, and a zeolite (Zeo). SEM, FT-IR, and XPS were also used to reveal the interaction mechanism between organic-inorganic pollutants and TiO2 on their stability and mobility in the environment. Compared to the single systems, the adsorption of Cd2+ and TiO2 in the Cd + TiO2 composite system decreased by 3.43% and 9.90%, respectively; the TC and TiO2 adsorption in the TC + TiO2 composite system decreased by 14.39% and 45.47%, respectively. The antagonism between Cd2+ and TiO2 was due to Cd2+ and TiO2 competing for the electrostatic attraction (-OH) and hydrogen bonding sites (Si-O), and TC and TiO2 competing for the hydrogen bonding sites (-OH and C = O) on Zeo. The presence of TiO2 will increase the mobility of Cd2+ and TC on a clay surface, and this effect is more significant for organic pollutants TC. Compared with Cd2+, TC has a more significant boosting impact on the TiO2 mobility.

Co-adsorption capabilities and mechanisms of bentonite enhanced sludge biochar for de-risking norfloxacin and Cu2+ contaminated water.

Various bentonite-sludge biochar composites were fabricated by a sequence of loading and pyrolysis for the simultaneous removal of norfloxacin (NOR) and copper (Cu2+) from an aqueous solution. The morphology and characteristics of obtained composites were reflected through cation exchange capacity (CEC), BET specific surface area (SBET), SEM, XRD, FTIR and XPS. The isothermal adsorption results showed that Sips adsorption model fitted better for the adsorption of NOR and Cu2+ during co-adsorption. The theoretical maximum adsorption capacity of BT:2 SB (the mass ratio of bentonite to sludge is 1:2) for NOR and Cu2+ was 89.36 mg g-1 and 104.10 mg g-1 at 25 °C in the co-adsorption system. The thermodynamic results showed the capture of NOR and Cu2+ was spontaneous, accompanied by an endothermic reaction with different randomness. In the co-adsorption system, the two were antagonistic to each other due to competition for the adsorption sites of hydroxyl, carboxylic acid and negatively charged provided by bentonite-sludge biochar. This study suggests that using natural mineral as a pyrolysis improver for sludge biochar can product the value-enhanced biochar for simultaneous removal of antibiotic and metal contaminants.

[Adsorption of BS-18 Amphoterically Modified Bentonite to Tetracycline and Norfloxacin Combined Pollutants].

Antibiotic pollution in the environment has become a hot topic. The amphoteric surfactant octadecyl dimethyl betaine (BS-18) was adopted to modify bentonite to investigate the effects and mechanisms of the composite adsorption of different types of antibiotics. Under the different modification ratios, temperatures, pH values, and ionic strength conditions, the adsorption of tetracycline (TC) and norfloxacin (NOR) by bentonite was studied under single and compound conditions, and the adsorption mechanism was analyzed and discussed in combination with the surface properties of amphoterically modified bentonite. The results showed that compared with those of CK, the CEC and specific surface area of the soil samples modified by BS-18 decreased, whereas the total carbon and total nitrogen contents increased. The adsorption order of BS-18 amphoterically modified bentonite to TC was CK > 100BS > 25BS > 50BS, which was in accordance with the Langmuir model; the adsorption order of NOR was 25BS > 50BS > CK > 100BS, which was consistent with the Henry model. The adsorption capacity of TC and NOR in the TC and NOR composite system was higher than that in the single system. With the increase in temperature, the adsorption of amphoterically modified bentonite to TC showed a positive warming effect, whereas the adsorption of NOR declined as the temperature increased. When the ionic strength increased from 0.001 mol·L-1 to 0.500 mol·L-1, the adsorption of TC and NOR on each soil sample was inhibited. The pH of the solution can affect the existing forms of TC and NOR, and the adsorption capacity showed different trends as the pH increased. The adsorption of TC by BS-18-modified bentonite was mainly caused by electric charge attraction, whereas the adsorption of NOR was mainly caused by the combination of electric charge attraction and the hydrophobic effect. The different values of the octanol/water partition coefficient and the difference in structure resulted in different adsorption modes. In the TC and NOR composite system, a TC+NOR mixture was formed to promote the adsorption of soil samples.

Co-existing TiO2 nanoparticles influencing adsorption/ desorption of tetracycline on magnetically modified kaolin.

Interaction of coexisting nanoparticles (NPs) and other pollutants may affect their behavior in the environment. In this study, we investigated the effects of TiO2 NPs on the adsorption and desorption of tetracycline (TC) by magnetized kaolin (MK). The interactions among TC, TiO2 NPs, and MK were then discussed through their morphology and characteristics by using scanning electron microscopy, X-ray energy dispersive spectrometry, Transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses. Results showed that TiO2 NPs increased TC adsorption on MK by 2.02% and increased TC desorption by 45.26%, TC increased the maximum adsorption of TiO2 on MK from 31.32 to 49.42 mg g-1 and decreased the amount of stable adsorption state TiO2 NPs on MK from 17.92 to 12.71 mg g-1. The characterization results demonstrated that TC molecules combined on MK though hydrogen bonding, π-π bonding and hydrophobic interaction. The adsorption of TiO2 NPs on MK can provide additional hydrogen-bonding sites for TC adsorption by increasing the number of hydroxyl groups. However, TC can decrease the electrostatic attraction sites for TiO2 NPs adsorption on the MK surface. The complexation of TC and TiO2 NPs weakened the electrical attraction between MK and TiO2 NPs and decreased the amount of stable adsorption state TiO2 NPs.

Comparison of Cd2+ adsorption onto amphoteric, amphoteric-cationic and amphoteric-anionic modified magnetic bentonites.

Organic-magnetic bentonites (OMBts), i.e., amphoteric modified MBt (BS-MBt), amphoteric-cationic modified MBt (BS-CT-MBt) and amphoteric-anionic modified MBt (BS-SDS-MBt), obtained by modifying magnetic bentonite (MBt) with amphoteric surfactant (BS), cationic surfactant (CT) and anionic surfactant (SDS) were investigated with the aim to remove cadmium (Cd2+). The modifier contents, surface charge and Cd2+ adsorption performances of OMBts were compared, and the influences of pH, temperature and ionic strength on Cd2+ removal were evaluated. Results showed that modifier contents of OMBts increased in the order: BS-CT-MBt > BS-MBt > BS-SDS-MBt. Although CEC of adsorbents increased in the order: MBt > BS-MBt > BS-SDS-MBt > BS-CT-MBt. The BS-MBt exhibited the highest Cd2+ adsorption capacity (233.19 mmol kg-1) than other adsorbents. The adsorption isotherms could be well described by Langmuir model. The Cd2+ adsorption capacities on MBt and OMBts increased with an increase in pH, temperature and with a decrease of ionic strength. According to characterizations (FT-IR and XPS) and experiments, Cd2+ adsorption on MBt and OMBts most possibly involved electrostatic interaction, ion exchange, and surface complexation. Furthermore, the adsorption of Cd2+ on BS-MBt was also attributed to the chelation. The amidocyanogen group of BS-CT-MBt inhibited adsorption of Cd2+ due to electrostatic repulsion, while Cd2+ was adsorbed on BS-SDS-MBt through electrostatic attraction induced by the sulfo group.

[Adsorption and Interaction of Cu2+ and Pb2+ on BS-12 Amphoteric Modified Bentonites].

Amphoteric modification can simultaneously improve the adsorption of organic pollutants and heavy metals on clay minerals. Study of the adsorption and interaction of multiple heavy metals on amphoteric modified soils is therefore of practical significance. Here, bentonite-(CK) and 150BS-12-modified bentonites (150BS-12) were characterized both before and after metal ion adsorption using Fourier-transform infrared spectroscopy (FTIR). The equilibrium adsorption characteristics and differences of Cu2+ and Pb2+ in single and binary systems were studied by batch methods. The interaction mechanism of the metals on modified bentonites is also discussed. The results showed that the adsorption capacity of Cu2+ and Pb2+ in single and binary systems was ranked, in descending order, as 150BS-12 > 100BS-12 > 50BS-12 > CK, and that the adsorption isotherm could be described by the Langmuir and Freundlich equations. Although the modification of BS-12 was more beneficial for the adsorption of Cu2+, the adsorption capacity and selectivity coefficient of Pb2+ on BS-12-modified bentonites were larger than for Cu2+. Cu2+ and Pb2+ had a mutually antagonistic effect on each other; modification with BS-12 enhanced the effect of Cu2+ on Pb2+ and weakened the effect of Pb2+ on Cu2+, which was always stronger than the effect of Cu2+ on Pb2+. Increases in temperature and pH, and a reduction in ionic strength, can increase the adsorption of Cu2+ and Pb2+; however, the influence of these factors varied between the two metals, which also affected the interaction between the metals.

Hydrogen and methane production by co-digesting liquid swine manure and brewery wastewater in a two-phase system.

Co-digesting liquid swine manure and brewery wastewater for hydrogen and methane production was studied using an integrated, two-phase system with different organic loading rates (OLR) under mesophilic conditions. The highest volumetric hydrogen and methane production rates achieved were 294.06 ±â€¯3.06 mL H2 L-1 d-1 and 497.94 ±â€¯10.01 mL CH4 L-1 d-1, respectively, at the OLR of 8613.6 mg COD L-1 d-1, together with the highest hydrogen-COD and -TVS yields (34.14 ±â€¯0.36 mL g-1 COD and 45.46 ±â€¯0.71 mL g-1 TVS) and the maximum methane-TVS yield (261.42 ±â€¯8.41 mL g-1 TVS). The highest hydrogen and methane concentrations in the biogas (31.86 ±â€¯0.68% and 82.66 ±â€¯0.33%, respectively) were also obtained at this OLR. The maximum methane-COD yield (270.3 ±â€¯3.93 mL g-1 COD), however, was from the lowest OLR (1148.6 mg COD L-1 d-1). The two-phase system removed 75.54 ±â€¯0.19% of COD from the influent.

[Comparison of Amphoteric-Cationic and Amphoteric-Anionic Modified Magnetic Bentonites:Characterization and Sorption Capacity of Phenol].

Magnetic bentonite is modified by an amphoteric surfactant (dodecyl dimethyl betaine, BS-12), then modified by a cationic surfactant (Cetyl Trimethyl Ammonium Bromide, CTMAB) and anionic surfactant (Sodium lauryl sulfonate, SDS). Amphoteric-cationic modified magnetic bentonite (BS-CT-MBT) and amphoteric-anionic modified magnetic bentonite (BS-SDS-MBT) are obtained. Structural identification of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analyses (TG), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometer (VSM). The carbon-nitrogen content, specific surface area, and pore volume were also evaluated. Batch isotherm studies were conducted to evaluate the sorption of phenol. The results show that BS-CT-MBT and BS-SDS-MBT can be separated by magnetic separation. The carbon content-nitrogen content and content of surfactants of the BS-CT-MBT increase, while surface area and pore volume decrease compared to those of BS-MBT. Compared with BS-MBT, the carbon-nitrogen content, content of surfactants, and pore volume of BS-SDS-MBT are decreasing and surface area is increasing. The desorption rate of the surfactants is less than 9% at pH 6.0 and in 0.1 mol·L-1 NaCl solution. The Henry equation is the optimal description for the phenol sorption isotherms, implying a partitioning sorption process. The amount of phenol sorption follows the order:BS-CT-MBT > BS-MBT > BS-SDS-MBT > BT > MBT, which significantly correlates with the variation of the content of surfactant. Amphoteric magnetic bentonites modified by CTMAB have better absorption performance for phenol than those modified by SDS.

[Application of Amphoteric-Cationic Combined Modification on Phenol Adsorption of Yellow Brown Soil].

Based on the best modification ration of adsorption of phenol on montmorillonite modified by a mixture of amphoteric modifier, dodecyl dimethyl betaine(BS-12), and cationic modifier, hexadecyltrimethyl ammonium bromide(CTMAB),an experiment was designed to prepare two series of amphoteric-cationic modified soils by two yellow brown soils with montmorillonite contents of 43% and 6%,respectively. The adsorption properties of phenol were studied, and the adsorption influence at different temperature, pH and ionic strength was also analyzed and moreover, the adsorption differences between co-modified montmorillonite and yellow brown soils and between two co-modified yellow brown soils were discussed by comparing with co-modified montmorillonite. The results showed that adsorption of yellow brown soils as well as co-modified montmorillonite on phenol increased with combined modification, adsorption capacity was in order of 215BS+215CT(215%BS-12+215%CTMAB) > 215CT(215%CTMAB) > 215BS(215%BS-12) > CK1(unmodified soil containing montmorillonite content of 43%),33BS+33CT(33%BS-12+33%CTMAB) > 33CT(33%CTMAB) > 33BS(33%BS-12) > CK2(unmodified soil with montmorillonite content of 6%) at 30℃.Henry model described the adsorption of phenol very well. The phenol adsorption of modified yellow brown soils decreased with increasing temperature and pH, but increased with increasing ionic strength at low concentration ranges as well as modified montmorillonite. The basic reason for adsorption difference between co-modified montmorillonite and yellow brown soils and between two co-modified yellow brown soils was Cation Exchange Capacity(CEC).

[Effect of Adding Compound Adsorbent on Phenanthrene and Cr(â ¥) Absorption by Lou Soil].

To study the effect of the addition of compound adsorbent on the phenanthrene and Cr(Ⅵ) adsorption of Lou soil, biochar (made from corn stover) and B200B (Bentonite modified by BS-12, dodecyl dimethyl betaine with modified ratio of 200% CEC of Bentonite) were mixed at mass ratios of 1:2, 1:1 and 2:1 as the compound adsorbents (CS1:2, CS1:1 and CS2:1). Different amounts (2%, 5% and 10%) of these three compound adsorbents were added into Lou soil. Batch method was used to analyze the phenanthrene and Cr(Ⅵ) adsorption isotherms of different Lou samples, and compare the effect of environmental conditions such as pH value and temperature on the phenanthrene and Cr(Ⅵ) adsorption. The results indicated: ① Adsorption amounts of Cr(Ⅵ) on different Lou samples were 3.02 to 13.61 times higher than CK (original Lou soil). Under the same adding conditions (amount), Cr(Ⅵ) adsorption showed the order of CS2:1 Lou > CS1:1 Lou > CS1:2 Lou > CK. Cr(Ⅵ) adsorption was a spontaneous process with decreased enthalpy (except CS1:2) and increased entropy. Adsorption amounts of phenanthrene on different Lou samples were 3.87 to 13.00 times higher than CK. Phenanthrene adsorption presented the ranking of CS1:2 Lou > CS2:1 Lou > CS1:1 Lou > CK at the adding amounts of 2% and 5%, while showed the order of CS1:2 Lou > CS1:1 Lou > CS2:1 Lou > CK when 10% of the compound adsorbent was added. The adsorption was also a spontaneous process with decreased enthalpy and increased entropy. ② When the temperature was 10-30℃, the adsorption amount of Cr(Ⅵ) increased by 5.84%, 4.63% and 8.22% on CK, CS1:1 and CS2:1 Lou soils, and reduced by 2.70% on CS1:2 Lou soils. Adsorption amount of phenanthrene increased by 1.69% of CK and reduced by 10.55%, 4.36% and 12.81% of CS2:1, CS1:1 and CS1:2 Lou soils respectively. ③ When the pH was 4-10, the Cr(Ⅵ) adsorption had no significant change for CK, while those for CS1:2, CS1:1 and CS2:1 Lou soils all reduced. Phenanthrene adsorption of CK, CS1:2 and CS1:1 Lou soils was all highest at pH=4, and phenanthrene adsorption of CS2:1 Lou was highest at pH=7.④ The higher the ratio of B200B in compound adsorbent, the better the phenanthrene adsorption was. The higher the ratio of biochar in compound adsorbent, the better the Cr(Ⅵ) adsorption was.

[Leaching Remediation of Copper and Lead Contaminated Lou Soil by Saponin Under Different Conditions].

In order to investigate the leaching remediation effect of the eco-friendly biosurfactant saponin for Cu and Pb in contaminated Lou soil, batch tests method was used to study the leaching effect of saponin solution on single Cu, Pb contaminated Lou soil and mixed Cu and Pb contaminated Lou soil under different conditions such as reaction time, mass concentration of saponin, pH, concentration of background electrolyte and leaching times. The results showed that the maximum leaching removal effect of Cu and Pb in contaminated Lou soil was achieved by complexation of the heavy metals with saponin micelle, when the mass concentration of saponin solution was 50 g x L(-1), pH was 5.0, the reaction time was 240 min, and there was no background electrolyte. In single and mixed contaminated Lou soil, the leaching percentages of Cu were 29.02% and 25.09% after a single leaching with 50 g x L(-1) saponin under optimal condition, while the single leaching percentages of Pb were 31.56% and 28.03%, respectively. The result indicated the removal efficiency of Pb was more significant than that of Cu. After 4 times of leaching, the cumulative leaching percentages of Cu reached 58.92% and 53.11%, while the cumulative leaching percentages of Pb reached 77.69% and 65.32% for single and mixed contaminated Lou soil, respectively. The fractionation results of heavy metals in soil before and after a single leaching showed that the contents of adsorbed and exchangeable Cu and Pb increased in the contaminated soil, while the carbonate-bound, organic bound and sulfide residual Cu and Pb in the contaminated Lou soil could be effectively removed by saponin.

[Effect of SDS on the adsorption of Cd2+ onto amphoteric modified bentonites].

Under different modified ratios, temperatures, pH and ionic strengths, the effect of sodium dodecyl sulfonate (SDS) on the adsorption of Cd2+ onto bentonites which modified with amphoteric modifier dodecyl dimethyl betaine (BS-12) was studied by batch experiments, and the adsorption mechanism was also discussed. Results showed that the adsorption of Cd2+ on amphoteric bentonites can be enhanced significantly by SDS combined modification, Cd2+ adsorption decreases in the order: BS + 150SDS (BS-12 + 150% SDS) > BS + 100SDS (BS-12 + 100% SDS) > BS +50SDS(BS-12 + 50% SDS) > BS + 25SDS (BS-12 + 25% SDS) > BS (BS-12) > CK (unmodified soil). The adsorption isotherm can be described by the Langmuir equation. The change of temperature effect from positive on CK and amphoteric bentonites to negative on BS + 150SDS bentonites is observed with an increase of SDS modified ratio. The pH has little influence on Cd2+ adsorption on bentonites. The adsorption of Cd2+ on bentonites decreases with ionic strength rise, but the effect of ionic strength can be reduced with an increase of SDS modified ratio also. The adsorption thermodynamic parameters demonstrated that the adsorption of Cd2+ on modified bentonites was spontaneously controlled by entropy increment. When the SDS modified ratio is lower than 100% CEC, the adsorption of Cd2+ on modified bentonites is a process with characteristics of both enthalpy increment and entropy increment, while the SDS modified ratio is equal to or higher than 100% CEC, the adsorption of Cd2+ on modified bentonites becomes a process of enthalpy decrement and entropy increment.

Dispersive liquid-liquid microextraction for the determination of phenols by acetonitrile stacking coupled with sweeping-micellar electrokinetic chromatography with large-volume injection.

The current routes to couple dispersive liquid-liquid microextraction (DLLME) with capillary electrophoresis (CE) are evaporation of water immiscible extractants and backextraction of analytes. The former is not applicable to extractants with high boiling points, the latter being effective only for acidic or basic analytes, both of which limit the further application of DLLME-CE. In this study, with 1-octanol as a model DLLME extractant and six phenols as model analytes, a novel method based on acetonitrile stacking and sweeping is proposed to accomplish large-volume injection of 1-octanol diluted with a solvent-saline mixture before micellar electrokinetic chromatography. Brij-35 and ß-cyclodextrin were employed as pseudostationary phases for sweeping and also for improving the compatibility of sample zone and aqueous running buffer. A short solvent-saline plug was used to offset the adverse effect of the water immiscible extractant on focusing efficiency. The key parameters affecting separation and concentration were systematically optimized; the effect of Brij-35 and 1-octanol on focusing mechanism was discussed. Under the optimized conditions, with ∼ 30-fold concentration enrichment by DLLME, the diluted extractant (8×) was then injected into the capillary with a length of 21 cm (42% of the total length), which yielded the overall improvements in sensitivity of 170-460. Limits of detection and qualification ranged from 0.2 to 1.0 ng/mL and 1.0 to 3.4 g/mL, respectively. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the phenol pollutants in real water samples.

[Adsorption of Cd2+ ions in aqueous by diamine-modified ordered mesoporous SBA-15 particles].

Highly ordered channel structure SBA-15 was widely concerned as new adsorbents in environmental protection, in order to increase its heavy metal ions adsorption ability from aqueous solution, the diamine -modified porous silicate SBA-15 was synthesized by a hydrothermal grafting method and characterized by TEM, X-ray diffraction, FTIR and N2 adsorption-desorption. The SBA-15 and modified SBA-15 samples were used as sorbents to adsorb Cd(II) ions from aqueous solution. The effect of experimental parameters, such as pH, contact time, sorbent dosage and temperature were examined, and the maximum adsorption amount was also calculated. The results showed that under same conditions, the Cd(II) removal rate was higher for 2N-SBA-15 than that of the unmodified SBA-15. The adsorption process was controlled by system pH. The highest removal rate could reached about 95% after pH was higher than 4. Adsorption equilibrium was reached within 30 minutes,and more than 95% Cd2+ was adsorbed when 7.5-20 mg sorbent was added into 100 mL solution contained 25 mg x L(-1) Cd2+. The adsorption capacity increased from 94.73% to 98.22% with temperature increased from 25 degrees C to 35 degrees C. The Langmuir model can be used to describe adsorption isotherms. The adsorption capacity of Cd2+ was 0.9 mmol x g(-1) which is comparable to the adsorption capacity of various adsorbents reported in the literature, and 0.1 mol x L(-1) HCl could remove nearly 93% Cd2+ from 2N-SBA-15 particles. Based on the thermodynamic, pH, XPS and Zeta potential analysis results in this study, it could be concluded that the adsorption process was an endothermic and spontaneous reaction which contained physical adsorption, ion exchange and chelating reaction etc. The study indicated that the diamine -modified ordered mesoporous material SBA-15 is a potential sorbent which could be used for the aqueous Cd2+ removal.

[Pollution levels of perfluorochemicals in chicken eggs and duck eggs from the markets in Beijing].

Pollution levels of perfluorochemicals in eggs purchased from the markets in Beijing had been investigated. The egg samples of chicken and duck were collected from the 59 stalls of 14 main eggs wholesale markets in Beijing, respectively. Systematic analyses were made for seventeen kinds of perfluorochemicals (11 perfluorinated carboxylates (PFCAs), 3 perfluorinated sulfonates (PFSAs), perfluorooctane sulfonamide (FOSA), 2-perfluorooctylethanoic acid (FOEA) and 2H-perfluoro-2-decenoic acid (FOUEA) by a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results showed that there was a certain perfluorochemical contamination in all egg samples. Nine kinds of perfluorochemicals were detected in chicken eggs, perfluorononanoic acid (PFNA), perfluoroheptanoic acid (PFHpA) and perfluorooctanoate acid (PFOA) are dominant, and their average concentrations were 0.105, 0.073 and 0.069 ng x g(-1), respectively. Ten kinds of perfluorochemicals were detected in the duck eggs, perfluorooctane sulfonate (PFOS) and PFOA are dominant, and their average concentrations were 0.378 and 0.296 ng x g(-1), respectively. Perfluoropentanoic acid ( PFPeA), perfluorotetradecanoic acid (PFTA), perfluorobutane sulfonate (PFBS) and 2-perfluorooctylethanoic acid (FOEA) were not detected in all samples. The total concentration of PFCs in the duck eggs was 3.4 times of that in the chicken eggs. A strong positive correlation (r = 0.954) was not only observed between of PFNA and PFHpA in chicken eggs, but also found between perfluoroundecanoic acid (PFUnDA) and perfluorotridecanoic acid (PFTrDA) in duck eggs (r = 0.915). The results of health-based risk assessment showed that there was little immediate risk of exposure to PFOS and PFOA via the consumption of chicken eggs and duck eggs purchased from the markets in Beijing.

Preparation of polydopamine coated Fe3O4 nanoparticles and their application for enrichment of polycyclic aromatic hydrocarbons from environmental water samples.

Core/shell structured magnetic Fe3O4/polydopamine (Fe3O4/PDA) nanoparticles have been successfully synthesized and developed as a magnetic solid-phase extraction (SPE) adsorbent in dispersion mode for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in environmental samples. The Fe3O4/PDA synthetic procedure is simple and involves no organic solvents. Only 20mg of Fe3O4/PDA adsorbents are required to extract PAHs from 500mL water samples. The adsorption attains equilibrium rapidly and analysts are eluted with acetonitrile readily. The extraction efficiency is not influenced by salt concentrations up to 300mM and pH values over the range 4-11. Under optimized conditions, the detection limits of PAHs are in the range of 0.5-1.9ngL(-1). The accuracy of the method is evaluated by the recoveries of PAHs from environmental samples. Good recoveries (76.4-107%) with low relative standard deviations from 1.0% to 9.7% are achieved. Comparison study shows that the recoveries of target PAHs are low when they are extracted using traditional SPE method even with the addition of methanol or tetrabutylammonium bromide surfactants in water samples, suggesting great application potential of magnetic SPE method to preconcentrate highly hydrophobic contaminants (such as PAHs) from large volume of water samples. This new SPE method provides several advantages, such as simplicity, low environmental impact, high extraction efficiency, high breakthrough volumes, convenient extraction procedure, and short analysis time.

Fast defluorination and removal of norfloxacin by alginate/Fe@Fe3O4 core/shell structured nanoparticles.

Alginate-Fe(2+)/Fe(3+) polymer coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@ALG/Fe MNPs) with core/shell structure are prepared and used as heterogeneous Fenton nanocatalyst to degrade norfloxacin (NOF). The Fenton-like process based on Fe(3)O(4)@ALG/Fe shows much higher efficiency on NOF degradation. Compared with Fe(3)O(4) nanoparticle-H(2)O(2) system, NOF degradation in Fe(3)O(4)@AlG/Fe-H(2)O(2) system can be conducted in a wide pH range (pH 3.5-6.5) and independent on temperature. With 0.98 mM H(2)O(2) and 0.4 g L(-1) Fe(3)O(4)@ALG/Fe, 100% of NOF and 90% of TOC is removed within 60 min, and the fluorine element in NOF molecule changes into F(-) ions within 1 min, indicating that NOF degradation in this Fenton-like reaction is performed through direct defluorination pathway. XPS analysis shows that TOC removal in reaction solution mainly results from the adsorption of NOF degradation intermediates on catalyst. Due to the paramagneticity and high saturation magnetization of Fe(3)O(4)@ALG/Fe, the used catalyst with adsorbed NOF intermediate is collected from aqueous solution by applying an external magnetic field, leading to complete removal of NOF from water samples. As being composed of inorganic materials and biopolymer, Fe(3)O(4)@ALG/Fe MNPs are robust, thermo-stable, nontoxic and environmentally friendly. These attractive features endow Fe(3)O(4)@ALG/Fe as a potent Fenton-like catalyst for fluoroquinolones degradation.

[Synthesis of core/shell structured magnetic carbon nanoparticles and its adsorption ability to chlortetracycline in aquatic environment].

Magnetic carbon nanoparticles with core/shell structure (Fe3C/Fe@C) and large surface areas were synthesized via hydrothermal method followed with heat treatment under N2 atmosphere. The adsorbent has strongly magnetic cores and graphitized carbon shell. The removal efficiency of chlortetracycline (CTC) from aquatic environment by Fe3C/Fe@C was investigated. The results showed that Fe3C/Fe@C exhibited ultrahigh adsorption ability to CTC. The adsorption behavior of CTC on FeC/Fe@C fitted the pseudo-second-order kinetic model, and the adsorption equilibrium was achieved within 24 h. The adsorption ability of CTC increased with solution pH at pH 3.5-7.5, but decreased with further increase of pH (pH 7.5-8.5). CTC adsorption decreased with solution temperature and increased with ionic strength. As the concentration of coexisting humic acid in solution ranged in 10-50 mg x L(-1), the adsorption ability of CTC on Fe3C/Fe@C was only decreased by 10%-20%. Under the optimal conditions (pH = 7.5, T = 293 K), the maximum adsorption capacity of CTC on Fe3C/Fe@C calculated by Langmuir was 909 mg x g(-1), which was significantly higher than those obtained on sediment or minerals. More importantly, Fe3C/Fe@C adsorbed with CTC can be collected from water sample under a magnetic field rapidly for special disposal, which avoids secondary pollution of water. These results indicate that Fe3C/Fe@C is a potentially efficient, green adsorbent for removal of tetracycline antibiotics from aquatic environment.