Pufeng Qin

Modifying Fe3O4 nanoparticles with humic acid for removal of Rhodamine B in water

Humic acid (HA) modifying Fe(3)O(4) nanoparticles (Fe(3)O(4)/HA) was developed for removal of Rhodamine B from water. Fe(3)O(4)/HA was prepared by a coprecipitation procedure with cheap and environmentally friendly iron salts and HA. TEM images revealed the Fe(3)O(4)/HA (with ≈ 10 nm Fe(3)O(4) cores) were aggregated as aqueous suspensions. With a saturation magnetization of 61.2 emu/g, the Fe(3)O(4)/HA could be simply recovered from water with magnetic separations at low magnetic field gradients within a few minutes. Sorption of the Rhodamine B to Fe(3)O(4)/HA reached equilibrium in less than 15 min, and agreed well to the Langmuir adsorption model with maximum adsorption capacities of 161.8 mg/g. The Fe(3)O(4)/HA was able to remove over 98.5% of Rhodamin B in water at optimized pH.

Fraction Distributions of Lead, Cadmium, Copper, and Zinc in Metal‐Contaminated Soil before and after Extraction with Disodium Ethylenediaminetetraacetic Acid

Abstract: The fraction distributions of heavy metals have attracted more attention because of the relationship between the toxicity and their speciation. Heavy‐metal fraction distributions in soil contaminated with mine tailings (soil A) and in soil irrigated with mine wastewater (soil B), before and after treatment with disodium ethylenediaminetetraacetic acid (EDTA), were analyzed with Tessiers sequential extraction procedures. The total contents of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) exceeded the maximum permissible levels by 5.1, 33.3, 3.1, and 8.0 times in soil A and by 2.6, 12.0, 0.2, and 1.9 times in soil B, respectively. The results showed that both soils had high levels of heavy‐metal pollution. Although the fractions were found in different distribution before extraction, the residual fraction was found to be the predominant fraction of the four heavy metals. There was a small amount of exchangeable fraction of heavy metals in both contaminated soils. Furthermore, in this study, the extraction efficiencies of Pb, Cd, and Cu were higher than those of Zn. After extraction, the concentrations of exchangeable Pb, Cd, Cu, and Zn increased 84.7 mg·kg−1, 0.3 mg·kg−1, 4.1 mg·kg−1, and 39.9 mg·kg−1 in soil A and 48.7 mg·kg−1, 0.6 mg·kg−1, 2.7 mg·kg−1, and 44.1 mg·kg−1 in soil B, respectively. The concentrations of carbonate, iron and manganese oxides, organic matter, and residue of heavy metals decreased. This implies that EDTA increased metal mobility and bioavailability and may lead to groundwater contamination.

Single and simultaneous adsorption of pefloxacin and Cu(II) ions from aqueous solutions by oxidized multiwalled carbon nanotube.

In this study, the oxidized multiwalled carbon nanotube (O-MWCNTs) was obtained by a simple method, and investigated by various techniques (SEM, TEM, FT-IR, XPS and zeta potential) for the removal of pefloxacin and Cu(II). The mutual effects of their adsorption onto O-MWCNTs were comprehensively clarified with sole and binary systems with adsorption kinetics, sorption thermodynamic and sorption isotherm models. The results indicated that there are site enhancement and competition of pefloxacin and Cu(II) on O-MWCNTs. According to mechanism investigation on the adsorption of pefloxacin and Cu(II) by XPS analysis, pH impact study, electrostatic interaction and π-π interactions, the low concentration of Cu(II)/pefloxacin could act as a bridge between pefloxacin/Cu(II) and O-MWCNTs, which significantly enhances the adsorption of pefloxacin/Cu(II). This study provided effective method and valuable reference for the elimination of pefloxacin/Cu(II) from aquatic environments.

Comparisons of three plant species in accumulating polycyclic aromatic hydrocarbons (PAHs) from the atmosphere: a review

Plant leaves play a key role in the accumulation of PAHs, as they are able to capture PAHs from the air. In this paper, the mechanism, including absorption and adsorption, for plants to scavenge PAHs from the air was reviewed. Moreover, the differences of PAHs accumulating capability are mainly compared among three representative plant species, including pine needles, Holm oak leaves, and moss. On the whole, it is shown that oak leaves present the strongest PAHs accumulating capability for total PAHs among three plants species. Oak leaves and pine needles show higher accumulating tendency for light and medium molecular weight PAHs, whereas moss presents stronger accumulating tendency for heavy molecular weight PAHs. Environmental factors (i.e., temperature, seasonality, and photolysis) also account for the process of PAHs transferred from air to plants. With the temperature climbing, the concentration of PAHs in the air will increase. Due to the meteorological conditions and the human activities changed with seasons, it was shown that the PAHs were greatly accumulated in leaf surface in winter than in summer. Photolysis was also able to influence the PAHs on leaf surface, which are significant to this process. In conclusion, oak, pine, and moss can be used to filter PAHs when considering urban landscaping. Besides combining the traditional analytical methods with in situ determination, there might be able to provide a novel method to further study the specific absorption mechanisms. The accumulation of PAHs in crop leaf surface related to the application of surfactants is also worth studying.

Population characteristics and influential factors of nitrogen cycling functional genes in heavy metal contaminated soil remediated by biochar and compost

Sixteen treatments of soil contaminated by Cu, Pb, and Zn by the addition of a different percentage of biochar and compost were incubated for 120 days. The abundance of denitrifying genes such as narG, nirK, nirS and nosZ and the ammonia-oxidizing amoA genes of ammonia-oxidizing archaea/bacteria (AOA/AOB), soil nitrite reductase activity (S-NiR) and their shaping factors were also determined. The relationships between functional genes, S-NiR, and physico-chemical parameters were analyzed using the Pearson correlation method. The study found that the changes in physico-chemical parameters, including water-soluble organic carbon (WSC), nitrate (NO3-) and ammonium (NH4+), were predominant in different treatments. The abundance of nirK and narG genes is most sensitive to the changes in the properties of the soil sample. Bacterial 16S rDNA gene abundance was significantly affected by NO3- and S-NiR (P < 0.05). Nitrifying genes were mainly correlated to WSC and S-NiR, while denitrifying genes were associated with pH, electrical conductivity, NO3- and S-NiR. The systematic study for the relationship between the genes and the environmental parameters will help us to deep understand the biological mechanisms of nitrogen cycle in heavy metal contaminated soils remediated by biochar and compost.