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2D carbon ribbon/Al2O3 was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods. Batch experiments of adsorption parameters such as pH, liquid/solid ratio, adsorption kinetics, adsorption thermodynamics, and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al2O3 and nitrogen-doped carbon ribbon/Al2O3. The adsorption of fluoride on carbon ribbon/Al2O3 could be described as the chemical and multilayer adsorption, while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al2O3 followed the chemical and monolayer adsorption phenomenon. The fluoride on nitrogen-doped carbon ribbon/Al2O3 had a much faster adsorption rate of 3.1×10−7 m/s than carbon ribbon/Al2O3, which was 1.2×10−7 m/s. The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride. Also, the diacetylene linkages (—C≡C—) and pyridinic-N were studied to understand their influences on removing fluoride. The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.

Bioremediation plays an increasingly important role in the remediation of chromium-contaminated soil because it is an environmentally friendly technology. To investigate the Cr(VI) reduction process by indigenous microorganisms in soil, a batch of incubation experiments were carried out in a bioreactor under aerobic conditions. The results showed that in the presence of indigenous microorganisms, the Cr(VI) concentration in the chromium-contaminated soil decreased from 1521.9 to 199.2 mg/kg within 66 h with culture medium addition, while a slight decrease in the Cr(VI) concentration was found in the sterilized soil, implying that the indigenous microorganisms contributed to the Cr(VI) reduction. In the microbial remediation process, Cr(VI) microbial reduction occurred after the reduction of, Mn 4+ and Fe 3+ and, before reduction. The reduction process of Cr(VI) can be divided into two phases, characterized by the exponential equation model of microbial reduction and the linear equation model of the combined effect of the major ions. It can be concluded that indigenous Cr(VI)-reducing bacteria have a potential application for in-situ remediation of Cr(VI)-contaminated soil.

A polymeric hydroxyl ferric phosphate (PHFP) was prepared by using a byproduct of titanium dioxide containing ferrous sulfate and phosphates under alkaline condition. The PHFP was used to immobilize lead (Pb) and cadmium (Cd) in soils. Fourier transform infrared spectra, X-ray diffraction were applied to revealing the characteristics of PHFP, and the modified Tessier sequential extraction and column leaching experiment with simulated acid rain were used to assess the effectiveness of immobilization of Cd and Pb in soils by PHFP. The results showed that PHFP was indeed a polymer with complicated OH—Fe—P structure and consisted of Fe6(OH)5(H2O)4(PO4)4(H2O)2 and Fe25(PO4)14(OH)24. Moreover, the removal rates of DTPA-extractable Cd and Pb in soils reached up to 33% and 45%, and the water-soluble Cd and Pb decreased by 56% and 58%, respectively, when PHFP was added in soils at 4% dosage. In addition, the immobilization of Cd and Pb contributed to transforming water soluble, exchangeable and carbonate-bonded fractions to Fe and Mn oxides-bonded, organic-bonded and residual fractions. Under leaching with simulated acid rain, Cd and Pb release amount in PHFP amended soil declined by 53% and 52%, respectively, as compared with non-treated soil. The result implied that PHFP had a potential application for the remediation of Cd- and Pb-contaminated soils.

A greenhouse culture experiment was used to evaluate the effects of antimony (Sb) stress on Ficus tikoua (F. tikoua). The results showed that the growth of F. tikoua leaves was significantly inhibited when Sb concentration was higher than 30 μmol/L, and no significantly inhibitory effect of Sb on the roots and stems of F. tikoua was found in all the treatments, implying that leaves were more sensitive to Sb toxicity than roots and stems. Antimony concentration in the roots was higher than that in the stems and leaves. To reduce reactive oxygen species (ROS) level in the F. tikoua, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased with Sb treatments, but the SOD and CAT were more early active than POD. Although the decrease of chlorophyll content with high Sb treatments (450 μmol/L) was observed at the end of the experiments, the positive impact on chlorophyll content was observed with all the Sb treatments at the early period. No significant difference of the maximum quantum efficiency of PSII and quantum yield of PSII electron transport values with different Sb treatments was observed at the end of this experiment, suggesting that the photosynthesis was not inhibited with Sb concentration below 450 μmol/L. The results implied a certain tolerance to Sb stress for F. tikoua. This meets the essential condition for utilization in Sb contamination environments.

A simple and effective method has been developed to reflect the growth of bacteria CH-1 via the potential of the solution. The results indicate that during the bacterial cultivation, the biomass increases and the potential of the solution decreases over time. The relationship between biomass and potential of the solution could be expressed by the equation with constants of a and b which are all related to species, batch, number, and growth environment of bacterial. When the initial pH value is 10 and the initial biomass is 6.55×10 7 cell/mL, the correlated equation of the biomass and the potential of the solution could be divided into two segments. The growth of bacteria CH-1 is different under various experimental conditions, but the biomass is directly related to the potential of the solution regardless of the conditions of different initial pH values and bacteria number.

The phosphate-embedded calcium alginate beads were successfully synthesized based on sodium alginate, calcium dihydrogen phosphate and sodium hydrogen carbonate. Scanning electron microscopy, Fourier transformed infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were conducted to characterize the morphology and structure of the phosphate-embedded calcium alginate beads. The effects of pH and the initial concentration of the metal ions on Pb(II) and Cd(II) sorption by the beads were investigated. The optimal pH values for Pb(II) and Cd(II) sorption are 4.0 and 5.5, respectively. The optimal initial concentrations of Pb(II) and Cd(II) are 200 mg/L and 25 mg/L, correspondingly, and the removal efficiencies are 94.2% and 80%, respectively. The sorption mechanism is that the heavy metal ions accessed the beads firstly due to the large surface area, combined with OH−, and then precipitated with phosphate radical, which was proven by FTIR and XRD. The sorption of Pb(II) and Cd(II) is fitted to Langmuir isotherm model with R2 values of 0.9957 and 0.988, respectively. The sorption capacities of Pb(II) and Cd(II) are 263.16 mg/g and 82.64 mg/g, respectively. The results indicate that the phosphate-embedded calcium alginate beads could be applied to treating Pb(II)/Cd(II)-containing wastewater and it could be implied that the synthesized beads also could be used as a kind of soil ameliorant for remediation of the heavy metal contaminated paddy soil.

The traditional zinc hydro-metallurgy generates a large amount of zinc ferrite residue rich in valuable metals. The separation of iron is crucial for resource recycling of valuable metals in zinc ferrite residue. A novel selective reduction roasting–leaching process was proposed to separate zinc and iron from zinc leaching residue which contains zinc ferrite. The thermodynamic analysis was employed to determine the predominant range of Fe 3 O 4 and ZnO during reduction roasting process of zinc ferrite. Based on the result of thermodynamic calculation, we found that V (CO)/ V (CO+CO 2 ) ratio is a key factor determining the phase composition in the reduction roasting product of zinc ferrite. In the range of V (CO)/ V (CO+CO 2 ) ratio between 2.68% and 36.18%, zinc ferrite is preferentially decomposed into Fe 3 O 4 and ZnO. Based on thermogravimetric (TG) analysis, the optimal conditions for reduction roasting of zinc ferrite are determined as follows: temperature 700–750 °C, volume fraction of CO 6% and V (CO)/ V (CO+CO 2 ) ratio 30%. Based on the above results, zinc leaching residue rich in zinc ferrite was roasted and the roasted product was leached by acid solution. It is found that zinc extraction rate in zinc leaching residue reaches up to 70% and iron extraction rate is only 18.4%. The result indicates that zinc and iron can be effectively separated from zinc leaching residue.

The taxonomy characteriazation and cadmium (Cd) biosorption of the high Cd-resistant fungus M1 were investigated. The internal transcribed spacers (ITS) region and β -tubulin genes of the strain were amplified, sequenced and analyzed by molecular biology technology. The Cd biosorption assay was performed by shaking flask. Fourier transform infrared spectroscopy was used to analyze the mycelium. The similarity of gene sequences and phylogenetic trees show the very close relation between the strain and Paecilomyces lilacinus , and the fungus M1 was identified as P. Lilacinus . The initial pH 6 and Cd concentration about 100 mg/L are optimum. Zn and Mn have a little effect on the Cd biosorption of the strain, while Cu and Pb present obvious effects. FTIR analysis shows that the fungus adsorbs Cd by esters, anhydride, and amide. With the preferable absorption capacity, fungus M1 is considered to have good prospects in bioremediation.

Study was carried out to analyze the distribution and migration patterns, soil-to-plant transfer and potential health risks of chromium in soil-vegetable system in areas near a ferro-alloy manufactory in Hunan province. The results show that soils near sewer outlet, sewer channel and in control area are averaged 2 239.5, 995.33 and 104.9 mg/kg, respectively. The total Cr has a relative accumulation in soil depth of 200-400 mm near the sewer outlet, mainly enriches in the surface layer (0-200 mm) near the sewer channel and decreases gradually in unpolluted soils. The differential concentration level of enrichment between layers is little. The results also indicate that the three vegetables of celery, lettuce and Chinese cabbage are able to convert the potentially toxic Cr (VI) species into the non-toxic Cr (III) species, and the chromium contents in the edible parts of the vegetables are averaged 11.95 mg/kg. The transfer factors of the three vegetables follow the order: Chinese cabbage > lettuce > celery. The estimated total daily intake of chromium substantially exceeds the dietary allowable value, which may pose health risks to local population.

Based on the principle of bacterial leaching and bacterial metallurgy, a novel technology for the detoxification of chromium-containing slag by Achromobacter sp. CH-1 and chromium recovery was proposed. Strain CH-1 cell morphology before and after Cr (Ⅵ) reduction was observed with a scanning electron microscope (SEM), and the reduction product is found to adhere to terminals of CR-1 cells. Energy-dispersive X-ray (EDX) and electron paramagnetic resonance (EPR) analyses reveal that the main component of the reduction product is Cr (Ⅲ). Furthermore, small and large-scale demonstration projects reveal that Achromobacter sp. can be used to detoxify chromium-containing slag and to selectively recover chromium by using this novel technique. Chromium recovery rate increases with decreasing particle sizes of chromium-containing slag and slagheap height. Chromium recovery rates in 10 t/batch and 20 t/batch of on-site demonstration projects for chromium-containing slag detoxification are more than 90%.

Lead-loaded modified spent grain regenerated by desorption process was investigated. HCl, H2SO4, H3PO4, NaOH, NaCl and ultrapure water were chosen as desorption agents to treat lead-loaded modified spent grain for 30 min. The structures and components of regenerated modified spent grain before and after adsorbing Pb(Ⅱ) were investigated using scanning electron microscopy (SEM), energy-dispersive analysis of X-ray(EDAX) and Fourier transform infrared spectrometry (FTIR). The results indicate that lead-loaded modified spent grain treated in 0.1 mol/L HCl exhibits higher elution efficiency (86.44%) as compared with other agents. The enrichment of carboxyl and hydroxyl groups susceptible to combine with Pb(Ⅱ) are observed in the regenerated modified spent grain, which may result in high re-absorption efficiency of Pb(Ⅱ). Moreover, C-Cl, N-H, C-N and O-H (polysaccharides) also play an crucial role in Pb(Ⅱ) binding to regenerated modified spent grain.

To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40–60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (VI) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (VI) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (VI) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100–150 cm. The results imply that the transportation of Cr (VI) can result in a potential risk of groundwater system in this area.

The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.