Abstract:Natural sphalerite as a novel cost-effective photocatalyst was characterized by means of electron microprobe analy-is (EMPA), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL),transmission electron microscope (TEM), scanning electron microscope (SEM) and Hall-effect measurements. The results show that the visible light response of the natural sphalerite sample results from the presence of substituting metal ions. Besides, the variable-valence element of Fe can act as a hole scavenger in the process of Fe2+ +h+→ Fe3+, thus improving the efficiency of conduction band electrons and strengthening the photoactivity. Cleavage planes and fracture surfaces can improve the photocatalytic activity by providing more active sites than perfect faces. Other defects like charge vacancies and lattice expansion with their possible roles of improving the efficiency of electron_hole pair separation are analyzed. The photoreductive reactions prove that the natural sphalerite sample exhibits a high photoactivity on reducing methyl orange under visible light irradiation, which is consistent with its specific characterization. The results also demonstrate that natural sphalerite as a new cost-effective photocatalyst driven by visible light will have certain application prospects in environmental remediation. 

Abstract:ZnS quantum_dots were assembled in synthetic chrysotile nano-tubes based on the ultrasonic chemical method, and the attributes of the assembled samples were studied by such means as powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis). Transmission electron microscope (TEM) observation shows that ZnS quantum_dots were assembled in the nano-tubes of synthetic chrysotile. XRD has revealed that the ZnS quantum-dots in the nano-tubes are β-ZnS and their average crystal granularity is 4.2 nm. The optical absorption side of the ZnS quantum-dots is shifted to the longer wavelength where the red shift is 5 nm.

Abstract:TiO2 pillared montmorillonite was synthesized by microwave irradiation, and the best synthesis condition was determined on the basis of a discussion on the influence of irradiation power and irradiation time. Samples with photodegradation methyl orange performance was studied in comparison with samples synthesized by the traditional method. When microwave irradiation power is 70%, TiO2 is well crystallized with anatase as the major form, which enhances the photocatalytic performance of the sample. The pillared structure exists well when the surface area is relatively large (237 m2/g), which also enhances the photocatalytic performance of the sample. In comparison with the sample synthesized by the traditional method, TiO2 pillared montmorillonite synthesized by microwave irradiation has well crystallized TiO2, with anatase being the major form, and there exists better photocatalytic performance of methyl orange under UV light.

Abstract:Two different means were employed to prepare nanoparticle TiO2-pillared montmorillonite. One was the conventional ion exchange method and the other was post hydrothermal treatment after ion-exchange. The calcined clay was characterized by different physicochemical techniques such as XRD, DSC-TG and nitrogen adsorption-desorption. The results demonstrate that the conventional ion-exchange method causes the titania pillared montmorillonite clay to have relatively large surface area and pore volume. The post hydrothermal treatment method gives rise to better crystallographic form, bigger crystallite and more stable pillared montmorillonite clay. Higher temperature results in shorter reaction time and better crystallographic form of anatase.

Abstract:Metaphase and late sanitary landfill leachate from Asuwei in Beijing was taken as the research object. By means of orthogonal experiments, the effects of dosage, stirring speed, stirring time and standing time of modified bentonite, natural bentonite, alum, and modified bentonite with alum on the CODcr elimination rate of landfill leachate were analyzed. After analyzing the mechanism of landfill leachate treatment by using natural bentonite, modified bentonite and alum, modified bentonite and natural bentonite were used to treat hydrophobic compounds and hydrophilic compounds of dissolved organic matter (DOM) in landfill leachate respectively, and alum was also used to flocculate landfill leachate. The CODcr and BOD5 values of the treated landfill leachate were much lower than values of the untreated landfill leachate, decreasing from 4700 mg/L to 839 mg/L and 700 mg/L to 263 mg/L, with the CODcr and BOD5 elimination rates of landfill leachate being 82.15％ and 62.43%, respectively. It is shown that the treatment of landfill leachate by combination of modified bentonite, alum and natural bentonite is an effective method.

Abstract:Using HTDMAB with different dosages as the surfactant, the authors modified montmorillonites and then described their free swelling properties in water and toluene on the basis of free swelling ratio experiments. A careful analysis led to the discovery that the free swelling ratio of the modified montmorillonite tends to decrease in water but increase in toluene, and that when the dosage of surfactant is around 15%, the swelling ratio of modified clay is rather low no matter whether it is in water or in toluene. This means that only when the de.age of the surfactant is strictly controlled can the modified montmorillonite without water and oil affinity be prepared. This conclusion is also applicable to the reservoir core rocks, and hence the damages caused by the clay minerals swelling in the water and the superfluous oil molecules adsorbed on the surface of the minerals can be prevented beforehand.

Abstract:According to chemical composition, exchangeable cation and thermal behaviors of crystal structure, Xuancheng zeolite should belong to calcium-rich clinoptilolite with low thermal stability. Optimal test conditions were determinedby orthogonal experiments, and then CEC values were measured under such conditions. The results show that when the roasting temperature is lower than 400℃, only an indistinctive change in CEC value of the clinoptilolite occurs, whereas at 250℃, the CEC value slightly rises and reaches its maximum. This is ascribed to the calculation basis discrepancy caused by the decrease of volume density. Between 250℃ and 400℃, the CEC value of Xuancheng zeolite decreases slowly. When the baking temperature exceeds 400℃, the CEC value drops sharply. Thermaland X-ray diffraction analysis has proved that there exists a starting point of 250℃ in structure destroy and an abrupt change at 400℃, which causes rapid decrease in CEC value at a high temperature. It is thus concluded that when calcium-rich clinoptilolite is used as an ion exchange reagent, the processing temperature should not exceed 400℃. 

Abstract:The interaction between NOM and minerals strongly affects the preservation and dynamic process of soil organic matter and other ecological processes.The study of the preservation and loss of the organic matter in soil is hence of great importance in environmental protection. Researches on the effect of simulated acid rain action indicate that, with the increasing soaking time, the gross content of iron and aluminum residues in red soil decreases, and aluminum is eroded and dissolved more significantly. Moreover, the morphological change of Fe/Al-oxide minerals in red soils finds expression in the fact that the crystalline Fe/Al_oxide minerals are dissolved remarkably, while the amorphous species of iron and aluminum and/or their complexes species change insignificantly or even increase to some extent. The soil organic matter(SOM) is dissolved notably under the condition of acidic pH,it suggests that the dissolution of the free species of Fe/Al_oxide minerals play a key role, and the hydrolysis of the SOM maybe occurs also. In addition, the SEM analysis shows that the action of simulated acid rain might cause the breakdown of the structure of soil aggregates.

Abstract:Raw product MnSO4·H2O from manganese mines of Guangxi was utilized to synthesize cryptomelane by an inexpensive and practical method. K_brinesstie was prepared by oxidation of the mixture of MnSO4 and KOH solutions with soluble oxygen and excessive OH-, and then transformed to cryptomelane during the heating process. According to the experimental results, the optimal operational parameters were confirmed: 0.2 M MnSO4·H2O and 1 M KOH in 500 mL system at room temperature reacted for 3 hours with 30L/min air flow rate and 100r/min stirring rate; the precipitate was washed again and again till pH=12， and dried and ignited at 600℃ for 1 hour. The results obtained provide fundamental data for further processing of manganese product on a large scale.

Abstract:Petroleum hydrocarbon and chlorinated hydrocarbon multi-plumes usually coexist under nature conditions. The disposal of the contaminated plume is focused on the utilization of the products from granular iron permeable reactive barriers (PRBs) which can remove chlorinated hydrocarbons as the electron acceptor to biodegrade BTEX in the aquifer. Benzene and toluene are the most toxic compounds and tend to exist for a long time in the aquifer. This study focused on the biodegradation of benzene and toluene by using Fe(Ⅲ) from the Fe(OH)3-coated sand under anoxic conditions. Data obtained show that the biodegradation of benzene and toluene occurs when Fe(Ⅲ) is used as the only electron acceptor. After incubating, the rate of biodegradation will obviously increase. The biodegradation experiment indicates that the biodegradation rate of toluene is faster than that of benzene. The half life of benzene and toluene are 4.02 and 3.81 days respectively.

Abstract:Iron hydroxides/oxides widely existent in soil can serve as importantmineral resources. Goethite, hematite and amorphous ferrihydrite generated in surface of the earth all assume nanometer particle size, have high specific surface area and perform specific adsorption capacity for phosphate, thus being potential adsorbents for low concentration phosphate in water. The adsorption of goethite, hematite and amorphous ferrihydrite for phosphate was studied through the isothermal adsorption experiment. The results indicate that amorphous ferrihydrite performs the strongest adsorption capacity for phosphate (5.5 mg/g minerals), followed by goethite, and hematite has the smallest adsorption capacity. Isothermal adsorption of phosphate on goethite, hematite and amorphous ferrihydrite is in accordance with the Freundlich equation. The time-dependent phosphate adsorption data are consistent with the Bangham equation.

Abstract:Mineral surfaces can alter the capacity of soil humic substances for binding hydrophobic organic contaminants. In this paper, two types of organo-mineral complexes of red soil and kaolinite bound respectively with humic acid were prepared. The sorption isotherms of naphthalene by the two complexes were nonlinear significantly, n=0.76 and/or 0.74, and the organic carbon-normalized sorption partitioning coefficient (Kadsoc) values of naphthalene by experimental determination were 5 times higher than the Koc values by theoretical calculation with simple Kow partitioning models. This shows that the sorption affinity of naphthalene to humics can be enhanced by the sorption of humics on the mineral surfaces of red soil and kaolinite. Moreover, the red soil is slightly stronger than kaolinte in affecting the sorption affinity of naphthalene to humics. The mainreasons seem to be that, besides kaolinite, red soils contain iron oxide minerals that can strongly bind humics, and the changes might occur in composition and conformation of the humics adsorbed on mineral surfaces, which is in favor of the sorption of naphthalene on these organo-mineral complexes.

Abstract:TiO2-coated palygorskite powder was prepared by different hydrolysable methods. Photocatalytic activity of TiO2-coated palygorskite powder was studied through photo-degrading the golden yellow BES dyestuff solution under a 300 W high-pressure mercury lamp. The amount of catalyst, the calcined temperature of catalyst and times of the repeated experiments on photo-degradation were studied.The experimental results show that 300℃ seems to be the most proper calcined temperature for the catalyst. This kind of catalyst prepared by hydrolysable method watered directly contains anatase TiO2. Nevertheless, it can only obtain amorphous TiO2 after the synthesis of catalyst hydrolyzed with steam. The experimental results show that, when the dosage is 1 g/L, hydrolysable method watered directly has more efficient catalytic activity compared with hydrolyzing with steamthrough contrast experiments of adsorption, photo-catalysis and repeated experiments. When the TiO2-coated palygorskite powder prepared by the hydrolysable method is watered directly, the decoloring rate can reach 93% after 2 h of reaction.

Abstract:The adsorption of organic contaminants in the vadose is one of the most important factors affecting their migration and transformation process. Basedon batch experiments, this paper deals with the adsorption behavior of trichlorinated hydrocarbon (TCE) on soil samples with different contents of organic carbon. The results indicate that the content of organic carbon in samples from the surface part is higher than that collected from the deep part. Generally speaking, the adsorption capacity increases with the increasing content of organic carbon, but the difference of the adsorption capacity can reach as high as 5 times for samples with the same organic carbon content, suggesting that there probably exists competition adsorption, and that mineral adsorption might be the major mechanism. The adsorption of surface soil fits the liner adsorption well, and there exists no saturated adsorption capacity. In deeper soil with lower organic carbon, however, the adsorption seems to be nonlinear.

Abstract:The optimized conditions for phosphorus recovery as hydroxyapatite from wastewater by synthetic tobermorite through seeded crystallization were studied in this paper. The results show that pH value of 8, Ca/P ratio of 2 (molar ratio) and 1.6 g/L seed concentration seem to be the favorable conditions. It is proved that under the optimized conditions the seed can yield alkalis. During the process in which tobermorite was used for eighteen times, all the concentrations of residual phosphorus were satisfactory. Characteristics of the products weredetermined by such analytical techniques as Powder X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and EDS. The results show that the main recovered product is hydroxyapatite with a lower cryst allization degree.

Abstract:In this experiment, Fe(OH)3 and Mg(OH)2 were prepared by using acid leaching filtrate of copper and nickel tailings from Jinchuan as raw materials. During the process, precipitates of Fe3+ (schwertmannite) and Mg(OH)2 were separated from this leaching filtrate according to different precipitation pH values of the metallic ions, and the precipitation mixtures of Al, Co, Ni and Cucan be obtained simultaneously. After that, the precipitates of schwertmannite were put into the NaOH solution at the pH value of 12 and aged at 60℃ for 36 hours so as to transform them into Fe(OH)3. The experiment shows that pH 3.8 and 9.8 were the appropriate pH values to separate Fe3+, Mg2+ and othermetallic ions in the acid leaching filtrate. The results obtained provide a new method for handling tailings in the metallic mine.

Abstract:The sulfuric acid leaching process of tailings by using microwave was studied in this paper. The effects of sulfuric acid concentration, liquid to solid ratio and reaction time on the leaching ratio were also investigated. Without agitation, the optimum microwave heating conditions of sulfuric acid concentration 5.0 mol/L and liquid/solid ratio 5.0 mL/g are superior to those of water bathing heating. In addition, microwave heating for 15 man can yield the same effect as that of water bathing heating for 2--3 h. In addition, microwave heating for 1/6 reaction time of water bathing time can produce the same acid-leaching rate, with much lower sulfuric acid and liquid to solid ratio. The microwave heating of railings for some time followed by addition of sulfuric acid for leaching can be helpful to the dissolution of tailings and enhance the acid-leaching rate. Under the conditions of microwave heating of 1 h, sul- furic acid concentration 8.0 mol/L and liquid/solid ratio 5.0 mL/g, most of the minerals in tailings can be dissolved except tremolite. The results indicate that, compared with the traditional heating methods, microwave heating could greatly improve the acid-leaching rate of tailings.

Abstract:The association and content of minerals in 51 soil samples from Chongqing segment of the Three Gorges Reservoir were investigated by XRD. The results indicate that quartz, plagioclase and K-feldspar comprise main mineral species in the soils, and quartz content is high in most samples. Clay minerals in the samples are composed mainly of illite and montmorillonite, together with minor other minerals. By reference to the surface water body quality standard, the authors calculated the thresholds of pollution of heavy metals CA, lag, Pb, Cu in the soils using the formula of critical adsorption capability of metal ions adsorbed on soil minerals, and evaluated the pollution situation of these soils. The results show that the contents of contaminative elements in the soils are inconsistent with their assessment values of ecologic effect. The contents of CA and Fig in the soils fail to reach the critical values of pollution, and the risk of geochemical time bomb for the two harmful elements should not be neglected in the area. There exists serious pollution of Pb and Cu in the studied soils as well as in their parent rocks, which probably reflects the high geochemical background of the two elements in this area.

Abstract:Using GIS, the authors studied an area of 5713 km2 in Hohhot, Inner Mongolia. The reference values of Cd in four subtypes of surface soil were established. An analysis of 933 soil samples has revealed that the reference value of Cd in new accumulative topsoil of Hohhot is highest (0.107 mg/kg) ,and that in light cinnamon topsoil is lowest(0.084 mg/ kg).The results obtained provide basic materials for the construction of the local soil environmental quality standard.

Abstract:Through sampling and measuring samples of ten modern sedimentary column cores (from 0 to 38 cm) in different sections of the Dianchi Lake, the authors determined the elements, the total phosphorus (TP) and the magnetic susceptibiity values (χ) by different methods. On such a basis, the vertical distribution of the elements, TP and χ in the lake sediments were studied, with a discussion on their environmental significance. It is indicated that the elements are increasingly concentrated and enriched with the depth. From the bottom to the surface of each sedimentary column core, Al2O3, Fe2O3, K2O, TiO2, Cu, Co, Ni, Pb, Zn, Cd, Sr, U, Zr and TP increase slowly, P2O5 and CaO increase similarly and reach the maximum at 12～0 cm, MgO, Na2O, MnO, Cr, V, Rb, Sc, Th, Cs and Ba vary steadily and decrease in the top sediments, and the rare elementsdecrease slowly. These changes show different tendencies, and χ values increase slowly too. These changes reflect the differences of material sources in different periods. Statistical analysis shows that the migration and enrichment of the elements were disturbed strongly by human activities. According to the previous 137 Cs dating results, the sedimentary accumulation rates of the Dianchi Lake in the past 150 years was estimated. It is found that the sedimentary pollution began at the early 1960s, and the pollution of Cu, Ni, Pb, Zn, Cr and some otherheavy metals occurred considerably during the period of more than 30 years after the late 1960s. Meanwhile, some sedimentary environmental change events from the late 1920s to the late 1930s were gained. It is demonstrated that the environmental pollution of the sediments in the Dianchi Lake was caused mainly by industrialization, municipal construction, and social and economic development. The resultsobtained provide a new means for understanding the environmental evolution and the pollution process of the Dianchi Lake.

Abstract:Particle distribution, morphology, mineral and chemical compositions of atmospheric particles were studied by optic and electronic microscopy, X-ray diffraction and synchrotron radiation X-ray fluorescence. Statistical results demonstrate that the coarse particles of atmospheric particles in Zhongguancun area decrease with the elevation of the relative height. There are three morphologi- cal types, namely, grained and columnar individual minerals, spherical flying beads and irregular aggregates. Other analytical results show that atmospheric particles come mainly from natural dust, concrete industry, coal-fire, and automobile exhaust pollution.

Abstract:The relapsed tremendous mineralization beside meningioma is a rare case. An analysis of its mineral composition may provide some support information for finding the reason of relapse. Using X-ray phase analysis, infrared spectrometry, environmental scanning electron microscopy and high_resolution transmission electron microscopy, the authors observed and analyzed the mineral composition of the samples. The results show that the particle size of the mineral is about 4.3 nm（statistical value, and the main component is carbon hydroxyapatite.It is supposed that there may also be a small amount of amorphous calcium phosphate.

Abstract:This paper deals with the basic application of clay minerals to environmental pollution control and systematically describes the structural features and basic performance of these minerals. Some viewpoints are put forward concerning the application of clay minerals to environmental pollution control, which are surely of valuable significance in the research work of this field.