首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
Heavy metal ions (Pb2+, Cd2+, Ni2+, and Zn2+) were biosorbed by brown seaweed (Hizikia fusiformis), which was collected from Jeju Island of South Korea. The metal adsorption capacity of H. fusiformis improved significantly by washing with water or by base or acid treatments. The maximum sorption by NaOH-pretreated biomass was observed near a slightly acidic pH (pH 4?6) for Pb2+, Cd2+, Ni2+, and Zn2+. This result suggests that the treatment of H. fusiformis biomass with NaOH helped increase the functional forms of carboxylate ester units. Kinetic data showed that the biosorption occurred rapidly during the first 60 min, and most of the heavy metals were bound to the seaweed within 180 min. The maximum metal adsorption capacities assumed by a Langmuir model were on the order of Pb2+ > Cd2+ > Ni2+ > Zn2+. Equilibrium adsorption data for the heavy metal ions could fit well in the Langmuir model with regression coefficients R 2 > 0.97.  相似文献   

2.
The objective of the present study is to evaluate the absorption efficacy of H. fusiformis biochar (HFB) for the removal of phenol and heavy metals from single and mixed solute systems of these species under different experimental conditions. The effects of contact time, pH change, initial phenol concentration, and heavy metal concentration on the adsorption capacity of HFB were investigated. The kinetics and equilibrium models of sorption of the components of the single and mixed solute systems on HFB were also studied. The experimental data were fitted to kinetic and equilibrium models. The batch experiments revealed that 360 min of contact time was sufficient to achieve equilibrium for the adsorption of both phenol and heavy metals. The adsorption of phenol and nickel by HFB followed the pseudo-second-order kinetic model, which was quite adequate for describing the adsorption mechanism. The equilibrium data for the adsorption of phenol and heavy metals fit well to the Langmuir model with regression coefficients of R 2 > 0.819. The maximum Langmuir adsorption capacities were 10.39, 12.13, 22.25, 2.24, 2.89, and 22.03 mg/g for phenol, Ni2+, Zn2+, Cu2+, Pb2+, and Cd2+, respectively. Moreover, HFB exhibited optimal sorption under slightly acidic conditions at pH 6. The HFB used in the present study exhibited higher adsorption capacity for the removal of phenol and heavy metals from aqueous solutions compared to documented sorbents. These results demonstrate that HFB is potentially useful for alleviating the harmful effects of phenol and heavy metal in wastewater treatment systems.  相似文献   

3.
Heavy metals are known to pose a potential threat to terrestrial and aquatic flora and fauna. Due to increasing human influence, heavy metal concentrations are rising in many mangrove ecosystems. Therefore, an assessment of heavy metal (Cd, Cr, Cu, Ni, Pb, Fe, Mn, and Zn) concentrations was conducted within the bulk soil and rhizosphere soil of Avicennia marina at the Pichavaram Mangrove Forest in India. The rhizosphere soil showed higher concentrations of metals than the bulk soil. Compared to the bulk soil, the metals Cd, Fe, Mn, and Zn were 6.0–16.7% higher, whereas Cr, Cu, Ni, and Pb were 1.7–2.8% higher concentration. Among the three selected sampling sites (dense mangrove forest, estuarine region, and sea region), the sea region had the highest concentration of all heavy metals except Zn. The trend of the mean metal concentration was Fe > Mn > Cr > Ni > Cu > Pb > Zn > Cd. Heavy metals concentrations elevated by the 2004 tsunami were persistent even after 4 years, due to sedimentary soil processes, the rhizosphere effect of mangroves, and anthropogenic deposition. Analysis of the heavy metal-resistant bacteria showed highest bacterial count for Cr-resistant bacteria and rhizosphere soil. The maximum level of heavy metal-resistant bacteria was observed at the site with the highest heavy metal contamination. The heavy metal-resistant bacteria can be used as indicator of heavy metal pollution and furthermore in bioremediation.  相似文献   

4.
The contents of Co, Cr, Cu, Mn, Ni, Pb and Zn in the dust samples collected from Changqing industrial park of Baoji city, NW China, were measured by XRF, while As and Hg in the dust samples were analyzed by AFS. Geo-accumulation index (I geo), pollution index (PI) and integrated pollution index (IPI) were calculated to evaluate the heavy metal contamination level of dust. The health risk due to exposure to heavy metals in dust was analyzed by the Health Risk Assessment Model of US EPA. The results show that the arithmetic means of As, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn are 23.3, 16.4, 1591.8, 178.2, 0.243, 346.5, 40.2, 1,586.2 and 1,918.8 mg kg?1, respectively, which are higher than the background values of Shaanxi soil, especially for Cr, Cu, Hg, Pb, and Zn. The mean values of I geo reveal the order of Pb > Zn > Cr > Hg > Cu > As > Co > Ni > Mn. The high I geo of Cr, Cu, Hg, Pb and Zn in dust indicates that there is considerable pollution from Cr, Cu, Hg, Pb and Zn, while the low I geo of As, Co, Mn and Ni presents no pollution in dust. The assessment results of PI support the results of I geo, and IPI indicates heavy metals in dust polluted seriously. The health risk assessment shows that ingestion of dust particles is the route for exposure to heavy metals from dust, followed by dermal adsorption. Exposure to As, Cr and Pb from dust may pose a potential health threat to children and adults. The risk of cancer from As, Co, Cr and Ni due to dust exposure is low.  相似文献   

5.
This study was carried out in order to determine the concentration of heavy metals, e.g., lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), nickel (Ni) and chromium (Cr) in road dust in Kuala Lumpur’s city centre. Samples were collected from four sampling locations, each of which had four sampling points and three replications. Heavy metals from different fractions of particles separated by different diameter sizes: d < 63 μm (Fraction A), 63 < d < 125 μm (Fraction B) and 125 < d < 250 μm (Fraction C) were analyzed using inductively coupled plasma mass spectrometry. The results from this study showed that concentration of heavy metals was dominated by the smallest particle size: <63 μm and that Fe was the most abundant heavy metal overall, followed by Cu > Mn > Zn > Pb > Ni > Cr > Cd. The fact that Cd had the highest enrichment factor value (EF) for all particle sizes indicates that anthropogenic activities contributed to the presence of this metal. There was also a higher EF value for heavy metals in small particle (Fraction A), compared to Fraction B and C, which suggests that fine particles were being produced through anthropogenic activities. Cluster analysis and principal component analysis demonstrated the likelihood of the heavy metals detected in the road dust, originating from road traffic and industrial activities.  相似文献   

6.
The ability of ochre to remove Pb(II) and Cu(II) from aqueous media has been studied by batch sorption studies varying the contact time, initial metal concentration, initial solution pH and temperature to understand the adsorption behaviour of these metals through adsorption kinetics and isotherms. The pH of the solution and the temperature controlled the adsorption of metal ions by ochre and rapid uptake occurred in the first 30 min of reaction. The kinetics of adsorption followed a pseudo-second-order rate equation (R 2 > 0.99) and the isotherms are well described by the Freundlich model. Adsorption of metals onto ochre is endothermic in nature. Between the two metals, Pb(II) showed more preference towards the exchangeable sites on ochre than Cu(II). This study indicates that ochre is a very effective adsorbent in removing Pb(II) and Cu(II) from the aqueous environment with an adsorptive capacity of 0.996 and 0.628 mg g?1 and removal efficiency of 99.68 and 62.80 %, respectively.  相似文献   

7.
Landfill leachate is a high-strength wastewater. If it is not managed properly, it can pollute surrounding environment. The aim of this study is to determine the simultaneous adsorption capacity of iron oxide-coated gravel for metals such as Cd(II), Cu(II), Fe(II), Ni(II) and Zn(II) in high-strength leachate sample. Different operating conditions such as pH, time, and dosages were investigated to determine the kinetics and mechanism of adsorption process. Coating with iron oxide changed the external surface of gravel. The adsorption capacities increased with increased pH, and the optimum pH was found to be 7. High removal rates were observed in a short period of time. The Freundlich model fitted reasonably well to the experimental data, indicating multilayer adsorption process and the heterogeneity of the surface (R 2 ranging 0.57–0.94). The Temkin model fitted well to the experimental data as well (R 2 ranging 0.67–0.98), indicating that the adsorption is an exothermic process. The adsorption of ions was found to obey second-order kinetics, indicating one-step, surface-only adsorption process. The degree of metal adsorption on iron oxide-coated gravel at pH 7 was in the order Cu(II) > Cd(II) > Fe(II) > Zn(II) > Ni(II).  相似文献   

8.
This study was conducted to investigate the effect of waterlogging on copper, lead and cadmium fractionation in Chinese purple soil. Heavy metals were added to purple soil at 80 % field capacity and waterlogging regimes as nitrate salts of 500 mg kg?1 of copper and lead, and 5 mg kg?1 of cadmium. Metals in the incubated soil samples were fractionated termly from 1 to 35 days by the sequential extraction procedure. Under both treatments, the heavy metals spiked in the soil were transformed slowly from the exchangeable fractions into more stable fractions, whereas their residual fractions barely changed. The transformation process of exchangeable fraction in soil was estimated by Elovich kinetic equation for the above incubation periods, and the constant B in Elovich equation was applied to reflect the transformation rates of metal speciation. It was found that waterlogging incubation could immobilize heavy metals, resulting in decreased lability and availability of the metals in purple soil. The effect of waterlogging on the redistribution of heavy metals in purple soil might be mainly related to the changes of pH, potential redox and hydrous oxides in varying soil-water systems.  相似文献   

9.
Sediments and surface water contamination by the industrial effluents containing heavy metals is the most detrimental environmental impact. Therefore, the present work attempts to determine the status of eight heavy metal distribution in sediments and water samples, and their ecological risks’ assessment in the studied area. The distribution pattern of heavy metals in the water and sediment follows the sequences: Zn > Cu > Pb > Cr > Mn > Ni > As > Cd and Mn > Zn > Cr > Pb > Cu > Ni > As > Cd, respectively. Gross water pollution is observed at different sampling points of Dhalai Beel and Bangshi River. The comparison of sedimentary mean metal concentrations with several environmental contamination monitoring parameters, viz, threshold effect level (TEL), probable effect level (PEL), and severe effect lever (SEL) indicates that the metal levels are less than PEL except Cr. Moreover, the level of contamination degree (C d) and modified degree of contamination (mC d) indicates ‘low’ and ‘nil to low’ degree of contamination, respectively. Pollution load indices (PLI) of the studied area are lower than unity, indicates no pollution. Furthermore, a toxic-response factor is applied to assess the potential ecological risk of these heavy metals into the water body. The results of this study exhibit a low potential ecological risk of heavy metals. The Pearson’s correlation and cluster analysis are also performed to assess the heavy metal interactions in water and sediment samples.  相似文献   

10.
Adsorption of chromium and copper in aqueous solutions using tea residue   总被引：5，自引：3，他引：2  
In this study, adsorption of copper and chromium was investigated by residue of brewed tea (Tea Waste) from aqueous solutions at various values of pH. It was shown that adsorbent dose, copper and chromium ion concentrations in such solutions influence the degree of these heavy metal ions’ obviation. The adsorption level of the prepared solutions was measured by visible spectrophotometer. The tea residue adsorbed copper (II) and chromium (VI) ions at initial solution pH by 25 % and 3 %, respectively. During the experiments the peak adsorption occured in hydrated copper nitrate aqueous solution at pH range of 5–6. Likewise the maximum adsorption appeared in potassium chromate aqueous solution at pH range of 2–3. In addition, tea residue adsorbed about 60 mg/g of copper (II) ion at pH=5, while chromium adsorption was registered at about 19 mg/g at pH=2. The data obtained at the equilibrium state, was compared with Langmuir and Freundlich models. Results showed that regarding the kinetics of adsorption, the uptake of copper (II) and chromium (VI) ions by tea residue was comparatively faster, with the adsorption process exhaustion completed within the first 20 min of the experiments. Furthermore, results revealed that adsorption data concerning the kinetic phase is closely correlated with a pseudo-second order model with R2> 0.99 for copper (II) and chromium (VI) ions  相似文献   

11.
Bioaccumulation of heavy metals and its associated histological perturbations were studied in various tissues of Chanos chanos collected from Kaattuppalli Island, and they were compared with those of fish collected from the Kovalam coast. The concentration of four heavy metals: copper, lead, zinc and cadmium were determined in water, sediment and different tissues of fish (gills, liver and muscle). The result showed a marked difference between the two sites as well as significant variations within the water, sediment and biota samples. The decreasing trend of metals from both Kaattuppalli Island and Kovalam coast was in the order of Cd > Cu > Pb > Zn. Overall, the highest metal concentration was found in the sediment, water and biota collected from Kaattuppalli Island. The accumulation in the gills and liver of C. chanos was found to be quite high in comparison with that of muscle. These tissues were further investigated by light microscopy and the results were compared with the tissues from the reference site (Kovalam coast). The presence of large lipid droplets in the liver and increase of mucous cells in the gills were some of the most noticeable alterations observed that were related to heavy metal contaminants. It is concluded that histopathological biomarkers provide reliable and discriminatory data to augment heavy metal pollution in Kaattuppalli Island. Therefore, long-term monitoring is necessary to assess the eco-health of the Kaattuppalli Island environment by choosing a bio-indicator species like C. chanos, which provide accurate, reliable measurements of environmental quality.  相似文献   

12.
A binary mixture of humic acid and geothite was prepared and used to modify kaolinite to produce geothite–humic acid (GHA)-modified kaolinite adsorbent useful for the adsorption of Pb2+, Cd2+, Zn2+, Ni2+ and Cu2+ from Single and Quinary (5) metal ion systems. The cation exchange capacity (CEC) and specific surface area of GHA-modified kaolinite clay adsorbent were found to be 40 meq/100 g and 13 m2/g, respectively, with the CEC being five times that of raw kaolinite clay (7.81 meq/100 g). The Langmuir–Freundlich equilibrium isotherm model gave better fit to experimental data as compared with other isotherm models. In Quinary metal ion system, the presence of Zn2+ and Cu2+ appears to have an antagonistic effect on the adsorption of Pb2+, Cd2+ and Ni2+, while the presence of Pb2+, Cd2+ and Ni2+ shows a synergistic effect on the adsorption of Zn2+ and Cu2+. The GHA-modified kaolinite showed strong preference for the adsorption of Pb2+ in both metal ion systems. Brouers–Weron–Sotolongo (BWS) kinetic model gave better fit to kinetic data compared with other kinetic models used. Data from BWS kinetic model indicate that adsorption of metal ions onto GHA-modified adsorbent in both metal ion systems followed strictly, diffusion-controlled mechanism with adsorption reaction proceeding to 50 % equilibrium in <2 min in the Single metal ion system and <1 min in the Quinary metal ion system. Adsorption of metal ions onto GHA-modified kaolinite is fairly spontaneous and endothermic in nature in both metal ion systems although the rate of metal ion uptake and spontaneity of reaction are reduced in the Quinary metal ion system.  相似文献   

13.
This research presents a detailed study which was performed to infer the quantity of metal (Cd, Cr, Pb, Zn, Cu and Fe) contents in sediments of Daye Lake, Central China. The geo-accumulation (I geo) and potential ecological risk (PER) of these metals were assessed. The results reveal that: (1) the mean value of I geo ranked an order of Fe (class 6) > Cd (class 5) > Pb (class 3) > Zn (class 2) > Cr (Class 1) > Cu (Class 0); (2) Potential ecological risk (PER) values calculated for all these metals at different sampled points in Daye Lake exceeded the value of very high risk. Multivariate statistical analyses were carried out to determine the relationship between these six metals and to identify the possible pollution sources, with the results suggesting that the metal content in the sediments has three patterns: the first pattern includes Pb, Cd and Cr which were mainly present due to discharged water by smelting industries; second pattern contains Zn and Cu which mainly originated from the waste residue of the copper mining industry; the third pattern is Fe which is mainly related to mine tailing leaches. This study indicates very high metal content levels in the sediments, which may have adverse risks (average PER = 7,771.62) for the lake’s ecosystem and human beings associated with Daye Lake.  相似文献   

14.
The use of agricultural wastes as biosorbents is gaining importance in bioremediation of heavy metal-polluted water and soils, due to their effectiveness and low cost. This work assesses the Cd, Pb and Cu adsorption capacity of the raw materials used in the production of substrates for mushroom production (Agaricus bisporus and Pleurotus ostreatus) and the spent mushroom composted (SMC), based on the functional groups of their organic carbon. The raw materials studied included agricultural wastes (wheat straw, wheat and rice poultry litter, grape pomace) and inorganic substances (gypsum and calcareous sand). Organic carbon from wastes and their composting products were characterized by CP-MAS 13C NMR. Langmuir adsorption isotherms of metals were plotted for each raw material, composting step, spent A. bisporus and P. ostreatus substrates and the final SMC. The maximum adsorption capacities of SMC were 40.43, 15.16 and 36.2 mg g?1 for Cd, Pb and Cu, respectively. The composting process modified the adsorption properties of raw materials because of the enhanced adsorption of Cd and Cu and decreased adsorption capacity of Pb. CP-MAS 13C NMR and potentiometric titration were used to identify the functional groups of the organic carbon responsible for the metal adsorption. The content of cellulose was correlated with Pb adsorption (p < 0.001), alkyl and carboxyl carbon with Cd adsorption (p < 0.001), and N-alkyl (p < 0.001) and carboxyl (p < 0.010) groups with Cu adsorption. These results are valuable to develop new biosorbents based on agricultural wastes and demonstrate the high potential of SMC to adsorb heavy metals from polluted environments.  相似文献   

15.
Analysis was carried out using tangerine peel aiming its use as a potential adsorbent of eight heavy metal ions (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) from aqueous solution. This agricultural waste was tested both in its untreated and also chemically modified form. Based on Fourier transformation infrared spectra, a comparison of biosorbent structure before and after chemical treatment was made. Batch adsorption tests were conducted at different pH and mass of sorbent to examine the influence on the effectiveness of simultaneous removal of tested ions. Kinetic studies were conducted at optimum pH 5.0 and sorbent dosage 300 mg. The pseudo-second-order kinetic model best fit the experimental data with high correlation coefficients (r2 > 0.9997). By optimizing listed parameters, high removal efficiencies (> 89%) were achieved. According to the results obtained in this study, the remediation of water polluted with heavy metals could be done using modified tangerine peel as an agricultural waste material.  相似文献   

16.
Street dust from 29 locations, in some of the busiest parts of north and south Kolkata, was analysed for heavy metal composition. The decreasing order of average metal concentrations (mg kg?1) found was Mn (390) > Pb (380) > Zn (300) > As (96) > Cu (61) > Cr (40) > Co (13) > Ag (2.1). The heavy metal composition of the Kolkata dust was compared with reported data for other cities. Enrichment factors of Pb and As were high. Multivariate statistical analysis of the heavy metals and analysis of lead isotopic ratios of the dust revealed a predominant anthropogenic influence in the contamination. The range of lead isotopic ratios found in the dust was between 0.8789 and 0.8998 with a mean Pb concentration of 383 mg kg?1. The three Pb isotope plots of street dust, diesel and rainwater clustered linearly, while coal did not fit into this trend. The highest 207/206 lead isotopic ratio obtained was from diesel with a mean value of 0.9015, followed by the rainwater sample. The application of the binary mixing model showed that about 66.86% of lead contamination in the street dust was sourced from the atmosphere. The two components extracted by the principal component analysis explained 64.34% of the total variance. Vehicular and industrial emissions appeared to be an important contributor to the accumulation of heavy metals in the dust. The health risk assessment study of the dust indicated carcinogenic risk associated with As and Cr.  相似文献   

17.
Effects of paper mill wastes on the status of soil copper (Cu), manganese (Mn) and zinc (Zn) in and around 16 sites near a paper mill in Assam, North East India (26°07.485′ to 26°07.915′ N latitude and 92°12.706′ to 92°15.065′ E longitude), have been investigated in the present study. The six-step sequential extraction techniques revealed that the water-soluble fraction had the least contribution (below detectable limit to 3.24 mg kg?1 of Cu, 13.87 mg kg?1 of Mn and 1.25 mg kg?1 of Zn) towards soil contamination, irrespective of the metals evaluated. Chemical fractionation of Cu, Mn and Zn in majority of the sampling locations showed non-homogenous orders of contamination. Comparison of the magnitude of local and individual heavy metal contamination factors against global values showed that the places near the paper mill waste disposal site displayed higher potential risk from metal contamination. Furthermore, the mobility factor related to ecotoxicity of soil environment was found to be metal specific and depended not only on total metal concentration but also on the nature of metal in the order Mn > Cu > Zn.  相似文献   

18.
Deepawali is one of the main festivals for Hindu religion which falls in the period October–November every year with great fireworks display. In this study, we investigated the levels of water soluble ions and heavy metals—during the fireworks festival in Rajnandgaon, Central India. The chemical compositions and noise level distributions are reported from the sampling site. First time during Deepawali, air quality was studied in this area, The Aerosol samples of PM10 (particle aerodynamic diameter <10 μm) are collected in October 24–28, 2011. Aims of the present studies are (1) To describe the particulate concentrations and associated chemical species during Deepawali festival, (2) To recognize the noise level in Deepawali festival. For study, the samples were collected in glass fiber filter paper and analyzed for the major water soluble ions F?, Cl?, NO3 ?, SO4 2?, Na2+, NH4 +, K+, Ca2+, and Mg2+ employing ion chromatograph. Concentration of heavy metals was analyzed by ICP-MS and was observed to occur in order Fe > Zn > Pb > Ni > Cr > Cd. The result revels that all concentration are above the permissible limit fixed by CPCB, USPEA, and WHO standard. It is concluded that the burning of fireworks during Deepawali festival was the main source of heavy metals and ion.  相似文献   

19.
This study investigated the effect of cations and anions on the sorption and desorption of iron (Fe) and manganese (Mn) in six surface calcareous soil samples from Western Iran. Six 10 mM electrolyte background solutions were used in the study, i.e., KCl, KNO3, KH2PO4, Ca(NO3)2, NaNO3, and NH4NO3. NH4NO3 and NaNO3 increased the soil retention of Fe and Mn, whereas Ca(NO3)2 decreased the soil retention of Fe and Mn. Iron and Mn sorption was decreased by NO3 ? compared with H2PO4 ? or Cl?. The Freundlich equation adequately described Fe and Mn adsorption, with all background electrolytes. The Freundlich distribution coefficient (K F) decreased in the order H2PO4 ? > Cl? > NO3 ? for Mn and H2PO4 ? > NO3 ? > Cl? for Fe. The highest sorption reversibility was for Fe and Mn in competition with a Ca2+ background, indicating the high mobility of these two cations. A MINTEQ speciation solubility model showed that Fe and Mn speciation was considerably affected by the electrolyte background used. Saturation indices indicated that all ion background solutions were saturated with respect to siderite and vivianite at low and high Fe concentrations. All ion background solutions were saturated with respect to MnCO3(am), MnHPO4, and rhodochrosite at low and high Mn concentrations. The hysteresis indices (HI) obtained for the different ion backgrounds were regressed on soil properties indicating that silt, clay, sand, and electrical conductivity (EC) were the most important soil properties influencing Fe adsorption, while cation exchange capacity (CEC), organic matter (OM), and Mn-DTPA affected Mn adsorption in these soils.  相似文献   

20.
Rapid increases in the amounts of fullerene C60 nanoparticles (nC60) being produced and used will inevitably lead to increases in the amounts released into the aquatic environment. This will have implications for human and ecosystem health. Wastewater treatment plants are key barriers to nC60 being released into aquatic systems, but little information is available on how adsorption processes in wastewater treatment plants affect the fates of nC60. We investigated the effects of the surface properties of activated sludge on the adsorption of nC60 and related mechanisms by modeling the adsorption kinetics and equilibrium process and performing correlation analyses. The adsorption of nC60 closely followed the pseudo-second-order kinetic model (R > 0.983), the Freundlich isotherm model (R > 0.990), and the linear partitioning isotherm model (R > 0.966). Different adsorption coefficients, 1.070–4.623 for the Freundlich partitioning model and 1.788–6.148 for the linear partitioning model, were found for different types of activated sludge. The adsorption coefficients significantly positively correlated with the zeta (ζ) potential (R = 0.877) and hydrophobicity (R = 0.661) and negatively correlated with particle size (R = ?0.750). The results show that nC60 adsorption is strongly affected by the surface properties of activated sludge because changes in surface properties cause changes in the electrostatic and hydrophobic interactions that occur.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号