Yi Nian Zhu

Research Advancement of the Joint Toxicity of Heavy Metals Mixture

Some researches on heavy metals treatment and disposal methods have been reported, the studies related to the single heavy metal toxicity are developed, but the relatively on toxicity of multi-compounds heavy metals and their mixture have been poorly discussed. This article describes the levels of single heavy metals, compares the strengths and weaknesses of diferent test methods, emphasizes on the characteristics of joint toxicity with mixture. The analysis results discover that the combined toxicity of heavy metals vary with different mixtures combinations, test target, methods and some predictive models were adopted to determine the dose-effect relationship. which propose the development direction of heavy metals toxicity, provide theoretical support for the establishment of environmental monitoring and evaluation methods system.

The Adsorption of Heavy Metal from Aqueous Solutions onto the Porous Biomorphic-Genetic Composite of Hydroxyapatite/Carbon with Eucalyptus and Bamboo Template

This study used two types of plant, eucalyptus and bamboo, to produce sorbents for copper (II), cadmium (II), zinc (II), and lead (II) metal ion removal in a water bath shake. The porous biomorphic-genetic composite of hydroxyapatite/carbon with eucalyptus template (PBGC-Fe/C-E) and the porous biomorphic-genetic composite of hydroxyapatite/carbon with bamboo template (PBGC-Fe/C-B) were prepared using eucalyptus and bamboo as plant templates, and through various processes including ammonia leaching, cyclical impregnation using calcium hydroxide and diammonium solutions, and aerobic firing inside muffle furnaces. Tests were conducted on the HAP/C composites to observe their adsorption effects on Cu (II), Zn (II), Pb (II), and Cd (II). The results show that the prepared composites were able to adsorb heavy metals in water effectively. The results indicated that the adsorbed amount of PBGC-Fe/C-E were found to be 16.4371, 4.6725,24.5528, 17.0194 mg/1 for Cu (II), Zn (II), Pb (II) and Cd (II) ions at initial concentration of 50mg/L (25°C), respectively. The adsorbed amount of PBGC-Fe/C-B were found to be 10.5876, 3.9142,21.2463, 13.4721 mg/1 for Cu (II), Zn (II), Pb (II) and Cd (II) ions at initial concentration of 50mg/L (25°C), respectively. The prepared adsorbent is expected to be a new material for the removal of heavy metals from contaminated water.

Characterization, Dissolution and Solubility of Mimetite[Pb5(AsO4)3Cl] at 25°C

Mimetite [Pb5(AsO4)3C was firstly synthesized by precipitation and characterized by various techniques, and then the batch dissolution experiment was conducted at 25°C and different initial pHs. XRD and SEM analysis indicated that the solid was indistinguishable before and after the dissolution. For the dissolution at the initial pH=2, the aqueous arsenate and lead concentration decreased firstly with time and reached a steady state after 480h. For the dissolution at the initial pH=4 and 6, the aqueous arsenate and lead concentrations varied between 0-0.0005mmol/L and 0-0.0008mmol/L, respectively.

Adsorption of Chromium (VI) from Aqueous Solution by Agricultural Waste Derived Activated Carbon

Activated carbon prepared from grapefruit peel, an agricultural solid waste by-product, has been used for the adsorption of Cr(VI) from aqueous solution. The effects of adsorbent dosage, pH and temperature on adsorption of Cr(VI) were investigated. The maximum adsorption yield was obtained at the initial pH of 3. The dynamical data fit very well with the pseudo-second-order kinetic model and the calculated adsorption capacities (23.98, 24.33 and 24.81 mg/g) were in good agreement with experiment results at 20°C, 30°C and 40 °C for the 100 mg/L Cr(VI) solution. The Freundlich model (R2 values were 0.9198-0.9871) fitted adsorption data better than the Langmuir model. The calculated parameters confirmed the favorable adsorption of Cr(VI) on the activated carbon prepared from grapefruit peel.

Dependence of Stability of Sr5(AsO4)3OH on pH Value

The object of this work was to determine the solubility and stability of the synthetic Sr5(AsO4)3OH solid solution at 25°C and the different initial pHs (pH at 2, 6 and 9) by batch dissolution experiments. The results indicated that with the initial pH value of 2, 6 and 9, the reaction system reached equilibrium after 2880h, and by that time the pH value of the solution reached, 7.90, 8.74 and 8.27 respectively. The concentration of strontium and arsenic in the initial solution pH at 2 are higher than that of solutions pH at 6 and 9. While the concentration of strontium in neutral or alkaline solutions is low and stays unchanged.

Adsorption Effect of NO3-, SO42- and PO43- about As (V) on the Porous Biomorph-Genetic Composite of Fe2O3/Fe3O4/C with Eucalyptus Wood Template

The adsorption effect of NO3-, SO42- or PO43- about As (V) on the novel porous biomorph-genetic composite of Fe2O3/Fe3O4/C was prepared with eucalyptus wood template (PBGC-Fe/C) was analyzed and considered. The results show that NO3-, SO42- and PO43- have different change trend onto the PBGC-Fe/C adsorbent under initial As (V) concentration of 5, 10, 50mg/L, the competitive adsorption capacity is: PO43-> NO3-> SO42-. And with increasing of NO3-, SO42- and PO43- concentration, the competitive adsorption phenomenon is more violent.

Characterization, Dissolution and Solubility of Pyromorphite [Pb5(PO4)3Cl] at 25°C

Pyromorphite was synthesized by precipitation and characterized by various techniques. The batch dissolution experiment was conducted at 25°C and different initial pHs (2, 4 and 6). The solid phase showed no obvious change before and after dissolution. The aqueous phosphate concentration decreased quickly from 0.22 to 0.01mmol/L and then increased very slowly with time. After 2160h dissolution, it reached a steady-state value of about 0.13mmol/L. The aqueous lead concentration increased initially and reached a peak value after 72h dissolution.

Experimental Study of Adsorption of Ammonia Nitrogen from Wastewater onto the Bagasse Adsorbent

Adsorption of ammonia nitrogen from aqueous solution onto the bagasse adsorbent has been investigated to evaluate the effects of Adsorbent dose, initial NH4+-N concentration, and pH on the removal systematically. With increasing initial concentration, the amount of ammonia nitrogen sorbed onto the adsorbent increased until it gradually decreased due to the initial concentration exceed 50 mg·L-1, and the maximum adsorption capacity was observed for the sample to be 1.31 mg·g-1 at the initial concentration of 30 mg·L-1, and the corresponding removal rates decreased from 94.01 to 3.89%, with increase in initial concentration from 5 to 100 mg·L-1. Adsorption capacities decreased from 6.04 to 0.49 mg·g-1 with increasing adsorbent dose from 0.1 to 1.5g. What’s more, under alkaline condition, the removal efficiency of ammonia nitrogen from aqueous solution onto the samples were superior to that under acidity and neutrality condition.

Speciation and Mobility of Heavy Metals in Tailings from Dachang Mine, China

Two carbonate tailing samples were collected from Dachang mine tailing reservoirs, Guangxi Province, China. The chemical speciation of Zn, As, Cd and Sb contained in tailing samples were determined by Dold seven-stage sequential extraction procedure, as well as mineralogical and chemical analysis. Then the potential migration abilities of these heavy metals were evaluated. The tailing analysis results showed that the main minerals were calcite, quartz, sphalerite and pyrite, the major elements were Si, S, Ca, Fe and Al, and the trace heavy metals included Zn, As, Cd and Sb. Zn mainly existed in secondary sulfide, primary sulfides and residual fraction, and As was in primary sulfide and residue, but Sb and Cd was residual fraction. The mobility of heavy metals followed the order: Zn > Sb > Cd > As.

The Characteristic Dissolution and Physical Chemistry Parameter of Synthetic Pyromorphite

The Dissolution of Synthetic Pyromorphite was Studied at 25°C in a Series of Batch Experiments. in Addition, the Aqueous Concentrations from the Batch Dissolution were Used to Calculate the Solubility Product and Free Energy of Formation of Pyromorphite. the Results of the Fourier Transform Infrared Spectroscopy Analyses Indicated that the Synthetic, Microcrystalline Pyromorphite with Apatite Structure Used in the Experiments has Not Changed after Dissolution. the Mean KspValue was Calculated for Pb5(PO4)3Cl of 10-78.31 at 25°C; the Free Energy of Formation ΔGf0[Pb5(PO4)3Cl] was-3756.82kJ/mol.