Zongqiang Zhu

Preparation and Properties of Porous Composite of Hematite/Magnetite/Carbon with Eucalyptus Wood Biotemplate

By using eucalyptus wood biotemplate, a novel porous composite material of iron oxides and carbon (PC-Fe/C) was manufactured for adsorption of oxoanion pollutants. The materials microstructure and characteristic were investigated by different characterization techniques. The experimental results show that the PC-Fe/C composite mainly consisted of hematite, magnetite, and carbon, and preserved the porous hierarchical texture of the wood with 70 ∼ 120 µm macropores, 4.1 ∼ 6.4 µm mesopores, and 0.1 ∼ 1.3 µm micropores. Its Brunauer-Emmtee-Teller (BET) surface area was 59.2 m2 g−1. The maximum adsorption capacities were 2.49, 2.96, and 0.69 mg g−1 for arsenic(V), chromium(VI), and phosphorus(V), respectively. The adsorption capacities of the unpulverized material as a novel filtration adsorbent are comparable to fine particles of the pulverized material, natural, and synthetic iron oxides.

Sorption-reduction removal of Cr(VI) from aqueous solution by the porous biomorph–genetic composite of α-Fe2O3/Fe3O4/C with eucalyptus wood hierarchical microstructure

AbstractA porous biomorph–genetic composite of α-Fe2O3/Fe3O4/C (PBGC-Fe/C) with eucalyptus wood hierarchical microstructure was prepared and characterized. The result indicated that the PBGC-Fe/C material retained the hierarchical porous structure of eucalyptus wood with three different types of pores (widths 70–120, 4.1–6.4 and 0.1–1.3 μm) originating from vessels, fibres, and pits of the wood, respectively. Batch experiments were conducted to evaluate the effects of different parameters on Cr(VI) adsorption systematically. With increasing initial concentration from 10 to 150 mg/L, the amounts of Cr(VI) adsorbed on the pulverized PBGC-Fe/C adsorbent ( 0.841 mm) were determined to be 0.20, 0.92, and 2.96 mg/g, respectively, which exhibited a similar average value to t...

Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3 solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The average values for Pb5(PO4)3OH were determined to be 10−80.77 (10−80.57−10−80.96) at 25°C, 10−80.65 (10−80.38−10−80.99) at 35°C, and 10−79.96 (10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol).

Prediction and Evaluation of the Mixture Toxicity of Twelve Phenols and Ten Anilines to the Freshwater Photobacterium Vibrio qinghaiensis sp.-Q67

Twelve substituted phenols and ten substituted anilines were chosen to investigate if the dose addition and independent action models can be used to evaluate the mixture toxicity of phenolic and aniline derivatives (PADs). Their photobacterium toxicity to the freshwater luminescent bacterium Vibrio qinghaiensis sp.-Q67 showed that the two-parameter Weibull or Logit function could be effectively applied to describe the dose-response relationships. The joint toxicity of three equivalent-effect concentration ratio (EECR) mixtures and twelve uniform design concentration ratio (UDCR) mixtures could be well evaluated using the dose addition (DA) or the independent action (IA) model within 95% confidence intervals.

Synthesis of the lead-calcium HAP solid solutions

A series of lead-calcium hydroxylapatite solid solution was synthesized by the precipitation method. Characterization by various means confirmed the forming of the continuous solid solution over a whole Pb/(Pb+Ca) mole fraction range. An obvious deviation of both a and c lattice parameters from Vegard’s rule was observed. The solids of XPb = 0–0.51 were typically prism crystals with hexagonal pyramid as a termination (particle size 50–100 nm); those of XPb = 0.61–0.69 were the typical hexagonal columnar crystals with pinacoid or hexagonal pyramid as termination, which elongated along c axis (particle size 200–600 nm); those of XPb = 0.80–1.00 were the typical prism crystals with hexagonal pyramid as termination (particle size 2–20 μm). The phosphate peak area for the symmetric P-O stretching decreased with increasing Pb/(Pb + Ca) ratio and disappeared as the Pb/(Pb + Ca) ratio > 0.61, and two phosphate peaks of the P-O stretching were diminished with the increase in XPb. These variations could be caused by a slight tendency of larger Pb2+ to prefer the M(II) sites and smaller Ca2+ to occupy the M(I) sites in the apatite structure.

Dissolution and Solubility Product of Cd-Fluorapatite [Cd5(PO4)3F] at pH of 2–9 and 25–45°C

Dissolution of the synthetic cadmium fluorapatite [Cd5(PO4)3F] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution, pure water, and NaOH solution. The characterization results confirmed that the cadmium fluorapatite nanorods used in the experiments showed no obvious variation after dissolution. During the dissolution of Cd5(PO4)3F in HNO3 solution (pH = 2) at 25°C, the fluoride, phosphate, and cadmium ions were rapidly released from solid to solution, and their aqueous concentrations had reached the highest values after dissolution for ) was determined to be 10−60.03 (10−59.74∼10−60.46) at 25°C, 10−60.38 (10−60.32∼10−60.48) at 35°C, and 10−60.45 (10−60.33∼10−60.63) at 45°C. Based on the values obtained at an initial pH of 2 and 25°C, the Gibbs free energy of formation for Cd5(PO4)3F ( ) was calculated to be −4065.76 kJ/mol (−4064.11∼−4068.23 kJ/mol). The thermodynamic parameters for the dissolution process were computed to be 342515.78 J/K·mol, −85088.80 J/mol, −1434.91 J/K·mol, and 2339.50 J/K·mol for , , , and , correspondingly.

Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(ZnxCa1−x)5(PO4)3OH] at 25°C

A series of Zn-substituted hydroxylapatites [(ZnxCa1−x)5(PO4)3OH, Zn-Ca-HA] with the Zn/(Zn

Dissolution and Solubility of the (BaxSr1-x)HAsO4·H2O Solid Solution in Aqueous Solution at 25˚C and pH 2

Six different members of the ()HAsO4·H2O solid solution were prepared and characterized, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments for 4320 h. With the increase in the Ba/() mole fraction of the solids, the aqueous pH decreased and the aqueous barium concentration increased. The aqueous strontium and arsenic concentrations had the highest values at . The solubility products for BaHAsO4·H2O and SrHAsO4·H2O were calculated to be and , respectively. The corresponding free energies of formation were determined to be − kJ/mol and − kJ/mol. The solid solution had a minimum solubility product of at . The Guggenheim coefficients were determined to be and . The Lippmann diagram was a typical Lippmann diagram for a nonideal solid solution with a negative enthalpy of mixing. The system shows an “alyotropic” minimum at the aqueous activity fraction of 0.87 where the solutus and solidus curves meet. At the end of the dissolution experiment, the dissolution followed the saturation curve for the pure endmember BaHAsO4·H2O and approached the intersection with the minimum stoichiometric saturation curve on the Lippmann diagram.