Qixiu Zhang

Sulfuric acid recovery from rare earth sulphate solutions by diffusion dialysis

Abstract Sulfuric acid recovery from rare earth sulphate solutions by diffusion dialysis was studied. The mass transfer model of diffusion dialysis was established, the comparison between the experimental results and mathematical results was carried out, and the numerical analysis on the effects of operational parameters was studied. The results indicate that the derived mathematical model shows good quantitative relation between sulphuric acid recovery ratio and operational parameters, and the mathematical results agree with the experimental results well. The numerical analysis results indicate that it is appropriate to keep the ratio of water and feed flow rates, processing capacity per membrane area and recovery ratio of sulphuric acid to be 1, 20 L/(m 2 ·d) and 0.7-0.8, respectively.

Treatment of stable oil/water emulsion by novel felt-metal supported PVA composite hydrophilic membrane using cross flow ultrafiltration

The novel felt-metal supported PVA composite hydrophilic ultrafiltration membrane was used for the treatment of oil/water(O/W) emulsion. The effects of transmembrane pressure(TMP), cross flow velocity, feed concentration on membrane performance were investigated, and ultrasonic cleaning of the fouled membrane was also investigated. The results show the flux increases with the increase of cross-flow velocity and TMP within the given TMP range from 0.20 MPa to 0.40 MPa. With increase of initial oil concentration increases, the oil rejection increases while the permeate flux decreases. The composite membrane shows more than 90% oil rejection within the initial oil concentration range from 0.05% to 0.50% (mass fraction) at TMP of 0.30 MPa. The fouling of the composite membrane increases rapidly during the initial 20 min at given TMP range from 0.20 MPa to 0.40 MPa, and it increases slowly after 30 min. The results also show that ultrasound is very effective in removing oil fouling of the fouled membrane, and the properties of the composite ultrafiltration membrane can be completely recovered by 10 min of sonication.

Leaching of nickel-molybdenum sulfide ore in membrane biological reactor

Abstract The bioleaching of molybdenum from its sulfide ore using a Mo-resistant thermophilic bacterium sulfolobus metallics combined with a membrane biological reactor (MBR) was studied. The experimental results showed that the concentration of Mo can be controlled by filter of the membrane in MBR and the toxicity of Mo to microorganism is decreased in the process of bioleaching. It was also evidenced that there were different leaching rates of Ni and Mo when the concentration of Mo was different. After leaching for 20 d in the MBR at Mo concentration of 395 mg/L, the leaching rates of Ni and Mo reached the maximum of 79.57% and 56.23% respectively under the conditions of 100 g/L of mineral density, 65 °C, pH=2 and 1.0 L/min of the aeration rate. While 75.59% Ni and 54.33% Mo were leached out in column without membrane under the same conditions.

Deep Removal of Copper from Cobalt Sulfate Electrolyte by ion-exchange

SP-C was applied for the removal of Cu(superscript 2+) from simulated cobalt sulfate electrolyte containing Co(superscript 2+) 50 g/L and Cu(superscript 2+) 0.5-2.0 g/L. Experimental conditions included pH of 2-4, temperature of 20-60℃ and contact time of 10-40 min. The investigation demonstrated that SP-C had recommendable efficiency in adsorbing Cu(superscript 2+) from the electrolyte with 25-to 100-fold of Co(superscript 2+). The optimal adsorption conditions of SP-C were pH of 4, contact time of 30 min and ambient temperature. The study also showed that the loaded resin could be effectively eluted with 2.0 mol/L H2SO4 solution at a contact time of 40 min; the peak concentration of Cu(superscript 2+) in the eluate was about 35 g/L. The sorption characteristics of Cu(superscript 2+) by SP-C could be described by Langmuir isotherm and the pseudo second-order kinetic equation. Infrared spectra showed that nitrogen atoms in the functional group coordinated with Cu(superscript 2+) to form coordination bands.

Removal of Vanadium from Ammonium Molybdate Solution by Ion Exchange

The separation techniques of vanadium and molybdenum were summarized, and a new method of removal V (Ⅴ) from Mo (Ⅵ) by adsorption with chelate resin was presented. Nine kinds of chelate resins were used to investigate the adsorbent capability of V (Ⅴ) in ammonium molybdate solution with static method. The test results show that DDAS, CUW and CW-2 resins can easily adsorb V (Ⅴ) in ammonium molybdate solution, but hardly adsorb Mo (Ⅵ). The dynamic experimental results show more than 99.5% of V (Ⅴ) can be adsorbed, and the adsorption rate of Mo (Ⅵ) is less than 0.27% at 294-296 K for 60 min at pH 7.42-8.02. The mass ratio of V to Mo decreases to l/50000 in the effluent from 1/255 in the initial solution. The loaded resin can be desorbed by 5% NH3•H2O solution, and the vanadium desorption rate can reach 99.6%. The max concentration of vanadium in desorbed solution can reach 20g/L, while the concentration of molybdenum is less than 0.8 g/L.