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Zhou Y.,Southwest University of Science and Technology | Deng Y.,Southwest University of Science and Technology | He P.,Southwest University of Science and Technology | Dong F.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | And 2 more authors.
RSC Advances | Year: 2014

The thermodynamic conditions of the AgOH precipitation-dissolution equilibrium were investigated by the solubility product principle and the Van't Hoff isobaric equation, and a mathematical expression was obtained about the influence of concentration, temperature and pH on the balance of AgOH precipitation-dissolution in the ion-exchange process. It was shown that the silver-loading process of zeolite had a theoretical equilibrium pH value under a certain concentration and temperature, and the optimal preparation conditions of silver-loaded antibacterial zeolite (Ag-Z) were 323.15 K, 0.50 mol L -1, 6.20, 4.00 h for temperature, concentration, pH and time, respectively. And the silver-loading content of Ag-Z was as high as 365.73 mg g-1. The minimum inhibition concentrations (MICs) of the as prepared Ag-Z to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were as little as 1.00 μg ml-1 and 3.50 μg ml-1, respectively, and the minimum bactericidal concentrations (MBCs) were as little as 3.50 μg ml-1 and 5.00 μg ml-1, respectively. The antibacterial mechanisms were analyzed based on the quantity of released Ag + and Na+. © 2014 The Royal Society of Chemistry. Source


Xiu F.-R.,Fujian University of Technology | Xiu F.-R.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Qi Y.,Fujian University of Technology | Zhang F.-S.,CAS Research Center for Eco Environmental Sciences
Waste Management | Year: 2013

Waste printed circuit boards (PCBs) contain a large number of metals such as Cu, Sn, Pb, Cd, Cr, Zn, and Mn. In this work, an efficient and environmentally friendly process for metals recovery from waste PCBs by supercritical water (SCW) pre-treatment combined with acid leaching was developed. In the proposed process, waste PCBs were pre-treated by SCW, then the separated solid phase product with concentrated metals was subjected to an acid leaching process for metals recovery. The effect of SCW pre-treatment on the recovery of different metals from waste PCBs was investigated. Two methods of SCW pre-treatment were studied: supercritical water oxidation (SCWO) and supercritical water depolymerization (SCWD). Experimental results indicated that SCWO and SCWD pre-treatment had significant effect on the recovery of different metals. SCWO pre-treatment was highly efficient for enhancing the recovery of Cu and Pb, and the recovery efficiency increased significantly with increasing pre-treatment temperature. The recovery efficiency of Cu and Pb for SCWO pre-treatment at 420. °C was 99.8% and 80%, respectively, whereas most of the Sn and Cr were immobilized in the residue. The recovery of all studied metals was enhanced by SCWD pre-treatment and increased along with pre-treatment temperature. Up to 90% of Sn, Zn, Cr, Cd, and Mn could be recovered for SCWD pre-treatment at 440. °C. © 2013 Elsevier Ltd. Source


Xiu F.-R.,Fujian University of Technology | Xiu F.-R.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Zhang F.-S.,CAS Research Center for Eco Environmental Sciences
Journal of Hazardous Materials | Year: 2012

In this work, an effective and size-controlled process for preparing Cu2O nanomaterials from waste PCBs by supercritical water (SCW) combined with electrokinetic (EK) technique was developed. SCW was used for the pretreatment of waste PCBs, and highly uniform and monodisperse Cu2O nanoparticles with different sizes were prepared successfully from waste PCBs in EK process. Cu2O nanoparticles with average sizes of 5, 11, 25 and 40nm could be prepared in the presence of nanoparticles stabilizer (PVP) with the concentrations of 40, 30, 20 and 10g/L, respectively. The average size of Cu2O nanoparticles decreased from 49.5 to 18.2nm when current density increased from 10 to 20mA/cm2, and the size uniformity of nanoparticles was improved distinctly at a higher current density. The size of Cu2O nanoparticles increased with the increase of EK time, and agglomeration of particles was observed after 8h EK reaction. Up to 90wt% of the Cu in waste PCBs could be recovered as Cu2O nanoparticles under optimized condition. It is believed that the process developed in this study is simple and practical for size-controlled preparation of nanomaterials from waste PCBs or other Cu-rich solid wastes. © 2012 Elsevier B.V. Source


Long Z.,Hunan University | Yang C.,Hunan University | Yang C.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Zeng G.,Hunan University | And 3 more authors.
Fuel | Year: 2014

In this paper, the performance of catalytic oxidative desulfurization (ODS) were studied using catalyst W/D152 which was prepared by depositing tungsten on resin D152, a macroporous polyacrylic cationic resin. Dibenzothiophene (DBT) was selected as the target compound, and oil-soluble cyclohexanone peroxide (CYHPO) as an oxidant. The effect of different reaction parameters, including reaction temperature, reaction time, the weight of catalyst W/D152 and the molar ratio of CYHPO/DBT were investigated, and the oxidation mechanisms as well as the kinetics were also examined individually. The conversion of DBT and the sulfur content reached 99.1% and 3.52 ppm, respectively at the optimal catalytic conditions of 100 °C, mass ratio of model gasoline to catalyst W/D152 of 100, molar ratio of CYHPO/DBT of 2.5 and reaction time of 40 min. The catalyst could be reused for 7 times before the total sulfur content of treated model gasoline was higher than 10 ppm. The catalytic oxidation of DBT fitted the first-order kinetic model pretty well. The catalyst W/D152 was analyzed by the scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR), and the data show that a thin layer of active components was covered on the catalyst surface which helps explain the satisfactory catalytic performance. © 2014 Elsevier Ltd. All rights reserved. Source


Long Y.-Y.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Feng Y.-J.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Cai S.-S.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Hu L.-F.,China Jiliang University | Shen D.-S.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling
Journal of Hazardous Materials | Year: 2014

Residues disposal from the dismantling of waste electrical and electronic equipment are challenging because of the large waste volumes, degradation-resistance, low density and high heavy metal content. Incineration is advantageous for treating these residues but high heavy metal contents may exist in incinerator input and output streams. We have developed and studied a specialized heavy metal reduction process, which includes sieving and washing for treating residues before incineration. The preferable screen aperture for sieving was found to be 2.36. mm (8 meshes) in this study; using this screen aperture resulted in the removal of approximately 47.2% Cu, 65.9% Zn, 26.5% Pb, 55.4% Ni and 58.8% Cd from the residues. Subsequent washing further reduces the heavy metal content in the residues larger than 2.36. mm, with preferable conditions being 400. rpm rotation speed, 5. min washing duration and liquid-to-solid ratio of 25:1. The highest cumulative removal efficiencies of Cu, Zn, Pb, Ni and Cd after sieving and washing reached 81.1%, 61.4%, 75.8%, 97.2% and 72.7%, respectively. The combined sieving and washing process is environmentally friendly, can be used for the removal of heavy metals from the residues and has benefits in terms of heavy metal recycling. © 2014 Elsevier B.V. Source

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