Jie Guan

Recovering lead from cathode ray tube funnel glass by mechano-chemical extraction in alkaline solution.

This study evaluates the efficiency of lead (Pb) extraction from cathode ray tube (CRT) funnel glass in strongly alkaline solution using mechanical activation in a ball mill as the chemical breakage and defects formed in the inner structures will contribute to the easy dissolution of the activated Pb glass. The combination of mechanical activation and a chemical leaching process in a single operation (mechano-chemical leaching) is more effective than the mechanical activation and subsequent chemical leaching. More than 97% of Pb in the CRT funnel glass can be extracted with a stirring ball mill leaching process in 5 M sodium hydroxide at 70°C. The diameter of the stainless steel balls as the activation medium is 5 mm; the mass ratio of ball to raw materials is 25:1. Pb powder with a purity of 97% can be obtained by electrowinning from the leaching solution. The Pb-depleted solution can be recycled into the leaching step. After Pb is removed, the solid leaching residues can be used for preparation of foam glass. Thus, a novel hydrometallurgical process for recovering Pb from CRT funnel glass in alkaline solution is proposed.

Photochemical characteristics of diclofenac and its photodegradation of inclusion complexes with β-cyclodextrins

Diclofenac is one of most frequently detected compounds in the water cycle. In this work, the effect of initial concentration, liquid inclusion complexes with β-Cyclodextrins (β-CDs) on the photodegradation of diclofenac were studied. Six phototransformation products were detected by HPLC chromatograms. UV-absorption spectra of diclofenac and phototransformation products were determined. One of the phototransformation products was identified. The degradation followed pseudo-first-order kinetics. The experiment showed that irradiation of diclofenac in the presence of β-CDs increase photodegradation rate and determined the optimal molar ratio of diclofenac to β-CDs as 1:2. The reduced photohaemolytic activity of diclofenac in the presence of β-CDs may be attributed to the sequestering and stabilizing of the radical intermediates and /or photoproducts by complexation.

Indium recovery from waste liquid crystal displays by polyvinyl chloride waste

Indium (In), a rare element existing only in a few natural minerals, is mainly used to produce indium tin oxide (ITO) thin films for applications including liquid crystal displays (LCDs). Therefore, developing an effective method to recover In from waste LCDs is of great significance. In the present study, In was extracted from indium oxide (In2O3) and LCD powder after alkali dissolution via a chloride volatilization process using polyvinyl chloride (PVC) as the chlorination precursor. High purity In2O3 was investigated firstly in a nitrogen atmosphere. The results indicated that high purity In2O3 could have a high recovery ratio of indium using polyvinyl chloride (PVC) as the chlorination agent. The recovery ratio of indium could reach 99.36%. The product was analyzed by X-ray diffraction (XRD), and the results indicated that the condensed products were InCl3 and InCl. Real LCD powder after alkali dissolution was also examined. The recovery ratio of indium was 97.50% and the utilization of hydrogen chloride was 53.91% under the conditions of a molar Cl/In ratio of 11, a degradation temperature of PVC of 400 °C, a chlorination temperature of 500 °C, carrier gas flow rate at 0.1 L min−1, and a reaction time of 30 min. The condensed products were also mainly InCl3 and InCl. It is an effective method to recover In from LCD panels.

An Environment-Friendly Method to Catalytically Oxidate NO in Waste Water by Supported Manganese Oxide on Graphite Oxide

In order to generate powerful radicals as oxidizing species for the complete oxidation of NO, homogeneous activation of peroxymonosulfate (Oxone: PMS) by the Mn3O4/GO catalysts was explored. The catalytic oxidation of NO from waste gas was investigated using advanced oxidation process based on sulfate radicals that produced. The manganese oxide immobilized on graphene oxide (GO) can activate PMS for the oxidation of NO in water. We not only took advantage of the high oxidation–reduction potential of produced sulfite radicals but also an opportunity to oxidize NO on less complex compounds with low dosages. The Mn3O4/GO catalysis system was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that Mn3O4 was well-distributed on GO. The Mn3O4/GO catalyst system exhibited high efficiency for NO oxidation when the Mn3O4/GO catalyst has an optimum Mn3O4 loading. In addition, the best catalytic oxidation can be achieved within 30 min with pH 4 and 6 mM PMS at 25 °C. Therefore, the results indicate promising potential for a system utilizing Mn3O4/PMS to oxidize NO for offgas treatment.

The Compounds Study of Waste PC Main-Board Pyrolysis

This paper has an explicit exposition on the study of waste PC-Main Board recycling by pyrolysis approach. The decomposing of PC-Main Board is completed above 400°C. For PC main boards around 77% solid residual (pyro-solid), 9 % pyro-oil and 14% pyro-gas were produced after the pyrolysis.The volatile detected by gas chromatography-mass spectrometry (PY-GC-MS) and the results indicated that:1) No significant influence of temperature on the products were observed over 400°C, only with the increase of temperature the small molecules volatile substance became a little high. 2) The characteristic pyrolysis products contained high concentrations of phenol, brom- phenol, while bisphenol A, tetrabromobisphenol A, methyl phenols, C1-C4 alkanes and alkanes were present.

Life Cycle Analysis on Regenerating and Energy Recovery of Plastic Solid Waste Management in Shanghai

Over the past several decades with significant technological advances there has been continuous increase in plastic manufacturing in China, which has contributed to the production of a great deal of plastics worldwide every year, and at the same time it has resulted in a large amount of plastic solid waste (PSW). It has great potential values for waste plastics to reuse as secondary materials, which may lessen pressure on resource and environment. The paper studies the status of waste plastics in recycling, reusing and reducing on management countering on the increase in the flow of waste plastics in Shanghai. In light of the methodology of life cycle, the study analyzes the environmental impacts associating with the alternatives in a ‘cradle to grave’ approve to PSW technological recycling systems. We will choose regenerating and energy recovery processes based on site investigation and literatures data in Shanghai to analyze recycling options and how various processes affect the environment. Life-cycle methodology was very suitable for evaluating the overall environmental consequences, and could be used for making decisions and planning strategies with the rapid increase of plastic solid waste generation for Shanghai.

Pyrolysis Behavior and Kinetics of Polyurethane Insulation Materials from Waste Refrigerators

Pyrolysis characteristics and kinetics of polyurethane insulation materials from waste refrigerators were investigated using TG-FTIR technique under N2 atmosphere. Results showed that the whole thermal process could be divided into three stages and the main pyrolysis occurred in 260-600°C. The distribution activation energy model (DAEM) was applied to analyze the pyrolysis kinetics. The estimated activation energies ranged from 122.8 to 188 kJ/mol and the pre-exponential factors k0 varied from 108 to 1013 s-1. The composition of evolved gas included CFC-11, CO2, CH4, CO, NH3, HCN and some organic compounds, the evolution characteristics of main gas products had also been discussed.

A Model of Batch Grinding of Talc Powders

Grinding of talc powders has been studied both theoretically and experimentally. The specific rates of breakage of talc powders were measured based on the first-order breakage kinetics model and the cumulative breakage distribution parameters of talc powders were measured from primary breakage products. Based on the measurement results, the specific rate of breakage and cumulative breakage distribution functions were correlated with particle size asand , repectively. A differential-integral equation was thus build to describe grinding as a rate process and was integrated numerically. Comparisons on size distribution showed that the specific rate of breakage of talc powders increased with grinding time at an increase rateabout 0.0066min-2.

An Investigation of the Mn3O4/graphite Oxide Catalytic Oxidation of NO in Waste Gas

The catalytic oxidation of NO from waste gas was investigated using advanced oxidation process based on sulfate radicals. The manganese oxide immobilized on graphene oxide (GO) can activate peroxymonosulfate (PMS) for the oxidation of NO in water. The Mn3O4/GO catalysis system was characterized via energy dispersive X-ray spectroscopy (EDS). The results showed that Mn3O4 was distributed on GO. The Mn3O4/GO catalyst system exhibited efficient activity for NO oxidation when the Mn3O4/GO catalyst has an optimum Mn3O4 loading. In addition, the best catalytic oxidation can be achieved within 30 min at 25oC. Therefore, the results may have significant technical implication for utilizing Mn3O4/PMS to oxidize NO for off gas treatment.

Study on the Membrane Fouling of the Process of Using Two Layer Flat-Sheet Membrane for Sludge Thickening and Water Reuse

In this paper, the critical flux was applied to represent the tendency of membrane fouling. The response surface model was used to study different factors, such as sludge concentration, space between membranes and aeration rate, affecting membrane fouling of the upper and lower layer membrane module. It was found that the model is fitting and significant, moreover, the sludge concentration, space between membranes and aeration rate has a significant impact on the upper and lower membrane fouling. Meanwhile, it was also observed that the critical flux of both upper and lower layer membrane module sharply decreased with the increase of sludge concentration. However, the different variation tendency of membrane fouling between upper and lower layer membrane module was detected due to the change of space between membranes and aeration rate, when it was under different sludge concentrations. Finally, optimum operating parameters under different sludge concentration simulated by response surface model were successfully applied to the process of using flat-sheet membrane for four-stage sludge thickening.