Mercury reduction studies to facilitate the thermal decontamination of phosphor powder residues from spent fluorescent lamps

This work investigates the thermal release of mercury from phosphor powder of spent fluorescent lamps. The treatment conditions and the ability of various reducing agents (primarily sodium borohydride) to lower the overall heating temperature required to improve the release of Hg have been evaluated. Hg species in samples were monitored in a thermal desorption atomic absorption spectrometer system, and total mercury was analyzed in a cold vapor atomic absorption spectrometer. Sodium borohydride was the best reducing agent among the ones studied. However, citric acid presented a high capacity to weaken mercury bonds with the matrix. When the sample was crushed with sodium borohydride for 40min in a mass ratio of 10:1 (sample:reducing agent) and submitted to thermal treatment at 300 degrees C for 2h, the concentration of mercury in a phosphor powder sample with 103mgkg(-1) of mercury reached 6.6mgkg(-1).     

Studies of the thermal degradation of waste rubber

One kind of Chinese waste tire's sample was pyrolyzed under an inert atmosphere by using thermo-gravimetric apparatus (TGA) and differential thermal analysis (DTA). Different pyrolysis temperature ranges were determined according to the reaction transition temperature obtained by TGA and DTA. Then, at each temperature range, the pyrolysis gaseous products were analyzed by gas chromatography (GC). The influence of the temperature range on the relative yields of the major decomposition products is studied, and a mechanism for the formation of the main components was also investigated. The results indicate that pyrolysis of waste rubber follows the radical mechanism, and the major products are not seriously affected by increasing the temperature from room temperature to 420 degrees C and from 421 to 600 degrees C, but the degradation of blend rubber is different for each of the compositional elastomer.     

Remediation of petroleum-contaminated soils by fluidized thermal desorption

A novel type of fluidized bed desorber was developed for the remediation of petroleum-contaminated soils at low temperature with high efficiency. Cahn balance® was utilized to investigate the thermal desorption behavior of soils contaminated by various hydrocarbons. The performance of the fluidized-bed desorber was investigated at different operating modes. Batch operation of the fluidized-bed desorber exhibited 99.9% desorption efficiency at temperatures of ca. 300°C within a half hour. Continuous operation of the fluidized-bed indicated that Q/F (the ratio of the mass flow rate of fluidizing gas to feeding rate of contaminated soils) is less important at higher temperature (>300°C), if proper fluidization is ensured. The periodic operation of the fluidized bed desorber shows the possibility to reduce off-gas volume significantly.     

Use of steel converter slag as nickel adsorber to wastewater treatment.

Magnetite, the main component of converter slag in the steel industry, can be used for the adsorption of Ni(II) from aqueous solutions, over a range of conditions: initial metal concentration (10-100 mg 1(-1)), stirring times (2-240 min), adsorbent dosage (1 g for 0.5 1 of metal solution) and temperatures (20, 30 and 38 degrees C). The adsorption rate increased with initial concentration but decreased with increase in temperature, due to competition of the dissolution process. The adsorption process obeyed the Freundlich isotherm model.     

Preparation, Thermal Properties and Thermal Reliability of Form-Stable Paraffin/Polypropylene Composite for Thermal Energy Storage

This study is focused on the preparation, characterization, and determination of thermal properties and thermal reliability of paraffin/polypropylene (PP) composite as a novel form-stable phase change material (PCM) for thermal energy storage applications. In the composite, paraffin acts as a PCM when PP is operated as supporting material. The composites prepared at different mass fractions of paraffin (50, 60, 70, 80, and 90 w/w%) by solution casting method were subjected to leakage test by heating the composites over the melting temperature of the PCM. The paraffin/PP composite (70/30 w/w%) is found as the maximum paraffin containing composite and was characterized using Fourier transform infrared spectroscopy, optic microscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) techniques. DSC analysis indicated that the form-stable paraffin/PP composite melts at 44.77–45.52 °C and crystallizes at 53.55–54.80 °C. It has latent heats of 136.16 and −136.59 J/g for melting and crystallization, respectively. These thermal properties make it potential PCM for latent heat thermal energy storage (LHTES) purposes such as solar space heating applications. Accelerated thermal cycling tests indicated that the form-stable PCM had good thermal reliability. TGA also showed that the form-stable PCM degrades in two distinguishable steps and had good chemical stability.     

Tertiary recycling of PVC-containing plastic waste by copyrolysis with cattle manure

The corrosion from pyrolysis of PVC in plastic waste was reduced by copyrolysis of PVC with cattle manure. The optimization of pyrolysis conditions between PVC and cattle manure was studied via a statistical method, the Box-Behnken model. The pyrolysis reaction was operated in a tubular reactor. Heating rate, reaction temperature and the PVC:cattle manure ratio were optimized in the range of 1-5 degrees C/min, 250-450 degrees C and the ratio of 1:1-1:5, respectively. The suitable conditions which provided the highest HCl reduction efficiency were the lowest heating rate of 1 degrees C/min, the highest reaction temperature of 450 degrees C, and the PVC:cattle manure ratio of 1:5, with reliability of more than 90%. The copyrolysis of the mixture of PVC-containing plastic and cattle manure was operated at optimized conditions and the synergistic effect was studied on product yields. The presence of manure decreased the oil yield by about 17%. The distillation fractions of oil at various boiling points from both the presence and absence of manure were comparable. The BTX concentration decreased rapidly when manure was present and the chlorinated hydrocarbon was reduced by 45%. However, the octane number of the gasoline fraction was not affected by manure and was in the range of 99-100.     

膜法解吸CO_2吸收富液

采用中空纤维膜接触器(FMC)作为解吸装置,对吸收了CO_2的N-甲基二乙醇胺(MDEA)溶液(富液)进行膜法解吸实验。考察了CO_2负荷、解吸温度、解吸压力、富液流速和N_2吹扫流量对CO_2解吸率的影响。结果表明,富液中CO_2负荷越大、解吸温度越高、解吸压力越低、富液流速越大、N_2吹扫流量越大,则CO_2解吸率越高。综合考虑,本实验优选的工艺条件为解吸温度45~65℃,解吸压力10~30 k Pa,富液流速0.08 m/s,N_2吹扫流量200 m L/min。     

Pyrolysis characteristics and kinetics of chicken litter

Chicken litter generally consists of a mixture of bedding, manure, feathers and spilled food. Flock of birds litter (flock) is a litter consisting of hardwood shavings, feed, feathers and manure; and broiler litter (broiler) is a cake of chicken litter. A kinetic investigation of the pyrolysis of chicken litter (flock and broiler) was carried out using thermogravimetric analysis (TGA) at heating rates of 5 degrees C/min, 10 degrees C/min and 20 degrees C/min. Most of the materials decomposed between 270 degrees C and 590 degrees C at each heating rate. The region of decomposition of flock and broiler was slightly lower than that of the wood chips. Wood chips (bedding material) decomposed in two stages, while flock and broiler decomposed in three stages. Apparent activation energies increased from 99 to 484 kJ/mol for the three samples when the pyrolytic conversion increased from 5% to 95%.     

Removal,Handling, and Thermal Desorption Treatment Techniques for Manufactured Gas Plant Wastes

Due to the nature of contamination typically found at former MGP (manufactured gas plant) sites, excavation and thermal desorption of MGP wastes has proven to be an effective method for the remediation of MGP‐contaminated soil. The use of on‐site thermal desorption enables MGP sites to be quickly remediated at a low cost. Tar pits, holders, and other underground storage structures typically contain coal tar residuals and waste from former operations, and the areas around these structures are often significantly contaminated. Thus, excavation techniques, odor and vapor management, and material preparation for the treatment method are important factors to consider when developing a site remediation strategy. This article reviews typical excavation and handling methods associated with the remediation of former MGP sites and discusses the treatment of MGP wastes using on‐site thermal desorption technology. © 2001 John Wiley & Sons, Inc.     

Evaluation of the optimal washing conditions for dioxin-contaminated soils from the circumference of an incinerator

 The optimal soil-washing conditions for dioxins were estimated on a soil sample from the circumference of an incinerator in Nose City, Osaka, Japan. The solvents ethanol, methanol, and acetone, together with a surfactant (100% of each) could extract 40% of the dioxins from contaminated soil at room temperature. From among these solvents, ethanol was chosen for a study on how to optimize the extraction conditions because of its low toxicity and its economic advantages. The time-course of the agitation showed that the extraction rate increased for 1 min, and thereafter the rate decreased. Therefore, the agitation time was fixed at 1 min. To estimate the effect of temperature on the extraction rate, the extraction temperature was changed. The amount of dioxins extracted was largest at the boiling point of ethanol (78.3°C), giving about 76% extraction. Furthermore, at this temperature, almost 100% of the dioxins in the contaminated soil were extracted when the ratio of water to ethanol was 20%. Received: March 6, 2002 / Accepted: September 9, 2002     

Thermal treatment for recovery of manganese and zinc from zinc-carbon and alkaline spent batteries

The aim of this paper is the recovery of manganese and zinc from a mixture of zinc-carbon and alkaline spent batteries, containing 40.9% of Mn and 30.1% of Zn, after preliminary physical treatment followed by removal of mercury. Separation of the metals has been carried out on the basis of their different boiling points, being 357°C and 906°C the boiling point of mercury and zinc and 1564°C the melting point of Mn(2)O(3). Characterization by chemical analysis, TGA/DTA and X-ray powder diffraction of the mixture has been carried out after comminution sieving and shaking table treatment to remove the anodic collectors and most of chlorides contained in the mixture. The mixture has been roasted at various temperatures and resident times in a flow of air to set the best conditions to remove mercury that were 400°C and 10min. After that, the flow of air has been turned into a nitrogen one (inert atmosphere) and the temperatures raised, thus permitting the zinc oxide to be reduced to metallic zinc by the carbon present in the original mixture and recovered after volatilization as a high grade concentrate, while manganese was left in the residue. The recovery and the grade of the two metals, at 1000°C and 30min residence time, were 84% and 100% for zinc and 85% and 63% for manganese, respectively. The recovery of zinc increased to 99% with a grade of 97% at 1200°C and 30min residence time, while the recovery and grade of manganese were 86% and 87%, respectively, at that temperature. Moreover, the chlorinated compounds that could form by the combustion of the plastics contained in the spent batteries, are destroyed at the temperature required by the process.     

Techno-economic evaluation of ultrasound and thermal pretreatments for enhanced anaerobic digestion of municipal waste activated sludge

To enhance the anaerobic digestion of municipal waste-activated sludge (WAS), ultrasound, thermal, and ultrasound + thermal (combined) pretreatments were conducted using three ultrasound specific energy inputs (1000, 5000, and 10,000 kJ/kg TSS) and three thermal pretreatment temperatures (50, 70 and 90 °C). Prior to anaerobic digestion, combined pretreatments significantly improved volatile suspended solid (VSS) reduction by 29-38%. The largest increase in methane production (30%) was observed after 30 min of 90 °C pretreatment followed by 10,000 kJ/kg TSS ultrasound pretreatment. Combined pretreatments improved the dimethyl sulfide (DMS) removal efficiency by 42-72% but did not show any further improvement in hydrogen sulfide (H₂S) removal when compared with ultrasound and thermal pretreatments alone. Economic analysis showed that combined pretreatments with 1000 kJ/kg TSS specific energy and differing thermal pretreatments (50-90 °C) can reduce operating costs by $44-66/ton dry solid when compared to conventional anaerobic digestion without pretreatments.     

Evaluation of in situ steam‐injection processes for reduction of petroleum compounds within an abandoned canal

A conceptual approach of a novel application of in‐situ thermal processes that would either use a steam injection process or a steam/surfactant injection process was considered to remediate petroleum contaminated sediment residing in an abandoned canal. Laboratory tests were conducted in an attempt to volatilize or mobilize contaminants of concern (selected polycyclic aromatic hydrocarbons [PAHs]) from the contaminated sediment into a phase that could be physically removed. The processes were operated above ambient temperature and pressure in an attempt to increase the removal of the contaminants of concern from the sediment. The ability of both the steam injection process and the steam/surfactant process to remove PAHs from the sediment was considered ineffective; as only two of the seventeen selected PAHs (naphthalene and C1 naphthalene) were associated with a percentage mass reduction greater than 34% for both treatments (four trials). The steam/surfactant injection process generally resulted in higher reductions than the steam injection process, but had larger variances within the two trials using the treatment type. This preliminary evaluation suggests that steam‐based injection processes for removing petroleum contamination from this canal sediment, using the surfactants selected, equipment set‐up, and operating conditions studied, would be considered ineffective. © 2010 Wiley Periodicals, Inc. *

1 This article is a U.S. Government work and, as such, is in the public domain of the United States of America.

     

Investigation of MSWI fly ash melting characteristic by DSC-DTA

The melting process of MSWI (Municipal Solid Waste Incineration) fly ash has been studied by high-temperature DSC-DTA experiments. The experiments were performed at a temperature range of 20-1450 degrees C, and the considerable variables included atmosphere (O(2) and N(2)), heating rates (5 degrees C/min, 10 degrees C/min, 20 degrees C/min) and CaO addition. Three main transitions were observed during the melting process of fly ash: dehydration, polymorphic transition and fusion, occurring in the temperature range of 100-200 degrees C, 480-670 degrees C and 1101-1244 degrees C, respectively. The apparent heat capacity and heat requirement for melting of MSWI fly ash were obtained by DSC (Differential Scanning Calorimeter). A thermodynamic modeling to predict the heat requirements for melting process has been presented, and it agrees well with the experimental data. Finally, a zero-order kinetic model of fly ash melting transition was established. The apparent activation energy of MSWI fly ash melting transition was obtained.     

Influence of dairy manure addition on the biological and thermal kinetics of composting of greenhouse tomato plant residues

A laboratory-scale bioreactor was used to investigate the influence of dairy manure addition (as an inoculum and a carbon source) on the biological and thermal kinetics of the composting process of tomato plant residues-wood shavings mixture. Urea was added (as a nitrogen source) to correct the initial C:N ratio to 30:1 and the initial moisture content was also adjusted to 60%. The result of this study indicated that manure addition to the tomato residues-wood shavings mixture is a good source of macro and micronutrients required for supporting the composting microorganisms. Manure addition increased the rate of temperature increase and the duration of maximum temperature and reduced the lag and the peak time, all of which resulted in a significant reduction in the retention time. However, thermophilic temperature (> or = 40 degrees Celsius) was only achieved with 30%, 40% and 50% manure addition for 3, 7 and 9h. Total carbon reductions were in the range of 9.4-10.8% and TKN reductions were in the range of 3.4-6.0%. Neither the nitrogen nor the moisture content were limiting factors as the C:N ratio remained in the range of 26:1 to 28:1 and the moisture content remained within the optimum range of 58-61%. The maximum temperature of each mixture correlated with the reduction of total carbon, but carbon availability was a limiting factor in these experiments. In order to attain and sustain a thermophilic phase during the composting process, the addition of a readily available carbon source to the tomato should be investigated and carbon type (carbohydrates, proteins and fats) should be taken into account.     

Thermal behaviour of chromium electroplating sludge

Galvanic sludge is classified as a hazardous waste and incineration is one of the techniques used for its treatment. The aim of this work is to study the thermal behavior of a galvanic sludge which contains only chromium as a restriction metal. Simultaneous DTA/TG coupled with mass spectrometer tests were performed to characterize the thermal behavior of the sludge. Besides thermal analysis, sludge samples were heated in a specially designed furnace and these samples were submitted to X-ray diffraction. Vapor from the heated sludge was condensed and the particles were analyzed by EDS microprobe coupled in a scanning electron microscope. The slag formed after the calcination of the galvanic sludge was mainly composed of a mixture of calcium phosphate and fluoride. and minor concentrations of metals. A total weight loss of 34% was observed. The greatest part of this weight loss corresponds to CO2, H2O and SO2. H2O is liberated in the temperature range of 500-1,250 degrees C. CO2 in the range of 500-750 degrees C and SO2 near 1,000 degrees C. Chromium evaporation was not observed in relevant quantities, about 99.6% of the Cr remained incorporated in the slag.     

Qualitative and Quantitative Analysis of Lignin Produced from Beech Wood by Different Conditions of the Organosolv Process

Lignins in general have been extensively studied, while beech wood lignin in particular is rarely researched. In the present work, Organosolv isolated lignin from beech wood (OBL) has been characterized. The isolation was done by two methods: (a) by using sulfuric acid at 170 °C and a reaction time of 120 min and (b) at a temperature of 180 °C for 240 min. A range of analytical methods were applied including elemental analysis, FT-IR, UV–Vis, ³¹P NMR, SEC, Pyrolysis-GC/MS and HPLC to gain information about establish the purity, structure, molecular weight, thermal behavior and to determine carbohydrate residues according to the NREL protocol. FT-IR and UV–Vis spectra of OBL revealed expected typical absorptions for lignins. NREL analysis presented a carbohydrate-free lignin fraction which has not been achieved to date. TGA and DSC are used to study the thermal behavior of the isolated lignins and showed a relatively low glass transition temperatures (T_g: 123 °C) and decomposition temperatures of 348 and 381 °C. The pyrograms generated from the pyrolysis–GC/MS at 550 °C consisted mainly of fragments of syringyl, guaiacyl and hydroxyphenyl units, thereby confirming the results of the NMR analysis. Our findings support Organolsolv as an efficient method to isolate pure lignin fractions from beech wood with practical value in industry.     

Alkyd-amino resins based on waste PET for coating applications

Waste polyethylene terephthalate (PET) flakes were depolymerized by using propylene glycol (PG) in the presence of zinc acetate as catalyst. Glycolysis reaction products of waste PET obtained by using PET/glycol molar ratio 1/2. Two short oil alkyd resins of high acid values (30-40mgKOH/g) were prepared from phthalic anhydride (PA), glycerin (G), coconut oil fatty acids (COFA) and glycolyzed products of waste PET (PET-based alkyd resins) or glycols (PG) (reference alkyd resins). These alkyd resins were blended with 30%, 40%, and 50% of a commercial urea-formaldehyde, melamine-formaldehyde and urea-formaldehyde/melamine-formaldehyde mixture (1/1 weight ratio) and heated at 140 degrees C. The physical and chemical properties such as drying time, hardness, abrasion resistance, adhesion strength, water resistance, alkaline resistance, acid resistance, gelation time, and thermal oxidative degradation resistance (with thermogravimetric analysis, TGA) of these alkyd-amino resins were investigated. The properties of the waste PET-based resins were found to be compatible with the properties of the reference resins.     

Glass-ceramics obtained by the recycling of end of life cathode ray tubes glasses

This work is concerned with open-loop recycling of end of life Cathode Ray Tubes glass (an unsolved problem when considering that in Europe almost 90% of EOL electronic goods is disposed of in landfills), focusing on the development of glass-ceramics from panel or funnel glass with dolomite and alumina, and the evaluation of the tendency towards crystallisation with particular attention on composition and thermal treatment. Glasses were melted at a temperature of about 1500 degrees C and transformed into glass-ceramics by different thermal treatments (900 degrees C to approximately 1100 degrees C temperature range and 0.5 to approximately 8h soaking time). By using the evaluation of thermal, mineralogical and microstructural data it has been pointed out that a good degree of crystallisation is reached at about 1000 degrees C and with a high proportion of waste glass (50-75%) if 40-45% of CaO and MgO bearer (dolomite) is introduced. In this way alkaline and alkaline-earth silicate and aluminosilicate mainly develop probably with a surface mechanism.     

土壤残留塑料的热降解脱附研究

针对土壤的塑料污染问题,提出一种采用热脱附降解技术修复污染土壤的方法.选取4种土壤中常见的残留塑料(聚乙烯(PE)、聚氯乙烯(PVC)、聚对苯二甲酸乙二酯(PET)、聚丙烯(PP))为研究对象,通过控制热解温度和土壤含水率对各污染土壤的修复效果进行探究.实验结果表明:在500℃的最佳热解温度下处理60 min,PE、P...