Catalysts based on foam materials for neutralization of waste gases

Catalysts of new structural type – foam metals – have been tested in the process of complete oxidation of aromatic compounds and neutralization of gas emissions of furnaces for wire enameling. Foam catalysts have better hydrodynamic and mechanical characteristics as compared with commercial catalysts, high catalytic activity and life time in the processes of neutralization of waste gases exceeding the indices of the traditional granular and honeycomb catalysts.     

Triboelectrostatic separation of pvc materials from mixed plastics for waste plastic recycling

This study covers the triboelectrostatic separation of Polyvinylchloride (PVC) materials from mixed plastics such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and polystyrene (PS). The PVC material generates hazardous hydrogen chloride gas resulting from the combustion in the incinerators. The laboratory scale triboelectrostatic separation system consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. Negative and positive surface charges can be imparted to the PVC and PET particles, respectively, due to the difference of triboelectric charging series between the particles in the fluidized-bed tribocharger. They can be separated by passing through an external electric field. A highly concentrated PVC (91.9%) can be recovered with a yield of about 96.1% from the mixture of PVC and PET materials in a single stage of processing. For the removal of PVC from the two-component mixed plastics such as PVC/PET, PVC/PP, PVC/PE or PVC/PS, separation results show the recovery of 96–99% with the pure extract content in excess of 90%. The triboelectrostatic separation system using the fluidized-bed tribocharger shows the potential to be an effective method for removing PVC from mixed plastics for waste plastic recycling.     

Production of alumino-borosilicate foamed glass body from waste LCD glass

A foaming process for waste LCD glass is presented, in which waste LCD glass is recycled to produce alumino-borosilicate foamed glass, which can eventually be used as a heat-insulating material, a light-weight aggregate for civil engineering applications, or a carrier for sewage treatment. The effects on waste LCD glass foaming of a variety of carbon foaming agents, metal salt foaming agents, and bonding agents are examined, as well as other factors such as chemical composition, foaming temperature, and grain size of the raw materials from the waste LCD glass. After examining all the variables that influence the foaming process, it was confirmed that the waste LCD glass is suitable as a raw material for producing alumino-borosilicate foamed glass. The alumino-borosilicate foamed glass has excellent physical properties, with density less than 0.14 g/cm³, heat conductivity less than 0.054 W/(mK) @20 °C, bending strength more than 35 N/cm², compressive strength more than 39 N/cm² and a coefficient of linear thermal expansion less than 4.5 × 10^?6 m/m °C. This clearly shows that the lightweight alumino-borosilicate foamed glass could be useful for various applications.     

The pozzolanic activity of a calcined waste FCC catalyst and its effect on the compressive strength of cementitious materials

Equilibrium catalyst (Ecat), one of the spent fluid catalytic cracking (FCC) catalysts from oil companies, shows pozzolanic activity. In this study, the effects on the pozzolanic activity of calcination of Ecat and on the compressive strength of the resulting cementitious materials were examined. The pozzolanic activity of this mineral additive was indicated from DSC measurements. The results show that the pozzolanic activity of Ecat increases with calcined temperature initially, reaches a maximum, and then decreases afterwards. Ecat calcined at about 650 °C becomes the most active. Mortars with 10% calcined catalyst at 3-28 curing days exhibit strength 8-18% greater than that with the untreated. Concrete with a 10% calcined Ecat at 3-28 curing days exhibits strength 7-11% greater than that with the untreated. If the calcined catalyst is further ground, its pozzolanic activity is enhanced, and the compressive strength of the resulting mortars or concrete becomes higher.     

Decomposition characteristics of residue from the pyrolysis of polystyrene waste in a fluidized-bed reactor

Effective treatment of residue generated from the pyrolysis of polystyrene wastes has been one of the important factors in the recovery of styrene monomer and oil from polystyrene wastes. Depending on the experimental conditions, the yields of oil and styrene monomer are considerably decreased in the presence of residue. Here the residue was decomposed effectively in a catalytic fluidized-bed reactor. Nitrogen and silica sand were used as a fluidizing gas and a bed material, respectively. Effects of catalyst, temperature and gas velocity on the characteristics of decomposition of the residue were examined. It was found that the residue could be decomposed to oil or chemicals effectively by means of a catalytic fluidized-bed reacting system. The yields of oil and individual chemicals and the composition of the products were dependent upon the operating variables such as reaction temperature, catalyst and gas velocity.     

Neutralizing capacity of bottom ash from municipal solid waste incineration of different particle size

This study measures the neutralizing capacity of bottom ash from municipal solid waste incineration of different particle sizes. We examine the effect of particle size on the weathering process, a method popularly used for stabilization of heavy metals in incineration of bottom ash. The distribution of particle sizes in municipal solid waste incineration bottom ash is rather broad, ranging from fine powder to as large as 40 mm in diameter. Although considered a by-product highly suitable as a road construction material, the high level of heavy metal leaching is an obstacle to its reuse. Weathering, a method used to reduce heavy metal leaching, is a lengthy process taking over thee months to complete. The chief reaction involved in weathering is carbonation occurring between Ca(OH)2 in bottom ash and CO₂(g) in the atmosphere. During this process, CaCO₃ is produced, causing the pH level to drop from over 12 to about 8.2 and reducing heavy metal leaching. In this paper, we attempt to determine the particle size best suited for reducing the period required for weathering bottom ash by identifying characteristics of different particle sizes that affect heavy metal leaching and neutralization.     

Recycling of inorganic waste in monolithic and cellular glass‐based materials for structural and functional applications

The stabilization of inorganic waste of various nature and origin, in glasses, has been a key strategy for environmental protection for the last decades. When properly formulated, glasses may retain many inorganic contaminants permanently, but it must be acknowledged that some criticism remains, mainly concerning costs and energy use. As a consequence, the sustainability of vitrification largely relies on the conversion of waste glasses into new, usable and marketable glass‐based materials, in the form of monolithic and cellular glass‐ceramics. The effective conversion in turn depends on the simultaneous control of both starting materials and manufacturing processes. While silica‐rich waste favours the obtainment of glass, iron‐rich wastes affect the functionalities, influencing the porosity in cellular glass‐based materials as well as catalytic, magnetic, optical and electrical properties. Engineered formulations may lead to important reductions of processing times and temperatures, in the transformation of waste‐derived glasses into glass‐ceramics, or even bring interesting shortcuts. Direct sintering of wastes, combined with recycled glasses, as an example, has been proven as a valid low‐cost alternative for glass‐ceramic manufacturing, for wastes with limited hazardousness. The present paper is aimed at providing an up‐to‐date overview of the correlation between formulations, manufacturing technologies and properties of most recent waste‐derived, glass‐based materials. © 2016 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Preparation of zeolitic adsorbents from waste coal fly ash

Power plants burning coal generate a large amount of fly ash as waste matter. The objective of this study is to produce zeolitic adsorbents that possesses high adsorptive capacity for toxic cations. The sample was first pretreated with a High Intensity Magnetic Separator for the removal of iron and magnetic materials (mainly Fe₂O₃ and TiO₂). The zeolitic adsorbents were prepared under the various conditions of NaOH concentration (1–5 N), reaction time from 3 to 96 hours and at the various temperatures of 60, 80 and 100°C. The results of the experiment showed that the coal fly ash should be synthesized with 4 N NaOH for 48 hours at 100°C in order to have good adsorptive capacity. The zeolitic adsorbents showed higher cation exchange capacity values than the natural zeolite in removing NH ₄ ⁺ , Pb²⁺, Ca²⁺and Cd²⁺ions.     

钯/活性炭催化剂中贵金属钯的回收

研究了废钯/活性炭催化剂中金属钯的回收。将废钯/活性炭催化剂用高温焙烧的方法除去其中大部分炭,钯渣用甲酸还原后用王水浸出。考察了焙烧、还原及浸出条件对钯回收率的影响,得到的氯化钯回收率95%,纯度99%。     

Solid oxide derived from waste shells of Turbonilla striatula as a renewable catalyst for biodiesel production

Biodiesel production via transesterification of mustard oil with methanol using solid oxide catalyst derived from waste shell of Turbonilla striatula was investigated. The shells were calcined at different temperatures for 4 h and catalyst characterizations were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) and Brunauer-Emmett-Teller (BET) surface area measurements . Formation of solid oxide i.e. CaO was confirmed at calcination temperature of 800 °C. The effect of the molar ratio of methanol to oil, the reaction temperature, catalyst calcination temperature and catalyst amount used for transesterification were studied to optimize the reaction conditions. Biodiesel yield of 93.3% was achieved when transesterification was carried out at 65 ± 5 °C by employing 3.0 wt.% catalyst and 9:1 methanol to oil molar ratio. BET surface area indicated that the shells calcined in the temperature range of 700 °C-900 °C exhibited enhanced surface area and higher pore volume than the shells calcined at 600 °C. Reusability of the catalysts prepared in different temperatures was also investigated.     

金属卟啉类仿生催化剂的合成、构效关系及在催化氧化碳氢化合物中的应用

综述了金属卟啉类仿生催化剂的理论基础、合成、构效关系及其在仿生催化氧化烃类绿色合成有机中间体和产品方面的研究进展。重点报道了该课题组和郭灿城课题组近年来在金属卟啉类仿生催化剂的分子设计、合成方法、构效关系及其在催化空(氧)气选择氧化各种芳烃侧链、环烷烃绿色合成芳醛、芳酸、环己酮、己二酸等重要有机中间体及精细化学品方面的研究成果,特别是由湖南大学郭灿城教授与中石化联合开发的完全拥有我国知识产权的仿生催化空气氧化环己烷(80～140℃,0.5～0.8MPa下反应2h)制取环己醇及环己酮的新技术,已于2003年首次成功地实现了产业化,其中,环己烷的转化率可达8%～10%,环己醇及环己酮的选择性可达90%。最后,对仿生催化技术的发展方向及应用前景进行了展望。引用文献57篇。     

Activated Carbon from Renewable Material as an Efficient Support for Palladium Oxidation Catalysts

Activated carbon prepared from cocoa pod husk, which is an abundant agricultural waste, was employed as a green support for palladium oxidation catalysts. Systematic characterization of the support and palladium catalysts by atomic emission spectroscopy, N₂ and CO₂ physisorption measurements, X‐ray powder diffraction, infrared spectroscopy, electron microscopy, temperature‐programmed reduction by hydrogen, and temperature‐programmed desorption of NH₃ and CO₂ allowed detailed monitoring of their characteristics. Subsequently, the catalytic performance and selectivity in the oxidation of ethanol as a model volatile organic compound (VOC) was studied and linked to physicochemical properties of the catalysts.     

Microporous and mesoporous materials with isolated vanadium species as selective catalysts in the gas phase oxidation reactions

The preparation of V-containing micro- and mesoporous (silicates, aluminosilicates and aluminophosphates) materials as well as the nature of V species incorporated in framework positions is reviewed. In addition, the catalytic performance of V-silicalite, VAPO-5 and V-MCM-41 in the gas phase selective oxidation of hydrocarbons has also been compared.     

A comparative study of liquid product on non-catalytic and catalytic degradation of waste plastics using spent FCC catalyst

Non-catalytic and catalytic degradation of waste plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS)) using spent fluid catalytic cracking (FCC) catalyst into liquid product were comparatively studied with a stirred semi-batch reactor at 400 ‡C, under nitrogen stream. Liquid product characteristics were described by cumulative distribution as a function of lapse time of reaction, paraffin, olefin, naphthene and aromatic (PONA) composition, and also carbon number distribution on plastic type of reactant. For degradation of waste PE with relatively high degradation temperature, the effect of adding spent FCC catalyst greatly appeared on cumulative distribution of liquid product with a reaction lapse time, whereas those for waste PP and PS with low degradation temperature showed a similar trend in both non-catalytic and catalytic degradation at 400 ‡C. In PONA and carbon number distribution of liquid product, the characteristics of waste PS that was mainly degraded by end chain scission mechanism were not much altered in presence of spent FCC catalyst. However, waste polyolefinic polymer that was degraded by a random chain scission mechanism significantly differed on PONA and carbon number distribution of liquid product with or without spent FCC catalyst. The addition of spent FCC catalyst in degradation of polyolefinic polymer, which economically has a benefit in utilization of waste catalyst, significantly improved the light olefin product by its high cracking ability and also the aromatic product by cyclization of olefin as shape selectivity in micropore of catalyst.     

Novel efficient procedure for biodiesel synthesis from waste oils with high acid value using 1-sulfobutyl-3-methylimidazolium hydrosulfate ionic liquid as the catalyst

Preparation of biodiesel from waste oils containing 72％ of free fatty acids catalyzed by a novel Brφnsted addic ionicliquid 1-sulfobutyl-3-methylimidazolium hydrosulfate ([BHSO3MIM][HSO4]) was systematically investigated.Theoptimum molar ratio of methanol to waste oils,catalyst amount,reaction temperature and reaction time were 8/1,10％ (based on the mass of waste oils),140 ℃ and 6 h,respectively,under which the obtained yield of biodieselreached 94.9％.Also,[BHSO3MIM][HSO4] as a catalyst still retained around 97％ of its original catalytic activityafter successive re-use of 5 batches (6 h per batch),showing the excellent operational stability.Moreover,the acid-ic IL [BHSO3MIM][HSO4] was able to efficiently catalyze conversions of waste oils with different amounts of FFAs(free fatty acids) into biodiesel,and showed tremendous application potential.Therefore,an efficient and environ-mentally friendly catalyst is provided for the synthesis of biodiesel from waste oils with high acid value.     

A novel foam glass obtained from solid waste: A sustainable strategy for application in the degradation of an environmental pollutant

Foams glass were obtained from solid waste of flat glass and exhausted alkaline batteries. The physical, chemical, crystalline and morphological properties of the samples were obtained using the Archimedes principle, X-ray diffractometry (XRD), scanning electron microscopy (SEM). The results revealed glass foams with apparent porosities in the range of 55–64% and apparent densities in the range of 0.40–0.79 g cm^?3. The manganese oxide and graphite contained within the cathode of alkaline batteries acted as both oxidizing agents and as foaming agents. The zinc contained in the anode acted as a pore stabilizing agent and the zinc oxide as a semiconductor material. The foam glass that was composed of flat glass with an anode of Zn and ZnO, and a cathode of Mn₂O₃ and Mn₃O₄ (named An8), showed the greatest potential for heterogeneous photocatalysis, with a maximum efficiency of 95.9% after 3 h of treatment of solution containing dye. These results suggest the feasibility of producing foam glass from waste, as well as its potential application in photocatalytic systems, such as in the low-cost treatment of water.     

Production of biodiesel from waste fryer grease using mixed methanol/ethanol system

Transesterification of waste fryer grease (WFG) containing 5–6 wt.% free fatty acid (FFA) was carried out with methanol, ethanol, and mixtures of methanol/ethanol maintaining the oil to alcohol molar ratio of 1:6, and initially with KOH as a catalyst. Mixtures of methanol and ethanol were used for transesterification in order to use the better solvent property of ethanol and rapid equilibrium using methanol. Formation of soap by reaction of FFA present in WFG with KOH instigated difficulty in the separation of glycerol from biodiesel ester. To untangle this problem, two-stage (acid and alkali catalyzed) method was used for biodiesel synthesis. More than 90% ester was obtained when two-stage method was used compared to ∼ 50% ester in single stage alkaline catalyst. In the case of mixed alcohol, a relatively smaller amount of ethyl esters was formed along with methyl esters. Acid value, viscosity, and cetane number of all the esters prepared from WFG were within the range of the ASTM standard. Esters obtained from WFG showed good performance as a lubricity additive.     

The harnessing of the waste arising from Y-TZP dental ceramics manufactured by CAD/CAM to be used as alternative dental materials

A large amount of yttria-stabilized zirconia (Y-TZP) waste is produced during the manufacture of dental prostheses by the CAD/CAM milling process. This work investigated the recycling and processing of zirconia waste powder (ZWP), generated from the manufacture of dental prostheses (CAD/CAM milling process). The physical and mechanical characteristics of the bodies produced with ZWP were evaluated. The received ZWP was calcined at 500 °C and de-agglomerated with a roll jar mill under different experimental conditions. The grinding condition with a relation between grinding medium mass (GM) and ZWP mass of 13 and a milling time of 90 min presented the best results. This procedure produced ZWP with the smallest mean particle size (0.4 μm) and the lowest tetragonal-monoclinic transformation (16.9%). The water absorption, apparent porosity, bulk density, and mechanical properties were evaluated from ZWP non-deagglomerated and ZWP de-agglomerated after sintering at 1300 °C, 1400 °C, and 1500 °C. ZWP de-agglomerated samples reached bulk density, microhardness, and flexural strength values of 5.8 ± 0.1 g/cm³, 1523 ± 173 HV, and 342.8 ± 66.7 MPa, respectively. The achieved values of bulk density and microhardness were similar to those of commercial ZrO₂ bodies processed under the same conditions, 6.0 ± 0.1 g/cm³ and 1412 ± 70 HV, respectively. But flexural strength of ZWP bodies was lower than that of commercial ZrO₂, 680.5 ± 96.0 MPa. However, the achieved strength is higher than that observed for porcelain and glass-ceramic dental materials used for single-unit anterior or posterior prostheses (<200 MPa), which depicts the ZWP potential as an alternative low-cost and high-strength material in ceramic prostheses.     

Three-liquid-phase salting-out extraction of effective components from waste liquor of processing sea cucumber

A three-liquid-phase (TLP) salting-out extraction system composed of n-hexane/ethanol/sodium carbonate/water was investigated to extract oils, saponins, proteins and polysaccharides simultaneously from waste liquor of processing sea cucumber. The effects of the ratio of ethanol to sodium carbonate, n-hexane concentration and extraction time were investigated. The results showed that 86.7% of oils were distributed in the top n-hexane phase, 82.9% of saponins in the middle ethanol phase, 93.2% of proteins and 92.9% of polysaccharides in the interface between the middle and the bottom salt phase when the system composed of 28% (w/w) n-hexane/11.52% (w/w) ethanol/8.64% (w/w) sodium carbonate was used at 37 °C for 0.5 h. When the system was progressively enlarged from 30 g to 25 kg, the yield of polysaccharides, proteins, oils and saponins was decreased only by 1.0%, 2.8%, 1.0% and 2.6%, respectively. The recycle of salt and solvents in three-liquid-phase system was also studied, and the results showed that the recovery of n-hexane, ethanol and salt were 81.4%, 80.8% and 72.0%, respectively. Recycling materials for the extraction, the yield for proteins and oils decreased by 2.0% and 5.4%, respectively, comparing with the pure system.     

Metal recovery by aged beads prepared using cell-suspension from the waste of beer fermentation broth

Lead, copper, and cadmium were adsorbed onto aged calcium alginate beads containing cell-suspension from the waste of beer fermentation broth. Beads prepared by adding 0.6% (w/v) sodium alginate into the cell suspension from the waste of beer fermentation broth and making the cell suspension drop into the 1% (w/v) calcium alginate solution were stored in the 1% (w/v) calcium chloride solution for 1 year. The specific metal uptake of the aged cell-suspension immobilized bead was 312 mg Pb²⁺, 158 mg Cu²⁺, and 112 mg Cd²⁺/g bead dry weight at pH 7.5 of the metal solution, respectively. The relation between the specific metal uptake by the aged cell-suspension immobilized beads and the equilibrium metal concentration was nonlinearly regressed and well described by the Freundlich isotherm. The specific cadmium uptake capacity of aged cell-suspension immobilized beads was between the specific cadmium uptake capacities of commercial beads Duolite GT-73 and Amberite IRA-400 and higher than those of the fresh Saccharomyces cerevisiae ATCC 834 and Saccharomyces cerevisiae ATCC 24858 immobilized beads.