Search

This work evaluated the effects of condensable syngas impurities on the cell viability and product distribution of Butyribacterium methylotrophicum in syngas fermentation. The condensates were collected during the gasification of two technical lignins derived from wheat straw (WST) and softwood (SW) at different temperatures and in the presence or absence of catalysts. The cleanest syngas with 169 and 3020 ppmv of H2S and NH3, respectively, was obtained at 800 °C using dolomite as catalyst. Pyridines were the prevalent compounds in most condensates and the highest variety of aromatics with cyanide substituents were originated during WST lignin gasification at 800 °C without catalyst. In contrast with SW lignin-based condensates, the fermentation media supplemented with WST lignin-derived condensates at 1:100 vol. only supported residual growth of B. methylotrophicum. By decreasing the condensate concentration in the medium, growth inhibition ceased and a trend toward butyrate production over acetate was observed. The highest butyrate-to-acetate ratio of 1.3 was obtained by supplementing the fermentation media at 1:1000 vol. with the condensate derived from the WST lignin, which was gasified at 800 °C in the presence of olivine. B. methylotrophicum was able to adapt and resist the impurities of the crude syngas and altered its metabolism to produce additional butyrate. [ABSTRACT FROM AUTHOR] more...

This study evaluates the application of biomass produced from the treatment of domestic sewage in high-rate ponds (HRPs) as feedstock for the production of bio-oil via hydrothermal liquefaction (HTL). The effects of reaction time, temperature, and biomass/water ratio on the yield of bio-oil were assessed. In addition, a balance of carbon and nitrogen among the products (bio-oil, aqueous phase, solid residue, and gas) was carried out, in order to evaluate the quality of the bio-oil and possibilities for increasing value from the byproducts. In a 15-min operation at 300 °C with biomass/water ratio of 1/10 (w.w −1 ), the bio-oil yield was of 44.4% (Dry Ash Free - daf-basis). Under every condition tested, the solid residue was the most abundant byproduct, mostly due to the high ash content in the biomass. The minimum nitrogen recovery in the bio-oil was 57%, obtained in the operation at 275 °C, which is considered the main disadvantage of the process. The use of biomass directly after its production may result in an excessive consumption of energy due to the high water content. However, the need for drying is reduced when compared to other microalgal-based bioenergy production processes, potentially achieving a positive energy balance in the HTL. [ABSTRACT FROM AUTHOR] more...

Eucalyptus globulus stumps has been used as biofuel for energy production. However, forest biomass presents some disadvantages (high moisture, volatiles and oxygen contents, hydrophilic nature, low calorific value, bulk density and energy density). To overcome this, torrefaction and pelletisation were tested. Based on the assays, 250 °C and 30 min were selected as the best conditions for the torrefaction. The summative chemical analysis has shown that torrefied stumps presented higher total extractives and lignin content and lower monosaccharides in relation to raw stumps. Eucalyptus stumps were also densified to produce pellets of raw and torrefied material. The materials obtained by the different pre-treatments studied were gasified in a fluidised bed reactor. Gasification gas obtained with raw stumps was compared to those obtained with pre-treated stumps by pelletisation (or densification), torrefaction and torrefaction followed by pelletisation. The results obtained showed that bio-syngas was improved when torrefied biomass was used, as there was an increase in gas yield and CGE (Cold Gas Efficiency) and lower tar were produced. The best pre-treatment for eucalyptus stumps was densification after torrefaction, as at 850 °C, gas yield was about 1.22 Nl/g daf and CGE was around 65%. This syngas contained around 38% of H 2 , 27% of both CO and CO 2 and 5% of CH 4 . [ABSTRACT FROM AUTHOR] more...

Rice production generates different types of wastes, rice husk and straw and plastics, mainly polyethylene (PE) used in bags for rice packaging and for seeds and fertilizers transport. Due to their contamination they are not suitable for physical recycling and end-up in landfills. Biomass rice wastes may have some utilisations, but each of them has drawbacks. This paper studies the possibility of using fluidised bed co-gasification of all these wastes for their energetic valorisation. Gasification gas composition and heating value is affected by the gasification and fluidisation agent. Mixtures of air, oxygen, steam and CO 2 with different compositions of two or more components were tested. Besides the high cost of producing oxygen, the results obtained showed that the best technical option was the use of steam and oxygen, because the gas was not diluted in nitrogen and thus gas HHV (higher heating value) on dry basis increased around 42%. However, the use of enriched air with up to 40% (v/v) of oxygen may be an alternative, due to the lower cost of producing this gas and also because better results were obtained than those for air-blown gasification. The use of CO 2 as gasification and fluidisation agent may be a good route, as the results obtained showed that CO 2 reforming reactions were promoted. The increase of CO 2 content in gasification agent led to a decrease of 45% in tar content, which was followed by a great increase in gas yield, around 70%. The main drawback of using steam and CO 2 is the need to supply the energy for the endothermic reactions, hence a good option could be the use of mixtures of CO 2 , O 2 and steam as gasification agent. [ABSTRACT FROM AUTHOR] more...

The aim of this work was the valorisation of rice crop wastes mixtures by pyrolysis to produce liquids to be used as bio-fuels or as raw bio-materials. The effect of waste mixtures composition on liquids yield and composition was studied. Rice husk (RH) and straw (RS) were pyrolysed with polyethylene (PE), the main plastic used in rice production process. Polypropylene (PP) and polystyrene (PS) were also studied, due to their presence in great amounts in solid wastes. The rise of rice husk amount in PE blends led to a decrease in the conversion of co-pyrolysis (pyrolysis of blends of biomass rice and plastic wastes) and to a reduction of liquid yields. Thus, the blend with 20% (w/w) of rice wastes was selected for further studies. No great changes were observed in the results when husk was replaced by straw, which is advantageous for the pyrolysis process. However, the same was not observed for the type of plastic waste. PS decreased total conversion and the formation of gases and liquids and increased aromatic compounds content in liquids. Some tests were done using hydrogen (hydropyrolysis) instead of nitrogen (pyrolysis) with the aim of improving liquids quality due to the presence of hydrogen in the reaction medium. Different pathways were analysed: (I) co-pyrolysis; (II) co-hydropyrolysis; (III) co-pyrolysis followed by hydropyrolysis and (IV) hydropyrolysis of co-pyrolysis liquids. Co-pyrolysis followed by hydropyrolysis was not favourable for further solids conversion and led to a great increase of gases. Co-hydropyrolysis led to the highest conversion, as both gas and total liquid yields increased. [ABSTRACT FROM AUTHOR] more...

Gasification of spent lignin pellets was used to obtain a gas suitable for energy production. Spent lignin was obtained from second-generation cellulosic ethanol demo plant using wheat straw as feedstock. Gasification of lignin did not give rise to any feeding problems, thus no significant changes were needed in the existing gasification installation. The rise of temperature and steam flow rate favoured the formation of H 2 , while hydrocarbons (C n H m ) and tar contents decreased. The increase of equivalent ratio (ER) also decreased hydrocarbons and tar contents, but syngas higher heating value (HHV) was reduced. The use of natural minerals improved lignin gasification. The presence of dolomite led to the highest H 2 and to the lowest C n H m and tar contents. Results obtained at bench-scale were confirmed at pilot-scale, as similar trends were obtained. However, as the residence time in pilot gasifier was higher, greater gas yields with higher H 2 and CH 4 concentrations were obtained, while tar contents decreased. After syngas hot cleaning and upgrading, the final syngas composition showed to be suitable for a wide range of applications (e.g. energy production and synthesis of chemicals), since it was substantially enriched in hydrogen, whereas tar and heavier gaseous hydrocarbons were completely destroyed. [ABSTRACT FROM AUTHOR] more...

Nowadays there is a great interest in producing energy through co-gasification of low grade coals and waste blends to increase the use of alternative feedstocks with low prices. The experimental results showed that the viability of co-gasification to process such blends and that by the right manipulation of coal and biomass or waste blends, syngas treatment and upgrading may be simplified and the cost of the overall process may be reduced. Blends of three different coal grades (sub-bituminous coal from Puertollano mines, South African bituminous coal and German brown coal) with two different types of biomass (pine and olive oil bagasse) or polyethylene (PE) were co-gasified. Blend co-gasification showed to be beneficial to reduce the negative characteristics of some coals, such as the high ash and sulphur contents, especially of Puertollano coal. Syngas obtained by these blends was hot cleaned and undesirable syngas components (tar, NH3 and H2S) were measured along the hot treatment tested, which proved to be suitable to treat syngas produced by a wide range of feedstocks. Different routes for syngas cleaning were analysed to reduce unsuitable components to values required by most common end-uses. The results obtained showed that the type of feedstock to be gasified is a key outcome on initial syngas composition, affecting greatly syngas cleaning needs, its application and the economic viability of the overall process. [ABSTRACT FROM AUTHOR] more...

Highlights: [•] Production of renewable liquid hydrocarbons through pomace oil hydrotreatment. [•] Hydrogenation at lower hydrogen pressure with catalysts commonly used in petrochemical industry. [•] Analysis of pyrolysis pre-treatment of pomace oil on the overall hydrotreatment process. [•] Comparison of the two-step process (pyrolysis+hydrotreatment) with single pyrolysis or hydrogenation. [•] Analysis of hydrogenated products applications as bio-chemicals. [Copyright &y& Elsevier] more...

The main objective of this work was to predict the influence of experimental conditions on product yields formed by waste mixtures pyrolysis, using response surface methodology (RSM). Accurate prediction of liquid yields at different experimental conditions and pyrolysis optimisation was achieved. The waste mixture studied contained 10% of pine, 10% of scrap tyres and 80% recycled plastic, whose main components were polyethylene (PE), polypropylene (PP) and polystyrene (PS). Experiment Factorial Design was used for the optimisation of reaction time, temperature and initial pressure to maximise the yield and composition of liquid products for the waste mixture studied. Experimental yields of liquids were fitted with a linear and second order model by the method of least squares with good correlation and high statistical significance. According to the model, the production of total pyrolysis liquids (including those obtained by solvent extraction) was maximised when the following conditions were used: reaction temperature of 350°C, reaction time of 30min and initial pressure of 0.2MPa, leading to liquid yield of 91.3% (w/w). The yield of only decanted liquids (not considering those obtained by solvent extraction) was maximised to the value of 54.9% at 426°C, 28min and 0.2MPa. The total liquid production at these conditions was 79.1%. The results obtained also showed that the approach used may be suitable for optimizing the experimental conditions that favour the formation of chosen gaseous and liquid compounds. [ABSTRACT FROM AUTHOR] more...

Abstract: The purpose of the present study was the analysis of possible routes for the pyrolysis reaction mechanism of rubber tyre wastes (RT). For this purpose, an evaluation was performed integrating both experimental data and different kinetic models. As none of the mechanisms found in literature allowed the numerical adjustment to the experimental data, new pathways were tested. Rubber tyre wastes kinetic studies were performed in order to evaluate possible direct conversions into new products (solids, liquids and gaseous), parallel reactions and/or reversible elementary steps. All experiments were carried out in a microautoclave system and based on the results obtained, at different temperatures and reactions times, kinetics models were evaluated and reactions pathways were established. Furthermore, products composition were analysed and according to the experimental data different reaction mechanisms were proposed. Afterwards, the kinetic data was compared with the experimental data. The proposed models were found to fit with the experimental data, which has allowed several explanations for the thermal degradation of rubber tyre waste to be proposed. Kinetics parameters were estimated, the dependence of activation energy and pre-exponential factor on temperature were evaluated. It was found that the rate constant of a number of reactions exhibited nonlinear temperature dependence on the logarithmic form of Arrhenius law, which strongly suggest that reaction temperature has an effect on reaction mechanism of rubber tyre wastes pyrolysis. [Copyright &y& Elsevier] more...

Abstract: Hydrogen separation from a syngas mixture with different compositions was studied by using a Pd–Ag membrane. The effect of temperature (from 300°C to 600°C) and of relative pressure (from 0.2MPa to 0.5MPa) was studied. In general, rises of both these parameters allowed increasing H2 permeate flux. The Pd–Ag membrane showed to have a great selectivity, as when inlet gas mixture contained different compositions of CO2, CO or CH4, these gases were never detected in membrane permeate side. However, when hydrogen content in inlet gas decreased, a significant reduction in H2 permeate flux was observed, especially when CO was present, probably due to the deposition of solid carbon in membrane surface by Boudouard reaction. It was also observed the formation of hydrocarbons, due to CO and H2 reactions. H2 permeances were calculated by application of Sieverts’ law and values between 4.9×10−4 and 1.5×10−3 molm−2 s−1 Pa−0.5 were obtained. The highest value was obtained at 600°C. H2 permeances at different temperature followed Arrhenius’ equation. Thus, activation energies values between 11.5kJmol−1 and 14.0kJmol−1 were calculated. [Copyright &y& Elsevier] more...

Abstract: It is predictable that in the near future fossil fuels will continue to have the greatest contribution to energy production. Thus, it is necessary to develop and improve technologies that ensure low CO2 emissions. Oxy-gasification is one of such technologies, as the use of oxygen instead of air will allow solving the problem of nitrogen dilution effect in syngas and consequently will simplify the process of CO2 capture. On the other hand, the use of oxygen will increase investment costs, as an oxygen production unit will have to be added to the overall installation, and operation costs will also rise, due to the extra energy necessary for oxygen production. Apart from this, it is important to check the performance of installations initially designed to operate with air, when retrofitted to use oxygen and to analyse the effect that this change may have on syngas composition. In this work the effect of gasification agent on syngas composition, including tar content was determined during co-gasification of two types of coals (German and Polish) mixed with several wastes, like pine, olive bagasse and polyethylene (PE). Air and steam or oxygen and steam mixtures were used as gasification agent, keeping constant ER (equivalent ratio), that is to say, for each coal and wastes blend the oxygen flow was the same for both gasification agents. However, when oxygen was used, gas flows fed into the gasifier were lower than those used in presence of air, which means that residence times were higher than when air was used. Therefore, syngas presented lower hydrocarbons contents and higher CO2 concentrations, probably because there was more time for reactions to occur in presence of oxygen. [Copyright &y& Elsevier] more...

Abstract: The release of H2S and NH3 into syngas during co-gasification of two coals (German and Polish) mixed with wastes (pine, olive bagasse and polyethylene) was studied. Sulphur and nitrogen contents in feedstock were found to have a great influence on H2S and NH3 concentrations in syngas, as the highest contents of these elements led to the highest releases. Air/steam or oxygen/steam mixtures were used in the gasification medium, keeping constant experimental conditions, including equivalent ratio. However, when air was added instead of oxygen, higher flow rates were used, due to the introduction of nitrogen and thus lower residence times were used. Different H2S and NH3 contents were obtained by changing the gasification medium. In presence of oxygen and steam higher H2S contents and lower NH3 concentrations were obtained than those produced in presence of air and steam. However, after syngas hot treatment in two fixed bed reactors, the first one with dolomite and the second one with a Ni-based catalyst (G-90 B 5) these differences lost significance. On the other hand, different final compositions of H2S and NH3 were obtained for different feedstocks. Those with highest sulphur and nitrogen contents led to the highest final H2S and NH3 contents in syngas. [Copyright &y& Elsevier] more...

Abstract: Syngas obtained by co-gasification of coal and wastes was hot cleaned in two catalytic reactors, which allowed destroying tar and gaseous hydrocarbons with more than one carbon atom. H2S and NH3 contents were also significantly reduced, but CH4 concentrations varying between 2% and 10% and small amounts of H2S (below 100ppmv) were still found in syngas, depending on coal type and waste composition. This paper studies the effect of experimental conditions on CH4 destruction by reforming reactions in absence and in presence of catalysts. The effect of experimental conditions (temperature, steam flow rate and syngas composition) on CH4 destruction and on CO conversion into CO2 in the absence of catalyst was studied first, using the Equilibrium Reactor model from CHEMKIN modelling software. The selected experimental conditions were then tested in a fixed bed reactor with and without catalyst and the results obtained were consistent with CHEMKIN Equilibrium Reactor model predictions. Commercial Ni-based catalysts were tested (G-90 B5 and G 56B from C&CS). These catalysts were capable of significantly reducing CH4 content, by promoting reforming reactions. At the experimental conditions used and in absence of steam, G 56B seems to be more effective in CH4 conversion, as lower CH4 contents were obtained. In presence of steam both catalysts were capable of completely destroying CH4. Both catalysts also promoted WGS (water gas shift) reaction to some extent, though they are not specific catalysts for this reaction. Thus, a high increase in H2 content was observed, due to its formation by both reforming and WGS reactions. For a complete conversion of CO into CO2 and H2 a specific catalyst for WGS reaction is still needed. [Copyright &y& Elsevier] more...

Abstract: Coal mixed with different types of wastes was co-gasified in a pilot-scale installation. The syngas produced was hot treated in two catalytic fixed-bed reactors. In the first one, dolomite was used and in the second reactor, a nickel-based catalyst was employed. Two different grade coals were tested, Puertollano and Colombian. Puertollano coal had high ash and sulphur contents, 42.5% and 2.4%, respectively, while ash and sulphur contents of Colombian coal were, respectively, 12.7% and 0.9%. Pine, bagasse, RDF and PE were the wastes mixed with both coals. After dolomite fixed-bed reactor, H2S and NH3 contents in syngas were much lower than those of the gas leaving the gasifier. For most coal and waste blends, NH3 reductions changed between 30% and 50% depending on feedstock nitrogen content, while H2S reductions achieved values from 68% to 74%, also depending on H2S concentration in syngas. After syngas had gone through the nickel-based catalyst, it presented H2S and NH3 contents that allowed its use in boilers and gas engines for most coal and waste blends. The overall syngas treatment led to H2S and NH3 reductions higher than 97%. For most experiments, final H2S and NH3 concentration in syngas were below 20ppmv and 30ppmv, respectively. [ABSTRACT FROM AUTHOR] more...

Abstract: Thermal degradation was studied as a method to decompose mixtures of rubber tyre (RT) and different plastic wastes (PE, PP and PS) with the aim of producing a liquid fuel , as well as valuable chemical raw materials. An experimental set of runs was performed to establish the operational conditions that maximize liquid fraction production in a 1 litre batch reactor. Waste blends used were composed of 30% w/w RT and 70% w/w plastics (20% PE, 30% PP and 20% w/w PS). The complex hydrocarbon liquid mixture obtained during pyrolysis of these residues was highly dependent on experimental parameters, namely temperature, initial pressure and reaction time, which are the three most important factors affecting liquid yields. Regression analyses of experimental data were performed according to response surface methodology (RSM). As a result, experimental conditions optimized based on Factorial Design Methodology were 370°C, 0.48MPa for initial pressure and 15min for reaction time. In order to validate the results obtained by the RSM model, three extra runs were conducted sequentially and average values were calculated and found to be: gas yield of 4.9% w/w, liquid yield of 81.3% w/w and solid yield of 12.7% w/w with an experimental deviation of 0.95%. [Copyright &y& Elsevier] more...

Abstract: Co-gasification of poor quality coals mixed with wastes has the advantage of diversifying energy resources and of decreasing the dependency on imported fossil fuels. However, the use of wastes like plastics increased the production of tar and gaseous hydrocarbons. Although, the correct adjustment of gasification experimental conditions, like temperature and air flow, may lead to some reduction of undesirable compounds, this procedure is not usually enough to accomplish effective reductions of tar and hydrocarbons, thus obliging to the use of further gas treatment. Co-gasification studies were undertaken in a pilot-scale installation. The syngas produced, after going through a cyclone to decrease particulates content, was further treated in two catalytic fixed bed reactors. In the first fixed bed reactor was used a low cost catalyst, like dolomite, to reduce H2S content in the gas and also to promote some tar destruction. In the second fixed bed reactor, Ni based catalysts were employed to achieve effective reduction of tar and other undesirable compounds. After the second fixed bed reactor, H2 content was much higher than that of the gas leaving the gasifier, values higher than 50% were obtained, while gaseous hydrocarbons contents were much lower, particularly C n H m contents were quite low, usually below the detection limit of the method used. The presence of tar was never detected after the second fixed bed reactor. [Copyright &y& Elsevier] more...

Abstract: This work aimed to study the recovery of three types of waste by the process of pyrolysis: biomass, plastics and used tyres. The effects of experimental conditions in products yield and composition were studied. The increase of reaction time increased alkane content both in gas phase from 53% to 70% v/v and in liquid fraction from 48% to 60% w/w. The rise of reaction temperature led to a decrease of liquid yield (from 82% to 73% w/w), which was followed by the increase of solids and gases. The increase of reaction temperature also allowed the increase of the alkane content in gas phase from 39% to 70% v/v. The parameter that most affected products yield and composition was plastics content on the wastes initial mixture. The enhancement of this parameter increased liquid yield from 33% to 92% w/w, at the expense of solids and gases contents and also decreased aromatic contents from 52% to 28% w/w. [Copyright &y& Elsevier] more...

Abstract: This paper analyses the formation of sulphur and halogens compounds during co-gasification of low grade coals with different types of wastes that include: pine, petcoke and polyethylene (PE) with the aim of taking profit of waste energy value with the smallest possible impact on the environment. The influence of different types of catalysts or sorbents was studied: calcined dolomite, dolomite enriched with nickel, olivine, nickel and magnesium oxides, zinc oxide and cobalt and molybdenum oxides. The presence of dolomite led to the lowest HCl, HF and H2S concentrations in the syngas produced. ZnO also gave rise to significant decrease in H2S concentration, though higher concentrations were obtained than those with dolomite. It was found that when catalysts or sorbents were used, a significant fraction of sulphur, halogens and heavy metals were trapped in the solid residue left behind in the bed and cyclone. Higher temperatures increased the volatility of some metals and sulphur. Leachability assays of solids showed that small quantities of and Cl− could be released and most metals were not leachable, although the use of dolomite slightly increased metals leachability, because of the higher alkaline nature of residual solids produced. [Copyright &y& Elsevier] more...

Abstract: The aim of this work is to analyse the possibility of using co-gasification technology to process coal mixed with wastes to take profit of its energy content and at the same time to minimize the environmental impact associated with the use of wastes and to diminish the costs of flue gas treatment. The addition to coal of different types of materials, like: pine based waste, petcoke and polyethylene (PE), was not found to give rise to any operational problems, regarding both the feeding system and gasification process and led to higher energy conversions, however, the gas presented higher tars and hydrocarbons content. Several catalysts were tested, such as, dolomite, olivine, nickel and magnesium oxides, zinc oxides and cobalt and molybdenum oxides. Catalyst action was analysed in tars release and also in ammonia compounds reduction. The presence of catalysts allowed increasing hydrogen release, whilst there was a decrease in hydrocarbons and tars contents. A nickel–magnesium oxide was the catalyst that led to the highest reduction in hydrocarbons and tars. This catalyst also led to the lowest NH3 content in the fuel gas produced, due to the catalyst efficiency in NH3 destruction. [Copyright &y& Elsevier] more...

Abstract: Co-gasification of bagasse wastes mixed with coal is technically feasible, without major installation changes. The effect of experimental conditions on co-gasification process was analysed, to enhance gas production and improve its composition and energetic content. The rise of bagasse content increased tars and gaseous hydrocarbons contents, which can be reduced by increasing gasification temperature and/or air flow rate. The rise of temperature till 890°C favoured hydrocarbons further reactions and allowed an increase of 45% in hydrogen release and a decrease in gaseous hydrocarbons of 55%. A reduction of around 30% in gaseous hydrocarbons was also achieved by rising O2/fuel ratio till 0.6g/g daf, which decreased gas heating value, due to nitrogen diluting effect. Though no significant changes in gaseous hydrocarbons composition were obtained, the presence of dolomite in the fluidised bed had the benefit of decreasing tars content and rising gas yield, being the gas richer in hydrogen content. [Copyright &y& Elsevier] more...

The effect of temperature and of gasification medium was studied, using only air, only steam and mixtures of both as gasification medium, with the aim of optimising co-gasification of coal and wastes. The rise in gasification temperature promoted hydrocarbons further reactions, leading to a decrease in tars and hydrocarbons contents and an increase in H2 release. Increasing temperature, from 750 to 890 °C, during gasification of a mixture with 60% (w/w) of coal, 20% of pine and 20% of PE wastes, led to a decrease in methane and other hydrocarbons concentration of about 30 and 63%, respectively, whilst hydrogen concentration increased around 70%. Hydrocarbons contents decrease was also achieved by increasing air flow rate, because partial combustion caused by oxygen decreased tars and gaseous hydrocarbons, with even a decrease in heating requirements. However, the presence of air is disadvantageous, because it decreases the higher heating value of the gasification gas, due to nitrogen diluting effect. The rise of steam flow rate has proven to be advantageous, because reforming reactions were favoured, thus hydrocarbons concentrations decreased and hydrogen release increased. [Copyright &y& Elsevier] more...

This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO2 activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. The study also examines the efficiency of leaching rare earth elements from NdFeB magnets using optimised acid leaching methods, providing insights into recovery processes. The adsorption capacity of the materials was assessed through batch adsorption assays targeting neodymium (Nd3⁺) and dysprosium (Dy3⁺) ions. Results highlight the superior performance of activated carbon derived from tyre rubber following CO2 activation, with the best-performing adsorbent achieving maximum uptake capacities of 24.7 mg·g⁻1 for Nd3⁺ and 34.4 mg·g⁻1 for Dy3⁺. Column studies revealed efficient adsorption of Nd3⁺ and Dy3⁺ from synthetic and real magnet leachates with a maximum uptake capacity of 1.36 mg·g⁻1 for Nd3⁺ in real leachates and breakthrough times of 25 min. Bi-component assays showed no adverse effects when both ions were present, supporting their potential for simultaneous recovery. Furthermore, the adsorbents effectively recovered rare earth elements from e-waste magnet leachates, demonstrating practical applicability. This research underscores the potential of tyre rubber-derived adsorbents to enhance sustainability in critical raw material supply chains. By repurposing waste tyre rubber, these materials offer a sustainable solution for rare earth recovery, addressing resource scarcity while aligning with circular economy principles by diverting waste from landfills and creating value-added products. [ABSTRACT FROM AUTHOR] more...

Hybrid bio-thermochemical based technologies have the potential to ensure greater feedstock flexibility for the production of bioenergy and bioproducts. This study focused on the bioconversion of syngas produced from low grade technical lignin to C2-/C4-carboxylic acids by Butyribacterium methylotrophicum. The effects of pH, medium supplementation and the use of crude syngas were analyzed. At pH 6.0, B. methylotrophicum consumed CO, CO2 and H2 simultaneously up to 87 mol% of carbon fixation, and the supplementation of the medium with acetate increased the production of butyrate by 6.3 times. In long-term bioreactor experiments, B. methylotrophicum produced 38.3 and 51.1 mM acetic acid and 0.7 and 2.0 mM butyric acid from synthetic and lignin syngas, respectively. Carbon fixation reached 83 and 88 mol%, respectively. The lignin syngas conversion rate decreased from 13.3 to 0.9 NmL/h throughout the assay. The appearance of a grayish pellet and cell aggregates after approximately 220 h was indicative of tar deposition. Nevertheless, the stressed cells remained metabolically active and maintained acetate and butyrate production from lignin syngas. The challenge that impurities represent in the bioconversion of crude syngas has a direct impact on syngas cleaning requirements and operation costs, supporting the pursuit for more robust and versatile acetogens. [ABSTRACT FROM AUTHOR] more...

Coal and waste direct liquefaction was carried out to decrease the hydrocarbons production negative bearing to environment. The wastes studied were glycerol, polyethylene waste and waste tyres pyrolysis oil. Glycerol and waste tyres pyrolysis oil were blended with tetralin and used as solvent for coal direct liquefaction (T = 350–450 °C; N 2 ; waste:tetralin at different weight ratios). Glycerol may be considered as a waste from the production of fatty acid methyl esters (FAME). Waste tyres pyrolysis oil showed to be a good hydrogen donor solvent. Solid polyethylene wastes were mixed with coal and used in coal co-liquefaction tests, which showed to be a good option to produce liquid hydrocarbons for fuels or raw materials for chemical industry. Although liquids yield using waste tyres pyrolysis oil or glycerol were high, respectively 62% wt. and 51% wt., the use of polyethylene allowed increasing them to 80% wt. Different experimental conditions were studied, namely: experimental temperature, run time, solvent type and composition and hydrogen initial pressure. The effect of commercial catalysts on co-liquefaction was also studied and the results obtained were compared with those obtained with coal impregnated with Fe or Mo (1% wt./coal). Response surface methodology (RSM) was used to predict the influence of the main experimental conditions studied on product yields. This methodology resulted to be a good one to predict coal liquefaction and co-liquefaction products yields, as predicted values were similar to experimental data. In addition, RSM approach led to the selection of tetralin as solvent and to the use of coal impregnated with 1% of Mo, as liquids yield increased up to 96% wt. • Coal liquefaction improvement by the use of glycerol, polyethylene and waste tyres pyrolysis oil. • Waste tyres pyrolysis oil showed to be a good H donor solvent. • Improvement of co-liquefaction by using impregnated coal with metals mixed with PE wastes. • Optimisation of liquids production by Response Surface Methodology (RSM). • The use of tetralin in co-liquefaction of PE wastes and coal impregnated with 1% of Mo led to liquids yield up to 96% wt. [ABSTRACT FROM AUTHOR] more...

Graphical abstract Highlights • First comparison between catalytic hydrothermal liquefaction of microalgae and sewage sludge (SS). • Tested catalysts always decreased O/C of biocrude. • CoMo and NiMo catalysts completely removed S from microalgae biocrude. • Among tested catalysts cheap activated carbon felt gave the highest H/C and lowest O/C with both biomasses. • Detected formation of a new product probably related to microplastics in SS. Abstract Production of biocrude through hydrothermal liquefaction (HTL) of sewage sludge (SS) and Chlorella vulgaris was investigated. NiMo/Al 2 O 3 (KF 851), CoMo/Al 2 O 3 (KF 1022) and activated carbon felt, tested as catalysts at 598 K for 30 min, did not change the biocrude yield but significantly improved its quality. Quantitative sulfur removal and lower oxygen content were found in biocrude when KF 851 and KF 1022 were used with C. vulgaris. The same catalysts decreased O/C and S/C ratio of the biocrude from SS. The highest HHV (38.19 MJ/kg) and H/C ratio (1.65) and the lowest O/C (0.11) of the biocrude from SS were obtained with the cheaper activated carbon felt. A new product phase, probably related to the presence of microplastics in the sludge, was found when SS were converted with catalysts. SS constitute a promising and costless alternative feedstock to microalgae for the HTL processes. [ABSTRACT FROM AUTHOR] more...

A methodology was developed to assess the allocation of different types of endogenous waste biomass to eight technologies for producing electricity, heat, biogas and advanced biofuels. It was based on the identification of key physicochemical parameters for each conversion process and the definition of limit values for each parameter, applied to two different matrices of waste biomass. This enabled the creation of one Admissibility Grid with target values per type of waste biomass and conversion technology, applicable to a decision process in the routing to energy production. The construction of the grid was based on the evaluation of 24 types of waste biomass, corresponding to 48 sets of samples tested, for which a detailed physicochemical characterization and an admissibility assessment were made. The samples were collected from Municipal Solid Waste treatment facilities, sewage sludges, agro-industrial companies, poultry farms, and pulp and paper industries. The conversion technologies and energy products considered were (trans)esterification to fatty acid methyl esters, anaerobic digestion to methane, fermentation to bioethanol, dark fermentation to biohydrogen, combustion to electricity and heat, gasification to syngas, and pyrolysis and hydrothermal liquefaction to bio-oils. The validation of the Admissibility Grid was based on the determination of conversion rates and product yields over 23 case studies that were selected according to the best combinations of waste biomass type versus technological solution and energy product. [ABSTRACT FROM AUTHOR] more...

Purpose: To determine intra- and inter-rater agreement of anterior lamina cribrosa depth (ALCD) manual measurements using enhanced-depth imaging optical coherence tomography (EDI-OCT). Methods: Observational study. EDIOCT of the optic nerve head was performed in healthy subjects. ALCD was defined as the perpendicular distance between the line connecting both edges of Bruch's membrane opening and the anterior border of the lamina cribrosa (LC), at the maximum depth point. Two experienced operators performed manual ALCD measurements of the LC independently, and one of the observers performed the same measurements twice. Intra- and inter-rater agreement was evaluated using intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC) for the right eye vertical (REV) and horizontal (REH) scans and left eye vertical (LEV) and horizontal (LEH) scans. Results: 120 eyes of 61 subjects, with a mean age of 62.1 ± 15.0 years. The mean REV, REH, LEV and LEH ALCD were 456.2 ± 84.3, 444.5 ± 92.2, 436.7 ± 81.6, 427.6 ± 82.7 µm, respectively. ALCD intra- and interrater ICC and intra- and inter-rater CCC varied between 0.85-0.95, 0.84-0.93, 0.85-0.95 and 0.84-0.93, respectively. Conclusions: ALCD manual intra- and inter-rater measurements with EDI-OCT showed high agreement. EDI-OCT is a reliable tool for ALCD measurement, which can provide potentially useful information for integrated glaucoma management. [ABSTRACT FROM AUTHOR] more...

Objective: To study the incidence, clinical presentation, risk factors, imaging diagnosis, and clinical outcome of perinatal stroke. Methods: Data was retrospectively collected from full-term newborns admitted to the neonatal unit of a level III maternity in Lisbon with cerebral stroke, from January 2007 to December 2011. Results: There were 11 cases of stroke: nine were arterial ischemic stroke and two were cerebral venous sinus thrombosis. We estimated an incidence of arterial ischemic stroke of 1.6/5,000 births and of cerebral venous sinus thrombosis of 7.2/100,000 births. There were two cases of recurrent stroke. Eight patients presented with symptoms while the remaining three were asymptomatic and incidentally diagnosed. The most frequently registered symptoms (8/11) were seizures; in that, generalized clonic (3/8) and focal clonic (5/8). Strokes were more commonly left-sided (9/11), and the most affected artery was the left middle cerebral artery (8/11). Transfontanelle ultrasound was positive in most of the patients (10/11), and stroke was confirmed by cerebral magnetic resonance in all patients. Electroencephalographic recordings were carried out in five patients and were abnormal in three (focal abnormalities n=2, burst-suppression pattern n=1). Eight patients had previously identified risk factors for neonatal stroke which included obstetric and neonatal causes. Ten patients were followed up at outpatients setting; four patients developed motor deficits and one presented with epilepsy. Conclusions: Although a modest and heterogeneous sample, this study emphasizes the need for a high level of suspicion when it comes to neonatal stroke, primarily in the presence of risk factors. The prevalence of neurological sequelae in our series supports the need of long-term follow-up and early intervention strategies. [ABSTRACT FROM AUTHOR] more...

Abstract: The study performed aimed at analysing possible routes for pyrolysis reaction mechanisms of polymeric materials namely RT (rubber tyre) and plastic wastes (PE (polyethylene), PP (polypropylene) and PS (polystyrene)). Consequently, and seeking sustainable transformation of waste streams into valuable chemicals and renewable liquid fuels, mixture of 30% RT, 20% PE, 30% PP and 20% PS was subjected to pyrolysis. Different kinetic models were studied using experimental data. None of the mechanisms found in literature led to a numerical adjustment and different pathways were investigated. Kinetic studies were performed aiming to evaluate direct conversions into new solid, liquid and gaseous products and if parallel reactions and/or reversible elementary steps should be included. Experiments were performed in batch system at different temperatures and reaction times. Kinetic models were evaluated and reaction pathways were proposed. Models reasonably fit experimental data, allow explaining wastes thermal degradation. Kinetic parameters were estimated for all temperatures and dependence of Ea and pre-exponential factor on temperature was evaluated. The rate constant of some reactions exhibited nonlinear temperature dependence on the logarithmic form of Arrhenius law. This fact strongly suggests that temperature has a significant effect on reaction mechanism of pyrolysis of mixtures of rubber tyre and plastic wastes. [Copyright &y& Elsevier] more...

Summary: The main objective of this paper is to carry out a techno‐economic evaluation for the direct coal liquefaction (DCL) process based on the two primary conversion options under consideration: (a) catalytic coal liquefaction (CCL) – the use of non‐donor solvents with added hydrogen pressure and (b) thermal coal liquefaction (TCL) – the use of solvents with some H‐donor properties without hydrogen pressure. For this purpose, steady‐state process models for the CCL and TCL are developed. The process modules addresses only the primary DCL process and do not include any upgrading to transport fuels as this will be conducted at refinery facilities. To better understand the process parameters and benefits of each option, detailed simulations have been conducted using the ECLIPSE modelling software. Technical results showed that daily oil yields (light and middle distillates) were around 1208 barrels from the CCL process and 924 barrels from the TCL process when the feed rate of brown coal was 256 t/d (on dry and ash free basis). Based on economic assumptions, the break‐even oil price would be €47.10/barrel with the CCL and €57.81/barrel with the TCL. [ABSTRACT FROM AUTHOR] more...

Summary: The main objective of this paper is to carry out a techno‐economic evaluation for the direct coal liquefaction (DCL) process based on the two primary conversion options under consideration: (a) catalytic coal liquefaction (CCL) – the use of non‐donor solvents with added hydrogen pressure and (b) thermal coal liquefaction (TCL) – the use of solvents with some H‐donor properties without hydrogen pressure. For this purpose, steady‐state process models for the CCL and TCL are developed. The process modules addresses only the primary DCL process and do not include any upgrading to transport fuels as this will be conducted at refinery facilities. To better understand the process parameters and benefits of each option, detailed simulations have been conducted using the ECLIPSE modelling software. Technical results showed that daily oil yields (light and middle distillates) were around 1208 barrels from the CCL process and 924 barrels from the TCL process when the feed rate of brown coal was 256 t/d (on dry and ash free basis). Based on economic assumptions, the break‐even oil price would be €47.10/barrel with the CCL and €57.81/barrel with the TCL. [ABSTRACT FROM AUTHOR] more...

Purpose: The purpose of the study was to evaluate the contribution of orbital biopsy for the management of patients with an orbital mass of unknown etiology using the Greenwich Grading System (GGS). Methods: This was a retrospective case series conducted at a tertiary hospital over a period of 10 years (2007-2017). Case records of all patients with an orbital mass were reviewed. All relevant data collected from the medical records electronic database were analyzed. The GGS was used to assess the contribution of orbital biopsy for the diagnosis, investigation, and treatment of each patient. Results: Ninety-two medical records were reviewed; 34 patients underwent orbital biopsy. The mean age was 53 ± 26 years and 58.7% were female. In the biopsied group, the most common histopathological diagnoses were lymphoma (44.1%), nonspecific orbital inflammation (14.4%), and squamous cell carcinoma (8.8%). After the biopsy, a new diagnosis was obtained in 41.2%, although in most patients (58.8%), the biopsy confirmed the suspected diagnosis. Regarding the therapeutic management, 32.4% started a new treatment, 29.4% did not change their treatment, 32.4% altered/stopped their treatment, and 5.9% allowed reassurance and explanation for the patients. Conclusions: Orbital biopsy was considered a valuable investigation for the management of patients with an orbital mass of unknown etiology. In most cases (58.8%), the result of the biopsy confirmed the suspected diagnosis, and in around 41.2%, a new diagnosis was made. Most of the patients (64.8%) changed their treatment or started a new one based on the histopathological result. [ABSTRACT FROM AUTHOR] more...

Abstract Direct coal liquefaction (DCL) seems to be a suitable way to convert low rank coals into liquid fuels, especially when problematic wastes are used together with this feedstock. It is also a solution to become energy independent for many countries which have significant coal resources and limited access to crude oil. The aim of this research was to investigate DCL process by the co-processing of brown coal with model-, petroleum- and waste-derived solvents. The brown coal with and without W, Fe and Mo metals supported on its surface was tested. Thirteen DCL tests with added hydrogen pressure were carried out in the autoclave. These tests were classified in two groups. First group covered reactions using model and petroleum-derived solvents (tetralin, 1-methylnaphthalene, light cycle oil (LCO), hydrotreated LCO, C9+ fraction and decalin) with non-impregnated brown coal. Then, LCO was chosen as solvent for carrying out three tests using the metals supported on coal. Finally, waste tires pyrolysis oil was used as a waste-derived solvent for other three tests with molybdenum supported on coal. For tests using LCO, the total amount of direct liquid and n-heptane soluble products was 20 wt% higher using metal covered brown coal in comparison to unmodified one. The test with the brown coal impregnated by 1% of molybdenum resulted in the best efficiency, thus this type of coal was chosen as a catalytic feedstock for the tests with waste tires pyrolysis oil. [ABSTRACT FROM AUTHOR] more...

Highlights: [•] Chars from the pyrolysis of mixtures composed by pine, plastics, and scrap tires. [•] Removal of Pb2+ from aqueous medium using chars. [•] Char from mixture of the three raw materials with worst Pb2+ removal performance. [•] Char from mixture composed by tires and plastics more efficient in Pb2+ adsorption. [•] Chemisorption with Ca2+, K+, and Zn2+ exchange on Pb2+ removal by tire derived char. [ABSTRACT FROM AUTHOR] more...

Abstract: This paper presents the study of the combustion of char residues produced during co-gasification of coal with pine with the aim of characterizing them for their potential use for energy. These residues are generally rich in carbon with the presence of other elements, with particular concern for heavy metals and pollutant precursors, depending on the original fuel used. The evaluation of environmental toxicity of the char residues was performed through application of different leaching tests (EN12457-2, US EPA-1311 TCLP and EA NEN 7371:2004). The results showed that the residues present quite low toxicity for some of pollutants. However, depending on the fuel used, possible presence of other pollutants may bring environmental risks. The utilization of these char residues for energy was in this study evaluated, by burning them as a first step pre-treatment prior to landfilling. The thermo-gravimetric analysis and ash fusibility studies revealed an adequate thermochemical behavior, without presenting any major operational risks. Fluidized bed combustion was applied to char residues. Above 700°C, very high carbon conversion ratios were obtained and it seemed that the thermal oxidation of char residues was easier than that of the coals. It was found that the char tendency for releasing SO2 during its oxidation was lower than for the parent coal, while for NO X emissions, the trend was observed to increase NO X formation. However, for both pollutants the same control techniques might be applied during char combustion, as for coal. Furthermore, the leachability of ashes resulting from the combustion of char residues appeared to be lower than those produced from direct coal combustion. [Copyright &y& Elsevier] more...

Pyrolysis chars derived from rice wastes were chemically activated and used in W(VI) oxyanion adsorption assays in synthetic and mining wastewaters. For comparison purposes, a commercial activated carbon (CAC) was also used. Different experimental conditions were tested in the adsorption assays: solid/liquid ratio (S/L), initial pH, contact time, and initial W concentration. The porous carbon P2C+KOH presented the overall best performance in both media, due to its high surface area (2610 m2 g−1), mesopore volume (1.14 cm3 g−1), and neutral pH pzc (6.92). In the synthetic wastewater, the highest uptake capacity of P2C+KOH (854 mg g−1) was found in the assays with an S/L 0.1 g L−1, an initial pH 2, and an initial W concentration of 150 mg L−1, for 24 h. This value was almost 8 times higher than the one obtained for CAC (113 mg g−1). In the mining wastewater, P2C+KOH showed an even higher uptake capacity (1561 mg g−1) in the assay with the same experimental conditions, which was almost 3 times higher than for CAC (561 mg g−1). These results suggest that P2C+KOH seems to be an efficient alternative to CAC in the W(VI) adsorption from liquid effluents. [Display omitted] • Porous carbons derived from rice wastes used in W(VI) adsorption assays. • Higher pH pzc , surface area and mesopore volume promoted the best adsorbents. • Best adsorption performances achieved in acidic aqueous solutions. • Uptake capacities up to 854 mg g−1 attained in a synthetic solution. • Uptake capacities up to 1561 mg g−1 achieved in a mining wastewater. [ABSTRACT FROM AUTHOR] more...

Chromium is one of the most important raw materials for the European Union. Adsorption has become an important process for the recovery of metals from wastewaters, which has led to a demand for low-cost and eco-friendly adsorbents. The objective of this work was to use new and renewable carbon-based adsorbents from rice wastes in the removal/recovery of Cr(III) from synthetic and real wastewaters. Rice wastes were submitted to co-pyrolysis and the resulting char was optimized through physical and/or chemical activations/treatments. A commercial activated carbon was used for comparison purposes. All adsorbents were characterized (including an ecotoxicity test for the char precursor) and submitted to Cr(III) removal assays from a synthetic solution, in which two solid/liquid ratios (S/L) were tested (5 and 10 g/L). The CO 2 activated carbon at a S/L = 5 g/L was the biomass-derived adsorbent that performed better, obtaining a maximum Cr(III) uptake capacity of 9.23 mg/g comparable to the one obtained by the commercial adsorbent at the same S/L (9.80 mg/g). The good results on this biomass-derived carbon were due to the effective volatile matter removal during the activation (from 22.7 to 4.25% w/w), which increased both surface area (from <5.0 to 325 m2/g) and ash content (from 30.0 to 40.4% w/w), allowing an increase in Cr(III) removal due to ion exchange mechanism and porosity development. The best adsorbent, under optimized conditions, was also applied to a chromium rich industrial wastewater. The results obtained in this real case application demonstrated a competition effect due to the presence of other ions. Image 1 • Pyrolysis rice waste char was optimized through different activations/treatments. • The activated carbons (AC) were characterized and used in Cr(III) removal assays. • Physical activation without washing originated the best pyrolysis AC (P1C+PA). • P1C+PA presented similar Cr(III) uptake capacities than a commercial AC. • P1C+PA performed better in an industrial wastewater than in a synthetic solution. [ABSTRACT FROM AUTHOR] more...