The search for a low cost and effective technique to control and remove volatile organic chemicals (VOCs) has gathered a great attention from the adsorption process field. Advances in manufacturing technology have enabled the creation of activated carbon monoliths (ACM) as promising substitute for traditional packed beds of granular adsorbent materials. The research described in this thesis comprises an extensive experimental study of a single component adsorption process onto square and hexagonal channel Novacarb™ ACM supplied by MAST Carbon Technology Ltd. ACM characterisation methods such as nitrogen and solvent adsorption isotherms, electron microscopy, thermo-gravimetric analysis and thermal dynamic characterization have been used. High BET surface area, high total pore volume and high total solvent mass uptakes have been found. ACM were tested by obtaining column breakthrough curves mainly using dichloromethane and acetone as the adsorbates at the bench-scale. The adsorption dynamics of the ACMs studied were also compared with those of extrudates manufactured by the same process as the ACMs. The influence of humidity on the adsorption process has been studied at the bench-scale. Finally, the adsorption system was scaled-up to about 60cm length monoliths in order to study both adsorption and electrical regeneration taking advantage of the particular electrical properties held by the Novacarb™ ACM. It has been found that ACMs are able to adsorb high levels of VOCs, up to 40% by weight of DCM, good behaviour under humidity conditions and low pressure drop. In contrast, kinetics of ACMs have been found to be somewhat inferior to those of equivalent packed beds, although the ACM performance can be improved by reducing the wall thickness. Adsorption of DCM at the pilot-scale has demonstrated that the Novacarb™ ACM could easily be used in a cyclic thermal swing adsorption process with a half cycle time of less than one hour.

No description available.

This thesis is concerned with the preparation of mixed silicon-titanium oxides (Ti02=4.1-21.9wt%) and silicon-zirconium oxides (Zr02=4.1-22.Iwt%) by the sol-gel route. Methods of preparing homogeneous Si02-TiO2 gels and SiO2-Zr02 gels have been explored. In this work bis(acetylacetonato)titanium diisopropoxide or bis(acetylacetonato)zirconium dipropoxide and tetraethyl orthosilicate (TEOS) have been hydrolysed simultaneously in iso-propanol to form homogeneous gels. Using these systems, the effects of the reaction conditions, amount of titania/zirconia present in the gel, drying conditions and thermal treatment of the dry gels on the bulk and structural properties have been investigated by a variety of experimental methods including X-ray diffraction, mid- and near-infrared spectroscopy and gas adsorption techniques. For SiO2-TiO2 powders and monoliths, and SiO2-ZrO3 monoliths, thermal treatment has been found to significantly reduce the surface area (from 750-1.0m2g-1), pore volume (from 0.56-0.001cm3g-1') and relative number of silanol groups on the surface of the sample above 700°C. Average pore diameters remain constant at temperatures below 900°C (ca 54-21Å for monoliths), although the micropore volume does decrease (0.04-0.0cm3g-1) suggesting that smaller pores are destroyed by the heating process. For SiO2-TiO2 powders, the average pore diameter was ca IOÅ larger than for the corresponding monolith suggesting that small pores are destroyed during powdering. At 1100°C, gas adsorption data indicate that the samples are fully densified. This is supported by NIR spectra which detect no silanol groups on the surface of the sample. Structural changes arising from compositional changes and differing thermal treatment regimes have been monitored using mid-infrared spectroscopy and X-ray diffraction. With increasing temperature the silica matrix strengthens and titanium/zirconium are incorporated into the matrix. Monolithic SiO2-TiO2 gels (Ti02=6.34 weight%) remained amorphous at 1100°C, whereas powders began to exhibit diffraction patterns predominantly from anatase at 700°C. Anatase crystallite sizes have been calculated using the Scherrer equation and have been found to be between 16.3 and 5.4nm. Monolithic SiO2-ZrO2 gels containing 4.1 and 4.9 weight% zirconia were found to be amorphous after treatment at 1100°C. Increasing the zirconia content to 6.4 and 22.1 weight% resulted in gels that were amorphous up to 900°C. Further treatment at 1100°C, resulted in tetragonal zirconia and some cristobalite being formed. Crystallite sizes have been calculated as being between 2.7 and 1.6nm for tetragonal zirconia and from 4.1 to 2.8nm for cristobalite. Increasing the levels of titania/zirconia in the sample resulted in higher relative levels of hydrogen-bonded silanol groups. On hydration, the increased levels of titania/zirconia resulted in no observable free silanol groups on the surface suggesting that the surface becomes more hydrophilic as the amount of titania/zirconia present in the sample increases. This suggests that water becomes more tightly bound to Ti-OH /Zr-OH groups on the surface and within the pores, resulting in fewer free silanol type groups. A double alkoxide bis(acetylacetonato)titanium di(triethoxysilane) [Ti(acac)2(OSi(OC2H5)3)2] has also been synthesised and characterised. Mixed Si02-TiO2 gels have also been prepared by the simultaneous hydrolysis of Ti(acac)2(OSi(OC2H5)3)2 and TEOS under acidic conditions in ethanol. The effects of reaction conditions and thermal treatment of the dry gels have been investigated. Increasing the treatment temperature of the samples resulted in the progressive decrease in surface area (533-3.0m2g-1), pore volume (0.18-0.003cm3g-1), micropore volume (0.06-0.00cm3g-1) and relative number of silanol groups on the surface. However, the average pore diameter remained constant at temperatures up to 700°C. Changes in pore volume (0.07-0.005cm3g-1), surface area (300-3.0m2g-1) and average pore diameter (26.9-91.9Å) were largest at 900°C, and the samples were found to be almost completely dense. This was confirmed by the absence of observable silanol groups by NIR spectroscopy. After heating at temperatures up to 900°C, the samples were found to be amorphous by XRD. However increasing the temperature to 1100°C resulted in the formation of some crystalline anatase. The anatase crystal sizes have been calculated as being from 16.3 to 10.8nm in diameter. NIR studies of silica-zirconia and silica-titania gels (prepared by both methods), indicate that decreasing the amount of acid used in the hydrolysis reaction resulted in higher relative levels of hydrogen bonded silanol species. Similarly, decreasing the amount of acid increased the micropore volume and decreased the mesoporosity of the resulting samples. Generally, decreasing the amount of acid used for the hydrolysis for silica-zirconia and silica-titania gels (prepared by both methods), results in a decrease in the overall surface area and pore volume of the resulting material. The resulting isotherms indicate that the samples became less mesoporous as the amount of acid used in the hydrolysis reaction decreased. This was accompanied by an increase in the micropore volume. For SiO2-TiO2 monoliths prepared from a double alkoxide and Si02-ZrO2 monoliths the resulting pore structure is more rigid and composed of smaller pores than that of SiO2-TiO2 powders and monoliths prepared from bis(acetylacetonato)titanium diisopropoxide.

L'objectif de ce travail est la synthèse et la fonctionnalisation de monolithes siliciques à porosité hiérarchique et leur utilisation en tant que microréacteur en catalyse sous flux. Une synthèse reproductible de monolithes siliciques a été mise à point. La fonctionnalisation avec une variété de fonctions a été réalisée, telle que la fonctionnalisation avec des groupements aminopropyle, avec de l'oxyde d'aluminium, par incorporation des MOFs (CuBTC) et par dépôt de nanoparticules de palladium. Les monolithes fonctionnalisés ont été testés en tant que microréacteurs catalytiques sous flux pour les réactions de Knoevenagel, de Diels-Alder et de Friedländer et montrent dans plusieurs cas une augmentation de la productivité des réactions par rapport aux réacteurs batch ou à lit fixe ainsi qu'une automatisation des procédés. La transformation pseudomorphique de monolithes siliciques en monolithes zéolithiques en phase SOD et LTA a été mise a point. Nous avons ainsi montré la première utilisation d'un monolithe macroporeux à base de zéolithes en tant que microréacteur pour la synthèse de produits de chimie fine en continu. Les monolithes zéolithiques ont aussi été analysés pour l'échange d'ions en dynamique et sont prometteurs pour une application en tant que matériaux pour la décontamination d'effluents radioactifs. / The aim of this work is the synthesis and the functionalization of silica monoliths with hierarchical porosity and their use as catalytic microreactors for flow-through chemistry. A reproducible synthesis of the silica monoliths was elaborated. The functionalization with a variety of functions has been performed, such as aminopropyl groups, aluminium oxide, MOFs (CuBTC), and palladium nanoparticles. These functionalized silica monoliths have been used for the Knoevenagel condensation, Diels-Alder reaction and Fiedländer reaction, where they show increasing productivities compared to classically used reactors (batch, packed-bed) and enable process automation. The pseudomorphic transformation of silica monoliths in zeolite monoliths in the SOD and LTA phase has been elaborated. We have preformed the first implementation of a macroporous zeolite monolith as microreactor for the fine chemical production in flow continuous conditions. The zeolite monoliths have been tested for dynamic ion exchange and are promising materials for the use as decontaminants of radioactive discharges.

There is great interest in miniaturized analytical systems for life science research, the clinical environment, drug discovery, biotechnology, quality control, and environmental monitoring and numerous articles have been written which predict the success of microfluidic based systems. It was demonstrated in this work that a microfluidic flow system could be quickly and easily manufactured in a research lab environment without the need for clean room facilities. The microfluidic device was created using polymethylmethacrylate, a CO2 laser and a standard oven. The device was designed, manufactured and ready for use within three hours. This work also investigated a chemiluminescent system which was intended for use in protease assays in the microfluidic device. This work also focused on the use of photoinitiated polymer monoliths, with immobilized tannic acid, as protein preconcentrators. The function of the monolithic devices was demonstrated by pumping low concentration solutions of BSA BODIPY® FL through the monolith. Both loading and elution were done using pressure. It was shown that BSA could be concentrated on and successfully eluted from the monolith. The elution volume for a 125 nl monolith was found to be 4 μl. Therefore an injection of a 60 μl sample of 1 x 10⁻⁹M BSA BODIPY ® FL gave rise to a concentration factor of 15. The pH optimum for the binding of BSA BODIPY ® FL was found to be pH 8.0 and the loading capacity of the tannic acid monolith was found to be 0.6 mg.ml⁻¹.

The project has demonstrated the use of both poly(styrene-divinylbenzene) PS-DVB and silica monolithic columns for the separation of nitro-compounds. Methods were developed with PS-DVB and ODS silica packed columns for the separation of these compounds. The first part of the project was the preparation of the monolithic stationary phases prepared from PS-DVB of (250 μm I.D. × 70 mm) functionalized with methacrylate by in-situ polymerisation. The alkylated PS-DVB then was used successfully for the first time in the separation of three aryl nitro-compounds (2-NA, 1,4-DNB and 4-NT) on micro-HPLC. However, the efficiency of this column was poor N = 318 (4675/m).The second part of the thesis used a commercial column (Chromolith Performance from Merck), with different diameters for the separation of nitro-compounds. Nitrocompounds were analysed on both Chromolith Performance 3 mm I.D. column and Chromolith Performance 4 mm I.D. column by HPLC/UV. Van Deemter plots showed that the 3 mm I.D. column gave higher efficiencies at higher flow rates than the 4.6 mm I.D. column. The plate number was 8216 (H = 0.0121 mm) at a flow rate of 0.4 ml/min (1.0206 mm/sec) and for Chromolith 4.6 mm I.D. it was 9436 (H = 0.0105 mm) at a flow rate of 0.8 ml/min (0.8577 mm/sec). The nitro-compounds analysed in this study were nitroaromatic, nitramines and nitrate esters which are used in the manufacture of explosives. These compounds were analysed for the first time using a Chromolith Performance 3 mm I.D. column on LCMS using both ESI and APCI in negative ionization modes. The sensitivity was higher in the APCI than the ESI mode in terms of higher intensity and lower background noise especially for nitroaromatic compounds. The LC-ESI-MS method was evaluated by injection of samples of pentaerythritol tetranitrate (PETN) in different concentrations. Calibration curves were constructed over the range of 1-1000 pg/μl with a correlation coefficient of (R2 = 0.9986) and with a concentration range between 1-200 ng/μl with a correlation coefficient of (R2 = 0.9971) and were found to be linear. The limit of detection (LOT) for pentaerythritol tetranitrate (PETN) was 5 pg/μl at a signal-to-noise ratio (S/N) of 3:1 and the limit of quantification (LOQ) was 10 pg/μl at a signal-to-noise ratio of 10:1. The applicability of the monolithic column for the LC-ESI-MS method was evaluated by injection of samples of the commercial explosives, P9 and Semtex 1H. The results showed that Semtex 1H contains 35% PETN using calibration curve 1-200 ng/μl and was much higher than in P9 0.0082% using calibration curve 1-1000 pg/μl.

Surfactant-templated, sol-gel based methodologies for the synthesis of tailored, nanostructured, hybrid inorganic–organic materials are incredibly powerful and versatile. Although growth in this field has been explosive in recent decades, a lot of room remains to contribute to the design and synthesis of new materials, as well as the development of advanced applications. In the work described herein, we firstly explored the synthesis of thick, mesoporous organosilica films and their application as functional coatings for solution-based, fibre-optic heavy metal sensors. Notably, sub-ppm level detection was observed for the detection of Pb(II) in mixed aqueous–organic media in short timeframes, and progress has been made toward synthesizing organotitania films that would allow for heavy metal sensing in purely aqueous solution. Furthermore, the utility of these types of surfactant-templated, organically-functionalized, mesostructured coatings has been preliminarily extended to other types of optical devices for heavy metal sensing. We have also explored the use of designer amphiphilic, alkyl oligosiloxane precursors for the tightly-controlled formation of thin, self-templated, hybrid nanostructured films. Moreover, films bearing uniaxial 2D hexagonal alignment over macroscopic length scales were obtained using polymer-treated substrates to control the interfacial interactions between the film precursors and the substrate surface. In addition, a relatively mild UV / ozone treatment was employed to remove the alkyl moieties from the films to yield porous materials without catastrophic loss of the as-synthesized, mesostructural order. Lastly, novel chiral, binaphthylene-based, periodic mesoporous organosilica (PMO) materials have been prepared. With the aim of demonstrating chiral recognition with such materials, porous, co-continuous capillary monoliths have been synthesized and applied as chiral stationary phases in nano-HPLC and CEC. Notably, enantioselective interactions between our materials and a chiral acetal-based analyte have been observed. Quantification of these enantioselective interactions in chiral PMOs by isothermal titration microcalorimetry is also being pursued. It has thus been demonstrated that a wide array of different functional materials may be accessed through template-based synthetic strategies. By varying parameters such the starting monomers, the sol composition, and the interfacial interactions between reacting species and a given substrate (to name a few), the resulting materials may be tailored to meet the demands of new and emerging technologies. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-05-24 19:50:17.478

L’objectif de cette thèse est la mise en œuvre de matériaux monolithiques à porosité hiérarchique pour le piégeage en continu des ions strontium et césium contenus dans des eaux de rejet de l’industrie nucléaire. Les zéolithes LTA et FAU-X sont connus pour piéger sélectivement ces cations, respectivement. Ce travail concerne d’une part la synthèse de matériaux, et d’autre part, leur utilisation en échange ionique. Nous avons d’abord optimisé la synthèse de monolithes siliciques à porosité hiérarchique méso/macroporeux qui constituent notre matériau de départ et qui présentent d’excellentes propriétés de transport. Nous avons ensuite développé la synthèse de monolithes zéolithiques par transformation pseudomorphique des monolithes de silice. L’étude des temps et températures de mûrissement et de cristallisation, a permis de suivre et de contrôler les processus de nucléation et de croissance des cristaux de zéolithes dans le squelette des monolithes. Des monolithes de zéolithe A avec un squelette formé de nanoparticules de 100 nm dans le cœur et de 400 nm en surface ont été obtenus, donnant des monolithes LTA à porosité hiérarchique trimodale (micro-/méso-/macroporeux). Des monolithes mixtes LTA/FAU micro/macroporeux ont également été obtenus. Des monolithes purement FAU-X ont été synthétisés mais s’effritent. Les monolithes LTA et LTA/FAU ont été utilisés en échange ionique en flux continu pour la capture du Sr2+ et celle simultanée du Cs+ et du Sr2+, respectivement. Les monolithes LTA à porosité hiérarchique trimodale ont montré des performances remarquables pour la capture du Sr2+ avec des courbes de percée presque idéales. L’ajout de la mésoporosité dans les monolithes LTA a permis un accès plus rapide aux sites d’échange de la zéolithe et ainsi d’augmenter le débit des solutions en maintenant un piégeage total. Les premiers résultats concernant l’utilisation des monolithes LTA/FAU pour la capture simultanée Sr2+/Cs+ sont encourageant et sont à améliorer en créant de la mésoporosité dans ces monolithes pour accroître leur vitesse d’échange en flux continu. / The aim of this thesis is the implementation of monolithic materials with hierarchical porosity for trapping strontium and caesium ions from nuclear wastewater in continuous flow. LTA and FAU-X zeolites are known to selectively trap these cations, respectively. This work is focused on the materials synthesis and their application in cation-exchange. We first optimized the synthesis of silica monoliths with hierarchical porosity meso-/macroporous that constitute our starting material and which have excellent mass-transfer properties. Then, we developed the synthesis of zeolite monoliths by pseudomorphic transformation of silica monoliths. Aging and crystallization times and temperatures were studied to follow and control the processes of nucleation and crystal growth of the zeolites in the skeleton of the monoliths. Zeolite A monoliths with skeleton featuring 100 nm nanoparticles in the core and 400 nm in the shell were obtained, giving rise to LTA monoliths with trimodal hierarchical porosity (micro-/meso-/macropores). Mixed LTA/FAU zeolite monoliths featuring micro-/macropores were also synthesized. Pure FAU-X monoliths were obtained, but were very fragile and crushed. Na-LTA and Na-LTA/FAU monoliths were used in cation-exchange in continuous flow processes to capture from aqueous solutions Sr2+ and simultaneously Cs+ and Sr2+, respectively. LTA monoliths with trimodal hierarchical porosity have shown outstanding performance for the capture of Sr2+ with almost ideal breakthrough curves. The addition of mesoporosity in LTA monoliths has enabled faster access to the exchange sites of the zeolite and has allowed to increase the flow rate of the process. First results obtained with LTA/FAU monoliths for simultaneous Sr2+/Cs+ capture are encouraging and must be improved by adding mesoporosity in these monoliths to increase their cation-exchange rate to be used in rapid continuous flow processes.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-09-23T16:07:28Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Lizete Stumpf.pdf: 4733186 bytes, checksum: 23ffa1dbdff5505a9beaa92369e29c37 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-09-23T18:45:21Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Lizete Stumpf.pdf: 4733186 bytes, checksum: 23ffa1dbdff5505a9beaa92369e29c37 (MD5) / Made available in DSpace on 2016-09-23T18:45:21Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese Lizete Stumpf.pdf: 4733186 bytes, checksum: 23ffa1dbdff5505a9beaa92369e29c37 (MD5) Previous issue date: 2015-04-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O desenvolvimento do solo a partir da recomposição de áreas mineradas fornece oportunidade para expandir o conhecimento existente sobre formação e estabilização de agregados, acumulação e distribuição da matéria orgânica e da biomassa microbiana, pois devido à magnitude da perturbação do ecossistema, criase um cenário de “tempo zero. Trabalhos sobre recuperação de áreas degradadas têm atribuído ao sistema radicular das plantas muitas das melhorias nos atributos físicos, químicos e biológicos do solo, entretanto poucos estudos são realizados para comprovar que tal comportamento é verdadeiro. Portanto, o objetivo geral do presente trabalho é analisar o desenvolvimento radicular de gramíneas perenes em solos construídos após a mineração de carvão e relacionar seus resultados com os atributos físicos e químicos do solo após 103 meses de implantação das espécies vegetais. O solo foi construído no início de 2003 e o experimento instalado em novembro/dezembro de 2003. As espécies vegetais avaliadas foram a Hemarthria altissima, o Paspalum notatum cv. Pensacola, o Cynodon dactylon cv Tifton e a Urochloa brizantha. No intuito de avaliar as mudanças decorrentes da construção do solo e o tempo aproximado de recuperação dos atributos do novo perfil formado, foi utilizado o solo natural sob vegetação nativa como referência. A amostragem de raízes foi realizada com a retirada de 16 monólitos de solo até a profundidade de 0,30m e a amostragem de solo foi feita através da coleta de 48 amostras com estrutura não preservada e 96 amostras com estrutura preservada até a profundidade de 0,30m. Após 103 meses de revegetação, as raízes das gramíneas promoveram a recuperação das condições físicas na camada de 0,00-0,10m através da formação de novos agregados, da diminuição da densidade, da resistência do solo à penetração e do aumento da macroporosidade do solo. A restrição do desenvolvimento radicular e o achatamento das raízes de todas as espécies em profundidade refletem as condições físicas inadequadas abaixo da camada de 0,00- 0,10m, devido à presença de agregados formados originalmente por compressão, e consequentemente alta densidade e resistência do solo à penetração e baixa macroporosidade. Abaixo dos 0,20m de profundidade, mesmo onde ocorre a presença de estéril com desenvolvimento do processo de sulfurização ativa, se observa a presença de uma pequena proporção de raízes. Independente da camada avaliada, todas as espécies vegetais apresentaram maior concentração de raízes de diâmetro 0,25-0,49mm, consideradas muito finas. Entretanto, nas camadas abaixo de 0,00-0,10m, a Urochloa brizantha aumentou a emissão de raízes com diâmetro de 0,50-0,99mm, enquanto que a Hemarthria altissima, o Paspalum notatum e o Cynodon dactylon aumentaram ainda mais a emissão de raízes no diâmetro de 0,25-0,49mm. Entre as espécies, a Urochloa brizantha se destaca pela sua maior densidade, volume, área e comprimento radicular, apresentando assim um maior potencial em recuperar os atributos físicos de áreas degradadas, principalmente abaixo das camadas de 0,00-0,10m. A indicação desta e das demais espécies na recuperação de solos construídos após mineração de carvão deve levar em conta a espessura da camada de solo reposta sobre os estéreis, pois as raízes destas espécies apresentam potencial de desenvolvimento em profundidade, podendo acelerar o processo de sulfurização. Nos primeiros 0,20m do solo construído, os atributos químicos mostram-se adequados ao desenvolvimento radicular. O baixo teor de carbono nas frações leve livre e leve oclusa até a profundidade de 0,20m estão relacionados à degradação da estrutura do solo, que dificulta o desenvolvimento das raízes em profundidade, assim como a presença de organismos do solo responsáveis pela transformação dos resíduos radiculares em matéria orgânica. A recuperação dos atributos físicos do solo construído, principalmente abaixo da camada de 0,00-0,10m, mostra ser lenta quando comparada com os atributos de um solo natural, possivelmente devido ao baixo aporte inicial de carbono orgânico no sistema. / The constructed soil development in mined areas provides an opportunity to expand the existing knowledge on the formation and stabilization of aggregates, as well as on the accumulation and distribution of organic matter and microbial biomass, since due to the magnitude of ecosystem disturbance, it creates a scenario of "zero time". Scientific research on the recovery of degraded areas has attributed to the root system of plants many of the improvements in physical, chemical and biological soil attributes; however, few studies have been done to prove that such behavior is real. Therefore, the overall objective of this study is to analyze the root development of perennial grasses in minesoils constructed after coal mining and relate the results of the physical and chemical soil attributes after 103 months of establishment of plant species. The soil was constructed in early 2003 and the treatments started in November/December 2003. The plants species evaluated were Hemarthria altissima, Paspalum notatum cv. Pensacola, Cynodon dactylon cv Tifton, and Urochloa brizantha. In order to evaluate changes due to soil construction and the estimated recovery time of the attributes of the new formed profile, a natural soil under native vegetation was used as reference. Sixteen (4x4) soil monoliths to a depth of 0.30m were taken for root sampling, 96 undisturbed samples and 48 disturbed samples were taken to a depth of 0.30m for determining soil attributes. After 103 months of revegetation, the roots of grasses are promoting the recovery of physical conditions along the 0.00 to 0.10m soil layer, through the formation of new aggregates, the decrease in soil bulk density and soil penetration resistance and increased soil macroporosity. The decrease in root development and the flattening of the roots of all species reflect the inadequate soil physical below the 0.00 to 0.10m layer due to the presence of aggregates formed originally by compression, high bulk density and soil resistance to penetration and low macroporosity. Below 0.20m depth, even in the presence of spoils with active sulfurization process, it is observed the presence of a small proportion of roots. Regardless of the layer evaluated, all the plant species showed higher concentration of roots with diameter from 0.25 to 0.49mm, considered very fine. However, in the layers beneath 0.00-0.10m the Urochloa brizantha increased emission of roots with diameter from 0.50 to 0.99mm, while Hemarthria altissima, the Paspalum notatum, Cynodon dactylon increased even more the roots with diameter between 0.25 to 0.49mm. Among the species, Urochloa brizantha stands out for its higher density, volume, area and root length, thus presenting a greater potential to recover the physical attributes of constructed soils from degraded areas by coal mining, especially those below the surface layer of 0.00 to 0.10m. The indication of this and other species for the recovery of soils constructed after coal mining should take into account the thickness of the topsoil layer placed over the overburden, because the roots of these species have potential to deepen their root system and thus accelerate the sulfurization process. In the first 0.20m layer of the constructed soil the chemical attributes are suitable for root development. Low carbon content in free light and occluded light fractions from 0.00 to 0.20m are related to degradation of soil structure, which hinders root development in depth, as well as the presence of soil organisms responsible for transforming the root residues in organic matter. A recovery of physical attributes of constructed soil, mainly below of 0,00-0.10-0.20m layer, proves to be slow compared to the attributes of a natural soil, possibly due to the low initial contribution of organic carbon in the system.

No description available.