Clay Research Articles

Cyclic behavior of RT-cement treated marine clay subjected to low and high loading frequencies

The weakening and softening behavior of soft clay subjected to cyclic loading due to the build-up of excess pore water pressure is well-known. During the design stage of the foundation of highways and coastal high-rise buildings, it is important to study the mechanical behavior of marine soils under cyclic loading as they undergo greater settlement during cyclic loading than under static loading. Therefore, this research evaluates the cyclic stress-strain and shear strength of untreated and treated marine clay under the effects of wind, earthquake, and traffic loadings. A series of laboratory stress-controlled cyclic triaxial tests have been conducted on both untreated and treated marine clay using different effective confining pressures and a frequency of 0.5 and 1.0 Hz. In addition, treated samples were cured for 28 and 90 days and tested under a frequency of 2.0 Hz. The results revealed significant differences in the performance of treated marine clay samples than that of untreated samples under cyclic loading. The treated marine clay samples were able to stand up to 2000 loading cycles before failure, while untreated marine clay samples could not stand few loading cycles. The untreated marine clay displayed a higher permanent axial strain rate under cyclic loading than the treated clay due to the existence of new cementing compounds after the treatment with recycled tiles and low amount (2%) of cement. The effect of the effective confining pressure was found to be significant on untreated marine clay while its effect was not crucial for the treated samples cured for 90 days. Treated samples cured for 90 days performed better under cyclic loading than the ones cured for 28 days and this is due to the higher amount of cementitious compounds formed with time. The highest deformation was found at 0.5 Hz, which cannot be considered as a critical frequency since smaller frequencies were not used. Therefore, it is recommended to consider testing the treated marine clay using smaller frequencies than 0.5 Hz.

Revision of Modified Cam Clay Failure Surface Based on the Critical State Theory

Revision of Modified Cam Clay Failure Surface Based on the Critical State Theory

Validity of sand dunes sediments as a fine aggregates for roads works: a case study on sand dunes sediments, Al-Nasiriya city, southern Iraq

In light of the development and urban growth of the city of Al-Nasiriya, the road construction sector consumes the largest amount of aggregates. The research aims to study suitability of the sediments of the sand dunes extending on one side of the international road between Nasiriya – Baghdad near the check point of Fadak as fine aggregate used for the purposes of roads construction. The results of the geotechnical evaluation of physical properties showed that the grain size analysis of the fine aggregate did not meet the requirements of the Iraqi specification and according to these results, the aggregate needs to modify. Based on liquid limits and plasticity indices and according to Iraqi specification the deposits are suitable for using as sub-grade course materials and to construct the shoulders of the road but not suitable for using as sub-base course materials. While the results of chemical tests indicate that incompatibility of the rates of organic matters and calcium carbonates with Iraqi specification. On the other hand, the chemical analysis of the sediments showed that the rates of the chlorides, sulfates, gypsum, total soluble salts and pH they were within acceptable limits of standard specifications. The mineral components of the soils were characterized by clay minerals (kaolinite and montmorillonite) and non-clay minerals (quartz, feldspar, and calcite).

Geotechnical study of a landslide reactivation in clay soils (central Piedmont, NW Italy).

In March 2015, exceptional meteoric events occurred in southern Piedmont caused a remarkable rise of the rivers water level of the Tanaro Basin with flooding and many landslides. The engineering geological study reported here, concerns a triggering of a previous landslide occurred in 1982 in the hills, shaped in the marine sedimentary succession (Lugagnano Clay, lower Pliocene) of the southern Asti Reliefs, near San Martino Alfieri village. Detailed geological, morphological and topographic surveys of this landslide, with the aim to recognize the morphological features linked to the previous landslide and those connected to the triggering of it, have been carried out. The reactivation of the landslide was highlighted by the presence of a main scarp with minor escarpments and tracks. The mechanism activation of the main landslide is due to a rotational movement. To define the engineering geological model of the landslide body, standard cone penetration tests. rotary drilling borings with S.P.T. and geotechnical laboratory tests were performed. Through surveys, both main slip surface and deep-water seepage have been detected. In details, failure mechanism in OC clays was caused by: a) rapid increase in the bulk density or volume weight during rainfall events; b) rise of interstitial pressures along the sliding surface with reduction of normal stress and consequent reduction of the shear strength along this surface (progressive failure); c) reduction of cohesion and friction angle, due to clay softening. The results of the study have highlighted the need, as a primary factor of slopes consolidation, to install sub-horizontal drainage pipes in order both to avoid subsoil imbibition and to control the changes of interstitial pressure. The consolidation works focused on the construction of containment structures with deep consolidation and the execution of drainage works in the landslide area.

Preparation of Polylactide/Modified Clay Bio-composites Employing Quaternized Chitosan-Modified Montmorillonite Clays for Use as Packaging Films

Composite materials of polylactide (PLA) have been a popular environmentally-friendly and low-cost bio-composite that is used for packaging applications. Clay has been used as fillers to improve the mechanical properties of PLA and enhance the gas permeation properties of the composites. However, adding unmodified clay to PLA leads to a reduction in its tensile strength and elongation at break, due to its incompatibility with PLA. In this study, Montmorillonite clay was modified with highly-positive charged quaternized chitosan (QC) by a solution mixing process. The modification efficiency was evaluated through the change in d-spacing values of the clays by X-ray diffraction spectroscopy. Fourier transform infrared (FTIR) spectroscopy was used to study the changes in the structures of the clays. QC with 50 % DQ at 10 % concentration, 2.5 % solid content, 1,000 rpm of stirring speed, and by ultra-sonication (70 % amplitude in 15 min) were observed as the optimum conditions to modify Montmorillonite. The d-spacing value increased from 12.4 A to 20.3 A, after the modification, which is comparable to the 18.2 A of commercial Cloisite 30B. The modified clays were then mixed with PLA to generate bio-composite materials. The results show that adding the modified clays (at up to 5 wt%) leads to a slight reduction in tensile strength and modulus, but a modest increase in the elongation at break of the material, compared to neat PLA. Tensile strength, strain, modulus, and elongation at break of the bio-composite are 41.60 ± 2.06 (MPa), 2.97 ± 0.15 (%), 1,740 ± 140 (MPa), and 3.00 ± 0.16 (%), in comparison with 46.20 ± 4.04 (MPa), 2.67 ± 0.26 (%), 2,015 ± 301 (MPa), and 2.79 ± 1.28 (%) for neat PLA. Moreover, the bio-composite shows an impact strength improvement of about 20 %, compared to neat PLA. Hence, QC can be applied as a promising agent to modify Montmorillonite clay for preparing bio-composites. These composites can maintain high mechanical properties and degradability with an improvement in impact strength are suitable for packaging applications.

Application of FGD Waste for Degraded Soil Amendment for Sustainable Agriculture

The product from coal-fired power plants is flue gas desulfurization (FGD) waste. FGD has been used in many industries such as wallboard and cement industries. It can be applied in agriculture to make soil higher quality. The application of this waste in agriculture is scarce. The benefit of FGD waste can change the acidic condition in soil and increase the substance for plant growing to enhance soil quality. The degradation of soil is one of the main impacts for agricultural industries. Degraded soil is the soil with a decrease in quality because of excessive land use, overuse of chemical fertilizers, deforestation and clearing the land. In Thailand, degraded soil is a crucial problem especially in the northern areas. The aim of this work is to use the FGD waste from coal-fired power plants to enhance the soil quality in Nan, Thailand and to evaluate the effects of FGD waste mixture ranging from 5-40 % by weight on soil texture, bulk density, pH and electrical conductivity (EC). Based on the results, the higher amount of FGD waste in the mixture, the better quality of soil can be obtained, specifically soil texture and pH. The soil texture can be adjusted from clay to silt loam or loam. The pH increases from 5.664 up to 6.861. The soil bulk density reduces for all ratios of mixing with FGD waste which is conducive to plant growth. This study can be used for soil improvement and enhance the agricultural yields. The potential mixing ratios of 30 % to 40 % of FGD waste are expected to investigate the effects on plant growing and soil improvement in the real field for further study.

Impact of different cover crops and termination methods on collard yield

A three-year experiment was conducted in Cullman, AL, to determine the impact of iron clay pea, sunn-hemp, soybean, velvet Bean, sorghum Sudan, and pearl millet cover crops terminated with two methods (rolling and flail mowing) on collard (brassica oleracea var. acephala, L.) yield. Overall, each of the three growing seasons (2013, 2014, and 2015) produced significant differences in cover crop biomass production among cover crops. Across three growing seasons sorghum Sudan and Pearl Millet generated the highest biomass (23,752 and 23,333 kg ha -1 respectively). During the same period, sunn hemp produced 10,908 kg/ha -1 and soybean, velvet bean and iron clay pea produced lower biomass (6,754, 6,068, and 4,360 kg ha -1 , respectively). Termination rates of cover crops used in this study were mostly below 90%. Termination rates above 90% have been recommended by agricultural extension services to plant cash crop into cover crop residue. In all three growing seasons volumetric soil moisture content during evaluation have showed that plots with rolled residue consistently held more VMC than the standing cover crops, indicating that rolled cover crop residue better preserved soil moisture content. Collard green yield was significantly different in each growing season for different covers and termination methods. Averaged over three growing seasons, the highest collard yield was observed for iron clay pea (12,623 kg ha -1 ), Velvet bean (11,020 kg ha -1 ) and sunn hemp (10,802 kg ha -1 ). Data suggest that higher collard yield was obtained with legume cover crops with the benefit of released nitrogen into the soil and utilized by collards. In addition, across all years, the average collard green yield was higher for cover crops which were flail mowed (11,875 kg ha -1 ) compared to rolled/crimped cover crops (7,349 kg ha -1 ).

ANALYSIS OF PEDOLOGICAL FACTORS AND USCS IN THE CONTACT AREA OF ĐAKOVO LOESS PLATEAU AND DILJ GORA, CROATIA

The pedological factors concerning the Unified Soil Classification System (USCS) in the contact area of Đakovo loess plateau and Dilj gora have been explored. The study was carried out to create a cross-country mobility map for vehicles. The spatial GIS analysis included soil units of Basic Soil Map (BSM) at a scale of 1:50000, which, according to the World Reference Base (WRB), contain within themselves the distribution of soil units, particle size distribution according to the United States Department of Agriculture (USDA) soil classification and organic content, as well as data from the Basic Geological Map (BGM) at a scale of 1:100000, together with the information on the original parent material from which the soils originate. Field sampling (72 samples) and laboratory sample analysis were performed according to the USCS. The samples were collected at the same locations (50 samples) as the profiles which had been extracted during the de- velopment of BSM to enable a comparison of the two classification systems. The analysis did not confirm a clear statisti- cal connection between the USDA and USCS. The compatibility of BSM pedological units and low plasticity clays (CL) is clearly visible in all units, except for the units located on the alluvium. The presence of low plasticity clay (CL) and high plasticity clay (CH) has been confirmed in the stagnosols on the alluvium. By incorporating the geological basis into the spatial analysis, low plasticity clays were found to belong to the Quaternary source material, whereas high plasticity clays were formed on the parent substrate of Neogene age. Data analysis and cartographic representation of the results accord- ing to the Waterways Experiment Station (WES) Method of the cone index were obtained using fuzzy logic. The princi- ples of fuzzy logic were used at the boundaries of pedological units due to the inability to define clear boundaries or the cessation of a particular type of soil’s presence.

Infill wall effects on the dynamic characteristics of RC frame systems via operational modal analysis

This paper presents an experimental study on the dynamic characteristics of infilled reinforced concrete (RC) frames. A 1/3-scaled, one-bay, three-storey RC frame was produced and tested by using operational modal analysis (OMA). The experiments were performed on five specimens: one reference frame with no infill walls and four frames with infill walls. The RC frame systems included infill walls made of hollow clay brick, which were constructed in four different patterns. The dynamic characteristics of the patterns, including the frequency, mode shapes and damping ratios in the in-plane direction, were obtained by 6 accelerometers. Twenty-minute records under ambient vibration were collected for each model, and the dynamic characteristics were determined using the ambient vibration testing and modal identification software (ARTeMIS). The experimental studies showed that the infill walls significantly affected the frequency value, rigidity and damping ratio of the RC frame system.

Los caminos del agua y la construcción de terrazas agrícolas en el país de la lluvia

espanolEn los territorios de los valles altos de Galicia, las aldeas responden al secular conocimiento y manejo de la escorrentia del agua. Se emplazan a media ladera, entre el monte -donde las branas, “chaos” y turberas funcionan como captadores del agua de lluvia- y las zonas de cultivo, donde las aguas broncas- que descienden arrastrando limos, arcillas y materia organica- se apaciguan y domestican para ser dirigidas sabiamente a fertilizar estas tierras mas bajas. Sobre su territorio, la comunidad de cada aldea fue construyendo terrazas cultivables y una intrincada y multifuncional red de riego, drenaje y escorrentia, ajustando progresivamente una compleja gestion comunitaria para su reparto proporcional y equitativo, sin apenas perturbar el ciclo natural del agua. Se muestra como la construccion de estos territorios aterrazados responde a un profundo conocimiento del manejo del agua en las condiciones locales, tanto al control de la escorrentia como al riego EnglishThe habitat of the territory of ancient Gallaeciain the NorthWest of the Iberian peninsula is characterized by the distribution of its population throughout tens of thousands of small hamlets which have configured their environment in such a way as to form their own distinctive territory, associated with its evolutionary dynamic with roots ina remote past of patterns of human settlement that culminates in the culture of the castros. This study describes the hamlet of A Burgeira and its associated territory which is located in the upper levels of the River Tamuxe valley in the district of Rosal. It can serve as a paradigm of how decisions concerning the location for a settlement were taken communally employing a profound knowledge of the environment with regard to the availability of water resources. These resources, managed wisely, have conditioned the successive elaborations of the terracing which have enabled intense traditional cultivation

Deformation characteristics of tunnel bottom after construction under geological conditions of long-term deformation

Mountainous areas cover more than 70% of Korea. With the rapid increase in tunnel construction, tunnel-collapse incidents and excessive deformation are occurring more frequently. In addition, longer tunnel structures are being constructed, and geologically weaker ground conditions are increasingly being encountered during the construction process. Tunnels constructed under weak ground conditions exhibit long-term deformation behavior that leads to tunnel instability. This study analyzes the behavior of the bottom region of tunnels under geological conditions of long-term deformation. Long-term deformation causes various types of damage, such as cracks and ridges in the packing part of tunnels, as well as cracks and upheavals in the pavement of tunnels. We observed rapid tunnel over-displacement due to the squeezing of a fault rupture zone after the inflow of a large amount of groundwater. Excessive increments in the support member strength resulted in damage to the support and tunnel bottom. In addition, upward infiltration pressure on the tunnel road was found to cause severe pavement damage. Furthermore, smectite (a highly expandable mineral), chlorite, illite, and hematite, were also observed. Soil samples and rock samples containing clay minerals were found to have greater expansibility than general soil samples. Considering these findings, countermeasures against the deformation of tunnel bottoms are required.

Strength characteristics and fracture evolution of rock with different shapes inclusions based on particle flow code

Natural rock mass contains defects of different shapes, usually filled with inclusions such as clay or gravel. The presence of inclusions affects the failure characteristics and mechanical properties of rock mass. In this study, the strength and failure characteristics of rock with inclusions were studied using the particle flow code under uniaxial compression. The results show that the presence of inclusions not only improves the mechanical properties of rock with defects but also increases the bearing capacity of rock. Circular inclusion has the most obvious effect on improving model strength. The inclusions affect the stress distribution, development of initial crack, change in crack propagation characteristics, and failure mode of rock. In defect models, concentration area of the maximum tensile stress is generated at the top and bottom of defect, and the maximum compressive stress is distributed on the left and right sides of defect. In filled models, the tensile stress and compressive stress are uniformly distributed. Failing mode of defect models is mainly tensile failure, while that of filled models is mainly shear failure.

A displacement controlled method for evaluating ground settlement induced by excavation in clay

Excavation usually induces considerable ground settlement in soft ground, which may result in damage of adjacent buildings. Generally, the settlement is predicted through elastic-plastic finite element method and empirical method with defects. In this paper, an analytical solution for predicting ground settlement induced by excavation is developed based on the definition of three basic modes of wall displacement: T mode, R mode and P model. A separation variable method is employed to solve the problem based on elastic theory. The solution is validated by comparing the results from the analytical method with the results from finite element method(FEM) and existing measured data. Good agreement is obtained. The results show that T mode and R mode will result in a downward-sloping ground settlement profile. The P mode will result in a concave-type ground settlement profile.

Use of alkaline activation for production of porous glass-ceramic material from clay mixture

Целью исследования являлось определение возможности использования местной легкоплавкой глины месторождения Кустиха и техногенного отхода производства гранитного щебня для получения экологически безопасного пористого теплоизоляционного материала с использованием метода щелочной активации. Изучено влияние щелочной активации на формирование пористого стеклокерамического материала из смеси легкоплавкой глины и отходов гранитного производства. Показано, что смесь глины месторождения Кустиха с гранитоидным отсевом, содержащая свободный диоксид кремния, способна вспучиваться под действием щелочи при температурах обжига до 950 градусов Цельсия. Методами термогравиметрии и ИК-анализа установлено, что под действием щелочной активации вода удерживается в исходной смеси за счет образования дополнительных гидроксильных связей вплоть до 500 градусов Цельсия. При дальнейшем обжиге наличие таких гидроксильных связей способствует переходу материала в пиропластическое состояние и его вспучиванию. Установлено, что полученный гранулированный стеклокерамический материал обладает высокой пористостью (коэффициент вспучивания 4,2), при этом его плотность в 5,4 раза меньше, чем у материала, полученного из неактивированной смеси глины с гранитоидным отсевом. По данным элементного и фазового анализа полученная стеклокерамика не содержит органических и других токсичных примесей, что позволяет отнести ее к экологически безопасным теплоизоляционным материалам. The objective of this study was to determine the possibility of using local low-melting clay from the Kustiha deposit and technogenic waste from the production of crushed granite to obtain an environmentally friendly porous heat-insulating material using the alkaline activation method. The alkaline activation's effect on the formation of a porous glass-ceramic material from a mixture of low-melting clay and granite waste was studied. It was shown that the clay mixture from the Kustiha deposit with granitoid’s screenings containing free silicon dioxide is able to swell under the action of alkali at calcination temperature up to 950 degrees Celcius. Using methods of thermogravimetry and IR analysis, it was found that under the action of alkaline activation water is retained in the initial mixture due to the formation of additional hydroxyl bonds up to 500 degrees Celcius. With further firing, such hydroxyl bonds contribute to the transition of the material into the pyroplastic state and its expansion. It was found that the obtained granular glass-ceramic material has high porosity (expansion coefficient is 4.2 plus/minus 0.2), while its density (0.26 plus/minus 0.03 gram/cubic centimeter) is 5.4 times lower than that of the material obtained from an inactive mixture clay with granitoid's screening. According to elemental and phase analysis, the glass ceramic obtained does not contain organic and other toxic impurities, which allows it to be attributed as an environmental friendly heat-insulating material.

Focolari e piastre di cottura nell’abitato dell’età del Bronzo di Mursia (Pantelleria TP)

The Bronze Age settlement of Mursia (XVIII – XV cent. BC) displays several examples of domestic structures related to the use of fire. They are mainly hearths and other features for food preparing, but also used for lighting and heating dwellings. They are mainly placed inside the huts, utilized repeatedly, presumably daily, by members of a small group, of family size. The most recurrent structure is the hearth constructed with four stone slabs, placed vertically, the so called lithic cist. They are of small size (side length from 25 to 60 cm) and allow to prepare fire and live charcoal in a safe place. Filling layers of these structures are usually made of ash and charcoal, while at the bottom or around the structure there are evident marks of firing. Beyond the basic interpretation of these structures as fireplace, it remains uncertain the details about use for firing or cooking and especially the interaction with other aspects of daily life. In some huts there are more than one hearths with the shape of lithic cists and in some cases we are sure they are contemporary, so we need to interpret it as a necessity to prepare a higher amount of food, or a different use. Very often the filling layer shows that the structure was regularly cleaned and the burned products removed. Very unusual is the discovery of a small coal-shovel made of a bone scapula placed next to the lithic cist. Another main aspect to investigate is also the way to manage the smoke disposal. Some post holes around the hearth suggest the presence of some kind of draw, made of a chimney or a simple cowl. At Mursia there are other types of structured fireplaces changing during the different phases of the settlement: stone slabs often combined with lithic hearths were used as cooking plates are peculiar in the earliest phase; round or oval cooking plates made of a thin layer of clay arranged above a bed of small stones or pottery fragments are typical of later phases. In small dwellings they are associated to andirons and kitchen ware. The aim of this paper is to define how these structures were used, stressing the changes in managing fire, preparing food in accordance with the archaeological phases of the settlement. The analysis of the structures concerns technical characters, the distribution inside the settlement, the association with other domestic facilities, as well as to go into the items (pottery, tools) related to the use of fire and to cooking. The first results of the micromorphological analysis carried on archaeological soil samples give additional information about the manufacture techniques and the sedimentary record of the hearts use and cleaning.

Cachimbos brancos da região do Valongo

Os cachimbos de caulim recuperados nas escavações do Cais do Valongo / Cais da Imperatriz e suas imediações foram atribuídos, na sua quase totalidade, ao século XIX. Foram utilizados e descartados no entorno e nas proximidades do cais, região portuária caracterizada por grande diversidade étnica. Tais pitos atestam a inserção do Rio de Janeiro, recém liberto das práticas monopolistas de Portugal, em uma economia cada vez mais global, na qual o trânsito de pessoas e mercadorias vindas de diferentes pontos era particularmente intenso. Nesse cenário, foi observada a predominância da fabricação francesa nos cachimbos de caulim encontrados, coerente com o que ocorreu na indústria e comercialização desses objetos no resto do mundo. Considerando as informações arqueológicas e alguns dados históricos sobre importação e venda de cachimbos no Rio de Janeiro, especula-se a respeito dos contextos em que eles podem ter sido utilizados, nessa cidade, nos oitocentos.

Assessment of Postharvest Losses of Dairy Products in Dawuro Zone and Konta Special Woreda of SNNPR

This study was conducted in Dawuro zone and Konta special woreda of SNNPR to assess the existing dairy cattle production, milk handling, and processing practices. A total of eighty respondents were purposefully selected and interviewed for obtaining general information such as dairy cattle production, milk handling, and processing practices, traditional milk processing equipment through structured questionnaire. Dairy cattle production system, local breeds were more dominant than cross breeds in both study areas. The higher numbers of both breeds were observed in Tocha woreda than that of Konta special woreda. The dairy animal performance assessment shows that the average lactation length and milk yield of local cows were lower than that of crossbred in both study areas. Labor division among family members concerning dairying activities such as milking, milk processing, and milk marketing were dominantly done by women rather than men in both study areas. Commonly and widely used for milk handling traditional utensils in the study areas were calabash and plastic materials. Few dairy farmers were using a small clay pot for milking purpose. Milk processing methods are a predominantly traditional type, and they use traditional milk processing materials. So, farmers in both study areas are highly encouraged in for cross bred. Further work should be done in improved milk processing materials in both study areas.

Evaluation of polycarboxylate ethers that can mitigate the detrimental effects of clay content of sand on concrete workability and strength

Clay tolerant superplasticizers can enable the use of low quality, clay containing aggregates and also alleviate the need for washing clay containing sand used in concrete fabrication, thereby promoting sustainable concrete production. Previous studies considered specific aspects of polycarboxylic ether (PCE) superplasticizer molecular design which influence their clay tolerance. In this study, the effect of a combination of various aspects of PCE molecular design on their clay tolerance was investigated. The aim of the study was to determine PCE structural differences that are more tolerant to clay contamination of sands used in concrete making. The objective was to evaluate the effectiveness of six recently developed proprietary PCEs with varying molecular designs in concretes fabricated with clay containing sands sampled from three South African quarries. The PCEs were evaluated by their ability to retain good workability and compressive strength in concretes fabricated using a standard laboratory clay free sand and high clay content sands from the three quarries. Workability was evaluated through slump flow tests and the compressive strength was evaluated through 24 h and 28 d compressive strength tests. Incorporation of an acrylic based PCE with low side chain graft ratio and long side chain lengths in the concretes resulted in a higher initial slump flow of at least 200 mm at 5 min, indicating relatively good workability, which however deteriorated rapidly in concretes made with the clay contaminated sands. Unexpectedly, the 28 d compressive strengths of concretes fabricated with higher clay content sands were found to be comparable to the compressive strengths of concretes made with the clay free standard sand when three of the PCEs were used. High compressive strength in the concretes fabricated with the sand containing the most clay was accomplished by incorporating a PCE with very high molecular weights, very long side chain lengths and a low graft ratio.

Adsorption of Phenol from Wastewater Using Modified Layered Double Hydroxide Clay

Phenol and its derivatives are some of the organic pollutants found in wastewater and they pose health risks to human beings and animals if left untreated. This work investigates the use of modified Layered Double Hydroxide clay as an adsorbent for removal of phenol from wastewater. High exchange capacities, capability to be modified with surfactants and through calcination, and the ability to regenerate are some of the properties of the clay reported in literature which make it an ideal adsorbent for phenol removal from wastewater. Modification of neat clay with silane increased the adsorption percentage from 6 % to 19 %, however the extent of adsorption was reduced from 87 % to 35 % when calcined clay was coated with a silane material. Calcination of the clay increased its BET surface area from 8.71 m2/g to 29.74 m2/g. The adsorption kinetics were best fitted by the pseudo second order model. The equilibrium isotherms which best fitted the adsorption data were the Freundlich isotherm and the Three Parameter Langmuir-Freundlich isotherm. The maximum adsorption capacity of 59.1 mg/g was observed using the Three Parameter Langmuir-Freundlich isotherm.

Oil Residue Pyrolysis Process in the Presence of Aluminosilicates

This paper presents a study of the pyrolysis process of oil residues in the presence of catalysts based on natural and synthetic aluminosilicates. The process of fast thermal decomposition was studied in a continuous reactor at a residence time of feedstock in the reaction zone less than 20 s. The optimum temperature of oil-sludge decomposition was determined taking into account the yield of gaseous and liquid pyrolysis products. The optimal pyrolysis temperature for the studied feedstock was found to be 600 °C. The study of the effect of the aluminosilicates on the oil-sludge thermal decomposition showed that among the studied catalysts, zeolites were found to be the most active. The highest yield of gaseous and liquid products was observed In the presence of three-dimensional porous pentasil zeolite H-ZSM-5. H-ZSM-5 was found to provide the 40 wt. % yield of liquid and 13.5 wt/ % of gaseous products during the fast oil-sludge pyrolysis at the optimal temperature. In order to reduce the cost of the catalyst used, a catalyst representing a mixture of zeolite H-ZSM-5 and bentonite clay was synthesized. This catalyst also showed high activity in the process of oil-containing residue composition providing 36 w. % yield of liquid products and 10 wt. % of gaseous products. It is interesting to note, that in the presence of the mixed catalyst the highest yield of light liquid fraction (50 wt. %) was obtained.