Natural Bentonite Clay Research Articles

Batch Sedimentation Studies for Freshwater Green Alga Scenedesmus abundans Using Combination of Flocculants.

Microalga is the only feedstock that has the theoretical potential to completely replace the energy requirements derived from fossil fuels. However, commercialization of this potential source for fuel applications is hampered due to many technical challenges with harvesting of biomass being the most energy intensive process among them. The fresh water microalgal species, Scenedesmus abundans, has been widely recognized as a potential feedstock for production of biodiesel (Mandotra et al., 2014). The present work deals with sedimentation of algal biomass using extracted chitosan and natural bentonite clay powder as flocculant. The effect of flocculant combination and different factors such as temperature, pH, and concentration of algal biomass on sedimentation rates has been analyzed. A high flocculation efficiency of 76.22 ± 7.81% was obtained at an algal biomass concentration of 1 ± 0.05 g/L for a settling time of 1 h at 50 ± 5°C with a settling velocity of 103.2 ± 0.6 cm/h and a maximum surface conductivity of 2,260 ± 2 μS/cm using an optimal design in response surface methodology (RSM). Biopolymer flocculant such as chitosan exhibited better adsorption property along with bentonite clay powder that reduced the settling time significantly.

Production of aromatic hydrocarbons from catalytic pyrolysis of lignin over acid-activated bentonite clay

Natural bentonite clay (mainly sodium-rich montmorillonite) both purified and acid activated using HCl, H2SO4, and H3PO4 acids were applied to the catalytic fast pyrolysis (CFP) of lignin. The modifications in crystalline structure and acidity of the activated clay were investigated via XRD, N2-adsorption-desorption, FTIR, TGA and NH3-TPD analysis. The activity and selectivity of the clays were evaluated for lignin conversion in down- flow micro reactor in the temperature range 500–650°0C in flowing Nitrogen (oxygen-free). The yields of high value added monocyclic aromatics such as BTX (benzene- toluene- xylenes) and naphthalene were increased by catalytic upgrading using HCl-activated bentonite clay. The selectivity for o&p-xylenes, naphthalene, and methyl naphthalene were greatly enhanced using HCl-activated bentonite in the temperature range 550–650°C. The catalyst: lignin ratio 3:1 and the nitrogen flow rate 75ml/min, at 600°C were the optimum conditions.

The Use of Eco-Friendly Catalyst in the Production of Ester

This study utilized an eco-friendly heterogeneous catalyst in the synthesis of ester via esterification of ethanol and acetic acid under refluxing conditions. The amount of acetic acid converted was determined by titrimetric method. Aluminum pillared material was produced from natural clay by ion exchange and calcined at 473 K. Powdered X-Ray diffraction (PXRD), Fourier Transform Infra-Red (FT-IR) and BET gas sorption analysis were employed to characterize the pillared material. The result revealed that significant improvement on physicochemical characteristics of the natural clay occurred as a result of pillaring. The results also revealed that the conversion of acetic acid was dependent on the catalyst/feed ratio of 2:2:1. The maximum conversion of acetic acid of 95.79% was obtained at the reaction temperature of 363 K and 150 minutes. The pillared clay material is more active in the conversion of acetic acid than the natural bentonite clay. This study illustrated that pillared bentonite clay is an eco-friendly solid catalyst for use in the production of chemical precursors for several industrial products.

INVESTIGATION OF THE EFFECT OF NATURAL NIGERIAN CALCIUM BENTONITE ON HAEMATOLOGICAL PARAMETERS OF WISTAR ALBINO RATS

Bentonite clay is widely distributed all over the world and it has been consistently used for its healing properties. In this study, the in vivo effect of natural Nigerian calcium bentonite clay on haematological parameters of wistar albino rat were investigated. The rats were fed for a total period of 28 days with varying concentrations of the bentonite clay. The haemoglobin count, packed cell volume, total white blood cell count, red blood cell count, platelet count, neutrophil and lymphocyte count were assayed. Test results showed that the bentonite had a lowering effect on haematological parameters studied in a concentration and time dependent manner with differences in concentration and time at 95 % confidence levels (P< 0.05). The highest decrease of 12.60 ± 0.36 vs control 14.35 ± 0.00 (g/dl) was obtained for Hb at the highest concentration of 0.07g at 28 days duration. PCV, WBC, RBC, platelet, neutrophil and lymphocyte analysis also showed highest decrease at 28 days duration at 0.07g/100g body weight. The results showed that using bentonite in small amounts for a short period of time had little effect. However, it is imperative that anyone intending to take large amounts of bentonite for long periods of time to undergo blood tests from time to time.

Adsorption of Congo Red by surfactant-impregnated bentonite clay

Due to an ever-changing climate and invasive foreign plant species increase, South Africa struggles with limited water resources. Water is important for the sustenance of all living organisms and it has to be protected. The development of different water treatment techniques becomes more popular to achieve efficient and cost-effective ways of removing contaminants from water. In this study, the property of bentonite clay was altered through impregnation with surfactants such as benzyltrimethylammonium chloride (BTMA), hexadecyltrimethylammonium bromide (HDTM) and tris(hydroxymethyl)aminomethane (THMA) and then used for the removal of the anionic dye, Congo Red (CR), from solutions. The characterization of the different clay samples was done with the use of X-ray diffractometer, X-ray fluorometer and FTIR spectroscopy. To determine the bentonite adsorption affinity the pseudo-first- and second-order kinetic models were used as well as the Langmuir- and Freundlich isotherm models. Other influencing factors that were tested include the effects of adsorbent dosage, initial dye concentration and contact time. The natural bentonite (NB) and bentonite impregnated with BTMA or THMA only adsorbed CR to a certain extent with an adsorption affinity of qe = 5.00 mg/g, qe = 1.87 mg/g and qe = 2.76 mg/g, respectively. The HDTM-impregnated bentonite performed very well in adsorbing CR with an adsorption affinity of qe = 16.04 mg/g. Evaluation of thermodynamic parameters such as ΔG° and ΔH° indicated that the adsorption process was thermodynamically favourable and endothermic in nature. HDTM can therefore be considered to improve the adsorption capacity of natural bentonite clay for the removal of an anionic dye such as CR.

Removal of cobalt(II) from aqueous solution by local Saudi bentonite: Kinetic and equilibrium investigations

Natural bentonite clay from Saudi Arabia was used to remove cobalt from aqueous solution. The clay samples were first characterized for their chemical composition and structure. Batch sorption studies were then conducted to assess their capacity to remove cobalt. The effect of contact time, initial analyte concentration, bentonite dose and temperature on the adsorption was investigated. The results showed that equilibrium was attained in 60 minutes. The metal adsorption was fitted to a Langmuir isotherm model and the maximum monolayer adsorption capacity was found to be 19.85 mg g−1 at 333 K. The pseudo-second-order kinetic model provided the best correlation to the experimental data. The application of an intra-particle diffusion model revealed that the adsorption mechanism of the cobalt ions is a rather complex process and that diffusion is involved in the overall rate of the adsorption process, but it is not the only rate-controlling step. The activation energy, Ea, ranged between 4.33 and 9.14 kJ mol−1, indicating a physical adsorption process.

Photophysical and adsorption properties of pyronin B in natural bentonite clay dispersion

The present study focused on the adsorption and photophysical properties of pyronin B (PyB) in bentonite aqueous dispersion. The photophysical properties of PyB in the aqueous dispersion were studied by using UV–vis absorption, steady-state and time-resolved fluorescence spectroscopy techniques. In this concept, the interaction of the dye with bentonite particles in the aqueous dispersion was spectroscopically followed depending on certain parameters such as interaction time, pH and the dye concentration. Obtained spectral data revealed that the aggregate structures (H-type) of PyB in the aqueous dispersion were formed in the dye concentration range studied. The non-fluorescence nature of H-aggregates and the clay minerals governed the fluorescence property of PyB. The mentioned non-radiative processes caused the fluorescence lifetime of the dye to decrease compared to that in water. The adsorption process of PyB on bentonite was examined depending on contact time and initial adsorbate concentration. An adsorption isotherm was good-fitted by the Freundlich model with a linear regression correlation value of 0.999. The adsorption of PyB on bentonite particles was in agreement with pseudo second-order kinetics.

Characterization of different types of bentonites and their applications as adsorbents of Co(II) and Ni(II)

In this research, the natural bentonite clays collected from different areas in Iran were utilized as adsorbent to study the removal behavior of different Iranian bentonitic clays vs. Ni(II) and Co(II) from their aqueous solutions. The original bentonite clays were characterized with the help of pH, Swell Index, Sediment Index, granulometric (screen) analysis, cation exchange capacity measurement, powder X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy dispersive atomic X-ray; Brunauer, Emmett, and Teller surface area measurements; and Barrett, Joyner, and Halenda pore size distribution analysis, Fourier transform infrared spectroscopy. While the thermal stability of the samples was studied using thermo gravimetry (TGA-DSC), adsorption experiments were conducted under some constant solution conditions and the removal of Co2+ and Ni2+ ions from their aqueous solutions was tested on various bentonite types and certain bentonite characteristics including pore size, surface properties, etc. The maximum adsorption of 92% took place on sample A1 in the removal process of Co2+ and Ni2+. The adsorption capacities followed the order of Co2+> Ni2+ in single-component systems for sample A2 and A3. The results showed the prevailing metal removal process was adsorption and cation exchange with the initiation in precipitation.

Hydration–dehydration behavior and thermodynamics of MX-80 montmorillonite studied using thermal analysis

The thermal dehydration of natural bentonite clay MX-80 chosen as a possible future backfill material, was investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The aim of this work is to provide a better understanding of the thermodynamics of the hydration–dehydration process of MX-80. The data obtained from thermogravimetry derivative curves at different relative humidities were used to determine the adsorption–desorption isotherm of MX-80. The total amount of water varies from 0.35 to 5.62 and from 0.78 to 6.12mol adsorbed H2O/mol of clay upon adsorption and desorption, respectively, for a RH between 11 and 91%. Furthermore, the heats released upon adsorption and desorption are not completely similar. Moreover, the analysis of DTA signals obtained at various hydration states provides insights about three types of water behavior in MX-80. Therefore, the surface area of DTA curves was taken into account to determine the dehydration enthalpy per mole of water; the values do not correlate with the amount of adsorbed water in MX-80, and the maximum enthalpy was approximately 12kJ/mol for the adsorption and desorption studies. The values obtained were combined with the standard enthalpies of the formation of liquid water to obtain the corresponding enthalpy of the formation of water relative to dehydrated MX-80.

Urban Wastewater Treatment by Adsorption of Organic Matters on Modified Bentonite by (Iron-Aluminum)

In this research, the natural bentonite clay (from Maghnia, western Algeria) was purified (Na+- montmorillonite, CEC = 91 meq/100 g), noted (puri.bent) and modified with mixed hydroxy-Fe-Al (FeAl-PILC). The purified bentonite clay and FeAl-PILC were heated at 383 K for 2 hr and characte-rized by the chemical analyses data, XRD, and N2 adsorption to 77 K techniques. Puri.bent and FeAl-PILC were applied to fix the organic matter (OM) present in urban wastewater from the city of Sidi Bel-Abbes (western Algeria). The adsorption of organic matter was followed by spectro-photometry at 470 nm, and the adsorption data were a good fit with Freundlich isotherm for pu-ri.bent but for FeA-lPILC, were well fit by Elovitch isotherm model. The maximum adsorption ca-pacity (qm) was 571.6 mg/g for puri.bent and 1120.69 mg/g for FeAl-PLC. The degree of OM removal was 67% for puri.bent and 97% for FeAl-PILC. FeAl-PILC can be considered as a promising adsorbent for the removal of OM from wastewater.

Swelling compositions based polycarboxylic acids and bentonite clays in solutions of salts of metals

This work is devoted to the synthesis of chemical cross-linked composite materials made of natural inorganic polymer bentonite clay of Manrak deposit, and polyacrylic and polymethacrylic acids. The swelling ability of the composition in solutions of salts of heavy metals (Ni2+ and Pb2+), influence of solution of concentration, pH and temperature on the swelling ability is investigated.

Kinetics and thermodynamics of Cr(VI) ion adsorption onto organo-bentonite from the Amazon region

A natural bentonite clay sample from the Amazon region (Amazonas State) was utilized for the synthesis of new hybrid materials (organo-bentonite) produced by the organofunctionalization process. The organo-bentonite types were composed of an Amazon bentonite sample, 3-aminopropyltrietoxisilane and 3,2-aminoethylaminopropyltrimetoxisilane. The natural bentonite and organo-bentonite samples were used in batch studies for the adsorption of Cr(VI) ions from aqueous solution. The adsorption data were fitted to equilibrium and kinetic models. The effects of stirring time, adsorbent dosage and pH on the adsorption capacity demonstrated that 90 min is sufficient to reach equilibrium at room temperature and over a pH range of 6.0–8.0, the batch results were confirmed by column method and show that the adsorption process of materials accorded with Redlich–Peterson, Sips, and Langmuir isotherm models. The exothermic enthalpic values reflected a favorable energetic process for chromium ions anchored in the material surfaces. The negative Gibbs free energy results supported the spontaneity of three adsorption reactions with Cr(VI) ions. The model of Adams–Bohart was used to analyze the adsorption experimental data and the model parameters were evaluated.

Organofilização de argilas bentoníticas com tensoativos não- iônicos visando seu uso em fluidos de perfuração base óleo

O uso de tensoativos não iônicos vem substituindo os tradicionais tensoativos iônicos dentre outros motivos pelo seu elevado potencial de resistência a degradação térmica. Assim, este trabalho tem por objetivo o desenvolvimento de argilas organofílicas através da incorporação de tensoativos não iônicos visando seu uso em fluidos de perfuração de poços de petróleo base óleo. Argilas bentoníticas natural, industrializadas e organofilizadas foram caracterizadas por análise química, difração de raios X e análises térmicas. Após a organofilização foi realizado o inchamento de Foster, visando a escolha dos tensoativos mais adequados aos meios líquidos orgânicos dispersantes: éster, diesel e parafina. Com as dispersões obtidas foram determinadas as propriedades reológicas através de viscosidades aparente e plástica. Os resultados evidenciaram que as argilas organofilicas apresentaram um aumento do espaçamento interlamelar e que as dispersões apresentaram propriedades reológicas dentro das especificações da Petrobrás, para uso como argilas organofílicas em fluidos de perfuração em base óleo.

Influence of Organophilization Process Variables in Bentonite Clays from Cubati-PB

This work aims at the development of organoclay from two varieties of bentonite for use in organic media using ionic surfactants, studying the influence of process variables in the organophilization process. We used the following materials: natural bentonite clay from Cubati-PB District, and the ionic quaternary ammonium salt: Praepagen WB® with 45% active matter. The clays were benefited and then turned into sodium form and subsequently into organoclays. The bentonites were characterized by laser diffraction (GA) X-ray fluorescence chemical composition (EDX), thermogravimetric analysis (TGA), thermogravimetry (DTA) and X-ray diffraction (XRD). The organoclays were characterized by (XRD) thermogravimetric analysis (TGA) and thermogravimetry (DTA). The results showed that the clay has potential for application in the organophilization process and that there is influence of process variables.

DEVELOPMENT AND EVALUATION OF NOVEL RADICAL-TRAPPING SHEETS COMPOSED MAINLY OF CLAY

The authors produced novel radical-trapping sheets mainly from an environmentally friendly material, natural bentonite clay. Using two identical radical-trapping reagents, their effectiveness was confirmed for high performance in active radical trapping. Radical-trapping sheets were prepared using casting from dispersion pastes including clay and radical-trapping reagents. Purified natural bentonite clay that had been treated by quaternary ammonium ions was used along with one of two radical-trapping reagents, a spin-trap reagent (α-phenyl-N-tert-butyl nitrone; PBN) or a radical-scavenging reagent (4-Oxo-2,2,6,6-tetramethylpiperidine 1-Oxyl; 4-Oxo-TEMPO·), yielding 40-μm-thick flexible self-standing sheets. The sheets' radical-trapping performance was investigated using electron spin resonance (ESR). Results confirmed the radical-trapping sheets' capability for capturing active radical species that were observed neither in the original radical trap reagents nor in the clay. The PBN spin-trapping sheet trapped hydroxyl radicals and hydroxyethyl radicals. The sheet provides long-term stabilization of radical species. The trapped radicals remained active more than one month after the trapping experiment. The 4-Oxo-TEMPO radical scavenging sheet also trapped both radicals. New basal-plane reflection was observed in the X-ray diffraction (XRD) pattern of the radical-trapping sheets, suggesting intercalation of radical-trapping reagents between the clay platelet crystals. These radical-trapping sheets might be applicable to packaging, catalytic sheets for radical reactions, and environmental analyses.

The molecular aggregation of pyronin Y in natural bentonite clay suspension

The molecular aggregation and spectroscopic properties of Pyronin Y (PyY) in the suspension containing natural bentonite clay were studied using molecular absorption, steady-state and time-resolved fluorescence spectroscopy techniques. Interaction between the clay particles and the cationic dye compounds in aqueous solution resulted in significant changes in spectral properties of PyY compared to its molecular behavior in deionized water at the same concentration. These changes were due to the formation of dimer and aggregate of PyY in the clay suspension as well as the presence of the dye monomer. The H-type aggregates of PyY in the clay suspension were identified by the observation of a blue-shifted absorption band of the dye compared to that of its monomer. In spite of diluted dye concentrations, the H-aggregate of PyY in the clay suspension was formed. The intensive aggregation in the clay suspension attributed to the localized high dye concentration on the negatively charged clay surfaces. Adsorption sites of PyY on the clay particles were discussed by deconvulated absorption and excitation spectra. Fluorescence spectroscopy studies revealed that the fluorescence intensity of PyY in the clay suspension is decreased by H-aggregates drastically. Moreover, the presence of H-aggregates in the clay suspension resulted in the decrease of fluorescence lifetime and quantum yield of PyY compared to those in deionized water.

Effect of natural bentonites on immune status of calves

The addition of natural bentonite clays to the ration has a positive effect on cellular and humoral immunity of calves. Effects in immunobiochemical homeostasis promoting an increase in the level of non-specific resistance of animals are revealed.

TiO 2/modified natural clay semiconductor as a potential electrode for natural dye-sensitized solar cell

TiO 2/modified natural bentonite clay semiconductor, as a potential electrode of dye-sensitized solar cell, having a Ti:Si molar ratio of 85:15 was, for the first time, compared with pure TiO 2 (commercial P25) electrode in terms of solar cell efficiency and characteristics. 4-Chloro-2,5-difluorobenzoic acid and 4-(chloromethyl)benzoyl chloride were added to the electrodes to increase light harvesting ability of natural dyes extracted from red cabbage, rosella, and blue pea. The results showed that the TiO 2/clay semiconductor provided a higher surface area but a slightly lower efficiency than the pure TiO 2. The best natural sensitizer was found to be the dye extracted from red cabbage. Besides, the 4-(chloromethyl)benzoyl chloride provided a higher short circuit current for the TiO 2/clay semiconductor.

Estudo do comportamento reológico das argilas bentoníticas de Cubati, Paraíba, Brasil

O estado da Paraíba possui jazidas de bentonitas utilizadas comercialmente para uma vasta gama de setores tecnológicos. No entanto, esses jazimentos estão se exaurindo, após dezenas de anos de exploração. Assim, este trabalho tem por objetivo dar prosseguimento à caracterização de argilas bentoníticas de Cubati, PB, estudando o comportamento reológico das dispersões argila-água de modo avaliar seu desempenho para fluidos de perfuração de poços de petróleo base água. As amostras estudadas foram secas a 60 ºC e determinou-se sua capacidade de troca de cátions. As argilas foram transformadas em sódica por tratamento com Na2CO3 e em seguida realizou-se o estudo do comportamento reológico das dispersões. As viscosidades, aparente e plástica, o volume de filtrado, os parâmetros reológicos do fluido e a sua força gel foram determinados. Os resultados evidenciaram que cada amostra apresenta um teor ótimo de carbonato de sódio e que as dispersões argila-água possuem um comportamento pseudo-plástico e tixotrópico. Duas amostras apresentam potencial para utilização como agentes viscosificantes para fluidos de perfuração.

Multi-scale study of permeability evolution of a bentonite clay owing to pollutant transport: Part I. Model derivation

This work deals with the modelling of permeability evolution of compacted natural bentonite clay owing to pollutant migration. The Homogenization of Periodic Media approach employed to derive the permeability tensor fully acknowledges the heterogeneous and multiscale microstructure of clay, as well as structural and textural changes induced by fixation of a metallic cation. In complementarity with existing experimental investigations of clay/metallic interaction, structural modifications that range from the nanometer scale to the micrometer scale have been accounted for and special attention is given to inter-aggregate porosity development. Consequently, three levels of description are considered: the microscopic level of clay particles, the mesoscopic level of clay aggregates, mineral grains and inter-aggregate porosity, and the macroscopic level of the sample subjected to permeability tests in the laboratory. Several cases are distinguished as inter-aggregate pores are not present within the compacted material before contaminant migration, while during macropores opening, inter-aggregate pores may form a connected flow path or remain occluded. For all three cases considered, starting from the local description of fluid flow, the expression of the effective permeability tensor is derived. The local problems to solve within the unit cells to obtain the macroscopic permeability are solved using the Finite Element Method. Numerical computations have allowed us to investigate the influence of several microstructural parameters, such as clay saturation, grain shape, macro-porosity in the connected and non connected configurations, eccentricity ratio for the non connected microstructures, threshold porosity for the connected microstructures.