Bentonite Powder Research Articles

The application of zeolite in thickeners for optimal water recovery and preventing environmental pollution

Thickener is the most important device that separates water from concentrate. Outlet water from thickener overflow must comply with the standards of transparency and the level of toxins. One way to reduce the hardness of water is ion replacement. In this paper we use the zeolite powder (coagulant) in combination with materials such as bentonite powder (coagulant aid), Fe C l 3 and poly aluminum chloride. If the settling time of particles in the deposition experiments was about an hour, this compound w as recorded as appropriate case for water purification. Results showed that polyaluminum chloride had the highest efficiency in removing turbidity and low color of the water. On the other hand, pH for coagulant was less effective in reducing alkalinity. Du e to cation exchange and high absorbing aqueous solution cations, such as ammonium and heavy metals, natural zeolite can be considered as an important material with low cost for water purification in a thickener. An interesting point is that the natural ze olite was not good adsorbent for organic and anionic ions. Bentonite as an adsorbent and heavier due to the high density and berry color properties and adsorption played an important role in clarifying water.

Pararosaniline and crystal violet tagged montmorillonite for latent fingerprint investigation

Use of cationic pigment-intercalated bentonite (montmorillonite, Mt) as the latent print development powder was investigated. The cationic dyes, crystal violet (CV) and pararosaniline (PS), were substituted with sodium ions present in the interlayers of Mt by ion exchange mechanism. Organophilic montmorillonites (OMts) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), elemental analysis and Fourier transform infrared spectroscopy (FTIR). TGA results determined the average amount of dye molecules in OMts as 52mmol/100g for both PS and CV. Modified bentonite powders were applied to develop fresh and aged (1, 7 and 15days) fingermarks deposited on non-porous surfaces such as glass, metal and porcelain using a fiberglass brush. Sharp and clear prints with complete ridge details were developed on glass and metal surfaces even for the 15-day-old fingermarks. Surprisingly, CV- and PS-intercalated fingerprint powders successfully worked for the development of the seven-month-old fingerprints on the glass surface. In contrast, physically mixed bentonite and dye mixtures were not very successful in the development of even fresh fingerprints on the glass surface. CV-tagged bentonite also exhibited strong fluorescence at around 500nm when excited at 450nm.

Manufacture of composite electrochemical materials from suspended electrolytes

New composite electrochemical materials on a metallic substrate synthesized from suspended electrolytes with additives of kaolin and bentonite powders of the nanosized fraction are studied. The limiting concentrations of the additives in the electrolyte that warrant the retention of the decorative and special properties of the microchromium coating are determined.

Synthesis and Characterization of Poly(acrylic acid)/PVP Modified Bentonite Superabsorbent Polymer

A novel superabsorbent composite has been prepared via aqueous solution polymerization of acrylic acid (AA) in the presence of PVP modified bentonite powder using N,N-methylenebisacrylamide (MBA) as a crosslinker and potassium persulfate (KPS) as an initiator. The amount of PVP modified bentonite in the superabsorbent affected on the ultimate water absorbency was optimized, and the swelling kinetics and water retention ability were systematically investigated. The composite structure was determined by Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric Analyzer (TG) and the scanning electron microscopy (SEM). The results indicate that the superabsorbents with PVP modified bentonite own superior water-swelling capability and water retention ability.

Study of bimacid dye removal from aqueous solution: a comparative study between adsorption on pozzolana, bentonite, and biosorption on immobilized anaerobic sulfate-reducer cells

The effluents emanating from industries such as paper, plastics, textile, and leather contain many dyes which are toxic and carcinogenic. The treatment of these effluents has become very important to reduce the potential toxicity of their pollutants and minimize their concentration prior to their discharge. This paper presents a comparative study between adsorption and biosorption processes for the red dye bimacid removal from aqueous solution. The experimental results show that the removal efficiency of the red bimacid using biosorption process which uses immobilized anaerobic sulfate-reducer cells onto a physical adsorbent is more significant (up to 91%) as compared to the adsorption process using bentonite and pozzolana powders. The kinetics of biosorption and the adsorption isotherms of the red dye bimacid on these materials showed great affinities to adsorbent-adsorbate. The pH of the aqueous solution influences positively the rate of the dye removal in the case of adsorption; however, it is a limiting factor in the case of biosorption.

Adsorption from n-heptane/benzene liquid mixture on acid leached bentonite powders

In this study, adsorption excess isotherms of n-heptane/benzene liquid mixture on hydrochloric acid leached bentonite powders were determined. Adsorptions were conducted at 25°C for 48h. Experimental results were evaluated with both Schay–Nagy (SN) and Everett (E) methods. Specific surface areas (SSN and SE) of the powders were calculated regarding monolayer adsorption capacity of the preferentially adsorbed benzene. Adsorption equilibrium constants (K≫1) were obtained by the E-method. The SE and SSN values are closed to each other. SE-values were found much lower than the corresponding Brunauer, Emmett and Teller (BET)-values. This difference was discussed with respect to the interaction of adsorbed molecules with solid surface, their collision diameter, molar cross sectional surface area and orientation in dense monolayer. Even the maximum for the SE was not associated with the maxima for K and nanopore volume (V), their values changed approximately parallel to each other with respect to the HCl% by the leaching.

Homogenization in clay barriers and seals: Two case studies

The paper presents two case studies that provide information on the process of homogenization of initially heterogeneous clay barriers and seals. The first case is the canister retrieval test performed in the Aspö Hard Rock Laboratory (Sweden). The heterogeneity arises from the use of a combination of blocks and pellets to construct the engineered barrier. The degree of homogenization achieved by the end of the tests is evaluated from data obtained during the dismantling of the test. To assist in the interpretation of the test, a fully coupled thermo-hydro-mechanical (THM) analysis has been carried out. The second case involves the shaft sealing test performed in the HADES underground research laboratory (URL) in Mol (Belgium). Here the seal is made up of a heterogeneous mixture of bentonite pellets and bentonite powders. In addition to the full scale test, the process of homogenization of the mixture has also been observed in the laboratory using X-ray tomography. Both field test and laboratory tests are successfully modelled by a coupled hydro-mechanical (HM) analysis using a double structure constitutive law. The paper concludes with some considerations on the capability of highly expansive materials to provide a significant degree of homogenization upon hydration.

Study on the Adsorption and Regeneration of Chloroacetic Acid on Polyacrylamide Bentonite Composite

Aiming at the removal of chlorinated disinfection by-products in water and the difficulty of separation of powder bentonite from water, the polyacrylamide bentonite composite was prepared and used as absorbent. The mechanism of adsorption and regeneration was discussed. The adsorption of chloroacetic acid on polyacrylamide bentonite composite followed Langmuir isothermal and Pseudo second order kinetic equation, and the adsorption capacity was 63.01mg/g at optimal temperature 30°C. The sorption heat were at the range of 9~16kJ/mol and decreased with the increase of temperature. It was indicated the adsorption mainly belonged to chemical adsorption, and the proportion of physical adsorption increased with the temperature increase. The thermodynamic parameters were ΔH0=-5.226kJ/mol, ΔG0=-27.753kJ/mol. These showed the adsorption was spontaneous and exothermal process. The composites were characterized by XRD and FT-IR. It was found the acrylamide intercalated in interlayer of bentonite and polymerized, then interacted with bentonite by hydrogen bonds. The d001 increased and decreased with adsorption and regeneration, the chloroacetic acid was considered to intercalate in the interlayer of polyacrylamide bentonite composite. The hydrogen bonds may exist between chloroacetic acid and CH2 groups. The polyacrylamide bentonite composite adsorbed chloroacetic acid could be regenerated by NaOH solution.

Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500°C can be reused for padding in stone blocks.

Preparation of PVC composite using reinforced Iraqi Bentoniet clay as a filler & study their mechanical and thermal properties

In this study , Iraqi Bentonite clay was used as a filler for polyvinyl chloride polymer. Bentonite clay was prepared as a powder for some certain particle size ,followed by calcinations process at (300,700,900) OC ,then milled and sieved. The selected sizes were D ~75 µm and D ~150. After that polyvinyl Al-Cohool solution prepared and used as a coated layer covered the Bentonite powder before applied as a filler ,followed by drying , milling and sieving for limited recommend sizes. polyvinyl chloride solutions were prepared and adding of modified Bentonite power at certain quantities were followed .Sheet of these variables on the mechanical and thermal properties of the prepared reinforced particular polyvinyl chloride composite Experimentally, it was found that the composite prepared by adding modified Iraqi Bentonite powder , that calcined at 700 oC as a filler have an advantage in heating insulator properties by 30 from that found for PVC as it is ,and the value of stress strength exceed by three times as that for original value.

Different methods for stabilisation of sand dunes using calcium bentonite

Sand dunes movement in the Arabian arid area hinder land development, expansion of city limits, and diversely affects rural roads, farms, irrigation, and grazing. Early attempts to curb sand movement used agriculture schemes required continuous supply of water; chemical treatment poses environmental concerns. Studies were conducted for sand dune fixation using agricultural and chemical means, but no concrete results to continue using them economically and environmentally were found. This paper is the summary of a study of the various methods of dealing with treatment of sand dunes by non-active bentonite in Saudi Arabia. The treatment, not only for surface, but in all directions, was done. This is due to the strong cohesion property of bentonite with granules of sand grains. In addition, this was a very simple use of raw bentonite which is widespread in most desert sediments. It was found that the best treatment method was the mixing and compacting with powder bentonite, by which the degree of improvement was attained 80 times more than the value before treatment.

Electrochemical behavior of H3PW12O40/ acid-activated bentonite powders

Electrochemical behavior of 12-tungstophosphoric acid (HPW)/acid-activated bentonite (AAB) powders with various loadings of HPW was investigated. The physicochemical properties of the prepared powders were examined by X-ray powder diffraction, nitrogen adsorption-desorption isotherms, atomic force microscopy and cyclic voltammetry measurements. The results indicated that the prepared powders are composed mainly of oriented domains of large rock blocks, probably resulting from a preferable deposition of bentonite particles having a face-to-face interaction. The particles had a mainly disordered mesoporous structure with a pore volume that varied according to the pore size in the range of 2-50 nm. In addition, the particles had crystallite size between 4.9 and 9.0 nm. The electrocatalytic activities of prepared HPW/Aelectrodes were studied in the oxidation of NO2-ions and the results revealed that the electrodes possessed relatively higher nitrite oxidation currents than Aelectrode. The best electroactivity was observed for HPW3/Aelectrode (AAB+20 wt. % HPW) and the limit of detection (3?) was determined as 8 ?M.

DEVELOPMENT OF PSEUDOMONAS FLUORESCENS AND BACILLUS COAGULANS BASED BIOFORMULATIONS USING ORGANIC AND INORGANIC CARRIERS AND EVALUATION OF THEIR INFLUENCE ON GROWTH PARAMETERS OF SUGAR BEET

ABSTRACT Use of plant growth promoting rhizobacteria (PGPR) can play important roles in developing sustainable systems for crop production. In search for efficient PGPR strains with multiple activities, we prepared eight bioformulations (BF) using two isolates of Pseudomonas fluorescens (B1) and Bacillus coagulans (B2) which were isolated from rhizospheric soil and plant roots in Iranian sugar beet fields. Carriers included talc and bentonite powders as inorganic carriers and peat and rice bran as organic carriers for increasing stability in interaction between associated PGPR and sugar beet plants. The efficacy of prepared bioformulations were then evaluated on promoting sugar beet seedlings growth characteristics including seedling height, seedling dry weight, seedling dry weight, root length and root weight, 60 days after sowing. Results indicated that above-mentioned growth characteristics except root length were significantly increased by all test BF but with different ratio. However, in the case of root length, 5 out of 8 BF (Peat-b1, Talc-b1, Talc-b2, R.B.-b1 and R.B.-b2) showed significant effectiveness in increasing seedling root length. The overall results of this study show that it may be possible to use PGPR based BF for promoting the health and growth of sugar beet.

Simultaneous determination of cation exchange capacity and surface area of acid activated bentonite powders by methylene blue sorption

To distinguish the ion exchanged and physically adsorbed methylene blue cations (MB+) on ionic surfaces, acid activated bentonite samples were used as porous adsorbents. A natural calcium bentonite (CaB) sample from Enez/Edirne, Turkey, was acid activated at 90°C for 16h with various HCl/CaB ratios. The irreversible exchange and physical adsorption of MB+ cations on the ionic solids have simultaneously occurred. The ion exchanged (mex) and physically adsorbed (mad) MB+ contents were obtained as the values of sorption capacity at c=0 and the increase to a plateaus of adsorption isotherms, respectively. The mad value was taken to be monolayer adsorption capacity. Cation exchange capacity (CEC) and specific surface area (SMB) for each sample were calculated from the mex and mad values, respectively. Also, the BET specific surface areas (SBET) and pore size distribution were determined from low temperature nitrogen adsorption/desorption data. A linear correlation between the SMB and SBET values was found.

Properties improvement of paper mill sludge-based granular activated carbon fillers for fluidized-bed bioreactor by bentonite (Na) added and acid washing

Properties improvement of paper mill sludge (PMS) based granular activated carbon fillers for fluidized-bed bioreactor (FBBR) was investigated in this study. Bentonite (Na) powders were blended in the dewatered paper mill sludge powders to strengthen the abrasion resistance strength of the fillers. Different acid washing treatments were studied to produce FBBR fillers with optimum performance. The results indicated that granulation was easy and the abrasion resistance strength of the fillers increased by 15% with 8wt% of bentonite (Na) added. Acid washing treatment prior to activation had a better effect on the removal of Fe than post-activation acid washing treatment. HCl was the most appropriate acid during the acid washing treatment. The optimum acid washing treatment was carried out prior to activation with 2M HCl soaking for 6h. After acid washing treatment, the fillers with grain density of 1170kg/m3, specific surface area of 176m2/g were obtained.

Hydromechanical behaviour of a heterogeneous compacted soil: experimental observations and modelling

The paper describes a theoretical and experimental study of the coupled hydromechanical behaviour of a compacted mixture of bentonite powder and bentonite pellets intended as sealing material in underground repositories for nuclear waste. One of the main advantages of the use of powder/pellets mixtures is the reduction of the compaction effort required to achieve the value of average dry density necessary to attain the required swelling potential. However, the heterogeneous fabric of the material requires special approaches in order to describe adequately its behaviour during hydration. A double porosity formulation is presented to account for the presence of two distinct structural levels in the material. Hydraulic equilibrium between the two porosities is not assumed; instead a water exchange term between them is postulated. The formulation is applied to the modelling of a number of one-dimensional swelling pressure tests performed in the CEA (Commisariat à l'Énergie Atomique, France) and CIEMAT (Spain) laboratories. A very satisfactory quantitative description of the experimental observations is obtained that includes a number of complex behaviour features such as size effects and non-monotonic development of swelling pressures. Some microfabric observations using X-ray tomography and mercury intrusion porosimetry lend support to the conceptual approach adopted. The formulation is then applied to the analysis of a long-term large-scale sealing test performed at the Hades underground facility in Belgium, using the same set of hydraulic and mechanical parameters employed in the modelling of the laboratory tests. Although the field observations exhibit a much higher degree of scatter, the basic behaviour of the field sealing test is satisfactorily simulated. A formulation that incorporates basic features of the microfabric of the mixture is thus able to span successfully over a large range of space and time scales.

Preparation and Properties of Carrageenan-g-Poly(Acrylic Acid)/Bentonite Superabsorbent Composite

A novel biopolymer-based superabsorbent hydrogel composite based on kappa-carrageenan (κC) have been prepared via graft copolymerization of acrylic acid (AA) in the presence of bentonite powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The hydrogel structure was confirmed using FTIR spectroscopy and the morphology of the samples was examined by scanning electron microscopy (SEM). The affecting variables onto graft polymerization (i.e. AA, MBA and APS concentration, as well as the bentonite amount) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The results of Brunauer–Emmett–Teller (BET) analysis showed that the average pore diameter of the synthesized hydrogel was 11.5 nm. The effect of various salt media and solutions with different pHs on the swelling of the superabsorbent was also studied.

COMPARISON BETWEEN BOTTOM AND SIDE INJECTION OF BENTONITE SLURRY IN TREATMENT OF SAND DUNES

Movement of sand dunes in the Arabian Peninsula hinder land development, expansion of city limits, and cause hazard in paved roads across arid areas. Population growth and environmental construction have been harmed by these sand dune blunders. Sand dunes stabilization has been the concerns of many government agencies and academic institutions. Many researches have contributed various methods to counter the sand dunes movement. Some of these researches have used agriculture scheme to attain stabilization. Such project requires continuous supply of water and needs several years to realize its objective. Lack of careful monitoring or a shortage of water supply would rapidly degrade the stabilization process, and sand dunes eventually bounce back to uncontrolled movement and desertification. Other researchers opted for chemical and polymers components as stabilization agents. It stabilizes only the top surface of the sand dunes. A moderate air draft/ gust of air would erode the top cover and thus frees the underneath sand dunes to move unrestrained/ uncontrolled. Additionally, using chemical and polymers components are not environmentally advocated. This research is a first part of competent research program studying different methods of sand dunes treatment using bentonite ore which are: mixing& compaction with bentonite powder and slurry; surface and subsurface spraying of bentonite slurry; bottom and side injection of bentonite slurry. This study has used the non- active calcium bentonite ore coming from khulais region, Saudi Arabia. This deposit has a very big reserve near to the surface and it is not used as commercial product until now and it is a natural clay deposit and has an ability to bind the sand grains and to conserve water for very long time. The stabilization process by this proposed method is not only on the surface of sand dunes but also to some depths from surface. That is to provide a relative thick bed on the sand dune surface that has the ability to resist wind blew and erosion. In addition, it is able to conserve water for very long time. This paper deals with the comparison between bottom and side injection of bentonite slurry in sand treatment. The method which used bottom injection gives some improvement in engineering properties of sand dunes. Their values increased to (3.5-4.0) times the original values compared with only (1.0-1.50) times the original values in the case of using side injection. These values have been obtained after 30 days of the treatment and using only 1% of bentonite concentration compared with 5 years after traditional treatments.

Analysis of colloids released from bentonite and crushed rock

Inorganic colloids are present in natural groundwater but colloids can also be produced from degraded Engineered Barrier System (EBS) materials. The potential relevance of colloids for radionuclide transport is highly dependent on the release and stability of colloids in different chemical environments and their interaction with radionuclides. In this work, release and stability of inorganic colloids were determined from bentonite and crushed rock which will be used in the tunnel back-fill. In the batch dispersion experiments, MX-80 bentonite powder or crushed rock samples of mica gneiss, unaltered and two altered tonalites were added to Milli-Q water, saline OLSO, and low salinity Allard reference water with adjusted pH values 7–9. After 4 months, pH, particle size distribution, zeta potential, morphology, elemental composition, and colloid concentration were analyzed. The release and stability of colloids depended significantly on groundwater salinity, pH, and the degree of alteration of the rock. In saline OLSO, zeta potential values near zero, wide particle size range, and low colloid concentrations indicated particle aggregation and instable colloidal dispersion. In low salinity Allard and Milli-Q water, high or moderate negative zeta potential values, smaller particle sizes, and higher colloid concentrations than in OLSO indicated the existence of stable colloids.

An investigation of the flocculation characteristics of polyacrylamide‐grafted chitosan

AbstractTo investigate the flocculation characteristics of polyacrylamide (PAM)‐grafted chitosan, a series of PAM‐grafted chitosan copolymer (Chito‐g‐PAM1 to Chito‐g‐PAM4) have been synthesized by ceric ammonium nitrate‐induced solution polymerization technique in nitrogen atmosphere. The flocculation characteristics of the polymer samples (PAM, grafted and ungrafted chitosan) were studied by settling test and jar test methods in the colloidal suspensions of kaolin, iron ore, silica, and bentonite powder. It was found that the settling performance of Chito‐g‐PAM3 is best among the polymer samples. The jar test results indicate that the ungrafted chitosan has better water clarifying performance than both the PAM and grafted chitosan. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009