Bentonite Fillers Research Articles

Swelling pressure of natural and modified smectite-bearing clay raw materials

Smectite clays, due to their barrier properties and swelling ability, are often applied for waterproofing purposes. A proper value of swelling pressure is one of the parameters, which must be met by the fillers used in hybrid waterproofing materials. The authors determined the swelling pressure of selected clay raw materials in their natural state and after chemical modification. This parameter was measured by the Komine method, as this procedure is more accurate than the standard edometric method. The authors introduced some changes in the method. The samples represent Krakowiec clays (Miocene) and a Triassic clay, collected in active pits of building clays, which are widely exploited in south Poland. The content of the smectite group minerals, determined from the sorption of methylene blue and copper(II) triethylenetetramine, ranges between 15 and 35%. Further characteristics of the clays were obtained with X-ray diffraction, chemical analyses (calcium carbonate content including) and pH measurements. It has been found that the activation of smectite clays with sodium lowers their swelling pressure as water penetrates easier the interlayer spaces of the smectites modified. This is important from the viewpoint of assessing the quality of bentonite fillers.

Removal of congo red and methyl violet from water using nano clay filled composite hydrogels of poly acrylic acid and polyethylene glycol

Abstract Superabsorbent hydrogels were synthesized from polyethylene glycol (PEG) and crosslinked polyacrylic acid. Nano clay filled composite hydrogels were also synthesized by incorporating 0.5, 1.0 and 1.5 wt% nano size bentonite filler in the hydrogels. These hydrogels were characterized by FTIR, SEM, XRD, DTA–TGA, swelling and diffusion characteristics. The filled composite hydrogels showing the best result in swelling was further used for adsorption of congo red (CR) and methyl violet (MV) dye from water. The composite hydrogel showed high adsorption and removal% for these dyes for both low (2.5–50 mg/L) and high range (100–600 mg/L) of feed dye concentration. The dye adsorption data were fitted to different kinetics and adsorption isotherm models. The external mass transfer coefficient, diffusion coefficient and thermodynamic parameters of dye adsorption were also determined.

Separation of benzene–cyclohexane mixtures by filled blend membranes of carboxymethyl cellulose and sodium alginate

Blend membranes were prepared by solution blending of sodium alginate (SA) and sodium carboxymethyl cellulose (CMC) in water with varied compositions. One of the blend membranes containing 25% SA and 75% CMC was found to show optimum flux and benzene selectivity for 19.6wt% benzene in cyclohexane. This unfilled blend membrane designated as F0 was further filled with 2, 4, 6 and 8wt% organophilic bentonite filler to obtained four filled membranes designated as F2, F4, F6 and F8, respectively. These five (one unfilled and four filled) membranes were characterized by various conventional methods like FTIR, XRD, DTA (for unfilled blend membranes) and SEM (for filled membranes). These membranes were used for pervaporative separation of benzene from its mixtures with cyclohexane over the concentration range of 0.5–20wt% benzene. The filled F8 membrane showed lower flux (35.65kgμm/m2h) than the unfilled F0 membrane (77kgμm/m2h) but separation factor for benzene of the F8 membrane (212) was much higher than the F0 membrane (88.7).

Synthesis and characterization of biopolymer based mixed matrix membranes for pervaporative dehydration

Several blend membranes were prepared from different weight ratios of polyvinyl alcohol (PVA) and hydroxyethyl cellulose (HEC) and these unfilled membranes were crosslinked with maleic acid. In a similar way mixed matrix blend membranes were also prepared by varying weight ratio of PVA and HEC with micro and nano bentonite filler in each of these blends. These membranes were used for pervaporative dehydration of 89wt% tetrahydrofuran (THF). Three membranes designated as UF (unfilled), MF2 (containing 2wt% micro filler) and NF2 (containing 2wt% nano filler) showing the best results for flux and selectivity were identified. These membranes were characterized by FTIR, UV, XRD and DTA-TG and used for separation of 80–99wt% THF from water by pervaporation. The NF2 membrane was found to show the best results in terms of flux and separation factor.

Processability, and Determination of Some Mechanical and Thermal Prosperities of Filled and Unfilled Polypropylene / Polyamide 6 Blend

A new type of Bentonite filled PP/PA6 and red Kaolin filled PP/PA6 blends has been developed. It is Polypropylene and Polyamide 6 at constant ratio (80/20) and different weight fraction (0, 5, 10, and 15) % of both local Bentonite and Red Kaolin fillers were added respectively. Filled polymer blends were developed on a single screw extruder. Hardness, compression impact strength, and thermal stability of BN/PP/PA6 and RK /PP/PA6 blend system were determined at different temperatures, and different weight fraction of filler. The results shown hardness and compression increase while impact strength decrease with increase in weight fraction content. Also the results shown that thermal stability increases with increased weight fraction of filler. Bentonite filler produces better mechanical properties, than Red Kaolin fillers. Empirical equations are proposed and show a best fit with experimental data. Relevant contour diagrams, based on the proposed equations, for optimization of properties were also presented

Analysis of sorption and permeation of acetic acid–water mixtures through unfilled and filled blend membranes

A systematic method was employed for making blend membranes from two different hydrophilic polymers. Accordingly, blend membranes of polyvinyl alcohol (PVA) and sodium carboxy methyl cellulose (CMC) at three different wt ratio i.e. PVA:CMC wt ratio of 1:0.25, 1:0.5 and 1:0.75 were prepared. These blend membranes were designated as PC1, PC2 and PC3, respectively. Each of these membranes was crosslinked with 2wt% (of total polymer) maleic acid. These membranes were used for pervaporative (PV) separation of acetic acid–water mixtures at different feed compositions and temperatures. PC2 membrane showing optimum flux and water selectivity was further filled with 1, 2 and 3wt% (of total polymer) hydrophilic bentonite filler to produce three different filled membranes i.e. B1PC2, B2PC2 and B3PC2, respectively. These filled membranes were also used for separation of acetic acid–water mixtures. Both unfilled and filled membranes were characterized by FT-IR and UV spectroscopy, SEM, XRD, DSC and mechanical properties. Sorption of the membranes was analyzed by Flory–Huggins thermodynamics. Partial permeability of water and acid through the membranes were determined. Diffusion coefficient of permeants was also determined using a model based on free volume theory. Among these six membranes B2 PC2 membrane showed optimum performance in terms of flux and selectivity.

Beta Phase Formation of Polypropylene with Bentonite Filler

In this paper, a study on Polypropylene (PP)/bentonite composites is presented. PP/bentonite composites were prepared using 5%, 10% and 25% of concentration in weight of unmodified and modified bentonite filler. The relative leve! of the beta phase of the samples was calculated using Wide Angle X-ray Diffraction (WAXD). Differential scanning calorimeter (DSC) was used to observe the melting and crystallization behaviour of the samples. The dispersion state of the composites was observed using optical rnicroscopy. The obtained results show the possibility of inducing the beta phase in PP material using bentonite as filler. However, only the composites of polypropylene with modified bentonite showed the beta signa! and higher content was at 10% of filler. Although at 10% of modified bentonite the dispersion is worse than in 5%, at 10% there are more nucleating sites for beta phase formation and consequently more beta content. However, as concentration ofthe filler increases to 25%, the nucleating sites also increase but its dispersion into the compound becomes worse which strongly decreases the beta phase formation.

The Effect of Surface Treatment of Bentonite on the Mechanical Properties of Polypropylene–Bentonite Composites

Bentonite filler was treated with different surface modifiers such as cetyl trimethyl ammonium bromide (CTAB), polyoxyethylene sorbitan monooleate (Tween 60), and compared with oleic acid. Polypropylene (PP) composites were prepared by blending with untreated and treated bentonite. The mechanical properties of the prepared composites were evaluated. It was found that the treatment with CTAB caused more deterioration to the mechanical properties relative to oleic acid, while the treatment with Tween 60 helped to keep the tensile yield unaffected (at 1% w/w) and to delay the loss in the elongation up to 10 pph loading of the filler (at 0.1% w/w), in comparison with the oleic acid treatment.