The contamination of Fe2+ in groundwater is a problem that needs to be handled seriously as it can cause health problems for humans. In this study, the adsorption process method is conducted by use ...of natural bentonite from North Aceh. This process is expected to reduce Fe2+ as effectively as possible. The adsorption process is carried out by varying the contact time, adsorbent dose, and pH of the sample. The most effective contact time is obtained at 160 minutes, the adsorbent dose is 1 g/L and the pH of the sample is in neutral condition. With the initial concentration of metal in the sample solution of 20 mg/L, the adsorption process is able to remove 85.5% of Fe with the remaining Fe in the water of only 2.82 g/L.
In the present work, Chitosan/bentonite, Chitosan/Ag-bentonite and Chitosan/AgNPs-bentonite composite materials were prepared and shaped in form of beads, and characterized using several methods. ...After that, their thermal stability, swelling properties and antibacterial and antifungal activity were evaluated. In the case of Chitosan/AgNPs-bentonite, the XRD analysis confirms the partial intercalation of chitosan in the interlayer of bentonite and the formation of silver nanoparticles, AgNPs, with an average diameter between 10 and 25 nm. The latter is confirmed by UV–Visible diffuse reflectance spectroscopy by the apparition of the large absorption band at 442 nm. For all prepared materials, the FTIR analysis shows the presence of strong interaction between chitosan reactive groups and bentonite interlayer materials. This result is confirmed by thermal analysis where it is observed that these composite materials exhibit a higher thermal stability than the biopolymer alone. The composite materials present also a very good swelling capacity. Indeed, the swelling rate carried out in water media at pH 7 and a temperature of 30 °C is 160% higher than that of the corresponding dried material. Otherwise, Chitosan/AgNPs-bentonite sample displays a very high antibacteria
Pseudomonas aeruginosa
l activity against pathogen bacteria strains such as
Staphylococcus aureus
ATCC 25923 and ATCC 27853. This activity is less important for
S. aureus
ATCC 43300 and no activity is observed for
Escherichia coli
ATCC 25922 and
Candida albicans
ATCC 10231. Since the starting chitosan and bentonite materials showed no antibacterial or antifungal activity, the antibacterial activity of Chitosan/AgNPs-bentonite sample is attributed to loaded AgNPs species.
Graphic Abstract
This work highlighted the effective activation of bentonite paste to produce nano-porous powder for removal of cationic dye from wastewater. The effects of activation parameters such as soda and ...moisture contents, ageing time and temperature were analyzed using response surface methodology (RSM). The significance of independent variables and their interactions were tested by blending the obtained powders with wastewater and then the adsorption was evaluated, spectrophotometrically. The experiments were carried out by preparation of pastes according to response surface methodology and central composite design, which is the standard method, was used to evaluate the effects and interactions of four factors on the treatment efficiency. RSM was demonstrated as an appropriate approach for optimization of alkali activation. The optimal conditions obtained from the desirable responses were 5.0wt% soda and 45.0wt% moisture, respectively in which the powder activation was carried out at 150°C. In order to well understand the role of nano-structured material on dye removal, the adsorbents were characterized through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and Brunauer–Emmett–Teller surface area measurement. Finally, the analysis clearly demonstrates that the dye removal onto prepared adsorbent is well fitted with Langmuir isotherm compared to the other isotherm models. The low cost of material and facile process support the further development for commercial application purpose.
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•Bentonite paste was activated to produce nano-porous powder for dye removal.•The significance of variables was tested spectrophotometrically.•The effects of alkali activation factors were analyzed by response surface method.•The optimal conditions obtained from the desirable response statistically•The facile process supports the further development for commercial application.
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•Slurry composition has a decisive influence on clogging in fluid supported excavations.•Laboratory results of mixing test and model TBM cutter-head tests are presented.•Increased ...slurry strength may lead to increased clogging of tunnel boring machines.•Pure polymer slurries can combine high slurry resistance with low clogging potential.
Mechanized excavation of tunnels and fabrication of deep foundation elements in soft ground often requires a fluid support of the temporarily created openings. The supporting fluids are generally mixtures of bentonite with water, enhanced by chemical additives for difficult geological conditions. The properties of the slurries are chosen to guarantee the stability of the excavation, in particular providing sufficient support to the coarse grained soil layers. When these are interlaid with clayey layers, excavation can be hindered by clogging problems, requiring time consuming cleaning works and causing construction delays. Clogging is caused by the stickiness of the excavated clay, which can be affected both by the clay mineralogy and the composition of the supporting slurry. The paper investigates these effects by means of a laboratory experimental study using novel stickiness tests: the mixing test and a model TBM cutter-head test. For bentonite slurries, the stickiness of the excavated soil was found to correlate with the shear resistance of the slurry. Therefore, increased slurry strength, while beneficial for excavations in coarse soils, may lead to increased susceptibility to clogging under mixed face conditions. In contrast, some pure polymer slurries can help to combine high slurry resistance with low clogging potential by protecting clay aggregate surface from penetration of water.
There is global concern about the contamination of ground, river, and tap waters as well as soil contamination with heavy metal ions; these chemical species are known to not degrade and to cause ...severe health problems if ingested by humans and animals. Such environmental and health concerns necessitate the development of ultrasensitive sensors and high-capacity adsorbents. This study demonstrates for the first time the potential of organophilic bentonite combined with tetra(2-pyridylmethyl)amide calix 4 arene as a high-performance hybrid material for the removal of toxic heavy metals.
After consecutive synthesis steps, the modified bentonites were thoroughly characterized by FT-IR, XRD, UV spectroscopy, and TEM. In particular, the XRD analysis showed strong supporting evidence for intercalation in the clay following each modification step.
The salient feature of the newly prepared hybrid material is its high extraction capacity for Cd(II) and Zn(II) metals, as determined by atomic absorption spectrometry and UV spectrometry. Different preparation methods, with respect to the quantity of the added cationic surfactant, were investigated to determine the optimal conditions for synthesis. The extraction percentage for the as-prepared hybrid material was measured to be as high as 97.4% and 94.2% for Cd(II) and Zn(II), respectively.
•New material that uses bentonite as natural resource and active platform to immobilize the calix 4.•The calix 4 molecule as well as the surfactant C14 were intercalated inside the bentonite interlayer space.•The as prepared nanohybrids served to remove Zn2+ and Cd2+ from aqueous solution with high efficiency.
Abstract
Consumption of synthetic plastic made the level of plastic waste in the world become massive problem in environment. Biopolymer is an alternative which produced from renewable material with ...an abundant amount in the world. This study aimed to produce bioplastic materials based on chitosan and bentonite, with addition of urea. The method in this research consisted of bentonite preparation, synthesis bioplastics and characterization. Characterization in this research include FTIR, XRD, mechanical strength, and biodegradation. The result in this research showed that the addition of bentonite increased tensile strength of bioplastic. The more bentonite added in the bioplastic system, the higher tensile strength value. The addition of 0,1; 0,5; and 1 g bentonite made the tensile strength of bioplastic increased become 4.17; 4,28; and 4.90 MPa. Whereas the addition of 2 g bentonite decreased the tensile strength of bioplastic become 2.69 MPa, as the structure which formed in bioplastic was exfoliation which was strengthen from XRD pattern. Biodegradation test showed that bioplastic contained of 2 g bentonite has the fastest time to perfectly lose in the soil which only 12 days.
The potential of osmotic distillation (OD) and coupled operation of membrane distillation (MD) and OD processes (CO) for concentration of pomegranate juice was investigated comparatively with a view ...to the impact on product quality and process performance. The pomegranate juice (17° Bx) which was previously clarified by combined application of fining agents (gelatin and bentonite) and ultrafiltration (UF), was concentrated up to 55–57° Bx by OD, CO or thermal evaporation (TE). Both membrane-based concentration techniques were very efficient in preventing the original characteristics (pH, total titratable acidity (TTA), color characteristics, total antioxidant activity (TAA), total phenolic content (TPC), total monomeric anthocyanins (TMA), individual phenolics and organic acid composition) of the clarified juice. Concentration with TE, however, resulted considerable losses in natural color and TAA, and in a marked formation of hydroxymethyl furfural (HMF). CO was the most feasible approach for concentration of pomegranate juice, allowing to reach higher concentration levels in shorter periods of operation time with a slight increase (5°C) in temperature of the juice in comparison with OD. The results of this study highlighted the need for an effective pre-clarification step prior to UF to contribute to the improvement of the efficiency of the overall membrane-based system.
•OD and CO were very efficient in preventing the quality of the clarified PJ.•The CO was found to be very challenging to improve transmembrane flux.•The CO was the most promising approach to achieve high quality PJ concentrate.•TE resulted considerable losses in color and TAA, and in a marked formation of HMF.•Pre-flocculation step improved the efficiency of the overall membrane-based system.
Zero-valent iron synthesized using bentonite clay as a template (CZVI) was tested for its reactivity toward polychlorinated biphenyl (PCB) dechlorination in soil slurries. Aqueous-phase ...decachlorobiphenyl (PCB209) was rapidly dechlorinated by CZVI with a reaction rate 10 times greater than that by conventional nanoscale zerovalent iron. This superior reactivity was due largely to the nanoscale size (∼0.5 nm) of the ZVI particles located in the clay galleries. In soil slurries where PCB209 was strongly soil-bound, adding ethanol as an organic cosolvent led to increased PCB209 desorption into the liquid phase, thereby enhancing the PCB209 dechlorination with CZVI. The more effective PCB209 dechlorination in such a cosolvent system also promoted the subsequent stepwise dechlorinative process, leading to a relatively more removal of chlorine in the product mixture. The dechlorination became more rapid as the ethanol fraction increased from 10% to 50%, due apparently to the increasingly greater PCB209 desorption and thus facilitated contact with CZVI. Further increase in ethanol fraction above 50% led to an insignificant enhancement in degradation rate, due partially to attenuated contact of PCB209 with CZVI and reduced proton source from limited water content in the liquid. It is suggested that addition of organic cosolvents may make CZVI potentially useful for remediation of soils containing halogenated organic contaminants.
This paper presents a method for removing organic dyes by sorption and photocatalytic processes on a bentonite bed modified with ZnO-CuO nanocomposite. The effect of the initial dye concentration and ...temperature on the amount of dye removed from the solution was investigated. The results obtained at equilibrium state allowed us to determine the equilibrium and kinetic models and the thermodynamic parameters for the studied processes. The Langmuir isotherm is the best model for describing the equilibrium processes for both sorption and sorption with photocatalysis. In terms of kinetics, both processes are accurately described by the pseudo-second order model, which demonstrates the chemical nature of sorption. Due to the negative ΔG values calculated from the tests, it was found that the studied processes are spontaneous. It was possible to obtain a better degree of purification of the dye solution using combined sorption and photocatalysis compared to the sorption process itself.
•Studies of equilibrium, kinetic and thermodynamic models were carried out.•The best suited for sorption and photocatalysis is the Langmuir isotherm model.•The best suited kinetic model for processes was the pseudo-second order model.•The combined sorption and photocatalysis process is effective in removal of the dye.
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