Photoluminescent Carbon Dot-Intercalated Bentonite: A Light Responsive Nanohybrid for Lead Removal

<p>This work describes the preparation of novel fluorescent bentonite clay (BP), modified with carbon quantum dots nanomaterials (CDs), and its usage as lead removal platform, the CDs was prepared using graphitic waste serving as carbon source material via hydrothermal method, and the as obtained CDs were found to be fluorescent, in spherical shape, positively charged and smaller than 5 nm. Encouraged by their structure and photoluminescence feature, they were used hereafter as intercalants or surface modifiers, in order to make fluorescent bentonite nanocomposites. Bentonite was used as negatively charged model of aluminosilicate and reacted with the positively charged CDs. Interestingly, CDs were found to intercalate bentonite as judged from XRD patterns, and TEM. Indeed, the basal distance of bentonite clay d(001) shifted from 1.2 nm to 2.9 nm, after bentonite modification using the prepared carbon dots; moreover the XRD pattern of BP-CDs recorded in the some regions show some additional diffraction peaks along with those for bentonite. The peaks centered at 2Ѳ =27 degree allocated to the facets of graphitic-like carbon, originated from the introduced carbon dots inside bentonite galleries. The prepared materials were characterized by XPS, FTIR and fluorescence analysis. The obtained results indicate that CDs were successfully intercalated inside bentonite matrix and found to be stable over time. The BP-CD nanocomposites were finally used as efficient hybrid platform for led removal with and extraction efficiently of 95% under light condition, room temperature under alkaline conditions and after only 10 min of reaction. </p>

Design of Fluorescent Bentonite/Carbon Dots Nanomaterial for Lead Removal

<p>This work describes the preparation of novel fluorescent bentonite clay (BP), modified with carbon quantum dots nanomaterials (CDs), and its usage as lead removal platform, the CDs was prepared using graphitic waste serving as carbon source material via hydrothermal method, and the as obtained CDs were found to be fluorescent, in spherical shape, positively charged and smaller than 5 nm. Encouraged by their structure and photoluminescence feature, they were used hereafter as intercalants or surface modifiers, in order to make fluorescent bentonite nanocomposites. Bentonite was used as negatively charged model of aluminosilicate and reacted with the positively charged CDs. Interestingly, CDs were found to intercalate bentonite as judged from XRD patterns, and TEM. Indeed, the basal distance of bentonite clay d(001) shifted from 1.2 nm to 2.9 nm, after bentonite modification using the prepared carbon dots; moreover the XRD pattern of BP-CDs recorded in the some regions show some additional diffraction peaks along with those for bentonite. The peaks centered at 2Ѳ =27 degree allocated to the facets of graphitic-like carbon, originated from the introduced carbon dots inside bentonite galleries. The prepared materials were characterized by XPS, FTIR and fluorescence analysis. The obtained results indicate that CDs were successfully intercalated inside bentonite matrix and found to be stable over time. The BP-CD nanocomposites were finally used as efficient hybrid platform for led removal with and extraction efficiently of 95% under light condition, room temperature under alkaline conditions and after only 10 min of reaction. </p>

Design of Fluorescent Bentonite/Carbon Dots Nanomaterial for Lead Removal

<p>This work describes the preparation of novel fluorescent bentonite clay (BP), modified with carbon quantum dots nanomaterials (CDs), and its usage as lead removal platform, the CDs was prepared using graphitic waste serving as carbon source material via hydrothermal method, and the as obtained CDs were found to be fluorescent, in spherical shape, positively charged and smaller than 5 nm. Encouraged by their structure and photoluminescence feature, they were used hereafter as intercalants or surface modifiers, in order to make fluorescent bentonite nanocomposites. Bentonite was used as negatively charged model of aluminosilicate and reacted with the positively charged CDs. Interestingly, CDs were found to intercalate bentonite as judged from XRD patterns, and TEM. Indeed, the basal distance of bentonite clay d(001) shifted from 1.2 nm to 2.9 nm, after bentonite modification using the prepared carbon dots; moreover the XRD pattern of BP-CDs recorded in the some regions show some additional diffraction peaks along with those for bentonite. The peaks centered at 2Ѳ =27 degree allocated to the facets of graphitic-like carbon, originated from the introduced carbon dots inside bentonite galleries. The prepared materials were characterized by XPS, FTIR and fluorescence analysis. The obtained results indicate that CDs were successfully intercalated inside bentonite matrix and found to be stable over time. The BP-CD nanocomposites were finally used as efficient hybrid platform for led removal with and extraction efficiently of 95% under light condition, room temperature under alkaline conditions and after only 10 min of reaction. </p>

New Attempts to Synthesize Layered Double Hydroxides Intercalated with SO4 2–/Cs+ Using Co-Precipitation and Exchange Reactions

Layered double hydroxides (LDHs) with the compositions (Cs+/NH4+)0.111[M2+0.667Al0.333(OH)2.0 (SO4)0.222] (M2+ = Mn, Zn) and basal distance of ca. 11 Å were obtained by co-precipitating Mn/Al and Zn/Al sulfate salts with aqueous NH3, using excess of Cs2SO4. [Mn0.667Al3+0.333(OH)2] Cl0.333 .nH2O and [M2+0.667Al3+0.333(OH)2](NO3)0.333 .nH2O (M2+ = Mn, Zn) were also synthesized by co-precipitation, presenting respective basal distances of 8.92 and 7.92 Å. After applying exchange reactions with excess of Cs2SO4, materials with basal distances of ca. 11 Å were obtained, indicating the exchange of chloride and nitrate with sulfate, without incorporation of Cs+. When Na+0.111[M2+0.667Al0.333(OH)2.0(SO4)0.222](M2+ = Mn, Zn) obtained by co-precipitation and having basal distances of ca. 11 Å was exchanged with excess of Cs2SO4, the content of sulfate remained constant and Na+ was partially replaced with Cs+, but the amount was lower, indicating the probable composition (Na+/Cs+)y[M2+0.667Al0.333(OH)2-y(SO4)y/2(SO4)0.222-(y/2)](M2+ = Mn, Zn), where some of the hydroxide anions were replaced with grafted SO42-.

Probing the Dehydroxylation of Kaolinite and Halloysite by In Situ High Temperature X-ray Diffraction

Textured kaolinite and halloysite-based materials were shaped by tape casting in order to promote the alignment of clay particles along the tape casting direction and to investigate the structure evolution of these phyllosilicates during the dehydroxylation process. The crystallinity indexes HI and R2 of the starting kaolins (KRG and KCS) were determined and appeared close to values found for the well-ordered reference kaolin KGa-1b. The halloysite clay exhibited trimodal grain size distribution and tended to be less textured than KRG and KCS according to the (002) pole figures performed on green tapes. The constant heating rate derived kinetic parameters matched the expected range. We followed the dehydroxylation of kaolinite and halloysite through in situ high-temperature X-ray diffraction measurements at the ESRF synchrotron radiation source on the D2AM beamline. The dehydroxylation of these kaolinite and halloysite occurred between 425 °C and 675 °C for KRG and KCS and from 500 °C to 650 °C for halloysite. In addition, the evolution of the basal distance of kaolinite regarding the heat treatment temperature confirmed that the dehydroxylation process occurred in three steps: delamination, dehydroxylation, and formation of metakaolinite. The calculated coefficient of thermal expansion (CTE) along the c axe values were close to 17 × 10−6 °C−1 for kaolinite (KCS and KRG) and 14 × 10−6 °C−1 for halloysite.

Influence of Content and Treatment of Clay in the Morphology of PES Membranes

Polymeric membranes were produced from the nanocomposites of polyethersulfone and clay (untreated-MMT and treatment-OMMT), by phase inversion technique, in the proportions of 3 and 5% w/w, using as the solvent N, N dimethylformamide (DMF). From XRD results it was noted a change in the structure of the MMT by organophilization process with increase of the interplanar basal distance. To the membranes it was observed an exfoliated and/or partially exfoliated structure. From SEM images the nanocomposite membranes showed a surface apparently exempt of pores, however in the cross-section images shows an anisotropic structure, where the skin is dense and the porous support displays macrovoids. By the flow measurement, it was found that the compositions presented the same tendency in the flow lines, where the flow is high on the beginning and drops over time; and the inclusion of clay increases the flow, especially to the membranes with MMT 5%.

Evaluation of a Sodic Organoclay as Adsorbent for Removing Oil/Water in a Synthetic Wastewater

This study aims to conduct an investigation on the performance of an organophilic clay as adsorbent in the oil/water separation process. One goal of this work is to prepare and characterize untreated sodium clay (BSN-01) from Argentina and treated BSN-01. The method used to prepare the organoclay replaces the interlayer cations of the clay (Na+) by quaternary ammonium cations. Tests used X-ray diffraction to verify the obtaining of organoclays. The diffractograms showed that the basal distance of the clay BSN-01 was modified, indicating that the quaternary ammonium salt was intercalated. The results of Cation Exchange Capacity suggested that the interlayer cations of the clay were exchanged with the quaternary cations of the surfactant. Finite bath tests determined the rate and capacity of oil removal by the treated clay. Up to 42.63 mg/g of oil removal capacity (92.34% efficiency) was reached, indicating that the clay treated with CTAC is an excellent alternative in the process of oil removal.

Thermal Analysis of Coal-Bearing Strata Kaolinite/potassium Acetate Intercalation Complex

The thermal decomposition of coal-bearing strata kaolinite-potassium acetate(CK/KAc) intercalation complex has been studied using X-ray diffraction (XRD), thermogravimetry and differential thermogravimetric (TG-DTG) and infrared emission spectroscopy (IES). The XRD results show that the KAc has been successfully intercalated into coal-bearing strata kaolinite with an obvious basal distance increase of the first basal peak. The TG results show that the thermal decomposition of the intercalation complex occurs in four main steps (a) the loss of adsorbed water (b) the loss of coordination water (c) the loss of potassium acetate and (d) water through dehydroxylation. The IES of CK/KAc give the evidence on the changes of structure. These make all explanation have the sufficient evidence.

Preparation of PEO/Clay Nanocomposites Using Organoclay Produced via Micellar Adsorption of CTAB

The aim of this study was the preparation of polyethylene oxide (PEO)/clay nanocomposites using organoclay produced via micellar adsorption of cethyltrimethyl ammonium bromide (CTAB) and their characterisation by X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra, and the investigation of certain mechanical properties of the composites. The results show that the basal distance between the layers increased with the increasing CTAB/clay ratio as parallel with the zeta potential values of particles. By considering the aggregation number of CTAB micelles and interlayer distances of organo-clay, it could be suggested that the predominant micelle geometry at lower CTAB/clay ratios is an ellipsoidal oblate, whereas, at higher CTAB/clay ratios, sphere-ellipsoid transition occurs. The increasing tendency of the exfoliation degree with an increase in clay content may be attributed to easier diffusion of PEO chains to interlayer regions. FT-IR spectra show that the intensity of Si-O stretching vibrations of the organoclays (1050 cm−1) increased, especially in the ratios of 1.0 g/g clay and 1.5 g/g clay with the increasing CTAB content. It was observed that the mechanical properties of the composites are dependent on both the CTAB/clay ratios and clay content of the composites.

Synthesis and characterization of organic–inorganic poly(3,4-ethylenedioxythiophene)/MoS2 nanocomposite via in situ oxidative polymerization

Here we demonstrate the synthesis of a new type of layered poly(3,4-ethylenedioxy- thiophene) (PEDOT)/MoS2 nanocomposite via flocculation of delaminated MoS2 with subsequent in situ oxidative polymerization of 3,4-ethylenedioxythiophene. The resulting nanocomposite was characterized by Fourier transform infrared spectroscopy, powder x-ray diffraction, x-ray photoelectron spectroscopy, thermal analysis, transmission electron microscopy, and four-probe electrical conductivity measurements with respect to temperature. X-ray diffraction results indicated that the exfoliated MoS2 and PEDOT are restacked to produce a novel nanoscale composite material containing alternate nanoribbons of PEDOT in between MoS2 with a basal distance of ∼1.38 nm. The nanocomposite, which could be used as a cathode material for small power rechargeable lithium batteries, has also been demonstrated by the electrochemical insertion of lithium into the PEDOT/MoS2 nanocomposite, where a significant enhancement in the discharge capacity is observed, compared to that of respective pristine molybdenum disulfide.