Laboratory investigation of arsenic removal from the aquatic environment using nano adsorbents extracted from native zeolite

The presence of arsenic in water is a major problem in communities due to its toxicity and hazard. The aim of this study was to evaluate the removal efficiency of arsenic by CTAB-modified clinoptilolite zeolite from aqueous solution. The effect of contact time, pH, ionic strength, zeolite dose and CTAB concentration on arsenic removal were investigated. Structural analysis of XRD showed that the adsorbent used in this study was composed of clinoptilolite due to three strong peaks in 9.8, 22 and 27 degrees with intervals of 8.9, 3.9 and 3.1. Optimum condition for effective adsorption were obtained at pH = 3, zeolite dose of 5 g L–1, CTAB concentration of 5 mM, ionic strength of 0.1 M sodium chloride and contact time of 10 minutes. This study suggested that, the CTAB modified zeolite can be used as an effective and inexpensive adsorbent to remove arsenic from aqueous solutions, since it is a low-cost, abundant and locally available.

Synthesis of Hierarchical MOR-Type Zeolites with Improved Catalytic Properties

Hierarchical MOR-type zeolites were synthesized in the presence of hexadecyltrimethylammonium bromide (CTAB) as a porogen agent. XRD proved that the concentration of CTAB in the synthesis medium plays an essential role in forming pure hierarchical MOR-type material. Above a CTAB concentration of 0.04 mol·L−1, amorphous materials are observed. These hierarchical mordenite possess a higher porous volume compared to its counterpart conventional micrometer crystals. Nitrogen sorption showed the presence of mesoporosity for all mordenite samples synthesized in the presence of CTAB. The creation of mesopores due to the presence of CTAB in the synthesis medium does not occur at the expense of zeolite micropores. In addition, mesoporous volume and BET surface seem to increase upon the increase of CTAB concentration in the synthesis medium. The Si/Al ratio of the zeolite framework can be increased from 5.5 to 9.1 by halving the aluminum content present in the synthesis gel. These synthesized hierarchical MOR-type zeolites possess an improved catalytic activity for n-hexane cracking compared to large zeolite crystals obtained in the absence of CTAB.

Analysis of genetic diversity among different Rose (Rosa) genotypes using morphological and molecular markers (ISSR)

Rose is a woody perennial of the genus Rosa within the family Rosaceae. In this study, phylogenetic relationship among seven different genotypes of Rose (Rosa) was determined using ISSR primers and morphological parameters. DNA was isolated using CTAB method with 0.5% of CTAB concentration. Out of 50 ISSR primers, 16 primers gave reproducible banding pattern with all the seven genotypes of Rose while others failed to produce polymorphism. A total of 108 bands were obtained with an average polymorphism of 54.69% and an average of 9.06 bands per primer. The average similarity was found to be 0.69 among all the seven genotypes using Jaccard’s similarity coefficient. On basis of polymorphism cluster analysis divided them into two major groups separating one genotype (light pink) from rest of the six genotypes and principle coordinate analysis confirmed the results. A parallel correlation was found between the morphological parameter (flower diameter) and the results of ISSR analysis as both of them divided the seven genotypes into two main groups.

Micro-structure and mechanical properties of microcrystalline cellulose-sisal fiber reinforced cementitious composites developed using cetyltrimethylammonium bromide as the dispersing agent

This paper reports new hierarchical cementitious composites developed using microcrystalline cellulose (MCC), sisal fibers and cetyltrimethylammonium bromide (CTAB) as the dispersing agent. MCC was dispersed in water without and with CTAB at different concentrations using ultrasonication and the optimum CTAB concentration for achieving homogeneous and stable MCC suspensions was found to be 40%. Hierarchical composites were fabricated using MCC (0.1–1.5 wt% of cement), sisal fibers (20 mm, 0.25% and 0.50 wt% of cement), 40% CTAB and tri-butyl phosphate as the defoaming agent. Mechanical strengths of composites improved significantly at 0.1 wt% MCC, which along with 0.5% sisal fibers improved compressive and flexural strengths by ~ 24% and ~ 18%, respectively. The hybrid reinforcement exhibited a synergistic effect on the fracture behavior of composites improving the fracture energy up to 40%. Hierarchical composites also showed improved fiber-matrix bonding, lower porosity and water absorption, superior hydration, carbonation resistance and durability up to 90 ageing cycles.

Characterization of Nanostructured Mn-Zn Ferrites Synthesized by Coprecipitation Method Using CTAB

In this work it was investigated the influence of CTAB surfactant concentration on the synthesis of the compound Mn0.75Zn0.25Fe2O4 by the coprecipitation method. It was also compared the influence of hydrothermal treatment on the synthesized materials. The magnetic properties were characterized by AC susceptometry for the determination of the magnetic susceptibility and magnetic density energy. The phases, crystal structure and morphology of the nanoferrites were determined by Rietveld analysis of X-ray diffraction data. It was found the presence of two phases: Franklinite and Akaganeite and it was shown that the samples synthesized only by coprecipitation presented the tendency to increasing the crystallite sizes of the akaganeite phase and decreasing of crystallite sizes of the Franklinite phase as a function of CTAB concentration. The samples submitted to subsequent hydrothermal treatment presented a tendency to decreasing the crystallite sizes of both phases and increasing in Franklinite phase fraction, compared to the samples synthesized only by coprecipitation, suggesting that the hydrothermal treatment was effective in obtaining nanostructured materials of smaller particles.

Facile Cetyltrimethylammonium Bromide (CTAB)-assisted Synthesis of Calcium Bismuthate Nanoflakes with Solar Light Photocatalytic Performance

Background: Wastewater with dyes will pollute the environment and cause serious risk to human health and aquatic biota. Gentian violet (GV) belongs to typical triphenylmethane dyes and is difficult to be degraded. Calciumbismuthate nanoflakes possess good photocatalytic activity toward GV under solar lightirradiation. Objective: The aim is to prepare calcium bismuthate nanoflakes by the hydrothermal method and research the solar light photocatalytic performance of the calciumbismuthate nanoflakes for GV degradation. Methods: Calcium bismuthate nanoflakes were synthesized via a facile hydrothermal route assisted by cetyltrimethylammonium bromide(CTAB) based on the reaction of sodium bismuthate and calcium chloride. The calcium bismuthate products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy and solid UV-vis diffuse reflectance spectrum. Results: The calcium bismuthate nanoflakes possess single crystalline mono clinic CaBi2O4 phase. The size of the whole nanoflakes is about 10 μm and thickness of the nanoflakes is about 40 nm. The morphology, size and phase of the products are closely relative to CTAB concentration, reaction temperature and reaction time. The band gap of the calcium bismuthate nanoflakes is 2.21 eV. The photocatalytic activity of the calcium bismuthate nanoflakes is high enough to completely degrade GV under solar light irradiation for 6 h.

Preparation of magnetite-silica–cetyltrimethylammonium for phenol removal based on adsolubilization

In this study, we successfully coated cetyltrimethylammonium–silica on magnetite. The material produced is used to degrade phenol waste in the waters. The effect of the addition of cetyltrimethylammonium bromide (CTAB) on the ability of phenol adsorption was assessed through changes in CTAB concentration of 1, 5, and 10 mM. The results of Fourier-transform infrared spectroscopy explain that CTAB has electrostatic interactions with the silica surface, which is induced by opposite-loaded patches on the opposite surface of silica oxide. The results of the vibrating sample magnetometer show that the magnetite that has been coated by silica–CTA has magnetic properties that are weaker than the initial magnetite, which indicates that the silica–CTA layer has blocked the magnetite. Based on the measurement of the gas sorption analyzer, the largest pore size is in the micro-mesh region, which is between 2 and 6 nm. All magnetite-silica–cetyltrimethylammonium (MS–CTA) showed good adsorption ability of phenol and correlated with the amount of loaded CTAB and admicelle density of the adsorbent. The amount of phenol adsorbed increases proportionately with the increasing density of CTAB admicelles. The maximum phenol adsorption capacity (0.93 mg g−1 adsorbent) is achieved by MS–CTA prepared at a CTAB concentration of 10 mM.

Anionic Surfactant Sensing by Optical Properties of Erythrosin B

The nonlinear optical properties, absorbance and fluorescence spectra of Erythrosin B (ErB) aqueous solution in different CTAB concentration was studied. Z-scan technique under laser light excitation at 532 nm, was used for study reverse saturable absorption (RSA) of ErB. it was observed that the RSA of solution depend on CTAB concentration. A enhancing of absorbance and quenching of fluorescence is observed with increase of CTAB concentration in solution and the RSA can reduce the fluorescence intensity. It was proposed that the micelle can reduce the dye aggregation is solutions and it can affect on linear and nonlinear optical properties of ErB.