Ionic liquid based periodic mesoporous organosilica: An efficient support for removal of sunset yellow from aqueous solutions under ultrasonic conditions

Magnetic Fe3O4 embedded chitosan-crosslinked-polyacrylamide composites with enhanced removal of food dye: Characterization, adsorption and mechanism

The water solubility in acid solution, relative low adsorption capacities and unsatisfactory separation performance limit application of traditional chitosan-based adsorbents in wastewater treatment. To break the limitation, a hydrophilic magnetic Fe₃O₄ embedded chitosan-crosslinked-polyacrylamide composites (abbreviated as m-CS-c-PAM) were prepared by a two-step method. The m-CS-c-PAM composites were systematically characterized using SEM, XRD, FTIR, VSM, TGA and BET. Sunset yellow (SY) was selected as model food dye to investigate adsorption kinetics and thermodynamic parameters of food dye adsorption onto m-CS-c-PAM. Compared with magnetic Fe₃O₄/chitosan, m-CS-c-PAM can adapt to a wider range of pH (2-10) and resist the presence of inorganic salts. m-CS-c-PAM was proved to have high adsorption capacity (359.71 mg g^-1) for SY dye at 298 K, much higher than magnetic Fe₃O₄/chitosan and many reported adsorbents. Moreover, m-CS-c-PAM could be rapidly and efficiently separated from treated solution within 15 s by an external magnet and regenerated by NaOH solution. With its excellent adsorption capacity, pH-independent adsorption capability for food dye, easy and convenient separation ability, satisfactory reusability, m-CS-c-PAM can be a promising material for food wastewater treatment.

Ionic liquid based composites: A versatile materials for remediation of aqueous environmental contaminants

Water pollution is one of the most aggravated problems threatening the sustainability of human race and other life forms due to the rapid pace of civilization and industrialization. A long history exists of release of hazardous pollutants into the water bodies due to selfish human activities since the Industrial Revolution, but no effort has been completely successful in curbing the activities that result in the degradation of our environment. These pollutants are harmful, carcinogenic and have adverse health effects to all forms of life. Thus, remarkable efforts have been geared up to obtain clean water by exploiting science and technology. The application of Ionic liquids (ILs) as sustainable materials have received widespread attention since the last decade. Their interesting properties, simplicity in operation and satisfactory binding capacities in elimination of the contaminants makes them a valuable prospect to be utilized in wastewater treatment. Immobilizing and grafting the solid supports with ILs have fetched efficient results to exploit their potential in the adsorptive removal processes. This review provides an understanding of the recent developments and outlines the possible utility of IL based nano adsorbents in the removal of organic compounds, dyes and heavy metal ions from aqueous medium. Effect of several parameters such as sorbent dosage, pH and temperature on the removal efficiency has also been discussed. Moreover, the adsorption isotherms, thermodynamics and mechanism are comprehensively studied. It is envisioned that the literature gathered in this article will guide the budding scientists to put their interest in this area of research in the days to come.

Ultrasonic assisted dispersive solid-phase microextraction of Eriochrome Cyanine R from water sample on ultrasonically synthesized lead (II) dioxide nanoparticles loaded on activated carbon: Experimental design methodology

The present research focus on designing an appropriate dispersive solid-phase microextraction (UA-DSPME) for preconcentration and determination of Eriochrome Cyanine R (ECR) in aqueous solutions with aid of sonication using lead (II) dioxide nanoparticles loaded on activated carbon (PbO-NPs-AC). This material was fully identified with XRD and SEM. Influence of pH, amounts of sorbent, type and volume of eluent, and sonication time on response properties were investigated and optimized by central composite design (CCD) combined with surface response methodology using STATISTICA. Among different solvents, dimethyl sulfoxide (DMSO) was selected as an efficient eluent, which its combination by present nanoparticles and application of ultrasound waves led to enhancement in mass transfer. The predicted maximum extraction (100%) under the optimum conditions of the process variables viz. pH 4.5, eluent 200μL, adsorbent dosage 2.5mg and 5min sonication was close to the experimental value (99.50%). at optimum conditions some experimental features like wide 5-2000ngmL^-1 ECR, low detection limit (0.43ngmL^-1, S/N=3:1) and good repeatability and reproducibility (relative standard deviation, <5.5%, n=12) indicate versatility in successful applicability of present method for real sample analysis. Investigation of accuracy by spiking known concentration of ECR over 200-600ngmL^-1 gave mean recoveries from 94.850% to 101.42% under optimal conditions. The procedure was also applied for the pre-concentration and subsequent determination of ECR in tap and waste waters.

Removal of sunset yellow FCF from aqueous solution using polyethyleneimine-modified MWCNTs

A novel adsorbent consisting of polyethyleneimine-modified multi-wall carbon nanotubes (PEI-MWCNTs) was synthesized by grafting PEI on the carboxyl MWCNTs. The surface properties of the PEI-MWCNTs were measured by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, and zeta potential. The adsorption behavior of the PEI-MWCNTs was investigated using sunset yellow FCF as adsorbate. The effects of dosage of adsorbent, the initial pH of solution, contact time and temperature on the adsorption capacity were studied. Then, the kinetics and thermodynamics of the adsorption process were further investigated. Experimental results showed that the adsorption kinetics fitted a pseudo-second-order model and the adsorption isotherms agreed well with the Langmuir model. The adsorption process occurred very fast and the adsorption capacity of PEI-MWCNTs was much higher than that of many of the previously reported adsorbents. Additionally, the plausible adsorption mechanism was discussed.

Characterization of the carbonaceous materials obtained from different agro-industrial wastes

This paper reports the preparation and characterization of carbonaceous materials obtained from three types of vegetable wastes provided by agricultural industries. Soft carbonization (280°C) and H3PO4-activation procedures were used to convert the agricultural wastes to carbon powders with high adsorbent capacities. This process is excellent for eliminating and exploiting the huge masses (many tons) of vegetable residues remaining after each harvest every year in several Colombian agro-industries. The powders were characterized by X-ray diffraction (XRD), IR spectroscopy, scanning electron microscopy (SEM), and N2-adsorption isotherms. XRD and IR verified the formation of carbons, and SEM showed small particles (20-500 µm) with characteristic morphology for each type of residue used and abundant cavities of different sizes. The N2-adsorption analyses showed that the carbons had high adsorption capacities with important surface area values and large pore volumes. The use of the activated carbonaceous materials as adsorbent of azo dyes (allura red and sunset yellow) from aqueous solutions was evaluated. The results showed a good adsorption capacity indicating the potentiality of these materials as pollutant adsorbents in food industry wastewaters. These results indicate that these powders can be used as potential adsorbents for different gaseous or liquid pollutants.

Temperature controlled ionic liquid-based dispersive micro-extraction using two ligands, for determination of aluminium in scalp hair samples of Alzheimer's patients: a multivariate study

A green and sensitive temperature controlled dispersive liquid-liquid microextraction (TIL-DLLME) methodology based on the application of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], as an extractant solvent was proposed for the preconcentration of trace levels of aluminium (Al(3+)) in scalp hair samples of Alzheimer's (AD) patients, prior to analyzing by flame atomic absorption spectrometry (FAAS). The Al(3+) was complexed with 8-hydrooxyquinoline (oxine) (L1) and 3,5,7,2'-4' pentahydroxy flavone (morin) (L2) separately and then extracted by IL at temperature (50±2.0°C). Some effective factors that influence the TIL-DLLME efficiency such as pH, ligands concentrations, volume of IL, ionic strength, and incubation time were investigated and optimized by multivariate analysis. In the optimum experimental conditions, the limit of detection (3s) and enhancement factor were 0.56 μg L(-1), 0.64 μg L(-1) and 85, 73 for both ligands, respectively. The relative standard deviation (RSD) for six replicate determinations of 100 μg L(-1) Al(3+) complexed with oxine and morin were found to be 3.88% and 4.74%, respectively. The developed method was validated by the analysis of certified reference material of human hair (NCSZC81002).and applied satisfactorily to the determination of Al(3+) in acid digested scalp hair samples of AD patients and healthy controls. The resulted data shows significant higher level in scalp hair samples of AD male patients with related to referents of same age and socioeconomic status.

Simultaneous ultrasonic-assisted removal of malachite green and safranin O by copper nanowires loaded on activated carbon: central composite design optimization

The present study investigates the simultaneous ultrasound-assisted adsorption of malachite green (MG) and safranin O (SO) dyes from aqueous solutions by ultrasound-assisted adsorption onto copper nanowires loaded on activated carbon (Cu-NWs-AC).