Removal of aniline from aqueous solution by PVC-CDAE ligand-exchanger

A highly efficient cathode based on modified graphite felt for aniline degradation by electro-Fenton

The graphite felt (GF) was modified through the concentrated sulfuric acid, potassium permanganate and ammonia activation with the aim of improving the specific surface area, hydrophilicity and the electrocatalytic activity for the electrogeneration of hydrogen peroxide and its application in the electro-Fenton (EF). The modified graphite felt (M-GF) was characterized by contact angle, scanning electron microscope, X-ray photoelectron spectroscopy, Raman spectrum, cyclic voltammetry and electrochemical impedance spectroscopy. The surface physic-chemical characteristics and morphology of the M-GF were considerably changed after the modification. The current efficiency for H₂O₂ generation was explored at an optimized current density of 10 mA cm^-2 and the value of H₂O₂ generation for the M-GF was 478.6 mg L^-1, while the GF was 276.5 mg L^-1 after 360 min of electrolysis. Finally, the M-GF was used for the mineralization of aniline (100 mg L^-1), reaching a mineralization percentage of 97% with EF process. The M-GF demonstrated good stability as the aniline mineralization percentage was above 90% after 10 cycles' degradation, indicating that the M-GF is a promising cathode material for improving the degradation and mineralization of others organic pollutants by the EF process.

A novel poly ligand exchanger - Cu(II)-loaded chelating resin for the removal of ammonia-nitrogen in aqueous solutions

In this paper, a poly ligand exchanger, Cu(II)-loaded chelating resin bearing the functional group of weak iminodiacetate acid was prepared to efficiently remove ammonia from solutions. Batch adsorption equilibrium experiments were conducted under a range of conditions to determine the optimum adsorption conditions. The effects of contact time, pH, resin dosage and temperature on the removal of ammonia by a Cu(II)-loaded resin were determined. The maximum removal efficiency was reached at pH 9.5 at room temperature, 25°C, in 300 min. The maximum ammonia adsorption capacity was found to be 45.66 mg/L. The maximum adsorption capacities decreased with the increasing of solution temperature. Langmuir, Freundlich and Temkin isotherm models were used for fitting the adsorption experimental data without competing ions and the Langmuir isotherm model was proved to be the best-fitting model by comparing the corresponding correlation coefficients (R²) of the listed models. The effect of competing ions Na⁺ and Ca²⁺ on the adsorption of the Cu(II)-loaded resin for ammonia was investigated. The results showed that the existing of competing ions had a negative effect on the ammonia removal. The adsorption capacities decreased with the increasing concentration of competing ions. The Langmuir isotherm model was used to fit the experimental data and proved efficient. The existing of competing ions in solutions was unfavorable for ammonia adsorption and the weakening effect of bivalent Ca²⁺ was stronger than the monovalent Na⁺. The ammonia adsorption capacity was relatively high compared with other ammonia adsorbents and the Cu(II)-loaded resin was an economically feasible and promising technology for ammonia removal.

Removal of ammonia from aqueous solutions by ligand exchange onto a Cu(ii)-loaded chelating resin: kinetics, equilibrium and thermodynamics

A poly ligand exchanger (PLE), Cu(ii)-loaded chelating resin (ammonia adsorption reagent, named AMAR) was prepared to efficiently remove ammonia from solutions by ligand exchange.

Electrochemical reduction of nitroaromatic compounds by single sheet iron oxide coated electrodes

Nitroaromatic compounds are substantial hazard to the environment and to the supply of clean drinking water. We report here the successful reduction of nitroaromatic compounds by use of iron oxide coated electrodes, and demonstrate that single sheet iron oxides formed from layered iron(II)-iron(III) hydroxides have unusual electrocatalytic reactivity. Electrodes were produced by coating of single sheet iron oxides on indium tin oxide electrodes. A reduction current density of 10 to 30μAcm(-2) was observed in stirred aqueous solution at pH 7 with concentrations of 25 to 400μM of the nitroaromatic compound at a potential of -0.7V vs. SHE. Fast mass transfer favors the initial reduction of the nitroaromatic compound which is well explained by a diffusion layer model. Reduction was found to comprise two consecutive reactions: a fast four-electron first-order reduction of the nitro-group to the hydroxylamine-intermediate (rate constant=0.28h(-1)) followed by a slower two-electron zero-order reduction resulting in the final amino product (rate constant=6.9μM h(-1)). The zero-order of the latter reduction was attributed to saturation of the electrode surface with hydroxylamine-intermediates which have a more negative half-wave potential than the parent compound. For reduction of nitroaromatic compounds, the SSI electrode is found superior to metal electrodes due to low cost and high stability, and superior to carbon-based electrodes in terms of high coulombic efficiency and low over potential.

Extraction of aniline from wastewater: equilibria, model, and fitting of apparent extraction equilibrium constants

Reactive extraction complexes of aniline to D2EHPA or P507 in various diluents are obtained by the fitting equilibrium models presented.

Kinetics of Diffusion-Controlled Adsorption of Adenine and Adenosine in a Carboxymethyl Diaminoethane Pvc-Mediated Column System

The adsorption kinetics of adenine and adenosine on a ligand-exchange matrix, carboxymethyl diaminoethane poly(vinyl chloride) in cobalt form (cobalt-CMEDA-PVC), have been studied in a fixed-bed column system. The initial ligand concentrations ranged between 1.25×10−5 and 2.0×10−4 mol L−1. The kinetic studies were carried out spectrophotometrically, in order to determine the ratecontrolling step of the adsorption. The kinetic data of the single-component systems were acquired from the breakthrough curves of the ligands on the basis of the equivalent points method. In this study, the homogeneous diffusion model was adapted to a fixed-bed column system to describe the differentiation in the ligand concentration of the effluent, beginning from breakthrough point as a function of time. The results obtained for the adsorption kinetics indicated that the diffusion step plays a significant role in the adsorption kinetics of the ligands, due to the fact that the adsorption performance was strongly affected by the initial concentration of ligands.

Equilibrium and kinetics of aniline adsorption onto crosslinked sawdust-cyclodextrin polymers

Equilibrium and kinetic studies of aniline adsorption onto crosslinked sawdust-cyclodextrin polymers.

Synthesis and properties of Fe3O4-activated carbon magnetic nanoparticles for removal of aniline from aqueous solution: equilibrium, kinetic and thermodynamic studies

In this study, powder activated carbon (PAC) and magnetic nanoparticles of iron (III) oxide were used for synthesis of Fe₃O₄-activated carbon magnetic nanoparticles (AC-Fe₃O₄ MNPs) as an adsorbent for the removal of aniline. The characteristics of adsorbent were evaluated by SEM, TEM, XRD and BET. Also, the impact of different parameters such as pH, contact time, adsorbent dosage, aniline initials concentration and solution temperature were studied. The experimental data investigated by Langmuir and Freundlich adsorption isotherms and two models kinetically of pseudo first-order and pseudo second-order. The results indicated that the adsorption followed Langmuir and pseudo second-order models with correlation r² > 0.98 and r² > 0.99, respectively. The equilibrium time was obtained after 5 h. According to Langmuir model, the maximum adsorption capacity was 90.91 mg/g at pH = 6, and 20°C. The thermodynamic parameters indicated that adsorption of aniline on magnetic activated carbon was exothermic and spontaneous. This synthesized AC-Fe₃O₄ MNPs due to have advantages such as easy and rapid separation from solution could be applied as an adsorbent effective for removal of pollutants such as aniline from water and wastewater.

Wet air oxidation of pretreatment of pharmaceutical wastewater by Cu2+ and [PxWmOy]q- co-catalyst system

This study concentrates on the pretreatment of real wastewater using catalytic wet air oxidation (CWAO). WO(3-) and PO(4)(3-) contained in fosfomycin pharmaceutical wastewater (FPW) and Cu(2+) contained in berberine pharmaceutical wastewater (BPW) were studied as CWAO influent. Mixture of this two streams were reused to form Cu(2+) and [P(x)W(m)O(y)](q-), namely polyoxometalates (POMs) as co-catalyst system to treat themselves. Experiments were conducted to investigate the effects of the initial oxygen pressure and temperature on the COD (chemical oxygen demand), TOC (total organic carbon) removal and biodegradable enhancement, it was discovered that over 40% of COD and TOC removal can be easily realized in an hour of WAO oxidation at 523 K, 1.4 MPa. The BOD(5)/COD (BOD(5), biochemical oxygen demand in 5 days) of this two pharmaceutical mixture ascended from nonexistent to maximum 0.41 depends on the optimal FPW:BPW volume ratio 4:1, to compose POM co-catalyst system. Organic pollutants were incompletely oxidized to propionic acid and other intermediates. Some properties (e.g., TGA, IR, XRF) of POM catalyst separated from effluent, were obtained to provide additional information.

Mesoporous aluminosilica monoliths for the adsorptive removal of small organic pollutants

Water treatment for the removal of organic or inorganic pollutants has become a serious global issue because of the increasing demand for public health awareness and environmental quality. The current paper, reports the applicability of mesoporous aluminosilica monoliths with three-dimensional structures and aluminum contents with 19≤Si/Al≥1 as effective adsorbents of organic molecules from an aqueous solution. Mesocage cubic Pm3n aluminosilica monoliths were successfully fabricated using a simple, reproducible, and direct synthesis. The acidity of the monoliths significantly increased with increasing amounts of aluminum species in the silica pore framework walls. The batch adsorption of the organic pollutants onto (10 g/L) aluminosilica monoliths was performed in an aqueous solution at various temperatures. These adsorbents exhibit efficient removal of organic pollutants (e.g., aniline, p-chloroaniline, o-aminophenol, and p-nitroaniline) of up to 90% within a short period (in the order of minutes). In terms of proximity adsorption, the functional acid sites and the condensed and rigid monoliths with tunable periodic scaffolds of the cubic mesocages are useful in providing easy-to-use removal assays for organic compounds and reusable adsorbents without any mesostructural damage, even under chemical treatment for a number of repeated cycles.

Effect of template in MCM-41 on the adsorption of aniline from aqueous solution

The effect of the surfactant template cetyltrimethylammonium bromide (CTAB) in MCM-41 on the adsorption of aniline was investigated. Various MCM-41 samples were prepared by controlling template removal using an extraction method. The samples were then used as adsorbents for the removal of aniline from aqueous solution. The results showed that the MCM-41 samples with the template partially removed (denoted as C-MCM-41) exhibited better adsorption performance than MCM-41 with the template completely removed (denoted as MCM-41). The reason for this difference may be that the C-MCM-41 samples had stronger hydrophobic properties and selectivity for aniline because of the presence of the template. The porosity and cationic sites generated by the template play an important role in the adsorption process. The optimal adsorbent with moderate template was achieved by changing the ratio of extractant; it has the potential for promising applications in the field of water pollution control.

Adsorption property and mechanism of composite adsorbent PMAA/SiO2 for aniline

In this paper, functional monomer methacrylic acid (MAA) was grafted onto the surface of silica gel particles using 3-methacryloxypropyl trimethoxysilane (MPS) as intermedia, and grafting particles PMAA/SiO(2) were prepared. The adsorption properties and mechanism of PMAA/SiO(2) towards aniline were researched through batch and column adsorption methods. The experimental results showed that PMAA/SiO(2) possesses strong adsorption ability for aniline with interaction of hydrogen bond. The saturated adsorption amount could reach up to 140 mg g(-1). The empirical Langmuir isotherm was found to agree well with the equilibrium adsorption data. pH and temperature were found to have great influence on the adsorption amount. Finally, PMAA/SiO(2) was observed to possess excellent reusability properties as well.

Comparative study of polymer containing beta-cyclodextrin and -COOH for adsorption toward aniline, 1-naphthylamine and methylene blue

Three different polymers P1, P2 and P3 (P1 containing both beta-CD and -COOH, P2 containing beta-CD and P3 containing -COOH) were synthesized and applied to adsorption toward aniline, 1-naphthylamine and methylene blue. The concentrations (C) before and after adsorption were determined and the adsorption capacities (q) of P1, P2 and P3 were calculated. The maximum adsorption capacities (q(max)) toward aniline: q(max) (P1)=104 micromol g(-1), q(max) (P2)=14.9 micromol g(-1) and q(max) (P3)=53.1 micromol g(-1); toward 1-naphthylamine: q(max) (P1)=184 micromol g(-1), q(max) (P2)=53.8 micromol g(-1) and q(max) (P3)=125 micromol g(-1); toward methylene blue: q(max) (P1)=200 micromol g(-1), q(max) (P2)=12.7 micromol g(-1) and q(max) (P3)=215 micromol g(-1). P1 exhibited remarkable adsorption toward all the three adsorbates. P2 was almost equal to P1 in adsorption toward methylene blue, but was less efficient than P1 in adsorption toward aniline and 1-naphthylamine. P3 also exhibited considerable adsorption toward aniline and 1-naphthylamine, but was inefficient toward methylene blue. P1 was obtained from nontoxic materials and through environment friendly procedures, so it was potentially an efficient and green adsorbent for water purification.

Computational design and synthesis of molecular imprinted polymers with high selectivity for removal of aniline from contaminated water

A computational approach was developed to screening functional monomers and polymerization solvents for rational design of molecularly imprinted polymer (MIP). It was based on the comparison of the binding energy of the complexes between the template and different functional monomers. The effect of the polymerization solvent was included using the polarizable continuum model. According to the theoretical calculation results, the MIP with aniline as template was prepared by emulsion polymerization method using acrylamide (AAM) as functional monomer and divinylbenzene as cross-linker in carbon tetrachloride. The synthesized MIP was then tested by equilibrium-adsorption method, and the MIP demonstrated high removal efficiency to the aniline. The results of this study have indicated the possibility of using computer aided design for rational selection of functional monomers and solvents capable of removal of aniline from contaminated water.

Adsorptive removal of Methylene blue and Methyl orange from aqueous media by carboxylated diaminoethane sporopollenin: on the usability of an aminocarboxilic acid functionality-bearing solid-stationary phase in column techniques

The adsorption phenomena of Methylene blue (MB) and Methyl orange (MO) on a carboxylated diaminoethane sporopollenin (CDAE-S) solid phase were investigated in a column arrangement by using breakthrough technique. The adsorption phenomena were evaluated using some common adsorption isotherm models and Scatchard plot analysis, and obtained results were interpreted for evaluating the usability of CDAE-S for removal, recovery and preconcentration of the studied dyes both at the laboratory and industrial scales. On the basis of Scatchard plot analysis, the interaction types between the CDAE-S and the studied dyes were criticized in terms of affinity phenomena. Thus, the usability of a biomacromolecule-derived material, CDAE-S, as a cheap, environmentally-friendly and effective solid-stationary phase exhibiting both cation-exchange and anion-exchange characteristics at the same time, is discussed through the present study. Besides, from the obtained results, the protonated CDAE-S, which functionally resembles an amino acid structure, are presented as a two-in-one solid-stationary phase, and its adaptability to common processes performed under column conditions is also drawn in detail.