Sonocatalytic removal of ibuprofen and sulfamethoxazole in the presence of different fly ash sources

We examined the feasibility of using two types of fly ash (an industrial waste from thermal power plants) as a low-cost catalyst to enhance the ultrasonic (US) degradation of ibuprofen (IBP) and sulfamethoxazole (SMX). Two fly ashes, Belews Creek fly ash (BFA), from a power station in North Carolina, and Wateree Station fly ash (WFA), from a power station in South Carolina, were used. The results showed that >99% removal of IBP and SMX was achieved within 30 and 60 min of sonication, respectively, at 580 kHz and pH 3.5. Furthermore, the removal of IBP and SMX achieved, in terms of frequency, was in the order 580 kHz > 1000 kHz > 28 kHz, and in terms of pH, was in the order of pH 3.5 > pH 7 > pH 9.5. WFA showed significant enhancement in the removal of IBP and SMX, which reached >99% removal within 20 and 50 min, respectively, at 580 kHz and pH 3.5. This was presumably because WFA contains more silicon dioxide than BFA, which can enhance the formation of OH radicals during sonication. Additionally, WFA has finer particles than BFA, which can increase the adsorption capacity in removing IBP and SMX. The sonocatalytic degradation of IBP and SMX fitted pseudo first-order rate kinetics and the synergistic indices of all the reactions were determined to compare the efficiency of the fly ashes. Overall, the findings have showed that WFA combined with US has potential for treating organic pollutants, such as IBP and SMX, in water and wastewater.     

Radon activity and exhalation rates measurements in fly ash from a thermal power plant

Radon exhalation rate from fly ash samples and from the homogeneous mixture of fly ash of different proportions additive in soil and cement samples to study the effect of the addition was measured by cup dosimeter using SSNTDs. Radon activities were found to vary from (1018±38) to ( whereas the radon exhalation rate varied from (366±14) to . A gradual increase has been observed in samples having fly ash as an additive in cement samples whereas a gradual decrease was observed in soil samples after the addition of fly ash. ²³⁸U in fly ash was measured by a low-level NaI (Tl)-based gamma ray spectrometer. The results show enhancement in U concentration in fly ash as compared to coal samples, whereas radon exhalation rate is less in fly ash samples.     

In situ ultrasonic diagnostic of zeolite X crystallization with novel (hierarchical) morphology from coal fly ash

In this paper the applicability of an in situ ultrasonic diagnostic technique in understanding the formation process of zeolite X with a novel morphology was demonstrated. The complexity of the starting fly ash feedstock demands independent studies of the formation process for each type of zeolite since it is not known whether the crystallization mechanism will always follow the expected reaction pathway. The hierarchical zeolite X was noted to follow a solution phase-mediated crystallization mechanism which differs from earlier studies of the zeolite A formation process from unaged, clear solution extracted from fused fly ash. The use of the in situ ultrasonic monitoring system provided sufficient data points which enabled closer estimation of the time of transition from the nucleation to the crystal growth step. In order to evaluate the effect of temperature on the resulting in situ attenuation signal, synthesis at three higher temperatures (80, 90 and 94 °C) was investigated. It was shown, by the shift of the US-attenuation signal, that faster crystallization occurred when higher temperatures were applied. The novel hierarchical zeolite X was comprised of intergrown disc-like platelets. It was further observed that there was preferential growth of the disc-shaped platelets of zeolite X crystals in one dimension as the synthesis temperature was increased, allowing tailoring of the hierarchical morphology.     

The determination of trace element concentrations in fly ash samples using ultrasound-assisted digestion followed with inductively coupled plasma optical emission spectrometry

A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of trace element (chromium, copper, lead, nickel, vanadium and zinc) concentrations in fly ash samples was developed. All the measurements were performed in robust plasma conditions. Ultrasound-assisted digestion procedures using digestion solutions of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 80% for all the analyte elements. Ultrasound-assisted two-step digestion with digestion solutions of 6 mL of HNO₃ (Step 1) and 3 mL of HNO₃ + 3 mL of HF (Step 2) resulted in recovery rates of over 92% for all the analyte elements with one exception, chromium, which had a recovery of about 85%. The analysis of SRM 1633b showed that the two-step ultrasound-assisted digestion method developed resulted in chromium, copper, nickel and zinc concentrations higher than the microwave digestion method standardized by the United States Environmental Protection Agency (USEPA method 3052). This is the very first time when a digestion method using ultrasound resulted in higher efficiency than microwave (USEPA method 3052) for chromium and nickel in very hard to dissolve samples. The major advantages of the ultrasound-assisted digestion over microwave digestion is the high treatment rate (about 30 samples simultaneously with a sonication time of 18 min) and the possibility to use new sample vessels without a significant increase in costs.     

Elemental analysis of trace elements in fly ash sample of Yata?an thermal power plants using EDXRF

Fly ash samples collected by means of an electrostatic precipitator from the lignite-fired Yata?an Power Plants of the located in Turkey was analysed using X-ray fluorescence technique. Five trace elements, namely Nd, Ba, Sr, Mo and As were quantified using XRF. These concentration values can be helpful in developing a environmental pollution abatement approach for various applications of fly ash such as cement manufacture, wastewater treatment, lightweight contraction aggregate, ceramic production, and secondary source in recovery of valuable elements. Present results compared with results of the Kemerkoy thermal power plants [?ahin Y, Karabulut A, Budak G. A practical method for the analysis of overlepped peaks in energy dispersive X-ray spectra. Appl Spectrosc Rev 1996;31:333-45].     

New concept to remove heavy metals from liquid waste based on electrochemical pH-switchable immobilized ligands

Absorption on resins is often used as secondary step in the treatment of water-based effluents, in order to reach very low concentrations. The separation of the trapped effluents from the resins and the regeneration of the resins for further use create wide volumes of secondary effluents coming from the washings of the resins with chemical reagents. We propose an alternative solution based on a “surface strategy” through adsorption phenomena and electrical control of the expulsion stage. The final goal is to limit or ideally to avoid the use of chemical reagents at the expulsion (or regeneration) stage of the depolluting process. Heavy metal ions were captured on active filters composed by a conducting surface covered by poly-4-vinylpyridine (P₄VP). Due to pyridine groups those polymer films have chelating properties for copper ions. Our strategy for electrical triggering of the copper expulsion in aqueous medium is based on pH sensitive chelating groups. Applying moderate electro-oxidizing conditions generates acidic conditions in the vicinity of the electrode, i.e. “inside” the polymer film. This allows a “switch-off” of the complexing properties of the film from the basic form of pyridine to pyridinium. Interestingly, no buffer washing is necessary to restore (or “switch-on”) the complexing properties of the polymer film because the pH of the external medium is left unchanged by the electrochemical effect that affects only the vicinity of the electrode. Switch-on/switch-off cycles are followed and attested by IR spectroscopy and EQCM method.     

Thermodynamic and kinetic parameters of ciprofloxacin adsorption onto modified coal fly ash from aqueous solution

Batch adsorption experiments were carried out for the removal of ciprofloxacin from aqueous solution using modified coal fly ash as adsorbent. The effects of various parameters such as contact time, initial solution concentration and temperature on the adsorption system were investigated. The optimum contact time was found to be 100 min. The isotherm adsorption data fit well with the Langmuir model, and the kinetic data fit well with the pseudo-second order and the intra-particle diffusion model. Intra-particle diffusion analysis demonstrates that ciprofloxacin diffuses quickly among the particles at the beginning of the adsorption process, and then the diffusion slows down and stabilizes. Thermodynamic parameters such as ΔG, ΔH and ΔS were also calculated. The negative Gibbs free energy change and the positive enthalpy change indicated the spontaneous and endothermic nature of the adsorption, and the positive entropy change indicated that the adsorption process was aided by increased randomness.     

Microstructural and magnetic characterization of fly ash from Kolaghat Thermal Power Plant in West Bengal, India

This paper reports on the physical nature of the fly ash sample of the Kolaghat Thermal Power Plant, India with an emphasis on its ultrafine nature. This paper also deals with the measurement of the magnetic properties of the fine particles of the fly ash sample. Particle sizes of this fly ash sample estimated from the SEM images lie within 0.16-5.50 μm, and the EDX spectral analysis indicates the presence of O, Al, Si, C, Fe, Mg, Na, K and Ti in this sample. From the XRD study, it is found that physical nature of conglomeration in the fly ash is crystalline and the major components are mullite (Al₆Si₂O₁₃) and quartz (SiO₂). Additionally, the presence of hematite, microcline, magnetite, maghemite and free iron in smaller fractions cannot be ruled out. A large magnetization observed at 5 K indicates the presence of magnetic components possibly due to superparamagnetism owing to very fine magnetic particles present. The hyperfine parameters obtained from the ⁵⁷Fe Mössbauer spectroscopy, in general, support the observations made from the XRD analysis and in particular, provides the quantitative estimation of the different iron ions present in the sample. Precisely, this report presents experimental data on physical aspects of the fly ash sample of a thermal power plant which consists of coarse, fine and ultrafine magnetic particulate materials (PMs) and deals with an in-depth analysis of it.     

Investigation of natural dyes and ancient textiles from korea using TOF-SIMS

The identification of the colorants used on ancient textiles provides a historical pathway to the understanding of the processes associated with one of the oldest of chemical technologies, namely textile dyeing. In this paper, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to detect dyes on textiles avoiding the time-consuming and destructive extraction procedures necessary for the spectrophotometric and chromatographic methods previously used. The plant dyes investigated belong to a variety of chemical groups, which include curcumin, crocin, carthamin, purpurin, alizarin, brazilin, shikonin, and indigo. Reference textile samples were prepared with dye extracts of plants and were characterized by TOF-SIMS. TOF-SIMS spectra for the dyed textiles showed element ions from metallic mordants, specific fragment ions, and molecular ions from organic dyes. Remnant dyes on excavated textiles have also been identified using TOF-SIMS. The ancient textile sample showed the presence of indigo clearly, although the fiber itself had degraded badly. From the results, it was concluded that most of plant dyes can be identified with TOF-SIMS and it is a very promising technique for the archaeology field.     

土壤重金属沿山地森林海拔梯度的分布特征

采用电感耦合等离子体发射光谱法与石墨炉原子吸收光谱法,研究了14种重金属(Fe,Al,Ti,Cu,Cr,Mn,V,Zn,Ni,Co,Pb,Se,Cd,As)沿山地森林海拔梯度的分布特征.结果表明海拔梯度对14种重金属中的6种重金属浓度(Fe,A1,Ti,V,Pb与As)有显著的影响,对其他八种重金属浓度(Cu,Cr,M...     

Flow microcalorimetry: Experimental development and application to adsorption of heavy metal cations on silica

Sorption of metal ions at the oxide mineral-water interfaces is a complex process involving many various contributions that can be explained using thermodynamics. The aim of this study is to obtain experimental thermodynamic data on adsorption of two heavy metal ions (Cd(II) and Pb(II)) on macroporous silica. Thermal signals of adsorption are studied by flow microcalorimetry which has been preferred because physico-chemicals conditions (pH, equilibrium concentration,…) can be controlled (the routine configuration was optimized in order to get a very stable pressure baseline and avoid important fluctuations in the determination of heat). Mechanisms driving the adsorption have been explained. The calculation of the effective charge of ions determined from the speciation diagrams and of the surface charges shows that the interactions between the two metals and the silica surface are mainly electrostatic. The differential enthalpies of adsorption Δ_adsH have been experimentally measured. The heat of cadmium adsorption is low, endothermic and quantitatively equivalent to that of desorption. In the case of lead, the adsorption is athermal. Free energies and entropic effects related to cation adsorption have then been deduced according to the Gibbs’law. The entropy is positive during the adsorption process and at this temperature (298 K) is quite equivalent to free energy. This entropy is due to modification of hydration shell of the ions during their insertion into the interfacial region.     

Surface modification of carbon nanotubes for enhancing BTEX adsorption from aqueous solutions

Carbon nanotubes (CNTs) were fabricated by the catalytic chemical vapor deposition method and oxidized by HCl, H₂SO₄, HNO₃ and NaOCl solutions for enhancing benzene, toluene, ethylbenzene and p-xylene (BTEX) adsorption in an aqueous solution. The surface nature of CNTs was changed after the H₂SO₄, HNO₃ and NaOCl oxidation, which makes CNTs that adsorb more BTEX. The NaOCl-oxidized CNTs show the greatest enhancement in BTEX adsorption, followed by the HNO₃-oxidized CNTs, and then the H₂SO₄-oxidized CNTs. The adsorption mechanism of BTEX via CNTs is mainly attributed to the π-π electron-donor-acceptor interaction between the aromatic ring of BTEX and the surface carboxylic groups of CNTs. The NaOCl-oxidized CNTs have superior adsorption performance of BTEX as compared to many types of carbon and silica adsorbents reported in the literature. This suggests that the NaOCl-oxidized CNTs are efficient BTEX adsorbents and that they possess good potential applications for BTEX removal in wastewater treatment.     

Effect of ultrasound energy on the zeolitization of chemical extracts from fused coal fly ash

This paper investigates the effects of ultrasound (UTS) energy at different temperatures on the zeolitization of aluminosilicate constituents of coal fly ash. UTS energy irradiated directly into the reaction mixture utilizing a probe immersed into the reaction mixture, unlike previously reported works that have used UTS baths. Controlled synthesis was also conducted at constant stirring and at the same temperatures using conventional heating. The precursor reaction solution was obtained by first fusing the coal fly ash with sodium hydroxide at 550 °C followed by dissolution in water and filtration. The synthesized samples were characterized by XRF, XRD, SEM and TGA. The crystallinity of crystals produced with UTS assisted conversion compared to conventional conversion at 85 °C was twice as high. UTS energy also reduced the induction time from 60 min to 40 min and from 80 min to 60 min for reaction temperatures of 95 °C and 85 °C, respectively. Prolonging the UTS irradiation at 95 °C resulted in the conversion of zeolite-A crystals to hydroxysodalite, which is a more stable zeolitic phase. It was found that at 85 °C coupled with ultrasound energy produced the best crystalline structure with a pure single phase of zeolite-A. It has been shown that crystallization using UTS energy can produce zeolitic crystals at lower temperatures and within 1 h, dramatically cutting the synthesis time of zeolite.     

Water ingression and the role of interface on the compressive properties of epoxy filled with treated fly ash

Polymer composites are generally filled with either fibrous or particulate materials to improve the mechanical properties. In choosing the fillers one looks for materials that are inexpensive and available in abundance, in order to realize a cost reduction also. Also, often these fibres/fillers are treated to improve the matrix adhesion and thereby mechanical properties. The present study is focussed on the influence of water ingression in such filler-modified composites and the attendant changes in the compressive properties. The changes in property effected following exposure to aqueous media and the influence interface modification has on the scenario is emphasized in the work. It is seen that for plain epoxy and fly ash filled systems the strengths are increased following exposure to aqueous media. The composites with surface-treated ash particles, on the other hand, record a drop in the values. Modulus values show are increased to varying degree in unfilled and filled systems. The study also includes a fractographic analysis of the tested samples with and without exposure to water.     

Electrochemical sensors of heavy metals using novel polymer-modified glassy carbon electrodes

Electroanalytical determination of heavy metals using stripping voltammetry is commonly employed and has many advantages over other methods. The sensitivity of the technique is greatly improved by employing different modified electrodes. Seven novel polymer-modified glassy carbon electrodes have been developed in this investigation for the trace analysis of heavy metals such as zinc, cadmium, lead, arsenic, and copper in formulated samples of waters by square wave stripping voltammetry. Very good responses have been observed for all the metals, while all the modified electrodes employed. The poly(3,4-ethylenedioxythiophene)-modified electrode has resulted in very low limit of detection (LOD) value. Comparison is made between literature results of LOD and the results obtained in this study. An independent atomic absorption spectroscopic analysis of the industrial wastewater sample was carried out and the results compared. The suitability of the method for practical application was ascertained by applying the procedure for the wastewater from a plating industry.     

Preparation and characterization of Fe-doped TiO2 on fly ash cenospheres for photocatalytic application

Fe³⁺-doped TiO₂ film deposited on fly ash cenosphere (Fe-TiO₂/FAC) was successfully synthesized by the sol-gel method. These fresh photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). The XRD results showed that Fe element can maintain metastable anatase phase of TiO₂, and effect of temperature showed rutile phase appears in 650 °C for 0.01% Fe-TiO₂/FAC. The SEM analysis revealed the Fe-TiO₂ films on the surface of a fly ash cenosphere with a thickness of 2 μm. The absorption threshold of Fe-TiO₂/FACs shifted to a longer wavelength compared to the photocatalyst without Fe³⁺-doping in the UV-vis absorption spectra. The photocatalytic activity and kinetics of Fe-TiO₂/FAC with varying the iron content and the calcination temperatures were investigated by measuring the photodegradation of methyl blue (MB) during visible light irradiation. Compared with TiO₂/FAC and Fe³⁺-doped TiO₂ powder (Fe-TiO₂), the degradation ratio using Fe-TiO₂/FAC increased by 33% and 30%, respectively, and the best calcined temperature was 450 °C and the optimum doping of Fe/Ti molar ratio was 0.01%. The Fe-TiO₂/FAC particles can float in water due to the low density of FAC in favor of phase separation to recover these photocatalyst after the reaction, and the recovery test shows that calcination contributes to regaining photocatalytic activity of Fe-TiO₂/FAC photocatalyst.     

Ultrasonic and mechanical soil washing processes for the removal of heavy metals from soils

In order to determine the optimal operating conditions of full-scale soil washing processes for the removal of heavy metals, the effect of high-power ultrasound on the conventional mechanical soil washing process was investigated in a large lab-scale 28 kHz sonoreactor. The soil samples were obtained from an abandoned railway station site in Seoul, Korea, which was contaminated with Cu (242.7 ± 40.0 mg/kg), Pb (441.3 ± 49.8 mg/kg), and Zn (358.0 ± 35.7 mg/kg). The treated concentrations of three heavy metal species in each process were compared with the regulation levels. It was found that higher performance, satisfying the regulation levels, was obtained in the ultrasonic/mechanical process due to the combined effects of macroscale mixing and microscale sonophysical effects. Moreover ultrasound played a more important role in less favorable conditions for the mechanical washing process (less acidic or less washing liquid conditions). Considering the application of the ultrasonic/mechanical soil washing process in real contaminated sites, the optimal conditions for the reactor with the bottom area of 15 × 15 cm² and the input ultrasound power of 250 W were determined as follows: (1) the amount of soil per an operation was a 300 g; (2) the ratio of soil and liquid was 1:3; (3) the concentration of acidic washing liquid was 0.5 M HCl.     

微波消解/ICP-MS测定水系沉积物中的9种重金属元素

优化了微波消解进行沉积物样品前处理的方法,选择了HNO3-H2O2-HF体系。以Ge,In,Bi为内标元素,建立了电感耦合等离子体质谱(ICP-MS)同时测定Cr,Mn,Ni,Co,Cu,Zn,Cd,Sb,Pb九种重金属元素含量的方法。该方法的相关系数都在3个9以上,测定了国家标准物质ESS-1GSBZ50011-88土壤中的元素,测定值与标准值或参考值一致,相对标准偏差0.48%～5.73%,加标回收率98.0%～100.7%,检出限在0.011～0.328μg.L-1。利用建立的方法测定了白洋淀11个代表性点位的水系沉积物中的九种重金属元素含量,为环境中土壤及水系沉积物中重金属元素含量的测定提供了可靠的分析方法。     

Ultrasonic degradation of selected dyes using Ti3C2Tx MXene as a sonocatalyst

MXene, a new family of two dimensional materials, was utilized as a sonocatalyst in an ultrasonic treatment (US) process for removal of methylene blue (MB) and acid blue 80 (AB). The physico-chemical properties of MXene were characterized using scanning electron microscopy, transmission electron microscopy, porosimetry, and a zeta potential analyzer. Degradation of dyes by US was systemically investigated under several experimental conditions including: power density of US (45, 90, 135, and 180 W L⁻¹), frequency of US (28 and 970 kHz), pH of dye solution (3.5, 7, and 10.5), solution temperature (293, 303, and 313 K), and addition of hydroxyl radical promotor (H₂O₂) and scavenger (t-BuOH) to concentrations of 25 mM. Based on the experimental results, the quantity of H₂O₂, which was used as an indicator of hydroxyl radical concentration, was an important factor in determining the degradation rate of MB and AB in this US study. Additionally, synergetic indices for removal of both dyes were higher than 1.0 in all cases, indicating the outstanding efficiency of MXene as a sonocatalyst in the US reactor for removal of both, due to an increase in both (i) the quantity of H₂O₂ in the US reactor and (ii) active sites for adsorbates from dispersion effects. A stability test on MXene in the US process was conducted using X-ray diffraction and five-cycle recycling performance tests. Based on our experimental data, MXene can be utilized as a sonocatalyst in the US process for a high removal rate for dyes (e.g., MB).     

Removal of heavy metals from aqueous solutions using Fe3O4, ZnO, and CuO nanoparticles

This study investigated the removal of Cd²⁺, Cu²⁺, Ni²⁺, and Pb²⁺ from aqueous solutions with novel nanoparticle sorbents (Fe₃O₄, ZnO, and CuO) using a range of experimental approaches, including, pH, competing ions, sorbent masses, contact time, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The images showed that Fe₃O₄, ZnO, and CuO particles had mean diameters of about 50?nm (spheroid), 25?nm (rod shape), and 75?nm (spheroid), respectively. Tests were performed under batch conditions to determine the adsorption rate and uptake at equilibrium from single and multiple component solutions. The maximum uptake values (sum of four metals) in multiple component solutions were 360.6, 114.5, and 73.0?mg?g^?1, for ZnO, CuO, and Fe₃O₄, respectively. Based on the average metal removal by the three nanoparticles, the following order was determined for single component solutions: Cd²⁺?>?Pb²⁺?>?Cu²⁺?>?Ni²⁺, while the following order was determined in multiple component solutions: Pb²⁺?>?Cu²⁺?>?Cd²⁺?>?Ni²⁺. Sorption equilibrium isotherms could be described using the Freundlich model in some cases, whereas other isotherms did not follow this model. Furthermore, a pseudo-second order kinetic model was found to correctly describe the experimental data for all nanoparticles. Scanning electron microscopy, energy dispersive X-ray before and after metal sorption, and soil solution saturation indices showed that the main mechanism of sorption for Cd²⁺ and Pb²⁺ was adsorption, whereas both Cu²⁺ and Ni²⁺ sorption were due to adsorption and precipitation. These nanoparticles have potential for use as efficient sorbents for the removal of heavy metals from aqueous solutions and ZnO nanoparticles were identified as the most promising sorbent due to their high metal uptake.