UV-irradiated fly ash-catalyzed Fenton-type process for the removal of paracetamol in wastewater: nickel, copper, and manganese as active sites

2021 ◽  
Vol 215 ◽  
pp. 160-166
Author(s):  
Asia Akram ◽  
Amir Ikhlaq ◽  
Farhan Javed ◽  
Mohsin Kazmi ◽  
Fei Qi
Keyword(s):  
Fly Ash ◽  
Active Sites ◽  
Type Process ◽  
Nickel Copper

scholarly journals In Situ DRIFTS Investigation on CeOx Catalyst Supported by Fly-Ash-Made Porous Cordierite Ceramics for Low-Temperature NH3-SCR of NOX

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 496 ◽  
Author(s):  
Shaoxin Wang ◽  
Ziwei Chen ◽  
Beini He ◽  
Zheng Yan ◽  
Hao Wang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Supported Catalyst ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
Cordierite Ceramics ◽  
Porous Cordierite

A series of CeOx catalysts supported by commercial porous cordierite ceramics (CPCC) and synthesized porous cordierite ceramics (SPCC) from fly ash were prepared for selective catalytic reduction of NOx with ammonia (NH3-SCR). A greater than 90% NOx conversion rate was achieved by the SPCC supported catalyst at 250–300 °C when the concentration of loading precursor was 0.6 mol/L (denoted as 0.6Ce/SPCC), which is more advantageous than the CPCC supported ones. The EDS mapping results reveal the existence of evenly distributed impurities on the surface of SPCC, which hence might be able to provide more attachment sites for CeOx particles. Further measurements with temperature programmed reduction by hydrogen (H2-TPR) demonstrate more reducible species on the surface of 0.6Ce/SPCC, thus giving rise to better NH3-SCR performance at a low-temperature range. The X-ray photoelectron spectroscopy (XPS) analyses reveal that the Ce atom ratio is higher in 0.6Ce/SPCC, indicating that a higher concentration of catalytic active sites could be found on the surface of 0.6Ce/SPCC. The in situ diffused reflectance infrared fourier transform spectroscopy (DRIFTS) results indicate that the SCR reactions over 0.6Ce/SPCC follow both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. Hence, the SPCC might be a promising candidate to provide support for NH3-SCR catalysts, which also provide a valuable approach to recycling the fly ash.

Study on Mercury Adsorption Performance of Modified Fly Ash

2011 ◽  
Vol 343-344 ◽  
pp. 246-249 ◽  
Author(s):  
Ting Yu Zhu ◽  
Jun Yan Kuang ◽  
Wen Qing Xu ◽  
Meng Ye ◽  
Yang Yang Guo ◽  
...  
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Active Sites ◽  
Chemical Adsorption ◽  
Mercury Adsorption ◽  
Adsorption Performance ◽  
Removal Efficiencies ◽  
Modified Fly Ash

The fly ash was modified by Cl, Fe, Cu salts to investigate the mercury adsorption performance and analyze the impacts on it. Experiment results indicate that significant improvement of removal efficiencies with FeCl3、CuCl2 and CuBr2 impregnation onto fly ash. The modification adjusted the pore structure of fly ash and formed more pores to absorb Hg, also it was found that new active sites were generated after the treatment, which can oxidize Hg0 and improve chemical adsorption.

Bamboo-Shaped Carbon Nanotubes on Coal Fly Ash Cenospheres for Pb(II) Adsorption

2020 ◽  
Vol 20 (8) ◽  
pp. 5089-5095
Author(s):  
Xiaomin Zhang ◽  
Jin Li ◽  
Bo He ◽  
Heng Li ◽  
Chao Qi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Fly Ash ◽  
Adsorption Capacity ◽  
Active Sites ◽  
Coal Fly Ash ◽  
Chemical Vapor ◽  
Structural Defects ◽  
3D Network ◽  
Supporting Material ◽  
High Level

The structural defects of bamboo-shaped carbon nanotubes (B-CNTs) provide abundant active sites for ion adsorption during wastewater treatment. However, a suitable supporting material for the growth of B-CNTs growth is less reported. In this paper, the catalytic growth of B-CNTs on the cenospheres (CSs) of coal fly ash was studied. The results showed that all CSs were covered by a layer of B-CNTs during the chemical vapor deposition (CVD) process, regardless of the fluctuation of the iron distribution from 0.52 to 2.09 wt%. B-CNTs with a diameter of 30–40 nm shared a similar morphology of compartment structures, which were uniformly scattered on the surfaces of the CSs and formed a 3D network structure. A high level of structural defects was present on the B-CNTs, which was denoted by an ID/IG value of 1.77 via Raman spectrum analysis. Adsorption experiments of the as-prepared CSs@B-CNTs revealed an excellent adsorption capacity for lead ions of 37.32 mg/g (pH 7, initial concentration of 70 mg/L). By excluding the function of CSs, the adsorption capacity of the pure B-CNTs was estimated to be as high as 275.19 mg/g, which has not been previously reported.

Coal Fly Ash as a Dual Site Material for Cr(VI) Adsorption: Comparation between Single Site and Dual Site Isotherm Models

2015 ◽  
Vol 1101 ◽  
pp. 149-152
Author(s):  
Widi Astuti ◽  
Triastuti Sulistyaningsih ◽  
Dewi Selvia Fardhyanti
Keyword(s):  
Fly Ash ◽  
Active Sites ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Single Site ◽  
Unburned Carbon ◽  
Isotherm Models ◽  
Equilibrium Data ◽  
Dual Site

The major problem in coal-based thermal power plants is related to solid waste called coal fly ash (CFA). CFA is mainly composed of some oxides including SiO2, Al2O3 having active site and unburned carbon as a mesopore that enables it to act as a dual site adsorbent for heavy metals including Cr (VI). To get different characters of dual site, CFA was treated by sulfuric acid (H2SO4) at different concentrations, temperatures and reaction time. Furthermore, treated CFA were used as an adsorbent to adsorb Cr (VI) in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded, although unburned carbon contributes on the Cr (VI) adsorption, the existence of unburned carbon decreases the amount of Cr (VI) adsorbed because unburned carbon can plug active sites where dominant adsorption occurs. However, dual site isotherm model yielded excellent fit with equilibrium data.

Study on Mechanical and Microscopic Properties of Nickel–Copper-Contaminated Soil Solidified by Cement, Fly Ash and Desulfurization Gypsum Under Carbonization Condition

2021 ◽  
pp. 036119812110415
Author(s):  
Qiang Wang ◽  
Xiaoliang Guo ◽  
Man Li ◽  
Jingdong Yang ◽  
Jinyang Cui ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Fly Ash ◽  
Contaminated Soil ◽  
Metal Ion ◽  
Microscopic Analysis ◽  
Hydrated Calcium Silicate ◽  
Nickel Copper ◽  
Practical Engineering ◽  
Carbonization Product ◽  
Copper Contaminated

The engineering characteristics of remediated soil are easily affected by CO2 erosion in nature. However, there are limited investigations on the mechanical and microscopic properties of heavy metal-contaminated soil. This study introduces effect of accelerated carbonization on the mechanical and microscopic properties of nickel–copper-contaminated soil, and the soil has been treated with a novel curing agent, formed by mixing cement, fly ash and desulfurization gypsum (CFG). The objective of the study is to ascertain CO2 erosion resistance of nickel–copper-contaminated soil solidified by CFG. Using unconfined compressive strength (UCS) tests, carbonization depth, X-ray diffraction, and scanning electron microscopy, the sample’s characteristics are investigated under different carbonization times and heavy metal ion concentrations. The results demonstrate that the UCS of samples of Ni0Cu0, Ni0.02, and Ni0.4 decrease with the increasing carbonization time, while that of Ni1, Cu1, and Ni1Cu1 increase initially and then decrease; in addition, when the concentration of heavy metals is lower, the effect of carbonization on UCS of samples is more significant. Moreover, the carbonization depth of samples increases with the increasing carbonization time, and the prediction model is given. Furthermore, the microscopic analysis demonstrates that calcium carbonate is the main carbonization product. The decomposition of hydrated calcium silicate gel leads to poor integrity of the structure and more pores produced in samples, which is the main reason for the decrease of the UCS in the process of carbonization. The outcomes of this investigation provide a reference for the durability in practical engineering of heavy metal-contaminated soil solidified by CFG.

scholarly journals Development of Heterogeneous Alkali Methoxide Catalyst from Fly Ash and Limestone

2020 ◽  
Vol 14 (4) ◽  
pp. 521-530
Author(s):  
W. Widayat ◽  
◽  
Marcelinus Christwardana ◽  
S. Syaiful ◽  
Hantoro Satriadi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Palm Oil ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Raw Materials ◽  
Fatty Acid Content ◽  
Physicochemical Characteristics ◽  
Biodiesel Production ◽  
X Ray Diffraction ◽  
Initial Value

This study is aimed to use fly ash and limestone as raw materials for preparing alkali methoxide heterogeneous catalysts for transesterification of palm oil into biodiesel. The heterogeneous catalyst was synthesized from fly ash and limestone through wet and dry methods and calcined within 1073–1273 K. X-ray diffraction and scanning electron microscopy analyses indicated the well-dispersed presence of the Ca(OCH3)2 crystal over the fly ash and limestone framework, which was mixed using wet method and calcined at 1073 K (W-800). Results showed that W-800 exhibited larger surface area and more uniform active sites than the other catalysts. About 88.6 % of biodiesel was produced from commercial palm oil with W-800 as the catalyst. The product possesses physicochemical characteristics, such as density, kinematic viscosity and free fatty acid content, which satisfy the international biodiesel standard. The catalyst was used for biodiesel production for four cycles, and the biodiesel yield was maintained up to 91.87 % from the initial value.

scholarly journals Fly Ash-Based Geopolymers as Sustainable Bifunctional Heterogeneous Catalysts and Their Reactivity in Friedel-Crafts Acylation Reactions

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 372 ◽  
Author(s):  
Mohammad I. M. Al-Zeer ◽  
Kenneth J. D. MacKenzie
Keyword(s):  
Fly Ash ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Coal Fly Ash ◽  
Solid Catalysts ◽  
Redox Sites ◽  
Redox Active ◽  
Porous Architecture ◽  
Acidic Sites ◽  
Catalytic Reactivity

This study presents the synthesis, characteristics and catalytic reactivity of sustainable bifunctional heterogeneous catalysts derived from coal fly ash-based geopolymer, particularly those with a high Ca content (C-class) fly ash. The developed catalysts were synthesized at room temperature and pressure in a simple ecologically-benign procedure and their reactivity was evaluated in the Friedel-Crafts acylation of various arenes. These catalysts can be produced with multilevel porous architecture, and a combination of acidic and redox active sites allowing their use as bifunctional catalysts. The acidic sites (Lewis and Brønsted acidic sites) were generated within the catalyst framework by ion-exchange followed by thermal treatment, and redox sites that originated from the catalytically reactive fly ash components. The developed catalysts demonstrated higher reactivity than other commonly used solid catalysts such as Metal-zeolite and Metal-mesoporous silicate, heteropolyacids and zeolite imidazole frameworks (ZIF).

Preparation of fly ash adsorbents utilizing non-thermal plasma to add S active sites for Hg0 removal from flue gas

Fuel ◽  
2020 ◽  
Vol 266 ◽  
pp. 116936 ◽  
Author(s):  
Ruize Sun ◽  
Hailu Zhu ◽  
Mengting Shi ◽  
Guangqian Luo ◽  
Yang Xu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Thermal Plasma ◽  
Active Sites ◽  
Non Thermal Plasma

Lead sorption performance on active silica derived from fly ash

2014 ◽  
Vol 71 (5) ◽  
pp. 661-666 ◽  
Author(s):  
Xizhu Zhang ◽  
Zhibao Zhu
Keyword(s):  
Fly Ash ◽  
Active Sites ◽  
Ph Value ◽  
Sorption Property ◽  
Residual Concentration ◽  
Linear Isotherm ◽  
Maximum Sorption ◽  
Negative Surface ◽  
Ph Dependent ◽  
Better Than

The object of this study was to estimate the sorption property of active silica derived from fly ash after separation of silica and aluminum. The specific surface area of active silica enlarged to 115 m2/g was compared with the original fly ash (4 m2/g). Field emission scanning electron microscopy displayed the active silica, which looked like a honeycomb or curly layer with many lamellae that formed many mesopores. The uptake kinetics indicated that the residual concentration of Pb2+ in the aqueous solution decreased rapidly from the initial 1.25 mg/L to less than 10 μg/L within 45 min. The removal efficiency of Pb2+ on active silica was pH dependent. The increase in pH value promoted Pb2+ removal because the negative surface provided more electrostatic attraction sites. A stepwise non-linear isotherm was obtained because the lamellae of active silica provided a heterogeneous surface with various kinds of active sites. The maximum sorption amount of Pb on active silica was more than 90 mg/g, which was better than some pristine-activated carbon.

scholarly journals Simultaneous Removal of Pb2+ and Zn2+ Heavy Metals Using Fly Ash Na-X Zeolite and its Carbon Na-X(C) Composite

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2832
Author(s):  
Rafał Panek ◽  
Magdalena Medykowska ◽  
Małgorzata Wiśniewska ◽  
Katarzyna Szewczuk-Karpisz ◽  
Katarzyna Jędruchniewicz ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Active Sites ◽  
Nitrogen Adsorption ◽  
Carbon Composite ◽  
Hard Coal ◽  
Adsorbent Surface ◽  
Developed Surface ◽  
X Zeolite ◽  
Adsorption Desorption

Pure zeolite (Na-X) and a zeolite–carbon composite (Na-X(C)) were investigated as adsorbents of heavy metals—Pb2+ and Zn2+ from an aqueous solution. These materials were synthesized from fly ash—a waste from conventional hard coal combustion. Both solids were characterized using XRD, SEM-EDS, nitrogen adsorption/desorption, particle size and elemental composition analyses. The adsorption study was performed at pH 5 in the systems containing one or two adsorbates simultaneously. The obtained results showed that the pure zeolite was characterized by a more developed surface area (728 m2/g) than its carbon composite (272 m2/g), and the mean pore diameters were equal to 1.73 and 2.56 nm, respectively. The pure Na-X zeolite showed better adsorption properties towards heavy metals than its Na-X(C) composite, and Zn2+ adsorbed amounts were significantly higher than the Pb2+ ones (the highest experimental adsorption levels were: for Zn2+—656 and 600 mg/g, and for Pb2+—575 and 314 mg/g, on the Na-X and Na-X(C) surfaces, respectively). The zinc ions are exchanged with the cations inside the zeolite materials structure more effectively than lead ions with a considerably larger size. In the mixed systems, the competition between both heavy metals for access to the active sites on the adsorbent surface leads to the noticeable reduction in their adsorbed amounts. Moreover, the hydrochloric acid was a better desorbing agent for both heavy metals, especially Pb2+ one (desorption reached 78%), than sodium base (maximal desorption 25%).

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