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%).

scholarly journals Porosity Design of Shaped Zeolites for Improved Catalyst Lifetime in the Methanol-to-Hydrocarbons Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 545 ◽  
Author(s):  
Rogéria Bingre ◽  
Renna Li ◽  
Qiang Wang ◽  
Patrick Nguyen ◽  
Thomas Onfroy ◽  
...  
Keyword(s):  
Pore Volume ◽  
Active Sites ◽  
Coke Formation ◽  
Effective Diffusivity ◽  
Nitrogen Adsorption ◽  
Breakthrough Time ◽  
Methanol To Hydrocarbons ◽  
Catalytic Stability ◽  
Temperature Programmed ◽  
Adsorption Desorption

Additional porosity, such as meso- and macropores, was introduced in zeolite extrudates with the intention intuit of improving the effective diffusivity of the catalysts. The samples were characterized in depth by nitrogen adsorption-desorption, mercury intrusion porosimetry, ammonia temperature programmed desorption and adsorption of pyridine followed by infrared spectroscopy. The results revealed no significant change in the acidity but an increase of the pore volume. According to significant improvement in the effective diffusivity, the samples were tested in the methanol-to-hydrocarbons reaction. The catalytic stability was greatly enhanced with an increase in the pore volume, demonstrating a relation between effective diffusivity and resistance to deactivation by coke formation. Further experiments also revealed a higher toluene adsorption capacity and a raise in the breakthrough time over the most porous samples due to better accessibility of toluene molecules into the active sites of the zeolite.

scholarly journals Adsorptive removal of methylene blue from aqueous solution using coal fly ash-derived mesoporous silica material

2019 ◽  
Vol 37 (3-4) ◽  
pp. 333-348 ◽  
Author(s):  
Ning Yuan ◽  
Hui Cai ◽  
Tian Liu ◽  
Qi Huang ◽  
Xinling Zhang
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Fly Ash ◽  
Mesoporous Silica ◽  
Coal Fly Ash ◽  
Nitrogen Adsorption ◽  
Mesoporous Silica Material ◽  
Adsorptive Removal ◽  
Silica Material ◽  
Adsorption Desorption

In the present work, coal fly ash-derived mesoporous silica material (CFA-MS) has been successfully fabricated without employing any extra silica source. The obtained CFA-MS was characterized by Fourier transform infrared spectroscopy, nitrogen adsorption–desorption measurement, powder X-ray diffraction and transmission electron microscopy. Nitrogen adsorption–desorption measurement disclosed that CFA-MS possesses Brunauer–Emmett–Teller-specific surface area of 497 m2·g−1 and pore volume of 0.49 cm3·g−1, respectively. Furthermore, CFA-MS was evaluated for the adsorptive removal of methylene blue from aqueous solution. Several influence parameters on the removal of methylene blue including contact time, pH, initial concentration and temperature were studied in detail. Moreover, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were employed for interpretation of the adsorption process, while the pseudo-first-order and pseudo-second-order kinetics equations were applied to investigate the adsorption kinetics. Results in the current work demonstrate that CFA-MS can be used as an efficient adsorbent for methylene blue removal.

Experimental Study on Microstructure of Fly-Ash from Circulating Fluidized Bed Boilers

2011 ◽  
Vol 354-355 ◽  
pp. 413-416
Author(s):  
Yan Jin ◽  
Cui Ying Feng ◽  
Juan Juan Liu
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Adsorption Isotherms ◽  
Circulating Fluidized Bed ◽  
Nitrogen Adsorption ◽  
Cfb Boiler ◽  
Nitrogen Adsorption Isotherms ◽  
Pore Types ◽  
Adsorption Desorption ◽  
Fluidized Bed Boilers

Circulating fluidized bed (CFB) combustion techniques have been widely used in China. In order to improve CFB boiler performance it is necessary to study on microstructures of fly-ash. With the help of nitrogen adsorption instrument and scanning electron microscopy, the pore structure of fly-ash in circulating fluidized bed boilers are studied by nitrogen adsorption/desorption isotherms of fly-ash, hysteresis loop and pore distribution. The results indicated that different particle sizes of fly-ash in CFB boilers are of similar nitrogen adsorption isotherms, pore types and the pore size distribution, and the most probable pore radius of fly-ash is about 2nm. Adsorption isotherms of fly-ash is the second type, and the macro-porous and meso-porous types are tapered hole, parallel plate slit hole and the ink bottle shape hole. And meso-pore in proportion is the largest. Micro-pores are not discovered in fly-ash from CFB boilers.

Synthesis of porous carbon nanotubes/activated carbon composite spheres and their application for vitamin B12 adsorption

2014 ◽  
Vol 21 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Yuemei Lu ◽  
Qianming Gong ◽  
Fangping Lu ◽  
Ji Liang
Keyword(s):  
Carbon Nanotubes ◽  
Activated Carbon ◽  
Vitamin B12 ◽  
Suspension Polymerization ◽  
Nitrogen Adsorption ◽  
Carbon Composite ◽  
Steam Activation ◽  
Large Molecules ◽  
Particle Size Analyzer ◽  
Adsorption Desorption

AbstractIn this paper, carbon nanotubes (CNTs) were added to activated carbon to enhance the mesopores. At first, different amounts of CNTs were added to phenolic resin and composite spheres were synthesized by suspension polymerization. Then, by carbonizing these spheres at 600°C followed by steam activation at 850°C for more than 90 min, we prepared highly developed porous CNTs/activated carbon composite spheres. The composite spheres were characterized by a laser particle size analyzer, scanning electron microscopy, Raman spectrum, and nitrogen adsorption-desorption isotherms. Results showed that the composite spheres had good sphericity even with high proportion of CNTs (45 wt.%). Analysis also showed that the pore size distribution of the composite spheres containing CNTs was “multi-peak”, especially with 20–100-nm pores. The improved 20–100-nm porous structures in the composite spheres can be ascribed to aggregated pores of CNT bundles. The amount of vitamin B12 adsorbed on the 45 wt.% CNT composite spheres was as high as 32.38 mg/g. The spheres could be used as adsorbents for middle-molecular-weight toxins or large molecules in hemoperfusion.

scholarly journals Adsorption of Acid Blue 25 on Agricultural Wastes: Efficiency, Kinetics, Mechanism, and Regeneration

2021 ◽  
Vol 14 ◽  
pp. 117862212110574
Author(s):  
Junaidi H Samat ◽  
Nurulizzatul Ningsheh M Shahri ◽  
Muhammad Ashrul Abdullah ◽  
Nurul Amanina A Suhaimi ◽  
Kanya Maharani Padmosoedarso ◽  
...  
Keyword(s):  
Active Sites ◽  
Adsorption Process ◽  
Surface Characteristics ◽  
Agricultural Wastes ◽  
Ambient Conditions ◽  
Adsorbent Surface ◽  
Equilibrium Data ◽  
Acid Blue 25 ◽  
Adsorption Desorption ◽  
Acid Blue

In this study, Acid Blue 25 (AB25), which is a negatively charged synthetic dye was removed from an aqueous solution by adsorption onto agricultural wastes, including banana (BP) and durian (DP) peels. The adsorption performances of AB25 were related to surface characteristics of the agricultural wastes, including their chemical functional groups, net surface charge, surface morphology, surface area, and pore volume. Parameters affecting the adsorption, including contact times, initial concentration, pH, and temperature were investigated. The results revealed that the adsorption of AB25 followed pseudo-second order kinetics, and that the adsorption process was controlled by a combination of intraparticle and film diffusion with a two-step mechanism. The equilibrium data could be simulated by the Langmuir isotherm model, suggesting that AB25 molecules are adsorbed on active sites with a uniform binding energy as a monolayer on the adsorbent surface. The adsorption process was spontaneous and exothermic, and the adsorption capacity decreased with the pH of the medium. The spent adsorbents were best regenerated by acid treatment (pH 2), and could be recycled for several adsorption-desorption processes. Under ambient conditions, the maximum adsorption capacities of AB25 on BP and DP were 70.0 and 89.7 mg g−1, respectively, which is much higher than on a large variety of reported adsorbents derived from other agricultural wastes.

Design of composite micro/mesoporous molecular sieve catalysts

2004 ◽  
Vol 76 (9) ◽  
pp. 1647-1657 ◽  
Author(s):  
I. I. Ivanova ◽  
A. S. Kuznetsov ◽  
V. V. Yuschenko ◽  
E. E. Knyazeva
Keyword(s):  
Mesoporous Materials ◽  
Active Sites ◽  
Nitrogen Adsorption ◽  
Mesoporous Molecular Sieve ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Temperature Programmed ◽  
Angle Spinning ◽  
Adsorption Desorption

Two series of composite micro/mesoporous materials with different contributions of micro- and mesoporosity were prepared by dealumination and recrystallization of mordenite zeolite. The materials were characterized by X-ray diffraction, infrared spectroscopy, 27Al magic angle spinning (MAS) NMR, nitrogen adsorption–desorption, and temperature-programmed desorption of ammonia (TPD NH3). Catalytic properties were studied in transalkylation of biphenyl with diisopropylbenzene. Both types of composite materials showed remarkably high activity, stability, and selectivity toward formation of di-isopropylbiphenyls with respect to both pure microporous and mesoporous materials. The effect is due to high zeolitic acidity combined with improved accessibility of active sites and transport of bulky molecules provided by mesopores.

Thermally Stable Metal(Cu, Fe)-Substituted Mesoporous Aluminophosphates: Synthesis and Application as Oxidation Catalysts

2012 ◽  
Vol 550-553 ◽  
pp. 306-311 ◽  
Author(s):  
Bin Xu ◽  
Kai Feng Lin ◽  
Yan Qiu Jiang ◽  
Jian Min Sun ◽  
Xian Zhu Xu
Keyword(s):  
Thermal Stability ◽  
Active Sites ◽  
Nitrogen Adsorption ◽  
Metal Species ◽  
X Ray Diffraction ◽  
Catalytic Activities ◽  
Ft Ir ◽  
Adsorption Desorption ◽  
Ft Ir Spectroscopy ◽  
Mesoporous Aluminophosphates

Metal-substituted mesoporous aluminophosphates with high thermal stability (Fe-JLU-50 and Cu-JLU-50) has been prepared by using preformed microporous aluminophosphate precursors. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms and FT-IR spectroscopy. The characterization results showed the presence of zeolite aluminophosphate structural building units in the framework of the mesoporous aluminophosphates, which is responsible for their highly thermal stability. Also, the metal species such as Fe and Cu were successfully incorporated in the framework of the mesoporous aluminophosphates via this approach. Fe-JLU-50 and Cu-JLU-50 were evaluated in the oxidations of phenol and trimethylphenol (TMP) with aqueous H2O2, giving highly catalytic activities in both reactions. This result suggests that the materials are versatile catalysts for both small and bulky substrates, ascribed to the accessibility of the substrates to the active sites in the framework of Fe-JLU-50 and Cu-JLU-50 by the retained mesopores after calcination.

scholarly journals Comparison of Physicochemical Properties of Fly Ash Precursor, Na-P1(C) Zeolite–Carbon Composite and Na-P1 Zeolite—Adsorption Affinity to Divalent Pb and Zn Cations

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3018
Author(s):  
Rafał Panek ◽  
Magdalena Medykowska ◽  
Katarzyna Szewczuk-Karpisz ◽  
Małgorzata Wiśniewska
Keyword(s):  
Heavy Metal ◽  
Fly Ash ◽  
Environmental Remediation ◽  
Heavy Metal Concentration ◽  
Carbon Composite ◽  
Icp Oes ◽  
High Carbon ◽  
Adsorption Affinity ◽  
Adsorption Desorption ◽  
Molecular Sieving

Considering the growing needs of environmental remediation, new effective solutions should be sought. Therefore, the adsorbed amounts of heavy metal ions, such as lead(II) and zinc(II), on the surface of high-carbon fly ash (HiC FA), zeolite-–carbon composite (Na-P1(C)) and pure zeolite (Na-P1), were investigated. The applied solids were characterized using the following techniques: XRD, SEM-EDS, TEM, porosimetry, SLS, electrophoresis and potentiometric titration. The heavy metal concentration in the probes was determined by applying ICP-OES spectroscopy. Adsorption/desorption and electrokinetic measurements were performed in the systems containing one or two adsorbates. The obtained results indicated that Pb(II) ions are adsorbed in larger amounts on the investigated solid surface due to the molecular sieving effect. The largest adsorption capacity relative to lead(II) ions was observed for pure Na-P1 zeolite (407 mg/g). The simultaneous presence of Pb(II) + Zn(II) mixed adsorbates minimally affects the amount of adsorbed Pb(II) ions and causes a significant decrease of Zn(II) ion adsorption (in comparison with analogous systems containing single adsorbates). It was also shown that all solids can be efficiently regenerated using hydrochloric acid. Thus, the selected pure zeolite can be successfully applied in soil remediation or other purifying technologies as an effective Pb(II) adsorbent.

Methodology of Research in Micropollutants – Heavy Metals

1982 ◽  
Vol 14 (12) ◽  
pp. 107-125 ◽  
Author(s):  
Roland Wollast
Keyword(s):  
Heavy Metals ◽  
Mathematical Models ◽  
Aqueous Phase ◽  
Suspended Matter ◽  
Solid Phase ◽  
Aquatic Organisms ◽  
Biological Processes ◽  
Particulate Phase ◽  
Sources Of Pollution ◽  
Adsorption Desorption

A comparison of the concentration of dissolved and of particulate heavy metals in the aquatic system indicates that these elements are strongly enriched in the suspended matter. The transfer between the aqueous phase and the solid phase may be due to dissolution-precipitation reactions, adsorption-desorption processes or biological processes. When these processes are identified, it is further possible to develop mathematical models which describe the behaviour of these elements. The enrichment of heavy metals in the particulate phase suspended or deposited and in aquatic organisms constitutes a powerful tool in order to evaluate sources of pollution.

Conditioning of oily sludges with municipal solid wastes incinerator fly ash

1997 ◽  
Vol 35 (8) ◽  
pp. 231-238 ◽  
Author(s):  
Tay Joo Hwa ◽  
S. Jeyaseelan
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Specific Resistance ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Solid Wastes ◽  
Municipal Solid Wastes ◽  
Capillary Suction ◽  
Optimum Dosage

Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability.

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