Fly ash from a Mexican mineral coal. II. Source of W zeolite and its effectiveness in arsenic (V) adsorption (original) (raw)
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Synthesis and characterization of zeolites prepared from industrial fly ash
Environmental Monitoring and Assessment, 2014
In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm 3 of 3 mol•dm −3 NaOH, 75°C), Na-P1 (20 g fly ash, 0.5 dm 3 of 3 mol•dm −3 NaOH, 95°C), and sodalite (20 g fly ash, 0.8 dm 3 of 5 mol•dm −3 NaOH+0.4 dm 3 of 3 mol•dm −3 NaCl, 95°C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N 2 isotherm adsorption/ desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m 2 •g −1 , while for the Na-P1 and sodalite it was 71 and 33 m 2 •g −1 , respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq•g −1 , Na-P1 at 0.72 meq•g −1 , and sodalite at 0.56 meq•g −1. The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination.
Synthesis of Zeolites from Coal Fly Ash and Their Environmental Application
Society of Economic Geologists and Mineral Technologists (SEGMITE), 2022
This study aims to make adsorption-capable zeolite from coal fly ash, a waste product from coal-fired power plants (CFA). When it comes to commercializing sorbent, the total cost and efficiency of the adsorbent material are critical. This work used tap water instead of distilled water (DW) to synthesis zeolite from fly ashes at 90°C crystallization temperatures. The discovery lays the door for a cost-effective but easy technique of synthesizing viable zeolitic materials for adsorption applications using waste products like coal fly ash. According to the comprehensive characterization, the support for the use of TP to make zeolites is based on its larger particle size, and lower carbon impurities. The generated zeolite was homogenous and A-type, and applied as an adsorbent to remove traces of heavy metals contaminants. During a 25-minute agitation period, the zeolites produced with TP had a greater adsorption capacity. In principle, the proposed approach permits the synthesis of low-cost, high-efficiency zeolite-based adsorbent materials for environmental remediation without the use of harmful or expensive chemicals
Arsenate Adsorption on Iron Modified Artificial Zeolite Made from Coal Fly Ash
Procedia Environmental Sciences, 2013
Arsenic in its organic and inorganic forms has threatened the human life since ages. Many researchers and scientists had made efforts in all the directions to find and remove poisonous arsenic from human surroundings. In the present study an attempt was made to see the adsorption behavior of arsenate on the chemically modified artificial zeolite, synthesized from coal fly ash. In the modification process the iron was rearranged and loaded on the surface of the fly ash by dissolution and precipitation processes. Artificial zeolite synthesized from coal fly ash was treated with iron nitrate solution. The decrease in the CEC indicates the reduction of negative charge on the zeolite structure by iron. The iron modified artificial zeolite has comparatively high capacity for arsenate adsorption which was described by the Langmuir isotherm model.
Potential Environmental Applications of Pure Zeolitic Material Synthesized from Fly Ash
Journal of Environmental Engineering-asce, 2001
A pure 4A/X (60/40) zeolite product was synthesized from silica extracts of the Meirama fly ash in northwestern Spain. A high cation-exchange capacity (4.7 meq/g) was obtained for the zeolitic material. The potential application of this coal fly ash conversion product for decontamination of high heavy metal waters was evaluated using three high heavy metal waters from acid mine drainage around the pyrite Huelva belt. The results were compared with those obtained with an equivalent pure commercial synthetic zeolite. A considerable reduction in the heavy metal content was attained (Zn from 174 to <0.1 mg/L, Cu from 36 to 0.1 mg/L, Fe from 444 to 0.8 mg/L, Mn from 74 to <0.1 mg/L, Pb from 1.5 to <0.1 mg/L, and Cd from 0.4 to <0.1 mg/L), even in high Ca and Fe waters using zeolite doses from 5 to 30 mg/L. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters. Leachable hazardous elements from coal fly ash, such as Mo, B, As, V, and Cr, were not fixed in the synthesis of pure zeolites from the silica extracts. Consequently, they did not restrict the potential applications of this material as an ion exchanger, unlike the zeolitic material obtained from fly ash by direct alkaline conversion.
2020
Owing to the high content of SiO2 and Al2O3, fly ash utilization as starting material for zeolite is becoming a great interest. In this research, fly ash was converted into zeolite using reflux method at 138 °C for 1 hour in NaOH 2M followed by heat treatment at 90 °C for 24 hours. The characterization of the resulting zeolite was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET surface area measurement. The study of its adsorption-desorption behaviors were also investigated using ammonium solution. Infrared spectra showed typical zeolite peaks for Si-O-Si or Al-O-Al stretching at 985 cm-1, Al-O-Si stretching at 663 cm-1, and Al-O or Si-O bending at 455 cm-1. XRD analysis confirmed the formation of sodium aluminium silicate hydrate, which is a sodalite zeolite. The surface areas of coal fly ash and zeolite were 6.9 m2/g to 34.1 m2/g, respectively. The ZFA was able to adsorb 2.9 mg/g ammonium ions u...
A comparative study using two methods to produce zeolites from fly ash
Minerals Engineering, 2004
Two methods have been evaluated for the synthesis of zeolites using a UK fly ash as raw material. One method consists of a conventional hydrothermal technique in which fly ash is mixed with NaOH solution and the other comprises a combination of alkaline fusion of fly ash with NaOH prior to a hydrothermal treatment, where the fusion product is mixed with water. Both processes have been evaluated at different conditions of temperature, time and proportion of NaOH:PFA:H 2 O in order to optimise the synthesis. Products have been characterised in terms of mineralogical composition and cation exchange capacity. Experimental results have demonstrated that parameters such as the NaOH/PFA ratio, time and temperature have a significant effect on the type and degree of zeolitisation achieved, with types X being dominant under optimised conditions. In both cases, the synthetic zeolite products display significantly increased adsorption capacities compared to the raw material. However the fusion method yield better results in terms of shorter times necessary to obtain a product with high crystallinity and excellent performance as cation exchanger.
Synthesis of zeolites from coal fly ash: an overview
International Journal of Coal Geology, 2002
Coal combustion by-products production in USA and EU is estimated in around 115 million tons per year. A large portion of this production is accounted for the coal fly ash (CFA). Cement and concrete manufacturing consumes most of the CFA produced. Zeolite synthesized from CFA is a minor but interesting product, with high environmental applications. Zeolites may be easily obtained from CFA by relatively cheap and fast conversion processes. This paper provides an overview on the methodologies for zeolite synthesis from CFA, and a detailed description of conventional alkaline conversion processes, with special emphasis on the experimental conditions to obtain high cation exchange capacity (CEC) zeolites. Zeolitic products having up to 3 meq g À 1 may be easily obtained from high-glass CFA by direct conversion. A review of potential applications of different zeolitic products for waste water and flue gas treatment is also given. The examination of the data presented by different authors reveals that one of the main potential application of this material is the uptake of heavy metals from polluted waste waters. The zeolitic material may be also used for the uptake of ammonium from polluted waters but high concentrations of other cations may considerably reduce the ammonium absorption efficiencies due to ion competition. Some of the zeolites synthesized may be also used as molecular sieves to adsorb water molecules from gas streams or to trap SO 2 and NH 3 from lowwater gaseous emissions. D
Characterization of Na and Ca Zeolites Synthesized by Various Hydrothermal Treatments of Fly Ash
Advances in Civil Engineering Materials, 2015
For the past several decades, researchers have studied the zeolitization of coal fly ash (class-F) by following different methods (viz., open and closed hydrothermal, and fusion followed by hydrothermal). In fact, these methods involve sequential processes like (i) dissolution of silica and alumina from the fly ash, (ii) nucleation of zeolite, and (iii) crystallization (growth of zeolite) in the reactant solution. Also, performance of these processes has been reported to vary with the type of alkali used as reactant and often, NaOH has been preferred for high cation exchange capacity, resulting in sodium zeolites. However, large scale applications of Na-based zeolites in soil and water are questionable due to the presence of high sodium, thereby increasing the sodicity and salinity of the soil/water. In addition, performance of the zeolites, as adsorbent, synthesized by different methods is expected to depend on various characteristics (viz., mineralogy, structural bonding, specific surface area, pore volume, and morphology), of the zeolites. In order to address the above issues, the present study is focused to investigate the various characteristics of the synthesized zeolites by (i) the above mentioned three methods, (ii) using Ca(OH) 2 as reactant, and (iii) considering Na and Ca present in the fly ash. Thus, the aim of the study was to ascertain (i) a suitable method out of the three and (ii) characteristics of the blend of Na-and Ca-zeolites from the fly ash, which can Manuscript be used as a controlled release fertilizer, as sorbent for water and soil decontamination.
Journal of the Brazilian Chemical Society, 2016
Coal fly ash has been proposed as an alternative raw material for zeolite synthesis, however, the mobilization of toxic elements of this material into zeolite products, washing water and effluent is rarely addressed. In this study, Brazilian coal fly ash was used in the integrated synthesis (two steps) of zeolites Na-P1 and 4A and the distribution of approximately 40 major, minor and trace elements was investigated in all the input and output flows involved in the process. The mobilization of several elements was observed in the zeolite products, a number of which are highly toxic, such as As, Cd, Cr, Ni and Pb. With regard to the amount present in the ash, both zeolites were enriched in several elements, such as Ni in zeolite Na-P1 and As in zeolite 4A. The latter exhibited high purity, with most of the elements investigated having concentrations close to those measured in commercial zeolite 4A. Important information was gathered regarding zeolite synthesis using fly ash, which will ensure safer application of these materials and, if necessary, propose a contaminant-free synthesis route.
Recent Advances in the Synthesis of Zeolite from Fly Ash
Zeolite is aluminosilicates, micro porous crystalline, with TO4 tetrahedral (T = Al, Si) and oxygen atoms are linked to each other with the corners. Zeolite has been unique ion properties as an adsorption and molecular sieving, dehydration and rehydration, biological activity, catalytic, and cation exchange and many more because of it has a wide application. The numbers of scientists have been developing various methods for the synthesis of zeolite. There are many ways for the synthesis of zeolite, which mainly included treatment of natural zeolite, pertaining minerals of natural clay, fusion with alkali, zeolite synthesis by hydrothermal conventional, and microwave assisted zeolite synthesis. The review’s objectives are depending on recent trends of zeolite synthesis from fly ash.