Coal-based Power Research Articles

Ecological and human health risks from pseudo-total and bio-accessible metals in street dusts.

Street dust samples were collected from industrial and commercial cities (Jamshedpur and Ranchi during monsoon and post-monsoon seasons) for detecting the levels of Cr, Cd, Cu, Ni, Pb, Zn, As, Co, Al, and Mn. The industrial city recorded higher metal concentrations compared to commercial. Similar trend of pseudo-total metal concentrations was observed in both the seasons at industrial city (Al > Mn > Zn > Cr > Pb > Cu > Ni > Cd) and only monsoon season at commercial city (Al > Mn > Zn > Cu > Cr > Pb > Ni > Cd). Zn > Cd was the most bioaccessible metal throughout the cities (monsoon and post-monsoon). The geochemical parameters (Igeo, EF, CF) were highest for Cd and lowest for Ni (both cities for the two seasons). Pollution Load Indices (PLI zone) were highest during the post-monsoon season in the industrial city. The highest carcinogenic risk was posed by Cr ranging from 1.87E-05 to 4.80E-05, in both the cities through ingestion and inhalation pathways. Children were found at higher risks, while the bioaccessible fractions posed neither carcinogenic nor non-carcinogenic threats to the population. Principal component analysis and correlation analysis indicated the influence of vehicular and industrial emissions, especially steel industry and coal-based thermal power plants as the major source of metals in street-dust. The outcomes of this work will be useful in providing baseline information of pollution along with their consequent environmental and human health risks of Jharkhand state.

Online optimization of boiler operation based on information integration and case-based reasoning

ABSTRACT Boiler combustion optimization is a crucial method to deal with the profound load changing of coal-fired units, improve thermal power plant flexibility, and ensure unit operation safety, energy-saving, and environmental protection. However, the strong coupling, non-linearity, time-variation and timeliness of boiler combustion systems bring challenges to the online application of boiler combustion optimization technology in practical engineering. This work proposes a new multi-objective online combustion optimization framework based on information integration and case-based reasoning (II_CBR), and establishes the II_CBR system platform to serve a 330-MW coal-based power plant. The framework is combined offline database construction and online combustion optimization. The offline database integrates simulation feature information and operation parameter information, which provides richer informative knowledge. The online approach achieves the online calculation of the simulated feature information and combustion optimization. The results show that boiler efficiency increased by 0.31%, and the maximum reduction in NOx generation was 41.22 mg/Nm3, which indicates the proposed method is suitable for online real-time combustion optimization and supports power plant operators for flexible optimization. In addition, it improves boiler efficiency, reduces nitrogen oxide emissions, and provides new directions for deep load-changing coal-fired units.

Total Factor Energy Efficiency of China’s Thermal Power Industry

Coal-based thermal power generation has long been the main source of power generation in the mainland of China. The efficiency of power generation is an important factor that determines the energy conservation and emission reduction as well as the sustainable development of the power industry in China. By comparing the regional differences of 30 provinces in the mainland from 2013 to 2017, this study uses the Super-DDF model and the TFEE to comprehensively evaluate the energy efficiency of thermal power generation. Empirical results: Overall efficiency: eastern efficiency (1.181) is the highest, followed by western (0.956), central (0.951) and northeastern (0.926). Total factor energy efficiency: eastern efficiency (0.923) is the highest, followed by western (0.754), central (0.742) and northeastern (0.710). The government and power industry managers should fully consider the regional differences in the field of thermal power generation when formulating policies so as to improve the power efficiency and promote the green development of power industry in China. Based on the analysis results, although the coal-fired power industry is more mature than other alternative energy industries, the expansion of thermal power generation cannot be considered if CO2 emissions are to be reduced. Additionally, the market share and competitiveness of the local power industry can be increased based on the different conditions of the resource endowments of each region.

Live-Life cycle assessment of the electric propulsion ship using solar PV

This paper was born to introduce a novel methodology termed Live-Life Cycle Assessment using a simulation-based data generation technique that can remedy the inherent shortcomings of conventional practices of lifecycle assessment. To demonstrate its excellence, the proposed method was applied to one of the most challenging topics in the marine industry. That was to tackle the fundamental doubt of whether solar-electric propulsion ships could truly be the future energy solution of maritime transports by fulfilling new environmental conventions and goals around the world. The case study began with an existing hybrid short route ferry running on diesel and plug-in battery power. Credible PV systems for the case ship was modelled to produce ship performance data under various operational/environmental circumstances of the coastal zones across 29 countries in the platform of MATLAB/Simulink. As a key functionality of Live-Life Cycle Assessment, the produced data was directly fed, as inputs, into life cycle assessment to avoid conventional practices that heavily rely on outdated data libraries. Results of the case study clearly revealed and quantified the correlations of the performance of PV-battery systems with climate parameters such as temperature and irradiance of subject areas as well as national power production methods. For example, in terms of Global Warming Potential, the case ship with the PV system was estimated to reduce 40,812 kg CO2 eq. per year in Brazil (average temp.: 27.4 ℃, major energy source: hydro). Interestingly, the same vessel was found to achieve greater reductions in India (average temp.: 27.5 ℃, major energy source: coal) or Australia (average temp.: 20.1 ℃, major energy source: coal) where are overly laden with coal-based power plants. Therefore, their reduction levels were estimated at 152,887 kg CO2 eq. per year and 141,517 kg CO2 eq. per year respectively. This paper clearly shows the excellence of the proposed method to demystify/quantify the impacts of parametric variables on the performance of the PV-electric ship. Moreover, it highly suggests the Live-Life Cycle Assessment could be a solution as a new standard to respond to strong demand to obtain general observation of lifecycle benefits/harms of new technologies across all industries, not necessarily limited to the maritime sector.

Evaluating the durability of stabilized conventional granular material with Pond Ash and lime used as subbase course of flexible pavement

The backbone of power capacity addition in India has always been the coal-based thermal power generation. The thermal power stations has been fueled by the coal produced in India, which are predominantly low grade with 30–22% ash content. The ever-growing disposal problem of the Pond Ash (PA) generated by these thermal power stations, on account of using the high ash content coal having, granular particle sizes has become a huge issue. The associated environmental hazard is the primary coencern along with the dumping zone, which covers large hectares of land over a prolonged period. On the other hand, a strictly regulated sand mining scenario restricted the progress of the construction activities in the related field. So effective reuse of such industrial waste by replacing the conventional granular material, may overcome the environmental and health hazard, as well as speed up the construction activities. Moreover, the PA will find effective bulk usage. Prior Investigational works have shown improvement in the geotechnical properties of stabilized coal combustion ash. This study involves sand and PA blended in varying proportions from 0% −100% at an increment of 10% by weight of sand, with addition of lime (0%, 1%, 2%, 3%, 4%, 5%, 6%, 7% and 8% by weight of sand) as stabilizer. The un-soaked bearing ratio of sand – PA optimum mix with different lime content was observed. The results indicated a considerable rise in the bearing ratio up to 4% lime content which gradually reduces on further addition. Experimental results showed a maximum CBR of 32.85% for standard compaction un-soaked sample. Sand – PA – Lime samples were further tested for their UCS values after curing them for 7, 14, and 28 days. The results maxed out at 0.8 MPa for 28 days curing at 4% lime content. Slake Durability Indices showed high to medium–high durability value for the optimum mix. Chemical composition of lime and PA along with XRD and FESEM of PA sample was also conducted to characterize the sample. The test outcomes satisfied the MORD and MORTH requirements to use the sand (71%): PA (25%): lime (4%) as suitable subbase material for pavement foundation construction as cost-effective mix proportion.

A review on life cycle assessment approach on thermal power generation

The global population is predicted to reach 9.9 billion people in 2050, with 80% of the population living in developing countries. As the world's population grows, the demand for electricity also increases. In most developing nations, coal is the most important source of energy. The environmental impacts of coal-based electricity generation are a key concern for long-term sustainability and hence an intensively studied topic in many nations. The life cycle assessment (LCA) method has been widely used around the world to assess the environmental impact of electricity generation. Because the results of LCA are generally dependent on geographical location, they must be carried out for a specific location. In the Indian context, there are still gaps to be addressed in this area. This review is part of the baseline research for a comprehensive LCA analysis of India's coal-fired power facilities. A literature analysis of a variety of worldwide studies is conducted with a focus on understanding the LCA technique and environmental assessment. The findings of the analysis demonstrate that, while prior LCA studies have proven useful, no comprehensive LCA on coal-fired power plants in India has yet been completed. As a result, the objective of this research is to undertake a systematic review of LCA studies conducted on coal-based thermal power plant operations, emissions mitigation strategies, and transmission and distribution. The paper also discusses the methodology adopted by the researchers and the results of the LCA of thermal power plants in the Indian context.

Mineral admixtures utilization in different areas: A review

Nowadays, the electricity required in the developing countries are mostly dependent on Coal-Based thermal Power plants. During the course of production of electricity, the solid waste residue namely Fly Ash (FA), which is left behind causes serious impact to the environment. On the other hand, another residue, Ground Granulated Blast Furnace Slag (GGBS) which is produced from the molten iron slag is also disposed on the land surface, resulting which several bad impacts occur on the heath of the environment. Apart from these mineral admixtures, one more such ash namely Rice Husk Ash (RHA) is also produced by the processes of burning of the rice husk itself. Some of the ashes which are directly produced by the burning of hard Bituminous coal together with hard Anthracite give rise to the mineral admixture to be often known as Silica Fume. Metakolin is also another type of Mineral Admixture which is produced by the burning of kaolin clay. In some countries, the production of Palm Tree is so high that electricity is generated there by burning of Palm shell and husk. During production, the residue, which is equally harmful to the environment, is known as Palm Oil Fly Ash (POFA). The problem does not lie with alone; the major issues is of storage of all these mineral admixtures. In most of the countries these solid waste mineral admixtures are placed on a large open area of the land. Such mineral admixtures are toxically associated with heavy metals which cause to leach the ground water and the soil as well. But researchers have found that these mineral admixtures being considered as solid waste, are, in fact, very useful materials and have also proven their worth over a period of time. This paper aims at focusing on the various ways of utilizing the different Mineral Admixtures in various areas of Civil Engineering. Also in the paper, there is strategical focus on the proper management of mineral admixtures to make use of these solid wastes, in order to save our Environment.

An experimental study on controlled low strength material (CLSM) for utilization as sustainable backfill

Disposal of ash produced by coal-based power plants is a global problem because of its fineness and lack of space for its pondage. In recent years, efforts have been made to reutilize ash for different applications, viz., manufacturing of cement, bricks, tiles, in concrete, for soil stabilization, construction material for roads and bridge abutments, etc. However, there is a need to find more applications for the complete utilization of ash. In this direction, the present work explores potential of fly ash and pond ash for development of controlled low strength material (CLSM), an alternative material for backfilling applications. The performance of different compositions of CLSM have been studied, by partially replacing sand and cement, with pond ash and fly ash, respectively. Experimental studies have been performed to obtain flowability, hardening time and compressive strength (soaked and unsoaked conditions) for different CLSM combinations. In the present study, 20% binder content and 80% filler content has been considered, with a water/binder (w/b) ratio of 1.7 based on initial trials. Further, variation in percentage of fly ash and pond ash as partial replacement of cement and sand, respectively, have been evaluated. From the test results, it can be concluded that upto 75% replacement of sand by pond ash (60% of overall mix) is possible for development of CLSM with desired properties. Furthermore, the 28-days average compressive strength observed for CLSM varies from 0.4 MPa to 1.8 MPa for the studied combinations. This range of strength is favourable for backfilling applications, wherein, excavation in future may be necessary. Though the study results are quite encouraging towards development of CLSM using pond ash and fly ash, further studies on durability properties and minimizing the variation in properties would help towards developing sustainable CLSM for environmentally friendly infrastructure development.

The progress toward more sustainable energy, water and environmental systems approaches and applications

This editorial provides an overview of ten scientific articles published as the Special paper selection in Thermal Science. The papers were selected from almost six hundred contributions, presented at the 16th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES 2021), held on October 10-15, 2021 in Dubrovnik, Croatia. The topics covered in the Special paper selection include economics of electricity markets, nuclear technology, repowering of the coal-based power plant, hybrid renewable energy system, sustainable biomass handling and conversion, post-combustion emissions control, and efficient cooling technology. The editorial also emphasised the papers recently published in the Special Issues of leading scientific journals dedicated to the series of SDEWES Conferences.

Development and testing of a new post-combustion CO2 capture solvent in pilot and demonstration plant

Post-combustion CO2 capture for coal-fired power plants is an important technical option to mitigate greenhouse gas emission from coal-based power generation. CO2 capture based on chemical absorption is currently the dominant technology for large-scale capture unit. The main obstacle of commercial application is the high cost and high energy consumption, innovation of new absorption solvent is one of the keys to the performance improvement. Based on the characteristics of flue gas, combined with the analysis and comparison of potential amine components, the formula of blended amines are developed, which is further screened by true-heat flux calorimetric test combined with vapor-liquid equilibrium test, HNC-5 is selected through the lab test, because of its lower heat of absorption and higher capture performance. The test on a 1000 t/a CO2 capture pilot plant under real flue gas conditions shows that the performance index of HNC-5 is consistent with the lab test results. The CO2 capture ratio is higher than 90%, and the heat consumption during regeneration is reduced by about 20% compared with MEA. The continuous operation results of the 120,000-ton/year CO2 capture unit show that heat duty of regeneration of HNC-5 is about 2.8GJ/tCO2, the cost per ton of CO2 captured is reduced by about 63 CNY, the usage life is longer, helping improve the system availability and reliability.

Icosahedral cluster formation in Ni-based hydrogen separation amorphous membranes and the effect of hydrogenation-a first principles structural study.

The demand for hydrogen is increasing due to commercialization of fuel cells. Palladium (Pd)-based crystalline membranes have been used for separation of hydrogen from a mixture of gases in coal-based power generation process. However, very high cost of Pd has prompted to explore inexpensive alternative alloys. Amorphous Ni-Nb-Zr alloy membranes are promising cheaper alternatives which exhibit comparable hydrogen permeability to Pd membranes at nominal temperature of ~ 400°C. Constant exposure to high temperature and hydrogen pressure may lead to changes in the local atomic structure and possible devitrification of membrane. It is critical to understand short-range order of these membranes in order to improve their hydrogen permeability and durability. Icosahedral clusters are the building blocks of amorphous material and hydrogen is expected to interact with them in various different ways. The density functional theory-based molecular dynamics (DFT-MD) approach is the best suited approach to study the local atomic structures for (Ni0.6Nb0.4)90Zr10 and (Ni0.6Nb0.4)70Zr30 amorphous membranes with the help of nearest neighbor distances and icosahedral cluster analysis. It can help predict the behavior of the membrane under extreme operating conditions. Three types of icosahedra (so called Ni-centered, Zr-centered, and Nb-centered) were identified in six different compositions in these amorphous alloys. Evolution of these icosahedra with temperature and in the presence of hydrogen gave an insight into the local structure of the membrane. Zr plays an important role in the formation of icosahedra. Hydrogen atoms interact with the icosahedra in three different ways. It is observed that H atoms did not show tendency to enter Ni-centered icosahedra leading to easier hydrogen diffusion outside the icosahedra. Hence, the more the number of Ni-centered icosahedra, the better the permeation properties of the alloy.

Computational analysis of influence of particle size, oxygen concertation, and furnace temperature on the ignition characteristics of pulverized high ash and high moisture coal particle

Energy is a critical component in any given region's growth. India has the world's fourth-largest coal reserves. Therefore, energy generation from coal-based power plants is still a significant source of power in the country. However, the performance of Indian coals is poor compared to foreign coals such as South African, Indonesian, and US coals due to the high ash and moisture content. Seventy percent of country electricity need is still dependent on coal power even with known negative environmental consequences such as the production of CO2 & greenhouse gases, and air pollution caused by SOx, NOx, coal sludge, coal dust, and by-products of coal combustion. In this work, effect of coal types, particle sizes, and furnace temperatures on the ignition delay time of pulverized coal particle is investigated. In the current study, the ignition delay time of four Indian coals (IS1, IS2, IS3, and IS4), two Indonesian coals (IAS1 and IAS2), and one South African coal (SA1) were examined for particle sizes ranging from 35 to 115 µm, furnace temperature ranging from 1000 to 1700 K, and oxygen concentrations ranging from 12 to 20% in gas. Furthermore, ignition delay analysis of different coal mixtures (Indian and foreign coals mixtures) has also been studied. Numerical analysis of ignition delay time has been performed using MATLAB. Results show that the ignition delay time of coal particles increases with a decrease in furnace temperature and an increase in particle size. Results also show that the Indian coals have a larger ignition delay time than other considered coals, and ignition characteristics of Indian coals can be enhanced by mixing with high-grade ones. An increase in oxygen concentration also reduces the ignition delay time of the coals.

Efficiency of Indian Thermal Power Plants and Suspended Particulate Matter: Findings Across Technological Assumptions and DEA Models

Suspended particulate matter (SPM) emissions from coal-based thermal power plants (CTPPs) cause respiratory illness. However, this has not been given its due importance in the efficiency assessment of CTPPs. This study contributes to the literature by incorporating suspended particulate matter in the benchmarking exercise for Indian CTPPs. In such a study, the theoretical assumptions regarding pollution generating technology or the choice of evaluation tool may impact the ranking of CTPPs. To draw robust inferences, we present a comparative study of two alternative microeconomic approaches (joint and by-production technologies) and two types of data envelopment analysis tools (graph–hyperbolic and directional distance function) applied on two representative samples of Indian CTPPs. Results indicate that Indian CTPPs are moderately inefficient. Choice of technological assumption or data envelopment analysis model does not impact the ranking of CTPPs. Ownership and plant load factor play vital roles in determining inefficiency, and impacts of these factors remain stable across models. JEL Classifications: C61, D22, Q40, Q50

Characterization of fly ash for potential utilization in green concrete

Coal-based thermal power plants are the residue material of the combustion of FA (Fly Ash). The use of FA has become an attractive alternative to disposals by raising the consciousness of the environment. The present study aims to examine the prospective use of FA in concrete and building applications, the physical, chemical, mineral and thermal properties of FA. FA obtained at the Rajiv Gandhi thermal plant, Hisar, Haryana, India, Electrostatic precipitations for experimental purposes. The FA sample is characterized as being mostly enriched in silicon; alumina and iron oxides fall into the F-type FA group. In the ash sample, Quartz and Mullite are the main mineral crystalline phases. Distinguishing thermal examination of the FA sample reveals degradation from 400 °C to 700 °C in a particular stage. The absorbed humidity and light volatility is removed in the sample during initial area. The findings of the characterization show that FA has the ability to replace the principal components of concrete like sand and to improve strength. The effects on the environment and economics of disposing FA will be reduced by establishing new opportunities for further use.

Analysis of the Effects of Failure of a Gas Pipeline Caused by a Mechanical Damage

Natural gas continues to be one of the basic energy sources used as fuel in the power sector, in industries and in households. The potential and attractiveness of this fuel is gaining special significance in the current energy transitions from coal-based power engineering to power generation based on renewable energy sources. Natural gas is supplied to consumers mainly through a network of pipelines, which ensures a relatively high reliability of the supply. Still, failures occur due to the corrosion of pipeline walls, material defects or human errors, which can result in uncontrolled release of gas. The released gas can trigger dangerous phenomena, such as fires and explosions. This paper presents an analysis of the causes and effects of damage to a medium-pressure pipeline caused by earthworks carried out within an area where a pipeline is located. Holes in the pipeline due to the impact of an excavator bucket are analysed. The impact of the excavator bucket may cause a rupture equal to 50% of the pipeline’s cross-sectional area. Hazard zones related to fires and explosions due to the released natural gas are presented. For the analysed pipeline with a diameter of 0.5 m and a gas pressure of 5 MPa, the range of hazard zones arising due to pipeline damage caused by an excavator bucket can reach about 200 m.

Mechanical properties and electrical resistivity of multiwall carbon nanotubes incorporated into high calcium fly ash geopolymer

High calcium fly ash (HCF) is a pozzolan material and is available in large quantity in Thailand due to the existence of coal-based electrical power plants. It is used as a supplemental material to partially replace cement content in concrete as a movement toward concrete sustainability. In order to lift the sustainability level, a cementitious material without Portland cement called ‘geopolymer’ was introduced. Geopolymer can be produced from raw materials containing high alumina and silica, for example fly ash, blast furnace slag, and metakaolin. For high calcium fly ash geopolymer (HCFG), the unique properties include fast setting, and high early strength. In this study, in order to enhance the properties of HCF geopolymer, multiwall carbon nanotubes (MWCNTs) were introduced into the matrix. In addition to the investigation into basic properties, the effect of MWCNT on electrical resistivity was also investigated to determine its potential use in piezoelectric sensor applications. The results showed that the addition of MWCNTs improved the mechanical properties of HCFG. The maximum compressive and flexural strengths were obtained with a mix containing 0.2% MWCNTs. The EDS test also indicated the increase in geopolymerization and hydration products with the addition of MWCNTs. To investigate the piezoelectricity potential, the electrical resistivity under different levels of compression loads was investigated. The resistivity decreased with the increasing load level up to the first crack, and then decreased. The changes in electrical resistivity indicated the potential use of HCFG incorporated MWCNTs in self-sensing for structural health monitoring.

Reduction of Emission Gas Concentration from Coal Based Thermal Power Plant using Full Combustion and Partial Oxidation System

Rapid growth in industrialization has led to high dependency of reliable electric power source for its operation. On the contrary, thermal power plants expel pollutants consisting of hazardous gases that result in degradation of environment and ecosystem. Thus, utmost importance is to generate clean and efficient energy from power plant. This current article resolves the problem of sustainable power production using coal-based thermal power plants, by integrating gasification technologies to the system. The performance of thermal power plant in terms of emission is numerically analyzed with varying gasifier pressure, air-fuel ratio, steam-fuel ratio and flue gas-fuel ratio. Numerical simulation of the gasification cycle with varying parameters is carried out using MATLAB. Optimum performance at gasifier pressure of 2 bar and the steam-fuel ratio of 0.25 was observed with relative air-fuel of 0.075. With increasing flue gas-fuel ratio from 0.25 to 1.00, although the mole fractions of components of syngas don’t differ much, the heating value and cold-gas efficiency of syngas produced decreases for each fuel. Considering the emissions, simulated results present co-gasification as better option over conventional systems. A reduction of two-third in kg of CO2 released per kg of fuel was observed with almost three-fourth decrement in kg of CO2 per kWh of power produced. Also, zero SOx and NOx emissions were observed compared to coal based thermal power plants. It is noted that optimum performance of gasification system at gasifier pressure of 2 bar, air-fuel ratio of 0.1, steam-fuel ratio of 0.25 and flue gas-fuel ratio of 1.00. The proposed cycle presents itself suitable for further research and its application to coal based thermal power plants, providing potential towards supplementary power generation and cleaner exhaust. This research would also significantly contribute to achieve sustainable development goals.

Sustainable recovery of plant essential Nitrogen and Phosphorus from human urine using industrial coal fly ash

Coal-based thermal power plants play a pivotal role in meeting global energy demand. The amount of fly ash generated from these plants increases every year, and its successful use has posed a significant environmental risk in the last decade. In this study, coal fly ash was packed in a fixed-bed adsorption column to remove Urea–N from synthetic human urine. To assess the efficacy of fly ash in the removal of Nitrogen, various process parameters were tested, including initial urea concentration in urine (20, 40, 60%), fly ash loading in column (100, 150, 200 g), and urine flow rate through the column (2, 4, 6 L h−1). The initial urea concentration and bed height were found to have a major impact on nutrient recovery. Following nitrogen removal, the effluent urine was de-phosphatized using struvite precipitation and approximately 83% of phosphorus was recovered. High inlet urine concentration (60%), high flow rate (6 L h−1) and minimal adsorbent loading (100 g) resulted in maximum struvite precipitation. The column breakthrough and characteristic parameters of four different models were predicted using kinetic modelling of the adsorption data, in which Yoon–Nelson and Thomas’ models suggested efficient removal and recovery of plant essential nutrients. Findings in this study suggests that the coal fly ash appears to be a promising adsorbent for extracting these important plant nutrients. The effect of initial urine concentration, fly ash loading in the column, and urine flow rate on dephospatisation was calculated. The findings of this study will shed light on the process of nutrient adsorption process selection and detail the comparative differences between continuous and batch nutrient recovery of human urine.

Alkaline Hydrothermal Synthesis of Zeolite from Class F Coal Fly Ash

Coal Fly ash is an industrial waste produced from coal-based thermal power plants. Of the total amount of fly ash generated, a small fraction is used as a supplement to Portland cement and rest of the fly ash is used as landfill. One of the novel ways of utilizing coal fly ash is through zeolitization, zeolites being hydrated aluminosilicates, and coal fly ash a rich source of alumina and silica. Coal fly ash obtained from the thermal power plant of NTPC Kaniha is subjected to alkaline hydrothermal treatment and the resulted zeolite is characterized for chemical analysis, crystal structure, thermal stability, FTIR studies, ion exchange capacities, etc. After zeolitization surface area of the product increases due to the formation of more pores and channels and also there is an increase in its crystallinity. When subjected to temperature its crystallinity first increases and then decreases and after a particular temperature the crystalline character almost vanishes. The resulted zeolite is found to be NaP1 zeolite with a high ion exchange capacity. High cation exchange (CEC) values ensure the adsorption of heavy metals by zeolites which can be used for the treatment of wastewater and industrial waste material. Thus zeolites can be hydrothermally synthesized from an industrial waste like coal fly ash at a much cheaper cost of production. The synthesized zeolite can be used for cation exchange, adsorption catalysis, and a host of other industrial applications.

Remediating oxytetracycline-contaminated aquaculture water using nano calcium peroxide (nCaO2) produced from flue gas desulfurization (FGD) gypsum

Antibiotic-contaminated water, particularly oxytetracycline (OTC), which is widely used in aquaculture, can threaten human health through the ingestion of edible aquatic organisms. The objective of this study was to develop novel and cost-effective calcium peroxide nanoparticles (nCaO 2 ), synthesized using flue gas desulfurization (FGD) gypsum for improving water quality and OTC removal. The nCaO 2 -FGD was synthesized using a 1:7 (FGD:H 2 O 2 ) mixture. The results showed that nCaO 2 -FGD had spherical particles with diameters of 20–60 nm. The dissolved oxygen production in water by nCaO 2 -FGD significantly increased, with an oxygen release rate of 0.0079 min −1 . The nCaO 2 -FGD achieved OTC removal of 83.92% within 48 h. Radical trapping experiments revealed that hydroxyl radical, superoxide ion, and singlet oxygen play important roles in OTC degradation. The mineralization of the OTC investigated by total organic carbon (TOC) was 71 ± 4%. The nCaO 2 -FGD dosage, initial OTC concentration, carbonate ion, and humic acid (HA) significantly affected OTC removal, while the initial pH and chloride ion did not at the 95% confidence level. Using response surface methodology, we found that the optimum conditions for treating 10 mg/L of OTC were 53.25 mg/L HA, 558.72 mg/L CO 3 2 − and 2,320.75 mg/L CaO 2 -FGD. The nCaO 2 -FGD encapsulated in alginate aided in maintaining the pH of water (pH 6.5–7). The nCaO 2 -FGD was then used to treat real aquaculture water. After 48 h, 10 mg/L of OTC was degraded by 75.83 ± 2.1%. The zooplankton communities in the aquaculture water did not significantly differ before and after treatment. Therefore, our results indicate that nCaO 2 -FGD is safe for implementation • FGD gypsum, a solid waste byproduct of coal-based power generation, was economically utilized. • As a novel dual-function material, nCaO 2 -FGD acts as an oxygen-release and effective oxidizing material. • O 2 was released mainly from nCaO 2 -FGD dissolution. • Active radicals generated in the nCaO 2 -FGD/water system play important roles in degrading OTC.