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Expansive clays feature high compressibility and large swelling-shrinkage potential, which may cause significant damage to the infrastructures, including pavements. This study investigates the potential use of industrial waste ash generated from municipal solid waste incineration (MSWI) as a more sustainable treatment method to treat expansive soils compared to the use of conventional coal fly ash. A series of tests was conducted to study the mechanical, durability, and environmental performance of the MSWI fly ash in comparison with the coal fly ash. The study reveals that the compressive strength and resilient modulus of 20% MSWI fly ash treated sample increased to 0.86 MPa and 213 MPa respectively, depicting an increase of 150% and 240% of the control clay specimen. Results also indicate that MSWI treated expansive clay shows better performance during the soaked California bearing ratio (CBR) testings, moisture susceptibility and cyclic wetting–drying tests compared to coal fly ash treated samples. Microlevel investigations reveal that the influence of cation exchange is more decisive in the MSWI-treated clays due to the presence of higher Ca2+ ions, during the early stages, and the influence of hydration is stronger at the later stage of stabilisation. X-ray diffraction (XRD) results show that gismondine, albite, calcite, portlandite, andradite, and ettringite are the main crystalline phases formed during the stabilization. Heavy metal concentrations after the stabilisation are within the allowable limit defined by state regulations. Applying MSWI fly ash as a ground treatment for expansive clays can reduce the consumption of natural resources, promoting a "zero landfill" policy. [ABSTRACT FROM AUTHOR]

Due to industrialization, soil heavy metal pollution is a growing concern, with humic substances (HS) playing a pivotal role in soil passivation. To address the long duration of the compost humification problem, coal fly ash (CFA) in situ catalyzes the rapid pyrolysis of the cotton stalk (CS) to produce HS to address Cd passivation. Results indicate that the highest yield of humic acid (HA) (8.42%) and fulvic acid (FA) (1.36%) is obtained when the CS to CFA mass ratio is 1:0.5, at 275 ℃ for 120 min. Further study reveals that CFA catalysis CS humification, through the creation of alkaline pyrolysis conditions, Fe2O3 can stimulate the protein and the decomposition of hemicellulose in CS, and then, through the Maillard and Sugar-amine condensation reaction synthesis HA and FA. Applying HS-CS&CFA in Cd-contaminated soil demonstrates a 26.69% reduction in exchangeable Cd within 30 days by chemical complexation. Excellent maize growth effects and environmental benefits of HS products are the prerequisites for subsequent engineering applications. Similar industrial solid wastes, such as steel slag and red mud, rich in Fe2O3, can be explored to identify their catalytic humification effect. It could provide a novel and effective way for industrial solid wastes to be recycled for biomass humification and widely applied in remediating Cd-contaminated agricultural soil. [ABSTRACT FROM AUTHOR]

CO2 mineralization plays a critical role in the storage and utilization of CO2. Coal fly ash (CFA) and red mud (RM) are widely utilized as CO2 mineralizers. However, the inert calcium species in CFA limit its carbonation capacity, meanwhile the substantial Ca2+ releasing of RM is hindered by a covering layer of calcium carbonate. In this study, CO2 mineralization in a composite system of CFA and RM was investigated to enhance the carbonation capacity. Multiple analyzers were employed to characterize the raw materials and resulting mineralization products. The results demonstrated that a synergistic effect existed in the composite system of CFA and RM, resulting in improving CO2 mineralization rate and efficiency. The produced calcium carbonate was ectopically attached the surface of CFA in the composite system, thus slowing down its coverage on the surface of RM. This phenomenon facilitated further releasing Ca2+ from the internal RM, thereby enhancing CO2 mineralization efficiency. Meanwhile, the inclusion of RM significantly improved the alkalinity of the composite system, which not only promoted the dissolution of Ca2+ of the inert CaSO4(H2O)2 in CFA, but also accelerated CO2 mineralization rate. The investigation would be beneficial to CO2 mineralization using industrial solid wastes. [ABSTRACT FROM AUTHOR]

AMD (acid mine drainage) with low pH and high content of heavy metals is a serious environmental problem in mining activities. Proper AMD management is crucial to ensure compliance with the standards of environmental quality before allowing the flow to the public water system. The objective of this study was to assess the efficacy of increasing pH and decreasing Fe alongside the concentrations of Mn in AMD with the addition of coal fly ash (CFA) and empty fruit bunch of oil palm (EFBOP). A total of four treatments, namely: (1) control (soil without treatment), (2) soil + EFBOP, (3) soil + CFA, and (4) soil + EFBOP + CFA were tested for the ability to improve AMD quality in a batch reactor experiment for 90 days. Weekly observations were carried out for pH, Fe, and Mn concentrations during the experiment, where part of AMD in the reactor was drained and replaced with fresh ones. The results showed that single treatment of EFBOP or CFA caused a pH increase at 2.8 to 5.1-5.4 and 6.3-6.8, respectively. Furthermore, a greater increase occurred from 2.8 to 7.0-7.8 when EFBOP was combined with CFA application. This combination also showed a greater reduction in the concentrations of Fe and Mn compared to the single treatment of EFBOP or CFA. The increase in pH and decrease in Fe alongside the Mn concentrations began in the 3rd week, and this effect was stable during the 90 days of the experiment. The results underscore the potential of EFBOP and CFA as agricultural and industrial wastes in long-term AMD management. [ABSTRACT FROM AUTHOR]

Complex dyes have an adverse impact on the environment since they have a high aqueous solubility and are very challenging to be removed using conventional approaches. A series of batch tests were performed to determine the optimum parameters for the direct blue 78 dye adsorption process as a function of chemically treated coal fly ash (TCFA) Effect of fly ash dose, contact time and dye initial concentration were studied using an industrial wastewater. A pilot plant, consisting of three stages; mixing, sedimentation and filtration was designed and implemented to investigate the ability of TCFA to remove COD, BOD5, TDS and TSS from textile wastewater under optimal conditions. A series of fly ash physico-chemical analysis including particles size analysis, zeta potential, XRD, EDX, BET, SEM and FTIR were investigated. The results showed that the particles size and zeta potential for raw coal fly ash were 1.2 µm and −20.70 mv. Chemical treatment process using hydrochloric acid resulted reducing the particles size of fly ash from 1.2 µm to 0.95 µm. Zeta potential value increased to + 7.20 mv. Batch adsorption process showed that the removal efficiency decreased as the primary dye concentration increased. It increased when fly ash loading and contact time increased. Dyes removal was achieved up to 99.7% using TCFA loading 3gL−1 for initial dye concentration10 mgL−1. Studies on equilibrium revealed that the equilibrium data was closely fitted to the Freundlich and Langmuir isotherm models. Kinetic study of adsorption process was studied in detial. Based on high correlation coefficient (R2 = 0.999), the results were followed pseudo second-order model. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA) is an anthropogenic industrial byproduct that is expected to increase exponentially to fulfill the needs of energy using coal and agro-waste as a cheap fuel. The disposal of this classified human carcinogen is a major concern in developing and underdeveloped economies due to lack of resources. Recycling and value addition of industrial waste, coherence with sustainable development goals is a viable solution. Zeolitization of coal fly ash is an ideal approach for recycling this waste into superior products to be used in a variety of industrial applications. This study was aimed to recycle CFA to useful zeolites using ultrasound assisted hydrothermal process. Sesamum indicum plant stems based fly ash (rFA) was found to belong to class “F" and has very low moisture and carbon contents. To investigate the morphology and elemental composition of rFA and UHSZ, SEM/ EDX was used along with XRD, FTIR and Raman spectroscopy which confirmed the existence of quartz, mullite and anhydrite. SEM/EDX results revealed the presence of Al, Si, S, K, Sb, Mg and Ta in raw ash. Adsorption studies of both rFA and synthesized zeolite(UHSZ) were conducted to determine the quintessential parameters of pH, time, initial dose of adsorbent for optimum results. Fabricated zeolites (2 g/100 mL) from raw fly ash removed 90–98% of chlorazol black E (DB38) from 100 mg/L solution within 40 min at pH ≈ 7. Both Langmuir and Freundlich isotherms gave best fit, which validated that the adsorption of DB38 to UHSZ was a blended process rather than a simple monolayer adsorption mechanism. Pseudo 1st-order and 2nd-order kinetic models were adopted to fit the obtained kinetic data. The pseudo 2nd-order kinetic model was found to be most related. [ABSTRACT FROM AUTHOR]

The main aim of this study was to develop and monitor an effective and cost-efficient industrial wastewater treatment system that utilizes sand, fly ash, and hearth ash. The latter two are potentially available and inexpensive industrial waste materials that can be used for filtration. The infiltration percolation method was utilized in a vertical cylindrical column to filter the raw wastewater from a detergent manufacturing plant. The main parameters analyzed before and after treatment included suspended solids (SS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and pH. The system successfully achieved significant reductions, including 89% in COD, 73% in BOD5, and 54% in suspended solids (SS), along with a 66% to 99% reduction in heavy metals. The COD/BOD5 rejection ratio decreased from above 4.24 before treatment to below 1.73 after treatment. Furthermore, impedance measurements were carried out across the frequency range of 100 to 1 MHz. The analysis of complex conductivity spectra revealed two Cole–Cole relaxation behaviors, and an equivalent circuit was developed to extract the primary parameters and further investigate both relaxation processes. The results of the electrical parameters deduced from the impedance spectra demonstrated a strong correlation with the parameters obtained through conventional methods. [ABSTRACT FROM AUTHOR]

Disposal of dyes wastewater into aquatic streams is considered as a major challenge due to its effect on water ecosystem. Direct dyes have a complex aromatic structure. Therefore, it is difficult to separate them from industrial wastewater. Conversely, fly ash is a main by-product pollutant generated from coal burning to fulfill energy requirements. In this study, thermochemical treatment process was applied to coal fly ash (CFA) in order to increase its surface area, improve its pore's structure and enhancing its adsorption capacity for direct blue 78 dye (DB78) removal. The treated coal fly ash (TCFA) was characterized by physicochemical analyses such as XRD, XRF, TGA, SEM, FTIR, surface area (SBET) and particles size analysis. Batch experiments were conducted to analyze the adsorption behavior for TCFA and to examine the DB78 dye removal efficiency. The physicochemical analysis results indicated that a higher increase in CFA surface area from 9.6 to 60.4 m2g−1 was obtained due to the modification process. The maximum removal efficiency using TCFA was 99.7% for initial dye concentration 10 mg/L and TCFA dose 2 g/L. The adsorption isotherm was studied by Langmuir and Freundlich model using different dye concentrations. The results showed that equilibrium data followed closely Langmuir isotherm model (R2 = 0.99) indicating monolayer and homogeneous adsorption process. [ABSTRACT FROM AUTHOR]

Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes from coal combustion account for 1.2% of all industrial waste generated in Poland. In addition, fly ashes are produced by fluidized-bed boilers. These are classified as a mixture of fly ashes and solid calcium-based reaction waste from flue-gas desulphurization, and constitute almost 2% of Polish industrial waste. This paper describes the amounts of fly ashes generated in Poland and considers activities related to their recovery and disposal. The high recovery levels of fly ashes (about 90%) and fluidized ashes (about 98%) mean that these waste products can also be considered anthropogenic raw materials. The use of these materials in the cement industry is an example of industrial symbiosis. Such usage benefits not only the economy but also the environment and, therefore, society as a whole. To describe the use of recovered fly ashes in cement plants, the authors use the anthropogenicity index, which characterizes the level of technological advancement and the substitutability of primary raw materials for secondary raw materials. [ABSTRACT FROM AUTHOR]

Currently, there is an increasing industrial demand for rare earth elements (REE) as these elements are now integral to the manufacture of many carbon-neutral technologies. The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable metals, particularly from waste streams. Although REE concentrations in most of the alternative resources are lower than current REE ores, some sources including marine sediments, coal ash, and industrial wastes, such as red mud, are emerging as promising with significant concentrations of REE. This review focuses on the alternative resources for REE, such as ocean bottom sediments, continental shelf sediments, river sediments, stream sediments, lake sediments, phosphorite deposits, industrial waste products, such as red mud and phosphogypsum, coal, coal fly ash and related materials, waste rock sources from old and closed mines, acid mine drainage, and recycling of e-waste. Possible future Moon exploration and mining for REE and other valuable minerals are also discussed. It is evident that REE extractions from both primary and secondary ores alone are not adequate to meet the current demand, and sustainable REE recovery from the alternative resources described here is also necessary to meet the growing REE demand. An attempt is made to identify the potential of these alternative resources and sustainability challenges, benefits, and possible environmental hazards to meet the growing challenges of reaching the future REE requirements. [ABSTRACT FROM AUTHOR]

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Water pollution has become one of the most acute environmental problems. One of the pollutants coming to water bodies from industries are dyes, which are harmful to human health, living organisms, and the esthetic appearance of water. Most dyes are toxic, carcinogenic, rarely biodegradable, and highly soluble in water. Therefore, industrial wastewater treatment has become important. Adsorption technique of removal of dyes from water is simple, efficient, and inexpensive as compared to other techniques. Adsorption efficiency depends on the type and surface area of adsorbents. Iron-rich coal fly ash (IRCFA)–Polydopamine (PDA)@ Silver (Ag) nanocomposite was prepared by separating the iron-rich part (IRCFA) from coal fly ash and coated with polydopamine. IRCFA was mixed with 10 mM tris buffer solution containing 1 g dopamine. The prepared IRCFA-PDA was added to an aqueous solution of silver nitrate, heated at 60 °C, and then 30 mL of flower waste extract was added to this solution. Solid IRCFA-PDA@Ag was obtained, and the prepared nanocomposite was used for the removal of methylene blue (MB) dye from water. The nanocomposite used was prepared by a cost-effective method and has high reusability, separability, and fast regeneration ability. The mechanism of removal of MB dye has been discussed in detail. [ABSTRACT FROM AUTHOR]

To reduce the filling cost of high-water backfilling material (HWBM) in mining backfill and improve the recycling utilization of the industrial waste such as the coal fly ash. The ultra-fine fly ash (UFA) was added to the HWBM as a partial replacement in this work. Therefore, a series of experiments were performed to investigate the effect of UFA on the mechanical properties of the HWBM at the different curing conditions, then the hydration mechanism of the HWBM blended with UFA was analyzed by XRD and SEM method. The result indicates that the strength of the HWBM decreased with the increasing of UFA dosages, but the addition of UFA can improve the residual strength of the initial HWBM. Additionally, when the HWBM was cured at the laboratory air condition, its carbonation process was restrained obviously as the UFA dosages were less than 15% at the ages of 28 days, which indicates the UFA can improve the weathering resistance of the HWBM with the curing ages increasing effectively. The XRD and SEM results also shows that the degree of crystallinity of the HWBM increased when UFA dosages were less than 15% effectively, while there were few obvious changes on types of hydration products. It indicates that the main affects of UFA on the performance of HWBM is filler and dilution, which reduced the contact area between hydration products of HWBM and CO2 in the air, further improved the carbonation resistance of HWBM. [ABSTRACT FROM AUTHOR]

Calcium looping (CaL) process relying on CaO as high-temperature CO 2 sorbents is a prospective alternative technology for simultaneously cyclic CO 2 capture and thermochemical energy storage. However, the cyclic stability and the energy storage density of the CaO-based sorbents decay drastically over repeated carbonation-calcination cycles. Herein, we yielded CaO-based sorbents derived from all industrial solid wastes with carbide slag (CS) as precursor and coal fly ash (CFA) as stabilizer featuring superior carbonation characteristics, stable CO 2 cyclic uptake and high thermochemical energy storage density over multiple operation cycles. The optimal sorbent (CCS–H-G-CFA-D) exhibited a high initial CO 2 uptake of 0.38 g CO2 /g sorbent , superior cyclic stability with an average decay rate of 1.05% per cycle and remarkably stable energy storage density of 1375 kJ/kg, retaining 89.5% after 10 repeated cycles. Thereby, the simultaneously enhanced cyclic CO 2 capture and thermochemical energy storage are attributed to adding CFA stabilizers in CS-derived CaO-based sorbents, forming stable skeleton to alleviate sintering, improving the uniform mixing degree between sorbent particles and promoting the carbonation reaction via synergistic effect. This simple and eco-friendly approach of cost-effective sorbents totally derived from industrial solid wastes provides a new avenue for large-scale practical CO 2 capture and energy storage processes. Coal fly ash (CFA)-stabilized carbide slag-derived CaO-based sorbents feature superior carbonation characteristics, stable CO 2 cyclic uptake and high thermochemical energy storage density over multiple reversible operation cycles. [Display omitted] • A process coupled calcium looping and thermochemical energy storage is proposed. • Facile cost-effective strategy to synthesize all-solid-waste-derived CaO-based sorbent. • Modified carbide slag with coal fly ash is employed in coupled process. • The optimal sorbent retains 89.5% initial capacity with stable energy storage density. • New-formed solid solutions and uniform doping enhance stability by isolating CaO grains. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zeolites are promising materials for the uptake of toxic pollutants from water. • The structure of zeolites has been discussed in this review. • The up-to-date advancement in zeolite-based materials for dye removal is presented. • The scope of future research is also provided. • The mechanism of adsorption and photodegradation is shown. One of the main causes of environmental contamination is the textile sector. Approximately 20 % of global industrial water pollution is caused by the textile dye industries. Although many different kinds of pollutants exist in industrial wastewater, dyes are particularly relevant to this work. Dyes are the class of emerging pollutants that severely affect water quality. Secondly, coal-powered thermal power plants, in addition to their major share in air pollution, also produce a huge amount of coal fly ash (CFA), which adds to land pollution. Disposing of CFA and removing textile dyes from water has remained a challenging problem for the world. However, with the innovation of science and technology, thanks to the discovery of synthetic zeolites, which significantly helped reduce the pollution caused by industries and thermal power plants. The synthesis of zeolites from CFA solves the problem of its disposal; additionally, zeolites are proven to be excellent adsorbents and support for photocatalysts, which aided in removing dyes from wastewater. The present articles discuss the structure and synthesis of zeolites from CFA, along with their application as adsorbents and photocatalysts for water treatment. This review aims to present an overview of the latest advancements in synthesizing and utilizing zeolite-based nanocomposites as photocatalysts and adsorbents for removing dyes from wastewater. [ABSTRACT FROM AUTHOR]

Electrolytic manganese residue (EMR) is known for high concentrations of Mn2+, NH 4 +, and heavy metals. Failure to undergo benign treatment and landfill disposal would undeniably lead to negative impacts on the quality of the surrounding ecological environment. This study sought to mitigate the latent environmental risks associated with EMR using a cooperative solidification/stabilization (S/S) method involving coal fly ash (CFA). Leveraging leaching toxicity tests, the leaching behavior of pollutants in electrolytic manganese residue-based geopolymer materials (EMRGM) was determined. At the same time, mechanistic insights into S/S processes were explored utilizing characterization techniques such as XRF, XRD, FT-IR, SEM-EDS, and XPS. Those results confirmed significant reductions in the leaching toxicities of Mn2+ and NH 4 + to 4.64 μg/L and 0.99 mg/L, respectively, with all other heavy metal ions falling within the permissible limits set by relevant standards. Further analysis shows that most of NH 4 + volatilizes into the air as NH 3 , and a small part is fixed in the EMRGM in the form of struvite; in addition to being oxidized to MnOOH and MnO 2 , Mn2+ will also be adsorbed and wrapped by silicon-aluminum gel together with other heavy metal elements in the form of ions or precipitation. This research undeniably provides a solid theoretical foundation for the benign treatment and resourceful utilization of EMR and CFA, two prominent industrial solid wastes. [Display omitted] • The optimal formulation for preparing C-A-S-H gel using EMR and CFA is determined. • Leaching tests demonstrate the environmental friendliness of EMRGM. • The Mn2+ and NH 4 + S/S mechanisms have been analyzed and discussed. • Correlation analysis of test outcomes was conducted using the Spearman method. • Endorsement offered for the harmless and resourceful utilization of EMR and CFA. [ABSTRACT FROM AUTHOR]

Geopolymer is an emerging material that is known to have excellent properties. Numerous applications of geopolymer have been reported in various studies, for example, in the construction and building sector, nuclear waste management, and wastewater treatment industry. It gains popularity in the wastewater treatment sector as it can effectively adsorb pollutants (e.g., heavy metals). However, the performance of this material varies depending on different factors such as the type of precursors, mix formulation, process conditions, etc. Moreover, optimal selection should also consider the potential environmental impact and safety to the general public before field application. The utilization of coal fly ash and other potential material was investigated to develop a pervious geopolymer. In this study, selection of optimized geopolymer mix for heavy metal removal using TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) and AHP (Analytic Hierarchy Process) with a spherical fuzzy approach was employed. An illustrative case study is presented for the proposed decision modeling technique in optimally selecting pervious geopolymer mix. [ABSTRACT FROM AUTHOR]

White mud is residue discharged during the acid method in the aluminum extraction process from coal fly ash, and this material is harmful to the environment. The implementation of an environmentally friendly and valuable way to use white mud is a key factor restricting the commercial application of the acid method in the fly ash alumina extraction technology. An analysis of white mud revealed the following: (1) it was highly enriched in SiO2 (70–80%) while concentrations of acid-soluble elements, such as Na, Al, and Fe, and some hazardous heavy metals, including Pb and Cr, were significantly lower than raw fly ash; (2) approximately 80% of SiO2 had relatively high reaction activity because of the foregoing Al-extraction treatment. Through an ingenious green chemical process, the complete conversion of white mud into silicon–calcium fertilizer (SCF) was achieved under very mild reaction conditions (approximately 100 °C and atmospheric pressure). Waste liquor was totally recycled, and no secondary solid waste was generated. The SCF had an available silicon content (ASC) of 35%, significantly higher than the commercial standard (20%). Converting them into soil conditioners or ecological remediation materials with the lowest possible energy consumption and secondary pollution may be the most promising approach for the future disposal of aluminosilicate industrial solid wastes. [ABSTRACT FROM AUTHOR]

High value-added NaHS zeolite was prepared using the microwave-assisted alkali fusion hydrothermal method from industrial solid waste coal fly ash as raw material without adding silicon and aluminum sources. The effect of mass ratio of alkali to coal fly ash, crystallization temperature, and crystallization time on the preparation of NaHS zeolite was investigated. The NaHS zeolite was characterized using XRD, SEM, BET, and FT-IR. The experimental results showed that the NaHS zeolite with complete crystal structure could be synthesized at m(sodium hydroxide):m(coal fly ash) = 2:1, crystallization temperature of 140°C, and crystallization time of 48 h. The prepared HS zeolite had high purity, complete crystal structure, and uniform grain size (2 μm). The NaHS zeolite was beneficial for CO2 adsorption properties with 110.9 cm3/g at 25°C. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA), an industrial by-product of high-temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amounts of industrial solid wastes generated in China. It is widely recognized that CFA should be considered as a potential alumina resource to substitute bauxite. In this review, the features of high-alumina fly ash and aluminum recovery technologies are first described. Later, the merits and drawbacks of alumina extraction technologies in recovering more valuable materials are compared in terms of extraction mechanisms and equipment requirements. It is shown that "predesilicating-sodium carbonate (Na2CO3) activation-acid leaching" is currently a promising method in achieving multimetal synergistic extraction. Finally, the hydrochloric acid and sulfuric acid combination process is proposed as a sustainable development of the predesilicating-Na2CO3 activation-acid leaching process. The findings of this review provide theoretical guidance for novel developments and applications of aluminum extraction technologies. [ABSTRACT FROM AUTHOR]

Using synthetic zeolite from fly ash to treat high concentration phosphorus wastewater does not only improve the utilization of fly ash as solid waste but also reduce the environmental pressure caused by eutrophication. A synthetic zeolite was prepared from coal fly ash by one-step hydrothermal synthesis and applied for phosphorus adsorption from industrial wastewater (∼8,000 mg-P/L), and its adsorption characteristics and performance were studied. The results indicated that the product was a well-crystallized Na-P1 zeolite with typical morphology of plate- and rod-shaped crystals. Compared with the original fly ash, the specific surface area and average pore volume of the synthetic zeolite were nine and six times larger than the fly ash, reaching 43.817 m2/g and 0.122 cm3/g. The results from phosphorus adsorption onto the synthetic zeolite showed that the synthetic zeolite had good phosphorus adsorption properties. The adsorption process highly conformed to the pseudo-second-order kinetic model with the regression coefficient R2 of 0.998. Phosphorus adsorption on the synthetic zeolite was fitted to the Langmuir monolayer adsorption model, and the regression coefficient R2 was 0.989. The maximum phosphorus adsorption capacity was 84.4 mg-P/g-zeolite. [ABSTRACT FROM AUTHOR]

Coal fly ash, commonly produced from thermal power plants, is not only an industrial waste but an aluminum-rich resource that needs to be disposed of properly. This study aims to extract aluminum from coal fly ash using pressurized sulfuric acid (H2SO4) leaching and to investigate the dissolution mechanism during the leaching process. The effects of initial concentration of H2SO4, reaction temperature and time on the extraction of aluminum were investigated. Under optimized conditions (3 mol/l H2SO4, 220°C and 180 min), the extraction of aluminum reached 82.51%. It was found that mullite (3Al2O3·2SiO2) contained in coal fly ash was completely dissolved during the leaching, while the dissolution of silica-alumina glass beads was at a limited degree. The un-leached aluminum was found to be locked inside the glass beads which H2SO4 was unable to access. [ABSTRACT FROM AUTHOR]

There is a growing demand for the development of sustainable electrical energy generation devices with a high energy-to-price ratio. On the other hand, industrial waste, such as fly ash is a hazard to environmental pollution. However, here for the first time, water-based self-rechargeable batteries have been fabricated by using bio-waste (golden shower tree bark ash (TBA)), a rural pollutant (cow dung ash), and industrial pollutant (coal fly ash). The TBA-based battery, out of all three batteries, shows the highest open-circuit voltage of ∼1.48 V and a specific capacity of 183 mAhg−1. Further, the TBA based cell has retained ∼97% columbic efficiency even after 2000 cycles. It has been found that pH of TBA ash is the highest, i.e. ∼12 in presences of tap water and it is found that the TBA ash is composed of a large number of metal oxides. The materials present in the ash powder have generated oxides and hydroxides ions which have, in turn, caused the generation of the potential difference between the two electrodes. The fabricated devices are portable and can power up a large number of electronic gadgets, including light-emitting diodes (LEDs). It is envisioned that this work may open the door to the development of sustainable, environment-friendly, and low-cost bio-waste ash-based self-rechargeable energy devices in future. Environment friendly self-rechargeable water-based bio-waste ash battery. [Display omitted] • Fabrication of commercial electrolyte free, bio-waste based self-rechargeable batteries. • The TBA based battery shows the highest open-circuit voltage of ∼1.45 V. • The TBA-based cell shows the highest specific capacity of 183 mAhg−1. • The TBA-based battery has retained of 97% columbic efficiency even after 2000 cycles. [ABSTRACT FROM AUTHOR]

Design of new efficient membranes from sustainable sources such as coal fly ash (CFA) has been receiving rapidly growing attention. In the present work, alumina-based tubular asymmetric membranes were incorporated with different amounts of CFA using the centrifugal casting technique. The amount of CFA added to the matrix of the alumina tubes was varied from 10 to 40 wt% on a dry weight basis. The development of the ceramic membranes containing CFA comprised the following steps: raw materials dispersion, membrane preparation by centrifugal casting using high-speed mold rotation, drying of the green body followed by sintering at 1200 °C. The techniques used for membrane characterization included measuring mechanical strength, apparent porosity, morphology by scanning electron microscopy, linear shrinkage, hydraulic performance, and cornstarch retention. High CFA fraction in the alumina-based membranes resulted in higher porosity and higher water permeability, accompanied by a decrease in mechanical strength and linear shrinkage. The observed permeate flux was between 116 and 370 L m−2 h−1 bar−1, and the observed retention was above 99% for all the membranes tested. The addition of CFA for the preparation of asymmetric tubular membranes based on alumina allows utilization of industrial waste, reduces the cost and is interesting from both an economic and environmental points of view. These membranes have the potential for applications such as wastewater treatment and as a support for selective layer coatings. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA) as an industrial solid waste has an extremely adverse influence on the environment. The high value utilization of CFA was a hot research topic with sustainable development for years. In this work, we found that CFA exhibits underoil superhydrophobicity and underwater superoleophobicity due to the special microstructures and chemical composition. And for the first time, CFA was used as a filter material for the separation of various oil/water mixtures and emulsions under the driven of gravity without any further chemical modification. Both light oil/water and heavy oil/water immiscible mixtures can be completely separated through CFA with almost 99.9% efficiency. More importantly, due to the "size-sieving" effect, CFA was capable of purifying various emulsions with high separation efficiency. After being pre-wetted with water, CFA displayed excellent separation capacity more than 92% and good flux as fast as 1050 L m−2 h−1 for water-in-oil emulsions. After being pre-wetted with oil, CFA exhibited a higher separation efficiency of 99.5% and a flux of over 935 L m−2 h−1 for water-in-oil emulsions. Therefore, this work provided an innovative, green, and low-cost approach for various oil/water mixtures and emulsions separation, which can also be widely used in wastewater treatment. Image, graphical abstract • CFA shows underwater superoleophobicity and underoil superhydrophobicity. • CFA was used for various emulsions separation without extra chemical treatment. • High efficiency of oil-in-water and water-in-oil emulsions separation was achieved. • The research presented an innovative approach for oil/water emulsion separation. [ABSTRACT FROM AUTHOR]

Featured Application: In this paper, the idea of the sustainability of durable solutions is very much present. The effect of four pozzolanic materials employed in four percentages in mortars made with two different reactive aggregates is assessed regarding alkali-silica reaction (ASR). The findings encountered here will help to optimize the cement-based materials mix design. The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash. [ABSTRACT FROM AUTHOR]

The use of industrial wastes such as coal fly ash (CFA) and carbide lime (CL) can enhance the long-term performance of recycled asphalt pavements under freeze–thaw conditions as well as reduce consumption of natural resources. Further improvement of the mechanical properties of such blends can be achieved by adding small quantities of sodium chloride (NaCl). Blends of recycled asphalt, CFA, CL and sodium chloride were therefore assessed in terms of their durability to freeze–thaw exposure. Additional splitting tensile tests were performed to evaluate strength improvements after adding sodium chloride. Specimens were moulded with three different dry unit weights and two different lime percentages, and cured for 7 d. The accumulated loss of mass was evaluated as a function of the porosity/lime index, which broadens the applicability of this index by demonstrating it, and influences not only strength but also long-term performance. The improvement in engineering properties provided by sodium chloride was found to be related to the formation of mineral phase thomsonite and to sodium chloride acting as a catalyser. [ABSTRACT FROM AUTHOR]

A kind of mesoporous aluminosilicate oxides (MAOs) were fabricated from industrial waste, coal fly ash. After loaded with zinc on MAO, the product MAO‐Zn was characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy (SEM). MAO‐Zn was incorporated with intumescent flame retardant (IFR) together and used in polypropylene (PP). Basic characterization including limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimeter test (CCT) were finished. The result showed the LOI value of PP was only 17.7 and cannot pass UL‐94 grade; however, 25 wt% IFR in PP help the composite obtained LOI value of 27.6 and passed UL‐94V‐1 grade. Surprisingly, with only 2 wt% MAO‐Zn substitution of IFR, the LOI of PP/IFR composite sharply went up to 37.2 and passed V‐0 grade. CCT results documented that heat, smoke, and fatal gas release were obviously suppressed by IFR/MAO‐Zn combination. By SEM observation and quantitative analysis of TGA results, the contribution of MAO‐Zn was summarized as adsorption of heat/smoke and promotion on charring. It was worth mentioning that the low dose of MAO‐Zn (≤ 3 wt%) did not bring further deterioration on mechanical properties. J. VINYL ADDIT. TECHNOL., 26:135–143, 2020. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Due to increase in the growth of industrial sectors the power requirement of the country is rapidly increasing. India depends on Thermal Power as its main source, thus there is increase in power requirement every year. Present scenario of our country shows 75 % of country's total installed power generation is thermal of which coal-based generation is 90%. The coal reserves of the country are predominately of lower grades (average of 35% ash content), non-cooking and as a result more than 110 million MT coal ash is being generated every year. Ash generation may likely reach to 170 million MT by 2012. Use of coal brings huge amount of ash every year. Research related to new and innovative use of waste materials is being undertaken worldwide. Properties of materials include strength, hardness, density, resistance to corrosion, etc. Materials in industrial wastage has properties like unit weight, specific gravity, shrinkage, absorption, resistance to freezing, etc. The industrial waste material is a bye-product of construction industries and other industries and their wastes are fly ash, pond ash, marble dust, store dust, slag and many more. In this research study modifications in normal concrete materials such as cement aggregate and sand were carried out. Properties of concrete were replaced by fly ash and pond ash. The construction waste material which gives better performance in special concrete was identified. Fly ash and pond ash materials were selected which simultaneously replaces the cement and sand of the special concrete and better results were obtained related to the properties of concrete. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA), a byproduct of coal combustion, is a hazardous industrial solid waste. Its excessive global production, coupled with improper disposal practices, insufficient utilization and limited awareness of its inherent hazards, poses a significant threat to both ecological environment and human health. Based on the physicochemical properties of CFA and its leachates, we elucidate the forms of CFA and potential pathways for its entry into the human body, as well as the leaching behavior, maximum tolerance and biological half-life of toxic elements present in CFA. Furthermore, we provide an overview of current strategies and methods for mitigating the leaching of these harmful elements from CFA. Moreover, we systemically summarize toxic effect of CFA on organisms across various tiers of complexity, analyze epidemiological findings concerning the human health implications resulting from CFA exposure, and delve into the biotoxicological mechanisms of CFA and its leachates at cellular and molecular levels. This review aims to enhance understanding of the potential toxicity of CFA, thereby promoting increased public awareness regarding the disposal and management of this industrial waste. • The properties of CFA determine its pathway into organisms and toxicity. • High CFA levels have detrimental to soil microbial activity and plant growth. • CFA exposure causes more toxic effects on lab animals than wild animals. • CFA exposure linked to neurological issues in children and respiratory/cardiovascular problems in adults. • Endocytosis and pinocytosis are the primary means by which cells ingest CFA particles. [ABSTRACT FROM AUTHOR]

• Solid industrial wastes were the selected precursors for alkali activated material. • Physico-chemical properties and natural radioactivity of materials were evaluated. • Dosimetric indexes of the precursors, paste and mortars were determined. • It was found that geopolymers (in paste and mortar form) comply to Euratom Directive. Alkali-activated materials were prepared from four typical precursors (coal fly ash, granulated blast furnace slag, metakaolin, and brick waste powder) characterized for granulometry, elemental composition, and microstructure. High-resolution gamma-ray spectrometry was used to determine the activity concentration of Naturally Occurring Radioactive Materials (NORM) in all the materials to assess their radiological impact. All the investigated materials have been found to comply with the European dosimetric index (I) according to Directive 2013/59/Euratom. The results suggest the need for an accurate check of radioactivity throughout the mixing phases to prevent I exceedances. The productive chains were also evaluated by principal component analysis. [ABSTRACT FROM AUTHOR]

Coal fly ash is industrial waste produced by coal power plants, containing large amounts of magnetospheres (MSs), where Fe 3 O 4 is abundant and magnetite is the major composition. However, the functional reuses of MSs are always restricted by the impurities of aluminosilicate and other forms of iron oxide including maghemite, magnesioferrite, as well as hematite. In this paper, a chemical vapor deposition (CVD) process was proposed to convert MSs into a magnetic core@ carbon shell structure, which would found its application in microwave adsorption field. The prepared samples were characterized by using SEM, HRTEM, EDX, BET, XRD, Raman spectroscopy and TGA analysis. Results showed that MSs burst during the CVD process and transformed into a loose agglomeration of submicron-sized particles with a typical core@ shell structure. Crucially, instead of single sphere of MSs, the ultrafine grains of ferrospinel within MSs served as the core. The mechanism of carbon deposition of graphite shells and phase transformation of ferrospinel cores during the CVD process were revealed. Magnetism and microwave adsorption properties were tested, and the structural dependence relationship between these properties and the core@ shell structure was clearly identified. For a sample time of 60 min, the minimum absorption peak was observed as −32.4 dB at 12 GHz, with the minimum frequency bandwidth below −10 dB at 4.3 GHz. We propose a low-cost, one-step preparation of cementite core@ graphite shell composites with high-performing microwave adsorption. Our method provides an alternative option for the practical reuse of the industrial waste. [ABSTRACT FROM AUTHOR]

Conventional synthesis conditions for each type of zeolite are tabulated and reported by the International Zeolite Association Structure Commission (IZA) and most of them are synthesized from commercial reagents, but they can also be synthesized from industrial by-products rich in Si and/or Al. In zeolite synthesis from wastes, concentration of alkali source, temperature, reaction time, liquid/solid ratio and type of waste determine the textural properties, crystal structure, Si/Al ratio and ion exchange characteristics of the fabricated zeolite and its applications. This work summarizes the main methods that have been developed to synthesize zeolites using industrial wastes as Al and/or Si sources, the parameters of synthesis and the advantages and limitations of each synthesis process. The main characteristics and the applications of these synthetic waste zeolites are also reported. Image 1 • Synthesis of zeolites from industrial wastes rich in Si and/or Al. • Valorization of coal fly ash, biomass ash, aluminum dross as zeolites. • Synthesis of zeolites from natural clays rich in Si and/or Al. • Characteristics and applications of synthetic waste zeolites. [ABSTRACT FROM AUTHOR]

The long-term storage of coal ash in impoundments can lead to concerns of structural stability as well as trace element migration to local surface water and groundwater sources. Microbial induced calcium carbonate precipitation (MICP) offers a potential approach for minimising leachability of heavy metal trace elements from coal ash by calcium carbonate cementation. In this study, a protocol for MICP treatment of coal ash has been experimentally developed. The MICP treatment is applied to three coal ashes from different power plants, and their response to the developed treatment protocol is assessed. Possible factors affecting the MICP treatment of coal ash are discussed in terms of efficacey and inhibition of the stabilisation process. For this purpose, several approaches such as shear wave velocity, electrical conductivity, pH measurement, acid washing, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were implemented. The results indicated that carbon/carbide content of the fly ash material has an important role in the efficacey of the MICP treatment process. The most likely explanation is carbon/carbide aids in the nucleation of calcium carbonate precipitation. [ABSTRACT FROM AUTHOR]

Coal fly ash is an industrial waste generated from the thermal power plant and a large amount of it could be produced annually in the world, which can cause serious environmental problems. Reutilization of coal fly ash could be imperative to alleviate the environmental pressure. Thus, in the present study, coal fly ash was used as silicon source for the synthesis of calcium silicate hydrates (C-S-Hs) though the desilication process. Two kinds of C-S-Hs was synthetized at 100°C and room temperature respectively, with the fixed Ca/Si molar ratio of 1.2, and adopted as the adsorbents for phosphate. The properties of them were characterized using XRD, SEM, FTIR, TG-DTA as well as surface area and pore analysis. Compared to C-S-H synthesized from high temperature, the C-S-H obtained at room temperature possessed high purity and larger surface area. Therefore, synthesis by agitation at room temperature could be an alternative method to produce C-S-H materials from desilication liquid of coal fly ash, and this could save infrastructure cost and energy consumption. Both C-S-H materials have good ability to immobilize phosphate pollutant (higher than 100 mg·g-1). The specific mechanisms of phosphate removal using C-S-H include several steps: firstly, phosphate ion was immobilized by binding with Ca2+and forming aggregates, and the C-S-H structures were gradually corroded. Eventually, hydroxyapatite was formed after the C-S-H structure was totally destroyed. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-sulfur coal fly ash residues was used to fix CO 2 and produce high purity carbonates. • The extraction efficiency of calcium was significantly influenced by pH and acidic conditions favored calcium release. • Adding acid progressively slows down silicon polymerization and promotes calcium leaching. • Gaseous CO 2 can simultaneously dissolve calcium and form carbonates on the solid surface. The aim of this study is to characterize potential utilization pathways of high-sulfur fly ash from coal combustion plants for the purpose of fixing CO 2 and producing high purity carbonates via carbon mineralization process. Unlike other typical fly ashes, the feedstock in this study contains a mixture of fly ashes and desulfurization residues. We present a multi-step approach for utilizing this industrial waste to provide a sustainable and economical alternative to landfilling or generating low-value products. The solubility of gypsum from the desulfurization residue limits the dissolution behavior of calcium, therefore, developing an efficient process to extract Ca for subsequent carbonation is needed. The dissolution process of different elements (Ca, Si, Fe, Al) was conducted under different pH values ranging from 0 to 13, various reaction temperatures, slurry densities and methods of dosing leaching agents. It was found that the extraction efficiency was significantly influenced by the pH, and the acidic conditions favored calcium release. Progressively adding acid at fixed pH during dissolution can slow down the polymerization of silicon which promotes calcium leaching compared with the rapid addition of acid. Gaseous CO 2 can act as a dissolution agent to dissolve calcium and simultaneously produce nano-crystalline calcite on the surface of the fly ash as a direct carbonation approach. Stepwise dissolution and carbonation combined with a pH swing process can produce high purity calcium carbonates and the carbonate polymorphs can be adjusted via controlling operating conditions. The findings presented in this study provide implications for how to sustainably utilize high-sulfur fly ash and design processes for its utilization. [ABSTRACT FROM AUTHOR]

• Resource utilization of industrial wastes in energy storage system. • Synergistic adsorption-electrocatalysis effectively suppresses the shuttle effect. • MCFA separator can effectively reduce internal resistance and polarization of LSBs. • MCFA helps to improve the transformation kinetics of LiPSs. The notorious shuttle effect severely limits the practical application of Lithium-Sulfur Batteries (LSBs). In line with the concept of "green chemistry", industrial solid waste is reasonably applied to the design of battery's interlayer. The modified coal fly ash (MCFA) can effectively accelerate the redox kinetics of the electrode and optimize the nucleation and decomposition of Li 2 S. The synergistic adsorption and catalytic action from rich pore structure and polar metal oxides can effectively capture and fix free polysulfide (LiPSs), which realizes the inhibition of shuttle effect. The LSBs with MCFA interlayer exhibit good cycle stability (decay-rate: 0.05% per cycle) and rate capability (703 mAh g−1 at 3C). Even under extreme conditions of poor electrolytes (E/S = 7.8 μL /mg), Cell-MCFA/PE with a high S loading (7.5 mg cm−2) still performs well (732 mAh g−1 after 100 cycles). This work provides an economical and environment-friendly strategy for the design of interlayer, which is conducive to the commercialization process of LSBs. [ABSTRACT FROM AUTHOR]

In this work, coal fly ash (CFA) was first converted to fly ash-derived zeolite (FAZ), then CuO particles were prepared and loaded onto FAZ to build a heterogeneous Fenton catalyst (CuO-FAZ) for bisphenol a (BPA) removal. The characterization results demonstrated that CFA was changed into a mesoporous structure with a higher specific surface area after FAZ conversion, and CuO showed granularity and was well distributed on the surface of FAZ. Under optimal experimental conditions ([BPA] = 50 mg/L, [catalyst] = 1.0 g/L, [H 2 O 2 ] = 140 mM, and temperature = 25 °C), over 85% of BPA was degraded within 60 min. After five consecutive cycles, BPA removal remained more than 70%, indicating that CuO-FAZ had excellent catalytic capability as well as superior stability. Furthermore, compared to other reactive radicals generated in the process, O H ∙ (s u r) radicals were found to play a major role in the removal, with a contribution of nearly 50%. A ligand complex could develop between CuO-FAZ and BPA, thereby enhancing the O H ∙ (s u r) radicals generation. Results further showed that CuO-FAZ can be employed to effectively and economically treat actual industrial wastewater containing phenolic compounds. This work introduces a method of preparing coal fly ash-based heterogeneous Fenton catalyst, which provides a novel idea for high-value coal fly ash reuse. • A coal fly ash-based heterogeneous Fenton catalyst (CuO-FAZ) was prepared. • CuO-FAZ exhibited excellent catalytic activity and stability. • The possible BPA removal mechanism was discussed. • This is cost-effective with potential industrial applications. [ABSTRACT FROM AUTHOR]

The large quantities of alkaline industrial wastes that are generated globally have the potential to be valorized in various applications instead of being landfilled. This study evaluated the potential reuse of green liquor dregs (GLD), wood ashes, coal ash, red mud, mussel, scallop, and oyster shells to control acid and metalliferous drainage (AMD). Low hydraulic conductivities (10−7 to 10−9 m/min) suggest that covers constructed from fine-grained GLD, red mud, coal ash and wood fly ash can limit the formation of AMD. Static and kinetic test leachates of pH 5.8 to 10.6 indicate that the tested materials can neutralize acidic drainage and immobilize metal(loid)s by precipitation. The alkalinity is proportional to the amount and reactivity of carbonate and hydroxide fractions with red mud followed by coal ash being the most alkaline over 100 weeks and wood ashes the least. The tested industrial wastes generate leachates with a low metal(loid) risk when screened against the Australian freshwater guidelines. However, oxyanions including Al, Cr, Cu, Se, and V were leached in deleterious concentrations ≤100 times more than the guidelines because of their mobility in alkaline conditions. The outcomes of this study highlighted that alkaline industrial wastes can be potentially used in the long-term remediation of AMD as part of an environmentally sustainable and cost-effective integrated mine waste management strategy. [Display omitted] • Limitation of AMD formation by materials with low permeability and high compaction. • Details long-term acid-neutralization and metal mitigation by alkaline wastes. • Relates alkalinity of waste to amount and reactivity of carbonates and hydroxides. • Evaluates low metal risk in alkaline leachates and high concentration of oxyanions. • Offers opportunities for value recovery of alkaline wastes and remediation of AMD. [ABSTRACT FROM AUTHOR]

Coal fly ash is an industrial waste product generated by coal fired powerplants which has been shown to contain elevated concentrations of several toxic trace metals. When stored in landfills or other repositories, these trace metals can enter nearby surface waters via a number of routes including leaching or runoff. Our study examined 1) the presence and concentration of eleven trace elements in a range of lab-created coal ash leachate solutions at neutral pH using ICP-OES, 2) the physiological effects of these leachate solutions on a freshwater gastropod (Planorbella duryi), and 3) the ability of these trace metals to bioaccumulate in the tissues of exposed individuals. As, Cd, Cu, Mg, Mn, and Pb were detected in solutions at increasing concentrations concurrent with ash concentration. Exposure to leachates caused significant delays in embryonic development, reduced juvenile shell growth, decreases in egg and clutch production, and the display of avoidance behaviors. Tissues of exposed snails contained elevated concentrations of As, Cd, Cu, and Cr, with bioconcentration factors 177,550 times higher in cadmium and 85,468 times higher in arsenic in the highest treatment compared to control organisms. Our results highlight the potential harmful effects of coal ash leachates on a novel freshwater invertebrate species using several unique methodologies, providing key information regarding their potential impacts on surrounding aquatic ecosystems. [Display omitted] • Exposure to leachates caused delays in embryonic development and reduced juvenile shell growth. • Exposures caused decreases in adult fecundity (clutch and egg deposition). • Snails were able to detect and avoid leachates above a certain concentration. • Exposed snails contained As, Cd, Cu, and Cr up to 177,553 times higher than control organisms. • Planorbella duryi is a novel, sensitive model species suitable for a range of chronic ecotoxicity tests. [ABSTRACT FROM AUTHOR]

The increasing requirement and consumption of coal has resulted in a large accumulation of coal gangue. The reuse and recycling of coal gangue have become a high priority for sustainable development. A sustainable and efficient ceramsite adsorbent was prepared for copper ions adsorption by using coal gangue, coal fly ash, and copper slag as the main materials. The appropriate performance of the ceramsite could be obtained at a mixture of coal gangue, coal fly ash, and copper slag at a weight ratio of 3:4:1. The optimal sintering temperature and time were 1050 °C and 20 min, respectively. The main crystalline phases of ceramsite were quartz, mullite, and anorthite. Many micropores are connecting the interior on the surface of ceramsite under scanning electron microscope. The maximum copper ions adsorption capacity reached up to 20.6 mg/g at 303 K when pH and time were 5 and 1440 min, respectively. The adsorption kinetics and isotherm could be described by the pseudo-second-order model and Freundlich model, respectively. The adsorption mechanisms of Cu2+ with ceramsite were attributed to Cu(OH) 2 precipitation formed on the alkaline surface of ceramsite and complexation reactions occurred between the O-containing groups (including C–O, Fe–O, and Si–O) from ceramsite and Cu2+. The prepared ceramsite may be also applied to other heavy metal wastewater treatments. • A green and efficient ceramsite adsorbent was prepared by industrial waste. • The adsorption capacity of copper ions with ceramsite was improved. • The adsorption kinetics could be described by the Freundlich model. • The adsorption mechanism of copper ions was studied deeply. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reviewed + 200 research papers related to geopolymer concrete. • Utilization of industrial waste and recycled aggregates in geopolymer concrete is focused. • 12 M + molarity of sodium hydroxide is efficient for geopolymer based concrete pavements. • Geopolymer based rigid pavements ensure a cleaner environment. After industrial sector, construction sector utilizes significant quantity of natural raw materials and energy sources. Construction sector waste needs dumping spaces whereas the industrial sector waste like, fly ash and coal bottom ash poses health hazards as they contaminate water, air and soil. Pozzolanic concrete utilizes industrial waste by substituting a portion of cement (<60 %) and offers better durability with similar mechanical properties to normal concrete. Geopolymer concrete, a durable and high-strength concrete, has been devised to fully substitute cement with industrial wastes. This study reviews the requisites of geopolymer concrete to perform like pavement quality concrete while utilizing maximum quantity of wastes in both the binder and aggregate phase. This paper concludes that geopolymer concrete can be used in pavements even with more than 50 % virgin aggregate substitution with recycled aggregates. Further, the mix should be enriched with ground granulated blast furnace slag with sodium hydroxide molarity within 12–16. [ABSTRACT FROM AUTHOR]

• LCGGM with a large content of CG was prepared by composite activation. • The comprehensive advantages of CG, BFS and FA can be utilized. • The RSM was utilized to obtain the quantitative trend of each response and each factor. • The main reaction products of LCGGM are C-(N)-A-S-H and C-S-H gels. To prepare a low-cost geopolymer grouting material (LCGGM), the industrial solid wastes coal gangue (CG), blast furnace slag (BFS) and fly ash (FA) were used as silica-alumina materials; desulfurized gypsum and an alkaline activator were used as ligands; and small amounts of additives were supplemented. The response surface methodology (RSM) was used to design macroscopic tests of the fluidity, setting time, compressive strength and impermeability of LCGGM, and XRD, FTIR, TG-DSC and SEM-EDS were used to analyse the mechanism of action. The results showed the following: (1) Optimized formulation could be achieved at coal gangue powder: slag: fly ash ratio of 5:4:1, 1.64 M sodium silicate modulus, 6.7% sodium silicate and 5% Na 2 O. The LCGGM possesses clean production, high fluidity, fast setting, low bleeding rate, high compressive strength and seepage pressure, providing appealing properties as grouting materials for reinforcement. The establish regression model and response surface well reflect the impacts of various factors on the properties of the LCGGM. (2) Microscopic analysis showed that the three materials with different fineness improved the density of the stone body and participated in the hydrolytic polymerization reactions of the multiple systems at different times, which ensured the strength of the stone body in the early and late stages. [ABSTRACT FROM AUTHOR]

Flash heating also induces chemical changes: Phosphates of REEs transform into REE oxides, which are more soluble and easily extractable. As chemists scramble to find ways to reclaim valuable metals from industrial waste and discarded electronics, one team has found a solution that sounds a little like magic: Zap the trash with flashes of electric heat. Tour's team tested its process on fly ash, a powdery gray byproduct of burning coal that contains concentrated levels of the REEs originally present in the coal. [Extracted from the article]

Abstract: High volume utilization of industrial wastes and by products is the solution for high disposal costs. Acceptable durability levels in addition to environmental factors are a key factor for safe utilization of wastes and by products of coal burning power plants in road construction activities. The durability levels of most fly ashes are similar to concrete if the strength and air content are kept constant. To obtain a better freeze–thaw performance from the fly ash samples, an air entraining agent must be added into the matrix. Snow can be added to the fly ash samples as an air entraining agent as presented. In this study a new technique involving the use of snow as an additive to the fly ash is presented. Compaction of fly ash is very sensitive to water content which complicates the use of fly ash in highway embankment construction. One or two percent additional water over optimum moisture content makes compaction of the fly ash impossible. On the other hand, an excess amount of water is needed to enhance the reactions leading to formation of cementitious products, which increases strength. The extra water is added in solid phase as snow, which allows compaction of the samples without liquefying. The 10% extra water added in the solid phase caused a 30% increase in the void ratio. The main objective of this investigation is to evaluate whether the increased void ratio causes a similar behavior expected from air entraining agents on the freeze thaw durability of fly ash. Type C fly ash at optimum moisture content and fly ash with additional 10% by weight snow are compacted, sealed and cured for 90 and 180days at the curing room. After the curing period, freeze–thaw durability tests are conducted with a freeze–thaw cabinet. The development of deterioration, resonant frequency variation and weight losses of fly ash and snow added fly ash samples compacted at optimum moisture content are determined throughout the test period. The relative dynamic modulus of elasticity of the control samples decreased to 55% of their original value after 90 freeze thaw cycles, for snow added fly ash samples the same amount of reduction occurred after 120 freeze thaw cycles for 90 and 180days cured samples. Higher freeze–thaw performance of the snow added samples is related to the increased void ratio after melting of snow and densification of the matrix around the pores due to higher level of cementitious mineral formation. The increase in the freeze–thaw performance of snow added fly ash samples will allow utilization of fly ash in highway embankment construction activities where large surface area exposure and large volume usage makes it more critical for the service life and longevity of the constructed road in cold regions. Another advantage of the developed technique is the reduction of transportation costs by more than 10% by using less material for construction. [Copyright &y& Elsevier]

Lignin-related material found in wastewater from thermomechanical pulping resists conventional biological treatment, entailing the use of advanced removal methods. In this work, the use of adsorption for removing lignin-related material was investigated. Activated charcoal and fly ash were used to study the adsorption behavior of lignin and to determine the adsorption capacities of these two adsorbents. Experimental data were fitted to various isotherm equations to find the best description of the sorption systems, and the corresponding thermodynamic parameters were calculated. Fly ash exhibited good sorption properties, although its sorption capacity was inferior to that of activated charcoal. Both the Freundlich and Langmuir equations provided reasonable models of the sorption processes, and the thermodynamic parameters indicated that sorption onto activated charcoal is endothermic, whereas sorption onto fly ash appears to be exothermic. Fly ash is a low-cost material that is often available on-site and offers an interesting alternative to high-cost advanced wastewater treatment systems for removing recalcitrant organic materials. [ABSTRACT FROM AUTHOR]

Advanced wastewater-treatment techniques such as adsorption are essential in the removal of non- biodegradable toxic wastes from water. In this study, the use of South African coal fly ash, an industrial byproduct, has been investigated as a potential replacement for the current costly adsorbents used for removing heavy metals from wastewater. We utilised coal fly ash for the adsorption of cobalt(II) ions from synthetic petrochemical wastewater and characterised its performance. A two-level three-factor full-factorial design was successfully employed for experimental design and analysis of the results. The combined effects of pH, initial concentration and adsorbent dose on cobalt(II) removal were assessed using response surface methodology. Although the focus was on removal of cobalt(II), the adsorption was carried out in the presence of phenol and other heavy metal ions using the batch technique. The applicability of the Freundlich and Langmuir models to the equilibrium data was tested. Consequently, the equilibrium data was found to conform more favourably to the Freundlich isotherm than to the Langmuir isotherm; in this case, the coal fly ash had a maximum adsorption capacity of 0.401 mg/g for cobalt(II). We conclude that South African coal fly ash, as a natural, abundant and low-cost adsorbent, might be a suitable local alternative for elimination of cobalt(II) from aqueous solutions. [ABSTRACT FROM AUTHOR]

Although many leaching methods have been used for various purposes by research groups, industries, and regulators, there is still a need for a simple but comprehensive approach to leaching coal utilization by-products and other granular materials in order to estimate potential release of heavy metals when these materials are exposed to natural fluids. A serial batch characterization method has been developed at the National Energy Technology Laboratory that can be completed in 2–3 days to serve as a screening tool. The procedure provides an estimate of cumulative metals release under varying pH conditions, and leaching the sample at increasing liquid/solid ratios can indicate the rate at which this process will occur. This method was applied to eight fly ashes, adapted to the acidic or alkaline nature of the ash. The leachates were analyzed for 30 elements. The test was run in quadruplicate, and the relative standard deviation (RSD) was used as a measure of method reproducibility. RSD values are between 0.02 and 0.70, with the majority of the RSD values less than 0.3. The serial batch leaching procedure was developed as a simple, relatively quick, yet comprehensive method of estimating the risk of heavy metal release from fly ash when it is exposed to natural fluids, such as acid rain or groundwater. Tests on a random selection of coal fly ashes have shown it to be a reasonably precise method for estimating the availability and long-term release of cations from fly ash. [ABSTRACT FROM AUTHOR]

Consumption of coal is increasing as an alternative for petroleum. During the process, coal fly ash particles are produced and are disposed as an industrial waste. Coal ash contains toxic heavy metals, which leads to a concern about the possibility of leakage into environment. The spatial distribution and chemical form as well as elemental concentration of the toxic elements in the particles are important factors in assessing the leakage into the environment. In this study, we analyzed individual coal fly ash particles with 1 µm spatial resolution by using the simultaneous micro-PIXE/RBS/off-axis STIM system at Tohoku University. Eighty fly ash particles were analyzed. The particles are mainly composed of O, Si and Al and estimated as dioxide. Hydrogen and carbon are not observed in these particles. V, Zn, Sr, Cu, Ni, Mn, Cr and As are contained in the particles. The content of each element is quite different in each particle. These elements are distributed homogeneously. As an exception, Al, Ca, Fe, Zn, As and Zr are distributed on the surface of the particle which might be related to the combustion process. [ABSTRACT FROM AUTHOR]