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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]

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]

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]

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]

• 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]

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]

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]

[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]

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]

Directive, acid and reactive dyes are the carcinogenic dyes which have complex structures and difficult to remove from the industrial wastewater. In this study, coal fly ash (CFA) was modified with HCl and NaOH solution and used for the removal of direct fast scarlet 4BS, direct sky blue 5B, acid navy blue R, and reactive turquoise blue KN-G dyes. Laboratory experiments were carried out to analyze the performance of modified coal fly ash (MCFA) to check the removal efficiency and adsorption capacity of dyes. The maximum removal efficiency of direct fast scarlet 4BS and direct sky blue 5B were recorded 96.03% and 93.820%, respectively using 0.05 g adsorbent dosage at 100 mg/L initial concentration. The results of MCFA were compared with carbon black, chitosan, starch, zeolite and unmodified coal fly ash (UMCFA) at lower dosage 0.05 g and higher dosage 0.4 g. Adsorption isotherm were analyzed by Langmuir and Freundlich model by different dyes concentrations, the result stated that Freundlich and Langmuir model (±0.9918, ±0.9974) was fitted by chemisorption and physisorption methods for all four dyes. Adsorption kinetic were also determined by Pseudo-first-order and Pseudo-second-order at different contact times with dye molecules and adsorbent active sites, and the results showed that the adsorption behaviors of all four dyes were described better by pseudo-second-order kinetics than pseudo-first-order kinetics. Recommended dosage of modified fly ash is between 10 ‱ to 20 ‱ for simulated textile industrial waste water and regeneration temperature is 300 ℃. [Display omitted] • Coal fly ash was modified by HCl and NaOH for the dye adsorption. • After modification the surface area and porosity of CFA were increased. • Modified coal fly ash was used for the removal of directive, acid and reactive dyes. • Maximum removal efficiency of directive dye was recorded up to 98% by using modified CFA. • The results of MCFA were compared with carbon black, chitosan, starch, zeolite and unmodified coal fly ash. [ABSTRACT FROM AUTHOR]

This paper presented an experimental investigation on epoxy mortar produced using industrial wastes, namely coal bottom ash as filler to replace sand, fly ash and silica fume as micro fillers. Four parameters investigated were: (i) the epoxy resin to filler ratio, (ii) particle size of coal bottom ash, (iii) types of micro filler, and (iv) proportion of micro filler. Experiments were carried out to determine the physical properties, mechanical properties and shrinkage of epoxy mortar with different proportions of epoxy resin, filler and micro fillers. The results demonstrated that the epoxy resin to filler ratio significantly impacted the properties of epoxy mortar. Moreover, the epoxy mortar with ground coal bottom ash showed higher mechanical properties and lower water absorption and shrinkage than the epoxy mortar with coal bottom ash. Mechanical properties were improved as the content of micro fillers increased up to 20% in the epoxy mortar. The mechanical strengths of epoxy mortar with ground coal bottom ash were about 30% lower than epoxy mortar with sand at the same epoxy resin and micro filler content. However, epoxy mortar with GCBA demonstrated 50% lower shrinkage than epoxy mortar with sand. [ABSTRACT FROM AUTHOR]

Addition of natural polymer or biopolymer is considered as a novel, cost-effective and eco-friendly soil modification approach mainly pertaining to erosion stability. The present study focuses on the interaction of three types of biopolymer i.e., xanthan gum, guar gum and carboxymethyl cellulose to stabilize two dispersive industrial waste materials i.e., fly ash and coal mine overburden soil. The results found that all the three biopolymers enhanced the index and geotechnical properties of fly ash and mine overburden due to their high viscosity, aggregation, adsorption and cross-linking bond formation. However, the rate of enhancement varies with the type and concentration of biopolymer. The biomodified soil were evaluated for erosion stability against wind and water by performing pinhole test, cylindrical dispersion, surface resistance and water retention test. It concluded that a very minimal fraction, 1% of biopolymer solution could mitigate the dispersiveness of the geomaterial. Additionally, the results of microscopic analysis by scanning electron microscope assist to correlate the morphological changes with the engineering properties of biomodified soil due to the interaction of soil with the long-chained biopolymers strings. Finally, leachate and cost analysis of the biopolymer modified material was assessed to evaluate the efficiency of the biomodification. • Bio polymeric interaction of two dispersive material with XG, GG and CMC. • Modifications in consistency, compaction, strength and toughness. • Erodibility study by dispersiveness, wind, water erosion and surface strength value. • The microstructure, leachate and cost analysis of biomodified geomaterial. • Biopolymer is effective due to viscosity, cross-linking and hydrogel formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel MIL 53(Al-Fe)@SiO 2 was synthesized from coal fly ash. • The ratio of aluminium, iron and silica was adjusted by adding waste aluminium foil and ferric chloride. • This metal organic framework composite removed methylene blue from waste water. • Integrated methodology of adsorption + photocatalytic degradation is proposed. • The adsorption isotherm, kinetics and thermodynamics models are studied. A novel MIL 53 (Al-Fe)@SiO 2 was formulated and employed to treat organic dye containing effluent by an integrated method of adsorption followed by photocatalytic degradation. The MIL 53 (Al-Fe)@SiO 2 was synthesized using coal fly ash. The in-depth characterizations of the newly synthesized material enlighten the phenomenal changes in the physical and chemical properties of MIL 53 (Al-Fe)@SiO 2 than that of raw fly ash, which enhances its adsorption capacity in three folds. Moreover, the PL spectroscopy analysis depicts that the newly produced MIL 53 (Al-Fe)@SiO 2 has slower electron-hole recombination than that of MIL 53 (Al) and MIL 53 (Al)@SiO 2. The MIL 53 (Al-Fe)@SiO 2 offered a maximum adsorption capacity of 681.782 mg g−1 and maximum 89.34 and 99.95 % degradation in the presence of visible and UV light radiations, respectively. This study shows that the proposed MIL 53 (Al-Fe)@SiO 2 , outperforms the conventional materials in treating the industrial effluents for harmful pollutants. [ABSTRACT FROM AUTHOR]

CO2 mineralization (aka mineral carbonation) is a promising method for the chemical sequestration of CO2 via reaction with oxides of alkaline or alkaline-earth metals to form carbonates. It has documented advantages over similar technological solutions to climate change. The huge amount of industrial solid waste, as a serious environmental issue confronted by China, can provide additional alkalinity sources for CO2 mineralization. In this study, we present an overview of the latest advances in the emerging technologies of CO2-mineralization via industrial solid waste in China, from the perspective of both theoretical and practical considerations. We summarize the types of industrial solid waste that are used (mainly coal fly ash, steel slag, phosphogypsum, and blast furnace slag) and the technological options available in the literature, with an emphasis on the discussion of the involved process-intensification methods and valuable chemicals produced. Furthermore, we illustrate the current status of pertinent policies, and research and development activities in China. Finally, we identify the current knowledge gaps, particularly in understanding the overall sustainability performance of these CO2-mineralization technologies, and indicate that the technical, economic, and environmental challenges of promoting and commercializing these technologies for the co-utilization of industrial solid waste and carbon resources call for, amongst other things, more joint efforts by chemists, chemical engineers, and environmental scientists, and more feedback from the energy and industrial sectors. [ABSTRACT FROM AUTHOR]

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials. [ABSTRACT FROM AUTHOR]

The MSWI fly ash (FA) is classified as hazardous waste and electrolytic manganese residue (EMR) as the harmful industrial waste. FA, water-washed FA (WFA), EMR and coal fly ash (CFA) were co-recycled to form lightweight MFCE ceramisites. The effects of FA, WFA and mixed MSWI fly ash on ceramisites were discussed. The approach to mixing FA and WFA increased the recycling amount of MSWI fly ash. The optimal mixture of 34.5% EMR, 24.1% CFA, 20.7% FA and 20.7% WFA sintered at 1160 °C for 12 min with a procedural heating rate (10 °C/min) and belonged to Class 800 artificial lightweight aggregate (GB/T 17431.1-2010); the quantity of MSWI fly ash in ceramisite was as high as 41.4%. Volatilization rates of Cd, Pb, Cu, Zn, Mn and Cr for ceramisite were higher 75.0, 24.2, 62.7, 133, 343 and 764% than FA respectively, attributed to the co-existence of chlorides and sulfates. The remained Zn, Cu, Pb, Mn and Cr were exchanged with Mg2+/Ca2+/Al3+ of diopside and wollastonite to form residual fractions. Our findings provided a feasibility method of co-recycling MSWI fly ash and electrolytic manganese residue to produce green lightweight aggregates. Image 1 • MSWI fly ash and electrolytic manganese residue were co-recycled to be ceramisites. • Mixing the raw and water-washed MSWI fly ash was firstly applied. • The recycling proportion of MSWI fly ash reached 41.4%. • Co-existence of chlorides and sulfates contributed to the volatilization of heavy metals. • The migration and transformation mechanism of heavy metals were revealed. [ABSTRACT FROM AUTHOR]

• Physico-chemical properties of CFA were summarised in detail. • Leachability of CFA was analysed using six aspects. • Adverse effects of CFA on humans, wild animals, and plants were reviewed. • Utilisation of CFA in the USA and EU were summarised. • Directions for the reuse of CFA in the near future were proposed. Coal fly ash (CFA) is a valuable industrial solid waste, but conventional methods used for its disposal can lead to serious and long-lasting environmental issues. The study of technologies for CFA recycling has been of major concern, while the harm caused by CFA is only partially understood, limiting its reuse. In this review, the basic physico-chemical properties of CFA are introduced, followed by a systematic summary and discussion of the leachability of CFA via different leaching methods and the chemical speciation of some typical metal elements in CFA, which is related to its harmful effects. The specific harm that CFA causes to humans, wild animals, and plants and the study status of magnetic property of CFA are presented. Because of the pervasive concerns of many people, the utilisation of CFA in the USA and Europe and an economic and environmental analysis of its disposal is provided and discussed. Finally, some possible directions for future research involving CFA are proposed. [ABSTRACT FROM AUTHOR]

• Geopolymer adsorbents was prepared from the precursor mixed fly ash and metakaolin. • The geopolymer can effectively remove Pb2+ and Cd2+ from solution. • There are some differences in the adsorption mechanism of geopolymers for Pb2+ and Cd2+. • Synthesize geopolymer adsorbent by industrial waste is a promising approach. In this study, geopolymers were prepared using a mixed precursor of coal fly ash (35 wt%) and metakaolin (65 wt%) in order to investigate the adsorption capacity for Pb2+and Cd2+ in solution. The specific surface area of the geopolymer was up to 82.8 mg/m2. The results show that the maximum adsorption capacity of the geopolymer for Pb2+ and Cd2+ removal were 164.1 and 78.2 mg/g, respectively. Mixing fly ash and metakaolin as raw materials for geopolymer synthesis not only yields an adsorbent material with excellent performance, but is also an effective way to utilize industrial waste resources. [ABSTRACT FROM AUTHOR]

Coal ash is one of the largest industrial waste streams in the United States and contains elevated concentrations of hazardous elements that could pose environmental and human health risks. Due to the relatively high strontium concentrations in coal ash and the distinctive 87Sr/86Sr ratios, strontium isotopes have been utilized to trace coal ash contaminants in impacted water resources. While previous studies have characterized the Sr isotope ratios for the water-soluble Sr derived from coal ash, the strontium isotopic composition of the bulk coal ash has not been systematically evaluated. In the current study, we report the 87Sr/86Sr ratios of bulk and water-soluble Sr in fly ash derived from coals of the three major coal-producing basins in the U.S., the Appalachian Basin, Illinois Basin, and Powder River Basin. The data show a wide range of 87Sr/86Sr ratios in the bulk fly ash samples (0.710788–0.722311), with the most radiogenic 87Sr/86Sr ratios in fly ash originating from Illinois Basin coals (0.718029 ± 0.003365; n = 16), followed by those from Appalachian Basin coals (0.712641 ± 0.000860; n = 16), and those from Powder River Basin coals (0.711663 ± 0.000489; n = 7). The 87Sr/86Sr ratios in the water leachates are significantly lower than the 87Sr/86Sr ratios of the bulk fly ash for Illinois Basin and Appalachian Basin (0.711660 ± 0.001172 and 0.710694 ± 0.000317, respectively, p-value < 0.01), whereas there is no significant difference for the Powder River Basin fly ash (0.711666 ± 0.000456, p-value = 0.13). These isotopic differences most likely reflect the different mineralogical compositions of the studied fly ash and the differential solubility of carbonate phases with low 87Sr/86Sr ratios relative to more radiogenic silicate phases. Overall, the distinction between the strontium isotope ratios of bulk fly ash versus water-soluble fly ash is important, as it refines the application of strontium isotopes as a forensic tracer for tracking coal ash spills and contamination in the environment. • The Sr isotopes of fly ash reflects the mineralogy and isotope composition of the feed coals. • The strontium isotope ratios of water-leachable Sr is different from that of bulk coal ash. • Soluble fractions in coal ash have typically lower 87Sr/86Sr ratios than bulk fly ash. • The isotope distinction between soluble and bulk Sr can be used to trace coal ash contamination in the environment. [ABSTRACT FROM AUTHOR]

Fly ash is a coal combustion by-product with low pozzolanic reactivity which limits its resource utilization and engineering properties in building materials. The present study investigates a wet-milling treatment to activate the coal fly ash and promote its sustainable utilization. It was found that wet-milling is a suitable, efficient and eco-friendly technology for solid waste refinement. The pozzolanic reactivity is greatly improved after wet-milling treatment, as high as 140% at 60 days with particle size of 2.51 μm. It was observed that ettringite formation has occurred during the wet-milling. Physical structure, chemical evolution and ion leaching behavior during the wet-milling were discussed. It was proved that activation mechanism of wet-milling is a combined effect of physical breakage and ion dissolution acceleration. Binding energy was found decreased and SiQn structural units were found less polymerized which are helpful for the depolymerization during the pozzolanic reaction. Furthermore, technical applicability of wet-milling for various industrial solid wastes was also investigated. Image 102651 • Wet-milling is a suitable, efficient and eco-friendly technology for solid waste refinement. • Pozzolanic reactivity of coal fly ash is greatly improved after wet-milling treatment. • The activation mechanism of wet-milling technique for solid wastes was addressed. • Technical advantages and applicability of wet-milling for various solid wastes were discussed. [ABSTRACT FROM AUTHOR]

• Mineral carbonation is a promising technology to reduce CO 2 emissions. • The wideliest materials used are: mining waste, coal fly ash and Steelmaking slag. • The sale of carbon credits generated can make the process economically feasible. • Computational optimization tools can determine the optimal settings of the process. Mineral carbonation has enormous potential for carbon capture and storage (CCS). CO 2 is a greenhouse gas that can be converted into environmentally stable products through mineral carbonation, which has been pointed out as the most promising technology to reduce CO 2 emissions and environmental impacts generated therefrom. Thus, this study presents an overview of the state of the art in terms of mineral carbonation research conducted between 2002 and 2018 with the aim of analyzing its evolution so as to identify the main scientific challenges in literature to indicate future research on it. The results reveal an increase in the number of publications and citations during the period under study and that there has been a fivefold increase in publications and citations on average in the latest five years. The analyzed works have made use of different kinds of industrial waste as raw material for mineral carbonation, whose most widely studied products were mining waste, Coal fly ash and Steelmaking slag. Mining waste is the most commonly studied material, which presents the greatest potential for mineral carbonation. Analyzes of recent articles have revealed that many challenges are yet to be overcome, such as the deployment of industrial carbonation technologies, mostly those that increase the efficiency of converting CO 2 into carbonates and reduce its overall budget. Thus, further studies are needed with the aim of increasing the process reaction rate, reducing the use of chemical reagents and defining the mineralogical characteristics of raw materials in order to determine an ideal raw material for carbonation processes and analyze the market and profitability of products generated through mineral carbonation. [ABSTRACT FROM AUTHOR]

Featured Application: In this paper waste bottom ash from a thermal power station was treated with lime and sand. This improves certain material characteristics leading to a potential use in a subbase in road construction. Industrial waste causes environmental, economic, and social problems. In Morocco, the Jorf Lasfar Thermal Power Station produces two types of coal ash with enormous quantities: fly ash (FA) and Bottom ash (BA). FA is recovered in cement while BA is stored in landfills. To reduce the effects of BA disposal in landfills, several experimental studies have tested the possibility of their recovery in the road construction, especially as a subbase. In the first phase of this study, the BA underwent a physicochemical and geotechnical characterization. The results obtained show that the BA should be treated to improve its mechanical properties. The most commonly used materials are lime and cement. In the selected low-cost treatment, which is the subject of the second phase of the study, lime is used to improve the low pozzolanicity of BA while calcarenite sand is used to increase the compactness. Several mixtures containing BA, lime, and calcarenite sand were prepared. Each of these mixtures was compacted in modified Proctor molds and then subjected to a series of tests to study the following characteristics: compressive strength, dry and wet California Bearing Ratio (CBR), dry density and swelling. The composition of each mixture was based on an experimental design approach. The results show that the values of the compressive strength, the dry density, and the CBR index have increased after treatment, potentially leading to a valorization of the treated BA for use in a subbase. [ABSTRACT FROM AUTHOR]