A critical global issue in the 21st century is water shortage, as well as its pollution with noxious metal ions and organic dyes. To extract these pollutants from wastewater, a variety of traditional methods have been employed but they lack reusability/recyclability, are expensive, environmentally unfriendly, unsafe and the remediation process takes a long time. Therefore, to treat these contaminants, nanotechnology (NT) has recently been granted several leeways in terms of making the desirable nanomaterials (NMs) with high surface-to-volume ratios and special surface functionalities. In particular, fly ash (FA) has stood out as one of the greatest exciting new-found affordable and high efficient materials for water decontamination owing to its high porosity, huge surface area, and exceptional features. Hence, this present review study will attempt to compile data from existing literature on the utilization of FA-based adsorbent for the removal of heavy metals (HMs) and dyes from wastewater. Based on the reviewed publications, Langmuir's isotherm models (LIMs) and Freundlich's isotherm models (FIMs) best described the sorption process thus signalling monolayer and multi-layer sorptions. Pseudo-second-order (PSO) model provided the best appropriate means in elucidating the kinetic process and both exothermic and endothermic processes revealed the nature of the thermodynamic process during sorption. Some recommendations in the form of future prospects on how to advance the capacity of the adsorption and effectiveness of FA on the removal of HMs, dyes and other environmental contaminants using innovative technologies such as the nanofiber technology is also been proposed.

Fly ash-based adsorbent for adsorption of heavy metals and dyes from aqueous solution: a review

A review on accessible techniques for removal of hexavalent Chromium and divalent Nickel from industrial wastewater: Recent research and future outlook

Synthesis of zeolite from sugarcane bagasse fly ash and its application as a low-cost adsorbent to remove heavy metals

Graded synthesis of highly ordered MCM-41 and carbon/zeolite composite from coal gasification fine residue for crystal violet removal

Utilization of industrial waste lithium-silicon-powder for the fabrication of novel nap zeolite for aqueous Cu(II) removal

Zeolite P synthesis based on fly ash and its removal of Cu(II) and Ni (II) ions

https://iopscience.iop.org/article/10.1088/2053-1591/aaea41/pdf

The thermodynamics and kinetics for the removal of copper and nickel ions by the zeolite Y synthesized from fly ash

Fly ash (FA) from coal-based thermal power plant was used to synthesize zeolite in NaOH solution with hydrothermal method in this work. Firstly, the effects of calcination and acid treatment on the removal of impurities in fly ash were studied. Then based on the pretreated FA, the effects of alkali concentration, reaction temperature and Si/Al ratio on the synthesis of zeolite were studied in detail. The mineralogy, morphology, thermal behavior, infrared spectrum and specific surface for the synthetic sample were investigated. The results indicated that calcination at 750 °C for 1.5 h can basically remove unburned carbon from FA, and 4 M hydrochloric acid treatment of calcined FA at 90 °C for 2 h will reduce the quality of about 34.3%wt, which are mainly iron, calcium and sulfur elements. The concentration of NaOH, reaction temperature and Si/Al ratio have important effect on the synthesis of zeolite. In this study, 0.5 M NaOH cannot obtain any zeolite. High temperature is beneficial to zeolite synthesis from FA, but easily lead to a variety of zeolites. The synthetic sample contains three kinds of zeolites such as zeolite P, sodalite and zeolite X, when the reaction conditions are 2 M NaOH and 120 °C for 24 h. In this research, quartz always exists in the synthetic sample, but will reduce with the increase of temperature. The synthetic zeolite has the specific surface area of about 42 m2 g−1 and better thermal stability.

https://iopscience.iop.org/article/10.1088/2053-1591/aac3ae/pdf

Synthesis and characterization of zeolite from coal fly ash

The invention relates to a method for controlling the intermittent vacuum evaporation mass of a sodium chloride aqueous solution, which is mainly applied to the intermittent vacuum evaporation and concentration of the sodium chloride aqueous solution as well as crystallization process design, computer simulation and process control thereof, and belongs to the field of chemistry and chemical engineering evaporation and crystallization. The method for controlling the vacuum evaporation mass of the sodium chloride aqueous solution provided by the invention uses a numerical method to carry out design calculation mainly according to a novel evaporation model and a temperature difference model, so as to achieve the purpose of accurately controlling the water evaporation mass in the vacuum evaporation process of the sodium chloride aqueous solution; the method for controlling the intermittent vacuum evaporation mass of the sodium chloride aqueous solution has wide laboratory and industrial application prospect, is beneficial to the design and control of the evaporation, concentration and crystallization process of the sodium chloride aqueous solution, can be applied to the processes of waste water desalination, sea water desalination and sodium chloride industrial crystallization, and is in favor of the promotion of the technological level in the environmental protection and resourcerecycling and utilizing in China.

Method for controlling intermittent vacuum evaporation mass of sodium chloride aqueous solution

The invention relates to an extraction and purification method of sludge compost fulvic acid. The extraction and purification method is a method for extracting from the sludge compost fulvic acid andpurifying fulvic acid by utilizing XAD-8 type macroporous resin. The extraction and purification method comprises the following steps: drying aged compost by air and grinding to obtain a raw materialfor extracting fulvic acid; adding acidic and alkaline extracting solutions into the compost in sequence according to a certain solid-liquid ratio; heating and stirring; centrifuging and separating toobtain a fulvic acid solution; feeding the fulvic acid solution onto an XAD-8 type macroporous resin column; then eluting salt remained in the column with distilled water; eluting fulvic acid adsorbed by the macroporous resin by taking an organic solvent as an eluting solution; obtaining a fulvic acid solid substance by adopting a vacuum drying method, wherein the content of organic elements C, H, N, S and O in a purified fulvic acid sample is 46.83 percent, 5.39 percent, 6.35 percent, 0.94 percent and 34.74 percent respectively, and other impurities mainly comprise Cl, Fe and Ca which have the content of 4.0 percent, 2.47 percent and 0.22 percent respectively.

Guodong Wang

Papers

Zeolite P synthesis based on fly ash and its removal of Cu(II) and Ni (II) ions

The thermodynamics and kinetics for the removal of copper and nickel ions by the zeolite Y synthesized from fly ash

Synthesis and characterization of zeolite from coal fly ash

Method for controlling intermittent vacuum evaporation mass of sodium chloride aqueous solution

Extraction and purification method of sludge compost fulvic acid