Coal is a porous medium and natural absorbent. It can be used for its original purpose after adsorbing organic compounds, its value does not reduce and the pollutants are recycled, and then through systemic circulation of coking wastewater zero emissions can be achieved. Thus, a novel method of industrial organic wastewater treatment using adsorption on coal is introduced. Coking coal was used as an adsorbent in batch adsorption experiments. The quinoline, indole, pyridine and phenol removal efficiencies of coal adsorption were investigated. In addition, several operating parameters which impact removal efficiency such as coking coal consumption, oscillation contact time, initial concentration and pH value were also investigated. The coking coal exhibited properties well-suited for organics' adsorption. The experimental data were fitted to Langmuir and Freundlich isotherms as well as Temkin and Redlich-Peterson (R-P) models. The Freundlich isotherm model provided reasonable models of the adsorption process. Furthermore, the purification mechanism of organic compounds' adsorption on coking coal was analysed.

To solve the unwieldy problem of coal chemical wastewater reverse osmosis concentrate (ROC), a novel treatment method in which coking coal was used to adsorb the organic from ROC and the adsorption mechanism involved was investigated. The results showed that the organic components in the ROC of coal chemical industry can be effectively absorbed by the coking coal and the total organic carbon, UV254 and chromaticity of treated ROC reduced by 70.18%, 70.15% and 59.55%, respectively, at the coking coal dosage of 80 g/L. The isothermal adsorption data were fitted to the Langmuir model well. The kinetics were expressed well by the quasi-second-order kinetic model. The intragranular diffusion model and the BET (Acronym for three scientists: Brunauer–Emmett–Teller) test showed that the adsorption occurred mainly on the surface of the coking coal and its macropores and mesopores. When the pollutants further diffused to the mesopores and micropores, the adsorption rate decreased. The result of X-ray photoelectron spectroscopy and fourier transform infrared spectroscopy spectra showed that the coking coal mainly adsorbed the nitrogen and oxygen species and the halogenated hydrocarbon organic compounds in the ROC. The chlorinated hydrocarbons and heterocyclic organics in ROC are adsorbed on the surface of coking coal.

The adsorption of quinoline from wastewater by coking coal (AC-1), HCl-modified coking coal (AC-2), HNO3-modified coking coal (AC-3), HF-modified coking coal (AC-4), and H2SO4-modified coking coals (AC-5) was investigated in this paper. The effects of acid-modified concentration, modification time, and adsorption time versus quinoline removal rate were studied by batch experiments. The quinoline concentration was measured by UV spectrophotometry, the average pore size and specific surface area of coking coal before and after modification were characterized through static nitrogen adsorption, the mineral composition of coking coal was tested by X-ray diffraction, the surface functional groups were tested by Fourier transform infrared spectroscopy, and the surface topography was tested using a scanning electron microscope. The experimental results showed that the adsorption capacity of coking coals was the best when both the modification time was 120 min and the acid-modified concentration was 0.1 mol·L–1 and the quinoline removal rate reaches the highest when the adsorption time was 120 min. The specific surface area of AC-2 increased from 2.898 to 3.637 m2·g–1, and the removal rate of quinoline increased from 77.64 to 90.61%. Acids reacted with inorganic mineral impurities within coking coal such as hydrogen vanadium phosphate hydrate, which caused an increase in the specific surface area. A new peak appeared in the Fourier transform infrared spectroscopy pattern at the wavenumber 2300 cm–1. The surface of coking coal modified by acids was rougher than that of AC-1. The adsorption capacity of coking coal was improved after modification, and modified coking coals have the highest potential as low-cost adsorbents for quinoline removal.

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The evaluation of flotation reagents performs an important role in the selection and green application of reagents. The green indexes and effect indexes of flotation collectors were selected by data literature method, system analysis method, mathematical model method, and qualitative and quantitative analysis method, and the green evaluation system of flotation collectors, flotation effect evaluation system, and comprehensive evaluation system of flotation collectors were established. The normalization method and expert evaluation methods were adopted to obtain the grade classification of quantitative and qualitative indicators, respectively. The analytic hierarchy process (AHP) was used to determine the weight of secondary indicators and tertiary indicators of the evaluation system and the weight of indicators at a lower level. Applying the fuzzy comprehensive evaluation (FCE), the trapezoidal function is selected to determine the index affiliation, the index system score is calculated according to the weighted average principle, and finally, the established evaluation system is applied in an example. The example application shows that the comprehensive evaluation system of flotation collectors can make a comprehensive evaluation of collectors from the aspects of the greenness of reagent, flotation effect, and cost, and it has a strong target and practicality for collectors evaluation. The establishment of the system has a guiding significance for the selection and use of flotation collectors.