Article Highlights• A novel betaine type asphalt emulsifier was synthesized • The optimum reaction condition was obtained • The chemical structure of the product was characterized by FTIR and 1 H-NMR • Based upon the experimental data, a plausible reaction mechanism was proposed for the reaction. The emulsifier is a rapid-set asphalt emulsifier Abstract A novel betaine type asphalt emulsifier 3-(N,N,N-dimethyl acetoxy ammonium chloride)-2-hydroxypropyl laurate was synthesized after three steps by the reaction of lauric acid, epichlorohydrin, dimethylamine and sodium chloroacetate. The optimum reaction conditions were obtained for the synthesis of the first step of 3-chloro-2-hydroxypropyl laurate. The esterification yield reaches 97.1% at the optimum conditions of reaction temperature 80 °C, reaction time 6 h, feedstock mole ratio of epichlorohydrin to lauric acid 1.5, mass ratio of catalyst to lauric acid 2%. The chemical structure of the product was characterized by FTIR and 1 H-NMR. The first synthesis step of 3-chloro-2-hydroxypropyl laurate was monitored by online FTIR technique. The by-product was detected by the online FTIR analysis. Based upon the experimental data, a plausible reaction mechanism was proposed for the reaction. The CMC of the objective product has a lower value of 7.4×10 -4 mol/L. The surface tension at CMC is 30.85 mN/m. The emulsifier is a rapid-set asphalt emulsifier.

The high moisture content limits the large-scale utilization of lignite. Hydrothermal dehydration (HTD) has been confirmed as an effective method to improve the quality of lignite for further utilization. In this study, the effects of the changes in the lignite interface properties caused by the HTD modified final temperature on the slurry ability were investigated in the range of 160–200 °C. The results indicated that with the gradual rise of the HTD modified final temperature, the content of the carboxyl groups and phenolic hydroxyl groups on the surface of lignite decreased by 21.95 and 36.34%, respectively. In the meantime, the atomic ratio of oxygen/carbon, the content of equilibrium moisture, and the thickness of the hydrated film were reduced from 0.293, 14.63%, and 34.26 nm to 0.252, 9.43%, and 13.33 nm, respectively. Therefore, these changes of interfacial properties improved the slurry ability of lignite, with higher fixed-viscosity solid concentration, lower yield stress, increased pseudo-plasticity, and gradually decreased static stability of the prepared lignite coal water slurry. hydrothermal dehydration; slurry ability; oxygen-containing functional groups; hydrated film

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To overcome the environmental and economic challenges posed by the increasing amounts of the coal gasification slag, here, a simple and efficient method for enriching the residual carbon from the coal gasification fine slag was proposed. The residual carbon enrichment pattern in the particle size distribution of coal gasification fine slags after the ultrasonic pretreatment was mainly enriched toward the 500–250 μm and 250–125 μm particle size classes by analyzing the changes in the particle size distribution and apparent morphology. The pulp pretreatment at the ultrasonic output power of 270 W for 4 min was determined as the optimal experimental condition with respect to the yield, ash content, and ash rejection of the concentrates. Compared to the conventional wet sieving separation, the yield and ash content of the final concentrates were reduced by 7.99 and 14.96%, respectively. Moreover, the ash rejection of the final concentrates was as high as 88.51%, indicating an increment of 11.63% than the conventional wet sieving separation. Furthermore, thermogravimetric analysis confirmed that the final concentrates exhibited the lowest reactivity; however, these demonstrated had the highest carbon content (nearly 70%) with 27.27% ash content. The combustion characteristics analysis showed that the wet screening concentrate after ultrasonic pretreatment had the highest composite combustion characteristic index (S) of 3.17 × 10–8, as compared to the raw and conventional sieving concentrates.