Graphene oxide (GO) has become a topic of interest in the field of anti-corrosion coating. However, in the field of oilfield wastewater corrosion prevention, there are few research reports on the application of GO aqueous solutions as corrosion inhibitors. This paper discovered that GO modified by acylating with imidazoline quaternary ammonium salt (IQAS) can be preferentially adsorbed on carbon steel surfaces to form a relatively dense protective layer, significantly improving the corrosion resistance of carbon steel in oilfield wastewater. N80# carbon steel was taken as the corrosion object, and oilfield wastewater as the corrosion medium to simulate the corrosion of metal equipment in oilfield wastewater during crude oil storage and transportation. The electrochemical polarization curve method, impedance spectrum method, weight loss method, corrosion morphology, and product characterization were used to understand the corrosion inhibition behavior and anticorrosion mechanism of the GO aqueous solution. The results showed that the corrosion rate of steel sheet with 0.06% GO added at 40 degrees C was 2.023 mm/a, which was 36.15% lower than 3.1685 mm/a in the blank control group. When 0.06% GO and 2.0% IQAS were added simultaneously, the corrosion rate was 1.6494 mm/a, which decreased by 47.94% compared with the blank control group. By weight loss method, the corrosion rate in the crude oil wastewater containing 0.06% GO and 2.0% IQAS at 40 degrees C for 72 h was 0.0768 mm/a, which was 47.5% lower than that in the blank group. The anti-corrosion mechanism involves the inhibition being adsorbed onto the surface of the steel sheet, thereby improving the electrochemical corrosion impedance and reducing the corrosion rate. This research result will provide a novel idea for the development of corrosion and corrosion inhibitors of GO.

The safe and efficient treatment of Cr(VI)-containing industrial wastewater has attracted increasing attention, owing to its substantial potential hazards to both the ecosystem and humanity. A modified carbon-silicon porous composite material (MGFS) was prepared for efficient adsorption of Cr(VI) in wastewater in this study, using original coal gasification fine slag (GFS) - a typical solid waste as precursor material. It is demonstrated that the prepared porous composite material exhibited the richer pore structure, larger specific surface area, and more abundant functional groups compared with that of GFS. Under optimal conditions (adsorption time:150 min, pH: 3, temperature: 25 degrees C, adsorbent dosage: 0.20 g), MGFS exhibited the highest Cr(VI) adsorption capacity of 4.94 mg/g with a removal rate of 98.85%, representing a 40.01% enhancement compared to GFS. Kinetic studies revealed that the adsorption process conforms to both the pseudo-second-order model and HoMcKay model, indicating a multi-step rate-controlling mechanism. Equilibrium data was well-described by Langmuir isotherm models, suggesting a monolayer adsorption behavior. Thermodynamic analysis confirmed that the adsorption was a spontaneous exothermic process. The adsorption mechanism of Cr(VI) onto MGFS was systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and other advanced analytical techniques. These findings not only provide theoretical support for the high-value utilization of coal gasification slag but also offer a viable strategy for heavy metal wastewater treatment.

The mechanism of using graphene oxide as a two-dimensional filler to increase the path length of the corrosive medium to the metal surface is limited to improving the corrosion resistance of the coating. This study propose novel dispersion and in-situ crosslinking reaction mechanism for constructing water-based heavy-duty anticorrosive coatings by using graphene oxide (GO) and waterborne epoxy resin (WEP). The results showed that GO can be uniformly dispersed directly into WEP without complex functional modifications. Oxygen-containing functional groups on moleculars structure of GO&WEP co-polymerized with diethylenetriamine (DETA) forming a continuous phase film which improved the density of the coating. Characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal conductivity measurement instrument, pencil hardness tester, adhesion tester, salt spray corrosion test chamber, and electrochemical impedance spectroscopy (EIS) were used to evaluate coating structure and performance properties. The results showed that graphene characteristics enhanced physical properties and anti-corrosion performance of composite coatings. The construction mechanism of the coating is different from that of the current GO modified and dispersed in the coating as a two-dimensional filler to extend the path length of the corrosive medium to the metal surface. The coatings prepared by adding the optimum mass ratio of 0.1–0.2 % GO to WEP have the best physical properties and anti-corrosion properties. When the GO content is 0.2 wt%, the thermal conductivity increases by 86.0 %. After added 0.025 wt% GO, the coating hardness is increased by two grades directly from 2B to HB. With the addition of GO concentration increased to 0.05 wt%, the adhesion is increased from 2 to level 1.When the GO content exceeds 0.05 %, the coating will not bulge off after 4 months of salt water immersion experiment.

As a bulk industrial solid waste, coal gangue has caused serious pollution to the environment, and its application in the field of soil amendments has been widely studied, but the mechanism of pore structure regulation of coal gangue as soil substrate has not been reported in the literature. In this paper, the physical and chemical properties of coal gangue are analyzed, and its particle size, element content, and occurrence state are defined. The regulation mechanism of pores and pores in preparing matrix soil with coal gangue is revealed, and an efficient and energy-saving fluidizing activation technology is proposed to prepare active matrix soil. The results show that matrix soil with optimal pore structure can be obtained by fluidized bed calcination at 700 °C for 15 min, with a porosity of 55.0 %, volumetric water content of 28.7 %, and gas phase rate of 24.8 %. The technology also removes carbon, which is prone to natural fires, and fixes sulfur, which is good for plant growth. The formation and regulation mechanism of pores structure of soil matrix prepared by fluidized calcination of coal gangue is as follows: The oxidation reaction of carbon and the decomposition of minerals in coal gangue will form pore structures. Adjusting the reaction temperature and time, controlling the rate of carbon oxidation reaction, and the rate of mineral decomposition can achieve the goal of regulating the pore structure. Large pores with a pore size greater than 0.03 mm are formed by the oxidation of carbon and the decomposition of kaolinite. The pores with a diameter of 0.0001–0.03 mm are formed by the overflow of carbon dioxide gas, which is generated by the oxidation reaction of carbon embedded in coal gangue particles and the decomposition of calcium carbonate. The results of this study will provide technical and theoretical support for promoting the comprehensive utilization of coal gangue and improving environmental protection.

The superamphiphobic coatings with high thermal conductivity and wear resistance have attracted wide attention in academic fields, but its construction through sheet fillers is very challenging. Herein, the graded filling of modified flake graphite and modified Al2O3 was used to prepare epoxy resin/polytetrafluoroethylene powder/modified flake graphite/modified Al2O3 (EP/PTFE/FG/Al2O3) coating by two-step spray method, which can ensure stable nonwetting performance toward water, acid-base solutions (pH = 1-14), glycerol and ethylene glycol. More importantly, it also promised excellent wear resistance (1000 cycle wear times) and high thermal conductivity (1.822 +/- 0.023 W/(m & sdot;K)). Furthermore, salt spray tests indicated that the EP/PTFE/FG/Al2O3 coating had an outstanding anticorrosion. It can be foreseen that the simple but effective superamphiphobic coatings are applied in the fields of heat conduction and anticorrosion.

The secure and harmless disposal for Cr-bearing tannery sludge (Cr-TS) has attracted an increasing concern, due to potentially adverse effect on ecosystem and human health. A greener alternative method about "waste treatment with waste" for thermally stabilizing real Cr-TS was developed via employing coal fly ash (CA) as dopants in this research. The co-heat treatment of Cr-TS and CA was carried out at the temperature range of 600-1200 °C to investigate the oxidation of Cr(III), immobilization of chromium and leaching risk of the sintered products, and the mechanism of chromium immobilization was further explored. The results indicate that the doping of CA can significantly inhibit the oxidation of Cr(III) and immobilize chromium by incorporating chromium into spinel and uvarovite microcrystal. At the temperature higher than 1000 °C, most of chromium can be converted into stable crystalline phases. Furthermore, a prolonged leaching test was conducted to study the leaching toxicity of chromium in sintered products, indicating that leaching content of chromium is much less than the regulatory limit. This process is a feasible and promising alternative for immobilization of chromium in Cr-TS. The research findings are supposed to offer a theoretical foundation and strategy choice for thermal stabilization of chromium, as well as safety and harmless disposal of Cr-containing hazardous waste.

The key step of the control reaction for the preparation of graphene oxide (GO) by chemical oxidation of KMnO4/ concentrated H2SO4 oxidation system is the intercalation mass transfer process of oxidizer in graphite. Ultrasonic field can promote the intercalation mass transfer process, but the mass transfer kinetics remains unclear. In this paper, the kinetic model of mass transfer coefficient of graphene oxide sheet intercalated by Mn2O7 oxidizer in ultrasonic field was established. The Mn2O7 intercalation process after the intervention of the ultrasonic was simulated by COMSOL Multiphysics 5.5 simulation software. The results show that the ultrasonic field makes the Mn2O7 solution inside and outside the graphite layer turbulent, and the ultrasonic intervening time has little influence on the concentration distribution and diffusion rate of the solution outside the graphite layer, while it has great influence on the concentration distribution and little influence on the diffusion rate change inside the graphite layer. These results contribute to the improvement of the mass transfer theory for the preparation of GO by ultrasonic assisted chemical oxidation.

Water-based superamphiphobic coatings that are environmentally friendly have attracted tremendous attention recently, but their performances are severely limited by dispersibility and mechanical durability. Herein, a dispersion of poly(tetrafluoroethylene)/SiO2@cetyltrimethoxysilane&sodium silicate-modified aluminum tripolyphosphate (PTFE/SiO2@CTMS&Na2SiO3-ATP) superamphiphobic coatings was formed by mechanical dispersion of poly(tetrafluoroethylene) emulsion (PTFE), modified silica emulsion (SiO2@CTMS), sodium silicate (Na2SiO3), and modified aluminum tripolyphosphate (modified ATP). The four kinds of emulsions were mixed together to effectively solve the dispersity of waterborne superamphiphobic coatings. Robust waterborne superamphiphobic coatings were successfully obtained by one-step spraying and curing at 310 °C for 15 min, showing strong adhesive ability (grade 1 according to the GB/T9286), high hardness (6H), superior antifouling performance, excellent impact resistance, high-temperature resistance (<415 °C), anticorrosion (immersion of strong acid and alkali for 120 h), and heat insulation. Remarkably, the prepared coating surface showed superior wear resistance, which can undergo more than 140 abrasion cycles. Moreover, the composite coating with 35.53 wt % SiO2@CTMS possesses superamphiphobic properties, with contact angles of 160 and 156° toward water and glycerol, respectively. The preparation method of superamphiphobic coatings may be expected to present a strategy for the preparation of multifunctional waterborne superamphiphobic coatings with excellent properties and a simple method.

Water-based superamphiphobic coatings are environment-friendly, which have attracted tremendous attention recently, but the performances are severely limited by the dispersibility of hydrophobic particles. To solve the poor dispersibility of modified silica powder with hydrophobicity, silica dispersion was blended with polytetrafluoroethylene (PTFE) emulsion and modified aluminum tripolyphosphate (ATP) dispersion to successfully prepare water-based coatings. Multifunctional coatings were prepared by one-step spraying. It possessed good adhesion (grade 1), excellent antifouling, impact resistance, chemical stability (acid and alkali resistance for 96 h of immersion), and corrosion resistance (3.5 wt % NaCl solutions for 20 days). More importantly, the superamphiphobic coatings had high contact angles (CAs) and low slide angles (SAs) for ethylene glycol (CAs = 154 ± 0.8°; SAs = 13 ± 0.7°) and water (CAs = 158 ± 0.7°; SAs = 4 ± 0.3°). Furthermore, the composite coating was still hydrophobic after 35 cycles of wear with high roughness sandpaper (120 mesh) under three different loads, which maintained superamphiphobicity at 425 °C. This work is expected to provide a facile idea and method for the preparation of waterborne superamphiphobic coatings.

The mechanism of oxidizing reaction in the preparation of graphene oxide (GO) by a chemical oxidation method remains unclear. The main oxidant of graphite oxide has not been determined. Here, we show a new mechanism in which Mn2O7, the main oxidant, is heated to decompose oxygen atoms and react with graphite. The whole preparation process constitutes of four distinct independent steps, different from the three steps of literature registration, and each step has its own chemical oxidation reaction. In the first step, concentrated sulfuric acid and nitric acid are intercalated between graphite layers in the form of a molecular thermal motion to produce HNO3–H2SO4–GIC. In the second step, Mn2O7 is intercalated between graphite layers in the molecular convection–diffusion to Mn2O7–H2SO4–GIC. In the third step, Mn2O7 is decomposed by heat. Oxygen atoms are generated to oxidize the defects in the graphite layer to PGO. This discovery is the latest and most important. In the fourth step, PGO is purified with deionized water, hydrogen peroxide, and hydrochloric acid to GO. Optical microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectrometry, and scanning electron microscopy analytical evidence was used for confirming Mn2O7 as the main oxidant and the structure of GO. This work provides a more plausible explanation for the mechanism of oxidizing reaction in the preparation of GO by a chemical oxidation method.

In the flue gas ammonia desulfurization process of the coal chemical industry, ammonium sulfate slurry in the desulfurization tower often foams and overflows, which wastes resources and pollutes the environment. The solution to this problem remains largely unknown. This paper aims to reveal the causes of foaming by analyzing foam composition, ammonia desulfurization process raw material source, and characteristics of the flue gas source of the coal chemical industries. It is seen that the organic carboxylate ammonium salt surfactant in the slurry was the main cause of ammonium sulfate slurry foaming. Moreover, due to ammonium sulfate crystals and ash in foam forming a skeleton to support the foaming structure, the foam was not easy to break. More importantly, an appropriate defoaming agent was screened and optimized by an ammonia desulfurization tower simulated device in the laboratory. The YLZ-3 compound defoaming agent, with the optimal defoaming efficiency, was obtained by combining a polyether siloxane copolymer, n-octyl alcohol, fumed silica, and deionized water. It had a good temperature stability and little influence on the ammonium sulfate slurry drying time. However, defoaming agent addition could affect the ammonium sulfate crystal form. The foam overflowing could be controlled by spraying the defoaming agent from the top of the tower. Thus, the problem of bubbling overflow of the ammonia desulfurization tower could be resolved very well.