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Carbon microspheres were synthesized using itaconic acid fermentation waste liquid as the raw material by the hydrothermal method. The sequential porous adsorbent was prepared (by chemical activation) using carbon microspheres as a carbonaceous framework. The adsorbent was characterized by SEM, BET, Raman, XRD, XPS, and elemental analysis. Also, the adsorption performance of the adsorbent was tested using the batch adsorption method. The effects of several parameters such as pH, adsorbent dose, and concentration of Cr(VI) on the sorption of Cr(VI) were investigated. The results indicate that an outstanding adsorbent with a specific surface area of 1802.16 m2 g−1 and a maximum adsorption capacity for Cr(VI) of 270.14 mg g−1 has been acquired. According to the adsorption isotherm model, the kinetic model, and the intra-particle diffusion model, it was found that the adsorption process of Cr(VI) by the adsorbent conforms to the Freundlich model and the quasi-second-order kinetic model. The evaluation of the thermodynamic parameters (ΔH > 0, ΔS > 0, and ΔG < 0) revealed that the adsorption process was endothermic and spontaneous. The mechanistic studies showed that the adsorption of Cr(VI) likely involved electrostatic attraction and a redox reaction. After 5 cycles of repeated usage, the adsorbent maintains good adsorption stability to Cr(VI), favoring its practical application.

Hypothesis Polyurethane plastic waste (PUPW), a port-abundant solid waste, is difficult to degrade naturally and poses a severe threat to the environment. Hence, the effective recycling of PUPW remains a challenge. Experiments Herein, a strategy of converting PUPW into stacked oil/water filtration layer grain through a layer-by-layer (LBL) assembly process is investigated. Notably, such PU-based, grain-stacked, and switchable wettability of the oil/water filter layer is first reported. Findings The grain-stacked filter layers are flexible for separating immiscible oil/water mixtures, water-in-oil emulsions (WOE), and oil-in-water emulsions (OWE) under gravity over 10 cycle-usages. They can withstand strong acid/alkali solutions (pH=1-14) and salt solutions over 12 hours. Besides, 100-times scale-up experiments have indicated that the obtained filter layers exhibit an upper to 98.2 % separation efficiency for 10 L real industrial oil/water emulsion in the 24 hours continuous operation. The demulsification mechanism for emulsions is that the electrostatic interaction along with adsorption between emulsion droplets and grains leads to the uneven distribution of surfactants on the interface film of the emulsion droplets, increasing the probability of tiny droplets colliding and coalescing into large droplets to achieve oil/water separation. This work proposes an effective and economical method of abundant plastic waste for industrial-scale oil-water separation rather than just on the laboratory-scale.

Improving the adsorption capacity of adsorbents is a good way to boost their desulfurization efficiency. Optimizing the dispersion of metal nanoparticles and enhancing the stability of the metal valence state are essential to maximizing the adsorption capacity of the metal-loaded desulfurization adsorbent. Pistia stratiotes can absorb the Cu in water and evenly disperse it throughout the plant, allowing the production of a highly dispersed Cu(I) adsorbent (PSAC-Cu(I)). During the usage and storage of PSAC-Cu(I), Cu(I) oxidizes to Cu(II) when it comes in contact with oxygen and water, reducing its adsorptive capacity; hence, we modified PSAC-Cu(I) hydrophobically using polydimethylsiloxane (PDMS) to generate PSAC-Cu(I)-P(200). The outcome of the two-month exposure experiments showed that only 4.7% of the Cu(I) of PSAC-Cu(I)-P(200) was oxidized in the humid atmosphere, whereas PSAC-Cu(I) was almost fully oxidized. Moreover, the dibenzothiophene adsorption capacity of PSAC-Cu(I)-P(200) in a model oil with a water concentration of 250 ppmw is 68 mg g

Adsorptive desulfurization (ADS) using activated carbon (AC) as adsorbent presents competitive potential in separating thiophenic sulfur from liquid fuels with high selectivity under mild operation conditions. It is also a highly economic remedy in ultra-low sulfur content situations. Most importantly, a suitable feedstock for macroscopic quantity preparation of AC adsorbents with good adsorptive desulfurization performance and low-cost is required to satisfy the requirements of this field. In this work, four representative substances (i.e., coal, coconut shell, polyurethane plastic waste, and petroleum coke) were selected as the carbon source for the preparation of various AC adsorbents. The physicochemical properties of the prepared AC adsorbents were characterized using BET, SEM, XRD, XPS, elemental analysis and Boehm's method. The corresponding adsorptive desulfurization performance was investigated. The corresponding desulfurization capacity obtained was in the order: CS-ACA > PUPW-ACA > PC-ACA > AT-ACA. Under the optimal conditions of 30 °C and 30 min contact time, the desulfurization rate of 0.5 g PUPW-ACA can reach about 98%. The HHV of non-condensable gas generated during the experiment was calculated, and the HHV of the pyrolysis oil was measured. The results showed that the by-products produced by PC had the highest HHV. The economics of the desulfurization of the four kinds of activated carbon were analyzed and evaluated. From a comprehensive analysis, PUPW-ACA has the highest economic production value and has the potential for industrial production. This plays a dual role in environmental protection.

The increase in demand for fuel oil has brought higher challenges to the high value-added process of heavy oil vacuum residue, especially for delayed coking units. For optimization of product distribution, the effects of reaction temperature and chemical additives were discussed. The results show that high temperature and 1 wt% of the heteropoly acid (HPA) could increase the light oil yield in the experimental delayed coking simulation device.

In response to the chemical industry's eco-friendly and high-value-added requirements, FCC slurry oil (SO) has been used as a raw material for novel solid carbon materials. As one of the most important chemically active intermediates and products in the FCC process, olefins may have a significant impact on the quality of the carbon materials produced. However, the existence and distribution of olefins have not been discussed. In this paper, olefinic hydrocarbons were first innovatively identified as important compounds that do exist in SO, and their distributions in sub-fractions below 500 °C, classified with the types and carbon numbers, were analyzed. However, there are great limitations for the existing analytical methods in the distribution detection of olefins in the whole fractions of heavy oils. In order to solve this problem, a newly-developed analytical method has been developed. Two different separation techniques were implemented to separate SO into six sub-fractions and eight group compositions, according to boiling point and molecular polarity respectively, before the analysis of olefin distribution for higher accuracy. The proposed method has been further verified by the GC × GC-TOFMS method and proved to have superior reliability. The olefinic carbons in the fraction of 350–400 °C possess the highest content among the detected narrow fractions, up to 1.55%, which decreases gradually with the increase of boiling points, and the first three sub-fractions between 350–470 °C take most of the olefinic carbons in SO, reaching around 74%.

In this study, the occurrence of olefinic bonds in asphaltenes separated from vacuum residue (VR) during thermal cracking was explored. Also, the effect of various thermal cracking conditions on the nature of olefinic bonds was discussed. The results showed that olefinic bonds were formed in asphaltenes during VR thermal cracking. The olefinic structure of asphaltenes detected by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy was mainly in the type of R–CH = CH–R′. An in-depth investigation revealed that increasing the severity of thermal cracking promoted the formation of more olefinic-bond-containing asphaltenes; the percentage of olefinic hydrogen in asphaltenes peaked at cracking under 420 °C for 40 min, was 2.7%. Meanwhile, the olefinic-bond-containing asphaltenes of high concentration consequently became precursors for the formation of coke by increasing the instability of the liquid system. Consequently, further prolongation of the cracking time led to a drastic decline of olefins content accompanying a sharp leap of coke yield. Finally, the hypothetical average molecular structures of the olefinic-bond-containing asphaltenes during VR thermal cracking were proposed based on the modified Brown-Ladner empirical formulas with improvement. They serve as intuitive insights into the existing olefinic bonds in asphaltenes.

Mesophase carbon microbeads (MCMBs) were synthesized by thermal polycondensation with fluidized catalytic cracking residue oil (FRO) as the feedstock. The evolution features of functional groups of the residual oils and the residual solid products from thermal polymerization were analyzed, and the effect of olefinic compounds on the coalescence between mesophase spheres was investigated in depth. The results showed that the olefin contents of residual oil, heptane-soluble, and heptane-insoluble/toluene-soluble decreased simultaneously as the reaction proceeded while that of toluene-insoluble increased, indicating that the olefins in the solvent phase could not only provide molecule sources for the development of carbonaceous mesophase but also directly assemble into the insoluble mesogens. More importantly, the involvement of olefins caused a sharp increase of the system viscosity, making it difficult for the mesophase spheres to completely coalesce into regular large ones after cohering, leading to the apparent deformation. In contrast, catalytic hydrotreatment can saturate olefinic species and enhance the hydrogen transfer ability of FRO to further avoid the induction effect of olefins, slow down the mesophase development, reduce the system viscosity, and consequently avoid the deformation of mesophase spheres.

FCC slurry oil (SO) is an important and yield-rich by-product of the FCC process, which can be regarded as the raw material of high-value-added carbonaceous products due to its abundant concentration of aromatic components, but essential pretreatments and purifications for SO are required before carbonization to eliminate the adverse factors. Appropriate sequential pretreatments aimed at achieving the high-value utilization of SO have been developed, and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR, 13C NMR) were implemented for the systematical properties analyses of SO and its derivatives after sequential pretreatments. Polarized-light microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to evaluate the microstructures and microcrystal parameters of intermediate species and final products during carbonization. Through the varying degrees of sequential pretreatments, the comprehensive properties of feedstocks were improved gradually which further led to the diverse development of carbonaceous mesophase at the early stage of carbonization. Furthermore, ordinary or superior needle coke can be synthesized from the obtained oil samples during sequential pretreatments. The synthesized needle coke had suitable performance for the application in anode material of lithium-ion batteries.