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[Display omitted] • Proposed a strategy for developing a low-temperature oil-in-water demulsifier. • Increasing the aromaticity and polarity could enhance the effectiveness and rate of demulsifiers. • The role of structure and interfacial activity in demulsifiers has been discussed. • Poly (amino acids) demulsifier performs well in terms of efficiency and rate at room temperatures. To improve the universality and efficiency of polymer demulsifiers at low temperatures, a unique type of biodegradable poly (ε-carbobenzyloxy-L-lysine) - block -poly (L-phenylalanine) (PZLL- b -PPA) demulsifier with stronger polarity and higher aromaticity was developed. The molecular structure and weight of PZLL- b -PPA were determined using Fourier transform infrared (FT-IR) spectroscopy, 1H nuclear magnetic resonance hydrogen spectra (NMR) and gel permeation chromatography (GPC). A bottle test was used to evaluate the demulsification performance of PZLL- b -PPA with different block ratios, structure and interfacial activity. Numerous critical variables, such as demulsifier structure and dosage, pH levels, emulsion salinity, oil content and oil type, were carefully examined. The demulsification results showed that PZLL 5 - b -PPA 25 has excellent low-temperature demulsification capability and can effectively separate oil from water emulsions with different pH values (4.0 ∼ 11.0) and oil contents ranging from 1.0 ∼ 20.0 wt% within 2 min at room temperature. The best demulsification efficiency reached 99.98 %, with only 6.0 mg/L of residual oil in the separated water. The analysis of interfacial self-assembly behavior revealed that PZLL- b -PPA has a strong affinity for aromatic molecules and exhibits high interfacial activity. The quantum chemical calculation indicated that the main chain polyamide skeleton of PZLL- b -PPA has a stronger interaction for asphaltene, resin and naphthenic acid molecules than conventional oxygen-containing skeleton polymers. Furthermore, the microscopy analysis indicated that PZLL- b -PPA has excellent capacity for flocculation and coalescence of oil droplets in an O/W emulsion. As a result, when PZLL- b -PPA is added to the emulsion, it can quickly migrate to the oil-water interface and interact with and displace the emulsion's stabilizers (asphaltenes and resins), promoting oil droplet coalescence and separation from water at low temperature. [ABSTRACT FROM AUTHOR]

Amphiphilic aromatic poly (amino acids) polymers were designed as biodegradability demulsifiers with higher aromaticity, stronger polarity, and side chain-like combs. The effects of demulsifier dosage, structural characteristics and emulsion properties such as pH, salinity, and oil content on the demulsification efficiency were investigated. The results show that the poly (L-glutamic-benzyl ester)-block-poly (L-phenylalanine) (PBLG 15 - b -PPA 15) as the demulsifier can remove more than 99.97% of the oil in a 5.0 wt% oil-in-water (O/W) emulsion at room temperature within 2 min. The poly (L-tyrosine)-block-poly (L-phenylalanine) (PTyr 15 - b -PPA 15) with environmental durability demonstrates high effectiveness, universality, and demulsification speed. It achieves a remarkable demulsification efficiency of up to 99.99% for a 20.0 wt% O/W emulsion at room temperature. The demulsification mechanism indicates that demulsifiers have sufficient interfacial activity can quickly migrate to the oil-water interface after being added to the emulsions. Additionally, when demulsifiers are present in a continuous phase in the molecular form, their "teeth" side chains are beneficial for increasing coalescence and flocculation capacities. Furthermore, according to the Density Functional Theory (DFT) calculations, enhancing the intermolecular interactions between demulsifiers and the primary native surfactants that form an oil-water interfacial film is a more efficient approach to reducing demulsification temperature and improving demulsification efficiency and rate. [Display omitted] • Proposed a strategy for developing a low-temperature oil-in-water demulsifier. • Improving the polarity and aromaticity of demulsifiers enhances their performance. • Aromatic poly (amino acids) demulsifiers perform well at low temperatures. • The intermolecular interactions determine the deoiling temperature and efficiency. [ABSTRACT FROM AUTHOR]

The integrated synergistic effect of the ligand and the strong metal-support interaction (SMSI) effectively improves the selectivity and stability of heterogeneous Pd-based catalysts for acetylene dicarbonylation under high-pressure CO conditions. [Display omitted] • Stabilizing the catalytic active site Pdδ+ for acetylene dialkoxycarbonylation. • Oxygen-containing functional groups of AC provide anchoring sites for stabilize active Pd2+ ions. • The coordination of I- not only accelerates the reaction but also stabilizes the catalyst. The support and ligand play a crucial role in regulating the catalytic performance, selectivity, and stability of heterogeneous catalysis. Herein, activated carbon (AC) supported palladium (Pd) catalysts (2.0 wt%) were prepared by impregnation for acetylene dicarbonylation. The oxygen-containing groups on the surface of the AC support were modulated by nitric acid (HNO 3) to investigate metal–support interactions on the catalytic performance and stability of the Pd/AC. The characterization of the chemical composition and structure of the supports and catalysts demonstrates that high concentrations of oxygen-containing groups on the surface of the carbon support lead to the fine dispersion of Pd nanoparticles. Notably, the finely dispersed Pd/AC 70 catalyst exhibited good activity and stability for acetylene dicarbonylation under high-pressure CO conditions after several rounds of regeneration. Furthermore, operational parameters including the type of support, co-catalyst (KI), and reaction time and temperature were identified for their impact on the reaction. It was found that I- anions serve as a co-catalyst and can ligate with Pd species, thereby preventing the leaching of Pd and improving reaction selectivity. This study presents a straightforward and sustainable modulation strategy to improve the dispersion of active metals, as well as to prevent the leaching and sintering of these metals during high-pressure CO reactions. [ABSTRACT FROM AUTHOR]

Fe(III) has been proved to be a more effective oxidant than dissolved oxygen at ambient temperature, however, the role of Fe(III) in pyrite acidic pressure oxidation was rarely discussed so far. In this paper, in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment. The results illustrated that increasing Fe(III) concentrations led to raising in redox potential of the solution, and decreased passivation of pyrite caused by deposition of elemental sulfur. Reduction of Fe(III) at pyrite surface was a fast reaction with low activation energy, it was only slightly promoted by rising temperatures. While, the oxidation rate of pyrite at all investigated Fe(III) concentrations increased obviously with rising temperatures, the anodic reaction was the rate-limiting step in the overall reaction. Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(III) concentration was increased from 0.05 to 0.50 g/L, showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(III) concentrations, while, it gradually turned to be diffusion control with increasing Fe(III) concentrations. [ABSTRACT FROM AUTHOR]