Long Cheng,Kui Wang,Shanyong Wang,Hailong Lu,Chunmin Xu,Jun Ye
As the main by-product of chemical pulping, lignosulfonate is mostly burned directly as fuel with low added value. Therefore, the conversion of lignosulfonate into multifunctional porous carbon materials is necessary for green sustainable development and practical applications. In this work, the pore size of sodium lignosulfonate-based porous carbons (LBCs) was regulated by green activator HCOOK and mesoporous manufacturing agent SiO 2 for the first time. The formation of micropores is beneficial to the improvement of surface area and adsorption performance, while the development of mesopores accelerates the mass transfer rate, but its adsorption performance is lower than that of micropores. The developed pore structure, sufficient oxygen content and graphene structure of LBCs lead to high adsorption performance for norfloxacin (NOR), reaching 341.9 mg g −1 . Characterization and Density functional theory (DFT) results show that the sorption process includes pore filling, π-π stacking, hydrogen bond and electrostatic interaction. In addition, pore volume and surface diffusion model (PVSDM) confirm that surface diffusion dominates the adsorption process. The above results provide an important reference value for the preparation and application of high-performance lignin-based adsorbents.
Yaqi Ding,Neng Gao,Nian Li,Guangming Chen,Yongmei Xuan
The vapour-liquid equilibrium (VLE) data of four ternary solutions HCOOK + [Emim]Ac /[Emim]Br / [Emim]Cl / [Emim]NO 3 + H 2 O were measured using the boiling method at the temperatures from 305.78 K to 387.08 K, at solute (HCOOK + IL) mass fractions ( w ) between 0.2 and 0.5. A total of 234 data points ( w = 0 included) were obtained and correlated with empirical Antoine-type equations. The absolute average relative deviations (AARD %) between calculated and measured vapour pressures were 0.58%, 0.50%, 0.49%, 0.63%, respectively, which showed good agreement. The comparison of the experimental and standard data and combined uncertainties of the experimental data confirmed good reliability of the experimental method and apparatus. The four ternary solutions with ILs as additives have lower vapour pressure compared to the corresponding binary solutions without ILs. The results showed that the four ternary solutions of HCOOK + [Emim]Ac / [Emim]Br / [Emim]Cl / [Emim]NO 3 + H 2 O can be the alternatives for traditional dehumidification and absorption media. [Emim]Cl has the best ability to reduce the vapour pressure of HCOOK + H 2 O at the solute (HCOOK + IL) mass fraction of 0.4 and 0.5. The [Emim]Ac has the most effect reducing the vapour pressure of HCOOK + H 2 O at the solute (HCOOK + IL) mass fraction of 0.3.
Partially hydrolyzed polyacrylamide (HPAM) hydrogels are widely used as fracturing fluids for extracting underground hydrocarbon resources. Weighting salts are incorporated to enhance hydrogel density to address the extreme pressure encountered in ultra-deep reservoirs. These salts exert significant effects on performance; however, the underlying mechanisms remain poorly understood, and the development of high-performance fracturing fluids remains a significant challenge. This study systematically examines the influence of potassium formate (HCOOK) and sodium bromide (NaBr) as weighting agents on the viscoelasticity of high-density HPAM hydrogels. The findings indicate that HCOOK exerts a more pronounced adverse impact on the viscoelasticity of HPAM hydrogels compared to NaBr. Molecular dynamics simulations reveal that the inferior viscoelasticity of the HCOOK-based polymer hydrogels is attributed to stronger supramolecular interactions between the crosslinker and HCOOK. This study develops an enhanced-performance high-density fracturing fluid with a density of up to 1.40 g/cm 3 , a maximum drag reduction rate of 75.1 %, and temperature tolerance up to 160 °C by integrating ultra-high molecular weight HPAM, a dual crosslinking strategy, and NaBr as weighting salt. This research not only provides fundamental insights into the complex interactions among weighting agents, crosslinkers, and polymers but also presents an enhanced-performance high-density fracturing fluid for ultra-deep hydrocarbon reservoirs.
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