Competitive Adsorption Mechanism Research Articles

Enhanced oil recovery by sacrificing polyelectrolyte to reduce surfactant adsorption: A classical density functional theory study

During the process of chemical enhanced oil recovery (CEOR), surfactants are widely used as they can reduce interfacial tension and change surface wettability, but the huge economic losses caused by the adsorption of surfactants on rock surface need to be resolved. Therefore, polyelectrolyte is introduced to reduce the adsorption amount of surfactant. However, how to select appropriate polyelectrolyte suitable for different reservoirs is always lack of theoretical guidance. Herein, the competitive adsorption mechanism between surfactant and polyelectrolyte on rock surface is studied by classical density functional theory (CDFT). Having investigated the effects of different polyelectrolytes on the adsorption of surfactants, the optimal polyelectrolyte concentration and chain length suitable for different potentials were found. Also, the influence of rock crevices width on displacement effect was considered. Moreover, we proposed a comprehensive evaluation of polyelectrolytes in terms of both the performance and economy. The findings of this study benefit for further understanding of the competitive adsorption in CEOR, and provide guidance for the practical application of polyelectrolytes.

Differential Surface Adsorption Phenomena for Conventional and Novel Surfactants Correlates with Changes in Interfacial mAb Stabilization.

Protein adsorption on surfaces can result in loss of drug product stability and efficacy during the production, storage, and administration of protein-based therapeutics. Surface-active agents (excipients) are typically added in protein formulations to prevent undesired interactions of proteins on surfaces and protein particle formation/aggregation in solution. The objective of this work is to understand the molecular-level competitive adsorption mechanism between the monoclonal antibody (mAb) and a commercially used excipient, polysorbate 80 (PS80), and a novel excipient, N-myristoyl phenylalanine-N-polyetheramine diamide (FM1000). The relative rate of adsorption of PS80 and FM1000 was studied by pendant bubble tensiometry. We find that FM1000 saturates the interface faster than PS80. Additionally, the surface-adsorbed amounts from X-ray reflectivity (XRR) measurements show that FM1000 blocks a larger percentage of interfacial area than PS80, indicating that a lower bulk FM1000 surface concentration is sufficient to prevent protein adsorption onto the air/water interface. XRR models reveal that with an increase in mAb concentration (0.5-2.5 mg/mL: IV based formulations), an increased amount of PS80 concentration (below critical micelle concentration, CMC) is required, whereas a fixed value of FM1000 concentration (above its relatively lower CMC) is sufficient to inhibit mAb adsorption, preventing mAb from co-existing with surfactants on the surface layer. With this observation, we show that the CMC of the surfactant is not the critical factor to indicate its ability to inhibit protein adsorption, especially for chemically different surfactants, PS80 and FM1000. Additionally, interface-induced aggregation studies indicate that at minimum surfactant concentration levels in protein formulations, fewer protein particles form in the presence of FM1000. Our results provide a mechanistic link between the adsorption of mAbs at the air/water interface and the aggregation induced by agitation in the presence of surfactants.

Asymmetric CoN3 P1 Trifunctional Catalyst with Tailored Electronic Structures Enabling Boosted Activities and Corrosion Resistance in an Uninterrupted Seawater Splitting System.

Employing seawater splitting systems to generate hydrogen can be economically advantageous but still remains challenging, particularly for designing efficient and high Cl- -corrosion resistant trifunctional catalysts toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Herein, single CoNC catalysts with well-defined symmetric CoN4 sites are selected as atomic platforms for electronic structure tailoring. Density function theory reveals that P-doping into CoNC can lead to the formation of asymmetric CoN3 P1 sites with symmetry-breaking electronic structures, enabling the affinity of strong oxygen-containing intermediates, moderate H adsorption, and weak Cl- adsorption. Thus, ORR/OER/HER activities and stability are optimized simultaneously with high Cl- -corrosion resistance. The asymmetric CoN3 P1 structure based catalyst with boosted ORR/OER/HER performance endows seawater-based Zn-air batteries (S-ZABs) with superior long-term stability over 750 h and allows seawater splitting to operate continuously for 1000 h. A self-driven seawater splitting powered by S-ZABs gives ultrahigh H2 production rates of 497μmol h-1 . This work is the first to advance the scientific understanding of the competitive adsorption mechanism between Cl- and reaction intermediates from the perspective of electronic structure, paving the way for synthesis of efficient trifunctional catalysts with high Cl- -corrosion resistance.

Highly selective adsorption of 5-hydroxymethylfurfural from multicomponent mixture by simple pH controlled in batch and fixed-bed column studies: Competitive isotherms, kinetic and breakthrough curves simulation

Fixed-bed column adsorption is one of the most promising technologies for the separation and purification of 5-hydroxymethylfurfural (5-HMF) from biomass hydrolysate from the point of view of industrial application. However, one of the most pressing issues to be resolved is how to improve the separation factor of 5-HMF and its by-product levulinic acid (LA) and formic acid (FA). In this study, we used poly (BDM-alt-DVB) resin (BD-11) as an adsorbent and a simple pH control in batch and fixed-bed column to explore the competitive adsorption behavior and mechanism of 5-HMF from multicomponent solution. Without adjustment for solution pH, the separation factors of α5-HMF/LA, α5-HMF/FA, α5-HMF/Glucose were 2.6, 11.3, and 22.2, respectively. Interestingly, the separation factors of α5-HMF/LA, α5-HMF/FA, α5-HMF/Glucose increased dramatically to 73.0, 72.2, and 49.2 by merely adjusting the solution pH to 7.02. Furthermore, when the pH was adjusted to 7.02, the equilibrium time of 5-HMF adsorption on the BD-11 resin was within 20 min, and the adsorption capacity reached 69.7 mg/g, which was 118 % of the equilibrium adsorption capacity of the unadjusted pH value. In addition, the proposed fixed-bed column multicomponent competitive adsorption model was shown to agree well with the experimental data and successfully simulated the adsorption behavior of 5-HMF under a variety of experimental conditions. In conclusion, the fixed-bed column had great potential in 5-HMF selective adsorption from an aqueous solution by simple pH control.

Effect of nitrogen functional groups on competitive adsorption between toluene and water vapor onto nitrogen-doped spherical resorcinol-formaldehyde resin-based activated carbon.

To elucidate the effect of nitrogen functional groups on the competitive adsorption of toluene and water vapor, a series of N-doped resorcinol-formaldehyde resin-based activated carbons using g-C3N4 as the nitrogen source were prepared, which possessed different N contents (1.29-6.14%). The competitive adsorption characteristics and mechanisms were investigated by characterizations, dynamic adsorption experiments, adsorption isotherms, and density functional theory calculations. Results showed that the normalized toluene adsorption capacity under 50 RH% was consistent with the N content, revealing that nitrogen functional groups can enhance the competitive adsorption for toluene under a humid atmosphere. Adsorption isotherms analysis suggested that nitrogen functional groups can not only accelerate the adsorption of toluene but also improve the hydrophobicity of carbon surface. Competitive adsorption mechanisms were ascribed to π-π interactions and electrostatic interactions. Specifically, graphitic-N and pyridinic-N enhance competitive adsorption for toluene through reinforced π-π interactions with toluene and weakened electrostatic interactions with water molecule. However, pyrrolic-N improve the competitive adsorption, which is principally attributed to enhanced π-π interactions with toluene. Furthermore, it was found that the reusability of activated carbon could be improved by nitrogen functional groups. This study provides theoretical hints to develop volatile organic compound adsorbents in the presence of water vapor.

Effect of oxidative aging of biochar on relative distribution of competitive adsorption mechanism of Cd2+ and Pb2+

In this study, aged biochar (CCB350 and CCB650) were obtained from pyrolysis of corn stalk biochar (CB350 and CB650) at the degree of 350 °C and 650 °C by artificial oxidation with hydrogen peroxide (H2O2). Also, the mechanism of Pb2+ and Cd2+ on fresh and aged biochars was analyzed qualitatively and quantitatively by batch adsorption experiments combined with characterization. The adsorption isotherm results showed that aging treatment decreased the adsorption capacity of Pb2+ and Cd2+ and inhibited the competitive adsorption behavior of heavy metals. In the single-metal system, precipitation and cation exchange were considered as the main adsorption mechanisms for CB350 and CB650, with a ratio of 40.07–48.23% and 38.04–57.19%, respectively. Competition between Pb2+ and Cd2+ increased the relative contribution of mineral precipitation, but decreased the contribution of cation exchange mechanism. Aging resulted in the rise of the contribution of surface complexation to the adsorption of Pb2+ and Cd2+ on biochars, especially in low-temperature biochars, but weakened the contribution of mineral precipitation to the adsorption. Further, the contribution of other adsorption mechanisms was significantly enhanced for high-temperature aged biochars. These results are important to evaluate its long-term application prospects in the natural environment.

Effects of Chelating Surfactants on Competitive Adsorption of Lead and Zinc on Loess Soil

The study of competitive adsorption of heavy metals on soil is important for heavy metals contaminated soil remediation. However, there have been few studies on the impact of desorption reagents on heavy metal adsorption in soil. Batch adsorption studies were used to investigate the competitive adsorption mechanism of two heavy metals, Pb and Zn, on a loess soil in the presence of a new chelating surfactant, sodium N-lauroyl ethylenediamine triacetate (LED3A). Results showed that competitive adsorption equilibria of Pb and Zn were reached at 3 and 10 h, respectively. The maximum equilibrium adsorption capacities were 19.55 and 18.35 g.kg-1, respectively. LED3A affected the competitive adsorption kinetics of Pb and Zn by increasing the change in external mass transfer and reducing the change in internal mass transfer. LED3A reduced Pb and Zn adsorption capacities onto the soil through competitive chelation of the heavy metals. The heavy metal chelating ability of LED3A was higher for Zn than for Pb. When its concentration was larger than 5 g.L-1, LED3A showed a significant effect on the competitive adsorption of Pb and Zn. In the competitive system, the effect of Pb concentration on the Zn adsorption capacity was greater than the effect of Zn concentration on the Pb adsorption capacity. LED3A weakened the effect of Pb concentration and enhanced the effect of Zn concentration. LED3A showed a significant potential for efficiently leaching remediation of Pb and Zn co-contaminated soil.

Single and competitive adsorption between Indigo Carmine and Methyl orange dyes on quaternized kapok fiber adsorbent prepared by radiation technique

Since industrial effluents contain several dye species, investigation on the competitive adsorption and selective adsorption mechanism is quite necessary. In this paper, single and competitive adsorption of Indigo Carmine (IC) and Methyl Orange (MO) dyes using methacryloxyethyltrimethyl ammonium chloride functionalized kapok fiber (DKF) were investigated. The maximum adsorption capacity of individual adsorption was 1011.3 mg/g and 1079.9 mg/g for MO and IC, respectively. However, IC has significant inhibitory effect on MO uptake but IC adsorption almost not change in binary system, which is in contrast to the reported results that competitive adsorption capacity was greatly reduced for each dye in binary system. The separation factor of IC/MO could reach 129.53 when the concentration of IC and MO equal 0.2 mol/L, indicating good selectivity toward IC. The selective adsorption mechanism between MO and IC was attributed to the displacement impact. Therefore, this work provided a potential adsorbent for selectively removing dye from industrial effluents and give a new sight to the competitive adsorption mechanism among dyes.

Feasibility study on using CO2-rich industrial waste gas replacement for shale gas exploration based on adsorption characteristics

Clean utilization of CO2-rich industrial waste gas (CO2-rich IWG) is of great significance to realize carbon neutralization. Due to the strong adsorption capacity of clay and organic matter in shale to CO2, it has a good potential for CO2-rich IWG storage and replacement. So, the feasibility of using CO2-rich IWG replacement for shale gas exploration from the perspective of adsorption was studied. A shale composite model was constructed based on the adsorption experiments, and the molecular simulation results were fitted with experiments for the model reliability. Then, the slit models of different minerals were constructed to study the adsorption mechanisms. Finally, the competitive adsorption mechanisms of different components with CH4 were revealed. The results show that the overall adsorption capacity on shale minerals are ranked as HF > CO2 > SO2 > H2S > NO2 > CH4 > CO；Hydrogen bond and electrostatic force are the main adsorption modes of HF, and electrostatic force between negatively charged atoms of gas molecule and mineral surface is the main adsorption modes of CO2, SO2 and H2S. That of NO2, CH4 and CO is the weak van der Waals force. In the competition with CH4, the absolute adsorption capacity of gas decreases, but the relative adsorption capacity increases. The relative adsorption capacities of HF, CO2, H2S and SO2 increase by 35, 26, 15 and 12 times, respectively. During competitive adsorption, negatively charged atoms in HF, CO2, H2S and SO2 are more likely to bind with free cations on the surface of illite and smectite, and generate electrostatic repulsion for C atoms in CH4, leading to the weakening or even disappearance of CH4 adsorption capacity.

From normal crosslinking to core–shell structure: Improved performance of β-cyclodextrin based adsorbent toward efficient separation of acetophenone and 1-phenylethanol

To efficiently separate acetophenone (AP) and 1-phenyethanol (PE) from petrochemical by-product, we herein report a novel feasible strategy to fabricate β-cyclodextrin (β-CD) based core–shell microsphere, which retains the cage-type crystal structure of β-CD and superior affinity to AP over PE. Using triphenylmethane-4,4′,4′'-triisocyanate (TTI) as monomer, the polymeric TTI shell can grow in-situ on the surface of β-CD particles, giving the core–shell structured CD@PTTI. The unique β-CD core and polymeric TTI shell structure was verified by a series of characterization methods. CD@PTTI-3 exhibits both high AP uptake (ca. 2.07 mmol·g−1) and AP/PE selectivity (ca. 7.2), outperforming the conventional TTI cross-linked amorphous β-CD polymer (TTI-CDP). The adsorption behavior of CD@PTTI-3 on AP and PE single-component solutions was investigated by batch adsorption experiments. Based on the experimental and theoretical results, a mechanism of competitive adsorption of AP and PE on CD@PTTI-3 involving host–guest inclusion, hydrogen bonding and π-π stacking is proposed. Furthermore, intense competition between AP and PE on CD@PTTI-3 was observed in column breakthrough experiments, and CD@PTTI-3 could purify AP from 77.16% to 93.6% by a single adsorption–desorption process.

Competitive adsorption mechanism of thiophene with diethyl sulfide in Y zeolite: Displacement and migration

In order to study the competitive adsorption relationship between sulfides in the adsorption desulfurization (ADS) process, as the loads increase gradually to saturation adsorption, the competitive adsorption mechanism of thiophene /diethyl sulfide on the all-silicon Y zeolite was investigated by GCMC simulation for the first time. A two-stage loads dependence adsorption mechanism was acquired which can be named ‘‘optimization-displacement adsorption” and “relocation-displacement adsorption” with an inflection point of 36 molecule/UC. At the ‘‘optimization-displacement adsorption” stage, both thiophene and diethyl sulfide molecules could occupy the optimization adsorption site ideally in the initial phase and the thiophene molecules on the S sites (refers to other sites except for W sites in the supercages) would be displaced by the diethyl sulfide ones and migrated to the W (refers to the 12-members ring connecting the supercages site) when the total loads approached the inflection point. At “relocation-displacement adsorption”, the thiophene molecules on the S site would be displaced by the diethyl sulfide ones and migrated to the W sites sequentially. Meanwhile, more and more proportions of the latter diethyl sulfide molecules are adsorbed away from the center of the supercage. This transformation of the competitive adsorption mechanism was proved to be related to the interaction energy. Besides, three more realistic factors on the adsorption behavior were investigated respectively. It was concluded that high temperature is conducive to enhancing the selectivity of thiophene adsorption, but lower temperature can remove the sulfide more completely. Cations may improve the selectivity of sulfide ether. Besides, mercaptan has a great effect on the adsorption of other sulfides.

Surfactant chemistry and polymer choice affect single-wall carbon nanotube extraction conditions in aqueous two-polymer phase extraction

Quantitative determination of the effects of surfactant chemistry and polymer chain length on the concentration conditions necessary to yield extraction of specific single-wall carbon nanotube (SWCNT) species in an aqueous two-polymer phase extraction (ATPE) separation are reported. In particular, the effects of polyethylene glycol (PEG) chain length, surfactant ratios, and systematic structural variations of alkyl surfactants and bile salts on the surfactant ratios necessary for extraction were investigated using a recently reported fluorescence-based method. Alkyl surfactant tail length was observed to strongly affect the amount of surfactant necessary to cause PEG-phase extraction of nanotube species in ATPE, while variation in the anionic sulfate/sulfonate head group chemistry has less impact on the concentration necessary for extraction. Substitution of different bile salts results in different surfactant packings on the SWCNTs, with substitution greatly affecting the alkyl surfactant concentrations required for (n,m) extraction. Finally, distinct alkyl-to-bile surfactant ratios were found to extract specific (n,m) SWCNTs across the whole effective window of absolute concentrations, supporting the hypothesized competitive adsorption mechanism model of SWCNT sorting. Altogether, these results provide valuable insights into the underlying mechanisms behind ATPE-based SWCNT separations, towards further development and optimization of the ATPE method for SWCNT chirality and handedness sorting.

Competitive adsorption characteristics based on partial pressure and adsorption mechanism of CO2/CH4 mixture in shale pores

• Gas partial pressure is the decisive factor under certain temperature and pore size. • Each adsorption layer of mixture gas can be explained by monolayer adsorption theory. • Appropriate timing and amount of CO 2 injection were proposed for CS-EGR technology. In the context that CS-EGR technology has received more and more attention, molecular dynamics simulation method was used to analyze the competitive adsorption characteristics and mechanism of CO 2 /CH 4 mixture in graphene-MMT heterogeneous surface pores. In the case of certain temperature and pore size, the gas partial pressure of mixture is found to be the decisive factor of the competitive adsorption behavior. It’s better to describe the competitive adsorption behavior by gas partial pressure. Langmuir equation was applied to fitting adsorption isotherm in the first adsorption layer and the second adsorption layer. The good fitting results indicate that although the competitive adsorption mechanism of CO 2 /CH 4 mixture can’t be considered as monolayer adsorption due to the existence of multiple adsorption layers, each adsorption layer can be explained by Langmuir adsorption theory. To enhance the CH 4 recovery and CO 2 storage, the appropriate timing and amount of CO 2 injection were proposed. The pressure should be reduced to as low as possible in the first pressure drawdown process, because the first pressure drawdown is obviously beneficial to CH 4 production. The Ratio should be controlled not to exceed 1.11 ∼ 1.21 when injecting CO 2 . The operation recommendations can effectively enhance the shale gas recovery and CO 2 storage and may help to optimize the design of CS-EGR technology.

Coal-CH4/CO2 high-low orbit adsorption characteristics based on molecular simulation

To study the competitive adsorption mechanism of CH4 and CO2, the structural parameters of Tianchi coal were obtained through proximate and ultimate, X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (13C NMR). Then the Tianchi coal molecular structure model was established. Finally, the adsorption of CH4 and CO2 was simulated using Materials Studio (MS). The results show that: (1) The lone electron pairs on the O atoms in CO2 molecules lead to the adsorption to be dominated by electrostatic force. In addition, hydrogen bonds that can increase adsorption are formed between coal and CO2 molecules but not between coal and CH4 molecules. (2) Due to the existence of the intermolecular interaction force, the low (L) orbit is greatly affected by the repulsive force, and the high (H) orbit is less affected by the gravitational force. Therefore, the adsorption mainly occurs in the middle (M) orbit, and the adsorption sites of CO2 on the L and M orbit are more than CH4. (3) The CO2 molecule has a smaller diameter and can enter the ultrafine pores. Hence the accessible solvent pore volume and surface area obtained using CO2 as a molecular probe are greater than those obtained using CH4 molecular.

DFT insights into competitive adsorption and reaction mechanism of benzothiophene and naphthalene on Fe-doped Ni2P catalyst

The competitive adsorption and reaction mechanism of benzothiophene (BT) and naphthalene at the active sites on the Ni2P (001) surfaces were systematically explored using density function theory (DFT) calculations. In the competitive adsorption process under reaction conditions, BT was preferred to occupy the P-hollow site and Ni-top site, while naphthalene was preferentially adsorbed at the Ni-hollow site on the Ni(I) structure surface. Fe atom doped was beneficial to improve the adsorption ability of probe molecules, in which the Ni-top site exhibited the highest adsorption ability for BT during competitive adsorption. In addition, the dominant reaction pathway of BT was HYD with the preferential cleavage route of the aryl C4-S bond, and the naphthalene tended to form tetralin and further saturated products through hydrogenation on the Ni(I) structure surface. Notably, the energy barrier for the C-S bond scission of BT, which was the rate control step, was significantly reduced after Fe atom doped on the Ni(I) structure surface (1.28 eV vs 1.05 eV). Meanwhile, the energy barrier for the cycloalkyl C–C bond scission of tetralin was also obviously decreased on the Fe-Ni(I) structure surface (2.02 eV vs 1.65 eV). Overall, Fe atom doped on the Ni(I) structure surface was of great significance to further improve the hydrogenation reactions activity and the selectivity of ring-opening products.

Review on the kerogen deformation mechanism

Shale gas is unconventional natural gas energy stored in shale, and is one of the important substitutes for conventional oil and gas resources. Since amorphous kerogen is the main component of shale organic matter and has a high degree of deformation ability, it is a key factor to improve shale gas recovery. As an emerging mining technology CS-EGR, the CO2 injection method replaces the hydraulic pressure method, thereby alleviating the greenhouse effect and energy crisis. The basic understanding of the microscopic mechanism of the multicomponent competitive adsorption and diffusion of the adsorbate in kerogen will provide a theoretical basis and guidance for further understanding of kerogen deformation and further CS-EGR. Starting from the summary of experimental research, this paper systematically summarizes the kerogen model used for kerogen deformation research and discusses the effects of adsorbate, load, moisture, temperature, pressure, and geological depth on different kerogen structures of different maturity. The effect of kerogen deformation.

Failure analysis of anion synergy on pitting behavior of liner 316L in sour water system by electrochemical tests

Electrochemical tests were employed to study the chloride, sulfate and carbonate ions synergistically effects on pitting. The results showed that SO42- increased the pitting potential of 316L at first and then decreased, peaking at 0.2 M. In this case, the highest critical pitting temperature (12 °C), the breakdown potential (0.45 VSCE), and the maximum impedance (257 kΩ cm2) were obtained. The existing CO32– raised the pitting potential but accelerated the general corrosion of 316L surface. The effective adsorption area based on the competitive adsorption mechanism of the anions was proposed to interpret the pitting and the passivation behaviors of 316L, and the properties of the passive film were comprehensive analyzed.

Mechanistic insights into the simultaneous removal of As(V) and Cr(VI) oxyanions by a novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite: A combined experimental and density functional theory study

A novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite (c-PMB/MnO2) was synthesized and used for the removal of As(V) and Cr(VI) from aqueous solutions. The experimental results indicated that the adsorption affinity order of c-PMB/MnO2 in the single-component system was As(V) (0.414 mmol/g) < Cr(VI) (0.421 mmol/g), whereas it was reversed in the binary-component system as As(V) (0.446 mmol/g) ≫ Cr(VI) (0.185 mmol/g), which were more pronounced in sequential adsorption systems. XPS results revealed that all components of c-PMB/MnO2 (i.e., Fe3O4, MnO2, and biochar) contributed to As(V) and Cr(VI) adsorption, while the selective reduction of adsorbed Cr(VI) to Cr(III) occurred via the redox reaction between Fe3O4 and Cr(VI). Density functional theory calculations further indicated that As(V) and Cr(VI) compete for the available binding sites in binary-component system, although the presence of reduced Cr(III) as a majority species serves as a strong binding site for As(V) via the formation of covalent bonding between Cr(III) and the O atom in As(V) with binding energies of − 123.1 and − 125.6 kcal/mol, thereby enhancing competitive As(V) adsorption in binary-component and sequential adsorption systems. These results may provide important information to better understand the competitive adsorption mechanisms for the simultaneous removal of As(V) and Cr(VI) in water.

Adsorption/desorption of naphthalene and phenanthrene in a binary competitive system in the riparian zone

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and phenanthrene (Phe) are organic pollutants that are of concern because of their environmental toxicity. Adsorption is a promising process for the removal of Nap and Phe from water and soil. The riparian zone between a river and a riparian aquifer, which is rich in adsorption medium, may be important for PAH remediation. Nap and Phe may be removed from the surface water through adsorption by the media in the riparian zone. However, there is still a lack of the removal patterns and mechanisms of media in the riparian zone to remediate water contaminated by Nap and Phe simultaneously. In this study, focusing on the typical PAHs (Nap and Phe) as target pollutants, batch static adsorption and desorption experiments of Nap and Phe were carried out to explore the competitive adsorption mechanisms of Nap and Phe in the binary system. Batch dynamic adsorption experiments were conducted to ascertain the adsorption regulation of Nap and Phe in sediments during the recharge of groundwater by river water in a riparian zone. The static adsorption experiment results showed that competitive adsorption of Nap and Phe occurred, and a mutual inhibitory effect of Nap and Phe adsorption was observed in the binary system. Phe had a stronger inhibitory effect on Nap, Phe was preferentially adsorbed on the medium in binary adsorption. The results of batch dynamic experiments showed that, in terms of adsorption, the riparian zone in the study area showed stronger performance for removal of Phe than Nap. The results of this paper could be useful for alleviating Nap and Phe pollution of groundwater and developing treatment protocols for groundwater exposed to Nap and Phe.

Roles of Nanostructured Bimetallic Supported on Alumina-Zeolite (AZ) in Light Cycle Oil (LCO) Upgrading

Light cycle oil (LCO) is one of the major products in Fluid catalytic cracking (FCC) processes, and has drawbacks such as high aromatics, sulfur, and nitrogen contents, and low cetane number (CN). Hydro-upgrading is one of the most typical processes for LCO upgrading, and alumina-zeolite (AZ) is an effective hydrotreating catalyst support. This paper examined the effects of different bimetallic catalysts (CoMo/AZ, NiMo/AZ, and NiW/AZ) supported by AZ on hydro-upgrading of both model compounds and real LCO. CoMo/AZ preferred the direct desulfurization (DDS) route while the NiMo/AZ and NiW/AZ catalysts favored the desulfurization route through hydrogenation (HYD). The presence of nitrogen compounds in the feed introduced a competitive adsorption mechanism and reduced the number of available acid sites. Aromatics were partially hydrogenated into methyltetralines at first, and then further hydrogenated, cracked, and isomerized into methyldecalins, monocyclic, and methyltetralines isomers. CoMo/AZ is the best hydrodesulfurization (HDS) catalyst for the model compounds at low H2 pressure (550 psi) and for LCO at lower temperature (573 K), while NiMo/AZ performs the best for LCO at higher temperature (648 K). NiMo/AZ is the best hydrodenitrogenation (HDN) catalyst for LCO. The hydrodearomatization (HDA) performances of NiMo/AZ and NiW/AZ improved significantly and overwhelmingly higher than that of the CoMo/AZ when the H2 pressure was increased to 1100 psi.