Adsorption Tendency Research Articles

Influence of Torrefaction Temperature and Climatic Chamber Operation Time on Hydrophobic Properties of Agri-Food Biomass Investigated Using the EMC Method

Due to the tendency for excessive moisture adsorption by raw, unprocessed biomass, various methods of biomass valorization are in use, allowing for the improvement of physical–chemical biomass properties, including hydrophobicity. One of the methods is torrefaction, which changes the hydrophilic properties of the biomass to hydrophobic. Therefore, in this study, the influence of the torrefaction temperature and the exposure time to moisture adsorption conditions on the hydrophobic properties of waste biomass from the agri-food industry (lemon peel, mandarin peel, grapefruit peel, and butternut-squash peel) were analyzed. The torrefaction was carried out at the following temperatures: 200, 220, 240, 260, 280, 300, and 320 °C. The hydrophobic properties were determined by using the EMC (Equilibrium Moisture Content) method, conducting an experiment in the climatic chamber at atmospheric pressure, a temperature of 25 °C, and relative humidity of 80%. The total residence time of the material in the climate chamber was 24 h. It was shown that the torrefaction process significantly improves the hydrophobic properties of waste biomass. Concerning dried raw (unprocessed) material, the EMC (24 h) coefficient was 0.202 ± 0.004 for lemon peels, 0.223 ± 0.001 for grapefruit peels, 0.237 ± 0.004 for mandarin peels, and 0.232 ± 0.004 for butternut squash, respectively. After the torrefaction process, the EMC value decreased by 24.14–56.96% in relation to the dried raw material, depending on the type of organic waste. However, no correlation between the improvement of hydrophobic properties and increasing the torrefaction temperature was observed. The lowest values of the EMC coefficient were determined for the temperatures of 260 °C (for lemon peel, EMC = 0.108 ± 0.001; for mandarin peel, EMC = 0.102 ± 0.001), 240 °C (for butternut-squash peel, EMC = 0.176 ± 0.002), and 220 °C (for grapefruit peel, EMC = 0.114 ± 0.008). The experiment also showed a significant logarithmic trend in the dependence of the EMC coefficient on the operating time of the climatic chamber. It suggests that there is a limit of water adsorption by the material and that a further increase of the exposure time does not change this balance.

Kinetic modeling and reaction mechanism of toluene and by-products in photocatalytic oxidation reactor

Photocatalytic oxidation (PCO) is an innovative and promising technology for removing VOCs from indoor environment. However, partial oxidation of reactants generates by-products that could be more harmful to human health than parent compound. This paper presents the development of a by-products predictive model for the estimation of generated by-products based on the degradation reaction pathway of toluene in PCO. A one-dimensional mathematical model by considering the axially dispersed plug flow and Langmuir-Hinshelwood (L-H)-based reaction rate as well as linear source spherical emission (LSSE) model for the irradiation distribution on the media surface was developed for the prediction of the by-products concentration. Toluene was tested in a continuous flow PCO reactor with a commercial PCO filter under various operating conditions; concentrations (0.05–1 ppm), relative humidities (17–67%), flow rates (10–30 L/min), and irradiance (7–23.5 W/m2). Several by-products from various chemical groups, including aldehyde, ketone, alcohol and light acid, were identified by analytical instruments. Aldehydes were the major by-products of toluene in PCO, in which light aldehydes (acetaldehyde and formaldehyde) had a higher concentration among others. The result of curve fitting using the proposed model showed a high accuracy of the model (with R-squared greater than 0.98) for parameters estimation. Kinetic analysis of toluene indicated that the rate coefficients followed the order of benzaldehyde > propionaldehyde > acetaldehyde > formaldehyde. Benzaldehyde and propionaldehyde had a greater value of the kinetic coefficient in PCO because of higher adsorption tendency towards TiO2. Changes in operating conditions highly affected generation of by-products and the developed model could predict the concentration of toluene and the by-products with acceptable accuracy. The carbon balance analysis at residence time of 0.24 s showed 16.6% of toluene mineralized into carbon dioxide and it increased at longer residence time. The health risk index (HRI) analysis of toluene and its by-products was performed and found out that formaldehyde was the most influential pollutant on HRI due to very low recommended exposure limit and higher generated concentration.

Zirconia-Intercalated Kaolinite: Synthesis, Characterization, and Evaluation of Metal-Ion Removal Activity

AbstractThe intercalation of kaolinite through the insertion of ions or molecules amongst the structural aluminosilicate layers is a vital process in numerous clay-based applications and products. Layer neutrality and hydrogen bonding limits direct intercalation into kaolinite, other than for small molecules. Synthesizing zirconia-intercalated kaolinite is not a straightforward matter. To overcome this barrier, raw Egyptian kaolin (UnK) or its acid-activated product (HK) was sonicated and impregnated in aqueous ZrOCl2·8H2O solution followed by thermal treatment at various temperatures (100, 200, 300, and 500°C). The intercalation process was confirmed using various spectroscopic and analytical techniques. The direct intercalation of ZrO2 into the kaolinite layers was observed even through a mild thermal treatment (100, 200, and 300°C). The mechanism of intercalation was suggested to occur by binding ZrO2 to the Si/AlO groups with a preference for the acid-activated HK, causing variable enlargements of the basal spacing and producing very perturbed layers. Interestingly, the surface area increased by 250% as a result of zirconia intercalation. Scanning electron microscopy (SEM) images showed a remarkable improvement in the stacking order of the kaolinite particles. The impact of ZrO2 intercalation into kaolinite also enhanced its adsorption efficiency for Pb2+, Cu2+, and Cd2+ ions. Preliminary investigations showed that the zirconia-intercalated HK demonstrated a removal efficiency, which is three times greater than that of pristine HK. The adsorption tendency toward Pb2+ ions was greater than those of Cu2+ and Cd2+ and followed the order: Pb2+ >> Cu2+ > Cd2+. The study suggests that the chemical modification of kaolin by zirconia via a direct intercalation technique, which greatly improves its functionality as demonstrated by the selective sorption of heavy metal ions, is worthy of further study.

Calotropis procera extract as an environmental friendly corrosion Inhibitor: Computational demonstrations

Plant extracts of different parts such as leaves, stem, bark, peel, flower etc. are widely utilized as environmental friendly corrosion inhibitors at the place of traditional toxic organic corrosion inhibitors. Ideally, use of aqueous extract would be preferred over organic extract as farmer one can be prepared more eco-friendly and economically than latter one. In the present investigation, corrosion inhibition potential, chemical reactivity and adsorption tendency of phytochemicals present in the Calotropis procera flower has been described with the aid of computational analyses. Literature study suggests that various phytochemicals are present in the Calotropis procera plant. Computational studies were performed on this phytochemicals to find out the most effective one. Results suggests that 4′Methyl-2 Phenylindole and 5,12-Naphthacenedione, 8-ethyl serve as the most effective inhibitors and they become effective by adsorbing on the metallic surface using their functional groups and aromatic rings. In other phytochemicals, polar functional groups and π-electrons of multiple bonds orient towards metal surface whereas long hydrophobic chains directed toward the solution side.

TiO2/CTS/ATP adsorbent modification and its application in adsorption-ultrafiltration process for dye wastewater purification.

Industrial dyeing produces highly polluting wastewater and threatens the environment. Effective treatment of dyeing wastewater is a crucial step to prevent toxic chemicals from entering receiving waters. This study aimed to assess a modified attapulgite (ATP)-based adsorbent for dyeing wastewater purification by introducing chitosan (CTS) and titanium dioxide (TiO2) into the adsorbent material named TiO2/CTS/ATP. It was found that after modification, the adsorbent showed a lower hydrophilicity, as demonstrated by an increase in the water contact angle from 9.1° to 42°, which could reduce the water adsorption tendency and potentially facilitate contaminants adherence. The modification also led to a significantly increased specific surface area of 79.111 m2/g from 3.791 m2/g and exhibited more uniform and smaller particle size (reduced from 3.99 to 2.52 μm). When the TiO2/CTS/ATP adsorbent was applied to the adsorption of Congo red solution, the adsorption efficiency was observed to reach to 97.6% at the dosage of 0.5 g/L. Furthermore, the combination of adsorption and ultrafiltration was able to achieve 99% Congo red removal. Adsorption pretreatment prior to the ultrafiltration also enabled to reduce membrane fouling, increased the reversible membrane fouling, and resulted in a considerably lower transmembrane pressure as compared with the direct ultrafiltration filtration system.

Adsorption and inhibition behavior of imidazolium tetrafluoroborate derivatives as green corrosion inhibitors for carbon steel.

The adsorption and inhibition mechanism of chain length increase and group substitution of imidazole tetrafluoroborate derivatives for the corrosion inhibition of carbon steel in HCl solution was revealed in detail via the density functional theory, molecular dynamics (MD) simulation, and quantitative structure-activity relationship (QSAR) methods. The main reactive site of an ionic liquid is located on its imidazolium ring. With alkyl chain lengthening or the introduction of methyl groups onto the imidazolium ring, its molecular reactivity and electron-donating ability increase the interaction between the ionic liquid and the Fe (110) surface. Therefore, the imidazolium rings of four IL inhibitors are more likely to lie on the Fe (110) surface in parallel through chemical adsorption. The interactions between N atoms in ionic liquids and the Fe (110) surface are stronger than those between the C atoms on the imidazolium rings of the four ionic liquid, and coordination bonds can be formed between N atoms and the Fe (110) surface. Therefore, ionic liquids can hinder the interaction between corrosion particles and the Fe (110) surface, hinder the diffusion of corrosion particles, and effectively reduce the number density of corrosion particles on the Fe (110) surface. A methyl substituent on the C2 atom of the imidazolium ring can enhance the electron-donating ability and adsorption tendency much more than an increase in the alkyl chain on the N3 atom. The four inhibitors are ordered in terms of corrosion inhibition efficiency as [C12DMIM]BF4 > [C10DMIM]BF4 > [C12MIM]BF4 > [C10MIM]BF4, which agrees well with the experimental results. A good correlation between experimental inhibition efficiency, concentration and microscopic structures parameters of ILs such as energy gap ΔE, polarizability P, electronegativity χ, hardness η, softness σ, number of electrons transferred ΔN, and electrophilicity ω was achieved.

Study of Zwitterionic Homopolymer Polysulfobetaine and Gel Properties in Various Solutions of Different Anion Species and Cation Valences

Z witterionic homopolymer polysulfobetaine (PBET) gels were synthesized using free radical polymerization. The effect of temperatures on adsorption behavior of the gel and transition temperature of the polymer in various solutions of LiCl, KCl, NaCl, Al(NO 3 ) 3 , Zn(NO 3 ) 2 , and NaNO 3 were studied. The tendency of poly(BET)s transition temperature in Cl solutions very identical. All of poly(BET) solution resulted in Upper Critical Temperature (UCST). Its number increased along with the elevation of salt concentration. The number declined again when the concentration was too high. BET gel successfully adsorbed various ions with the amount of adsorption tendency of LiCl < NaCl < KCl.

Mitigation of membrane particulate fouling by nano/microplastics via physical cleaning strategies

Membrane fouling by nano/microplastics (NP/MPs) is an emerging concern threatening the performance of water and wastewater treatment facilities. The NP/MPs can lead to surface adsorption, fouling and potential mechanical abrasion of the membranes. In this work, periodic gas scouring was applied during the filtration of nano/microplastics across ultrafiltration membranes to investigate the impact of shear forces on the adsorption of nano/microplastics. A series of surface energy and chemistry-modified membranes were also used including acrylic acid, cyclopropylamine and hexamethyldisiloxane plasma-modified membranes, allowing for a set of materials with controlled hydrophilicity, roughness and surface charge. Bubbling gas within the system at a gas flow rate of 0.5 to 1 L·min−1 and a water flow rate of 2 L·min−1 was found to limit the water flux decline across the pristine and hydrophobic membranes compared to the filtration experiments performed without cleaning from 38 to 22 and 23%, respectively. The adsorption of nano/microplastics onto the surface of the membranes was also simultaneously decreased from 40 to 25 and 19%, respectively. Interestingly, for the hydrophilised membranes no enhancement in permeance was observed when performing gas scouring due to the already low tendency for selective adsorption of the nano/microplastics onto their surface. The correlation of a dimensionless fouling number to the shear stress number suggested that the shear forces induced by gas scouring reduced nano/microplastics adsorption up to a gas injection ratio (volume fraction of gas) of 0.3, where the wall shear stress at the surface of the membrane was limited. This work offers an advanced physical strategy to reduce and control membrane fouling by nano/microplastics, with potential for this strategy to be adapted for more complex water matrices and plastic particles.

Mechanistic interaction of ciprofloxacin on zeolite modified seaweed (Sargassum crassifolium) derived biochar: Kinetics, isotherm and thermodynamics

Modification of biochar for efficient removal of antibiotics from water could be a valuable approach in the environmental applications. In this study, a brown seaweed (Sargassum crassifolium) was pyrolyzed at 500 °C and the obtained biochar (SWBC) was modified with zeolite through the slurry method maintaining the ratio at 1:5 (zeolite: biochar) (SWBC-Z). Batch adsorption experiments were conducted to evaluate the adsorption tendency of SWBC and SWBC-Z for the removal of ciprofloxacin (CPX) from water via pH edge, kinetics, isotherm and thermodynamic experiments. The highest adsorption was in the pH range of 6.5–8, supported by the electrostatic attractions and hydrogen bonding with zwitterionic CPX. Experimental kinetics data was well-fitted to the pseudo-second-order and Elovich models (R2 of 0.992 and 0.976, respectively), while the Langmuir and Freundlich isotherm models best described the isotherm data (R2 of 0.954 and 0.976, respectively). The maximum adsorption capacity of 93.65 mg g−1 was recorded for the SWBC-Z. The models predicted chemisorption and physisorption interactions on the heterogenous biochar surface. Well-defined peaks of silanol groups in the FTIR spectrum of SWBC-Z and its electron microscopy confirmed the incorporation of zeolite minerals. Post adsorption FTIR analysis elucidated the changes in the surface functional groups of the SWBC-Z. Thermodynamic data revealed spontaneous and exothermic reaction between CPX and both the biochars. It was concluded that modification of pristine biochar with zeolite imparted greater surface area and additional active sites, which subsequently enhanced the overall CPX adsorption by the SWBC-Z.

Molecular dynamics investigation of membrane fouling in organic solvents

Membrane fouling, which is a key obstacle in implementing membrane technology, has been studied extensively for aqueous feeds. With increasing interests in organic solvent applications, a corresponding effort on understanding membrane fouling is warranted. This study employs molecular dynamics simulations to unveil the mechanisms underlying the different adsorption behaviors of dextran onto a polyacrylonitrile (PAN) membrane in three polar and protic solvents, namely, water, formamide and ethanol. The dextran-membrane separation distance is the lowest for water, followed by ethanol then formamide, which agrees with the worse flux decline for water relative to formamide observed experimentally. The greatest adsorption tendency in water is tied to the most attractive dextran-membrane interaction. On the other hand, the lower adsorption tendency in formamide and ethanol is linked to enhanced solvation of the dextran molecule and membrane, which deters dextran adsorption onto the membrane. Specifically, formamide, which leads to the least adsorption, exhibits the most attractive solvent-dextran and solvent-membrane interaction energies, the highest solvent-accessible surface area (SASA) for dextran, and also the highest density of solvent molecules in the solvation shell closest to the membrane. As for ethanol, it gives the highest density of solvent molecules in the solvation shell closest to a part of the dextran. The solvation of foulant and membrane by water deviates from that by other similarly polar and protic solvents, which has important implications in membrane fouling and highlights the need for enhancing the understanding of membrane fouling behaviors in organic solvents.

Optimization and Computational Approach to Understand the Adsorption Behavior of Alizarine Red S on the Surface of Fish Scales

The key components of fish scales are hydroxyapatite and collagen, which form a natural composite. In this present study, fish scales were used as biosorbent to uptake Alizarine Red S dyes from the wastewaters. Here, dye concentration, adsorbent amount, pH, and temperature were optimized using complete factorial design analysis. Sixteen experiments were required, and a linear mathematical model representing the influence of the different variables and their interactions was obtained. The discussion covered analysis of variance (ANOVA), normal probability plots of residuals, and surface plots. Theoretical calculations by Metropolis Monte Carlo (MC) methods, the density functional theory (DFT), and the electrostatic potential surface (ESP) analysis were achieved to obtain a more understanding of the dyes adsorption mechanism on both collagen and hydroxyapatite (HDA) surfaces. The findings results exhibited that the ARS dye presents more tendency of adsorption on the collagen than on the HDA surface.

Biocompatible MIP-202 Zr-MOF tunable sorbent for cost-effective decontamination of anionic and cationic pollutants from waste solutions

This reported work aims to fabricate an eco-friendly Zr bio-based MOF and assessment its adsorption efficiency towards the cationic and anionic dye pollutants including methylene blue (MB) and direct red 81 (DR-81), respectively. Also, its adsorption tendency for the highly toxic heavy metal of hexavalent chromium (Cr(VI)) was compared with dyes. The adsorption performance of bio-MOF showed that the maximum monolayer adsorption capacities were recorded as 79.799 mg/g for MB, 36.071 mg/g for DR-81, and 19.012 mg/g for Cr(VI). Meanwhile, the optimum dosage of as-synthesized MIP-202 bio-MOF was 0.5, 1, and 2 g L−1 for MB, DR-81, and Cr(VI), respectively. Thermodynamic analysis demonstrated the spontaneous, thermodynamically, and endothermic nature of the decontamination processes onto the fabricated Zr bio-based MOF. The adsorption data were fitted by Langmuir isotherm model compared with Freundlich and Temkin models for all studied water pollutants. Pseudo-second-order kinetic model was a fit model for description of the adsorption kinetics of the different cationic and anionic pollutants onto Zr bio-based MOF. These outcomes indicated that Zr bio-based MOF has potential application for adsorption of different types of industrial water pollutants including cationic and anionic dyes and heavy metals.

CO2 Removal Using Adsorption Onboard A Floating Production Storage and Offloading (FPSO) Vessel

Offshore operations gas purification has always been limited to the marketable associated value of the gas where purification would either be onsite or sent to surface facilities for treatment. CO2 and H2S removal and gas sweetening in remote offshore locations is for the most part non-existent and CO2 is either being released into the atmosphere, within the acceptable operation limit of the platform, or being captured using conventional techniques with physical solvents such as in the selexol, rectisol, or sulfinol processes. Approximately 429.61 kg of CO2 exists in a 42-gallon barrel of distillate fuel oil and a CO2 coefficient of 0.0549 kg exists in 1 cubic foot of gas thereby emphasizing the need for an engineering solution on floating production storage and offloading (FPSO) units [1]. With strict regulation on greenhouse gases, it is increasingly paramount to utilize engineering measures to provide a contingency plan in mitigating carbon footprint with emerging novel technologies. The purpose of this study is to retrofit an existing FPSO with a CO2 capture plant; the efficiency of the capture plant, its capture capacity, and energy requirement based on experimental data will be thoroughly investigated during the scale up procedure. The research proceedings will require the use of a plethora of simulation suites which include Autodesk Fusion 360 for plant design. Further simulation will be carried out with numerical suites using Mathcad Prime 3.0 to study the scale up procedure from experimental to industrial sized adsorption unit complete with dimensions, energy requirement, capture capacity, and thermal values. The FPSO in figure 1 above presented by (Araujo et al., 2016) indicates the availability of a capture plant as part of the process train on an FPSO. Efficiency loss contribution to the system may be deduced but also it is relevant to note the custom nature of the FPSO design being independent in its operation mode compared to other profiles. The availability of the stage compressors, dehydration units, and steam generation plant as part of the FPSO operation aid in minimising the need for additional equipment for the adsorption plant, however investigation has to be made on the redirecting of processes to serve the additional components highlighted above. Primary results have shown a low tendency for dual adsorption from the initial kinetic stoichiometric balance which could also be due to the force field parameters and charges affecting the active sites. For the current concept the fixed bed experimental model from the Research and Innovation Centre on CO2 and H2 is scaled up numerically to a fixed bed height of 6.56 feet, and filled with precipitated silica impregnated with PEI solution pressurized with CO2 inflow rated at 13 lb/hr at a fixed 1.2 Bar 60°C. The operational nature of the FPSO will be modified to account for the changes requested in gas sweetening and capture programs or enhanced oil recovery. Results from the simulation will also assist in providing a tangible and relatable understanding to the complexity of solid sorption technology integration within existing processing plants. The findings of this study will help comprehend the viability of an integrated adsorption plant within an existing process train. The efficiency of the plant operation for an oil production offshore facility with associated gas or for a standalone gas field will be addressed using a feasibility study conducted for the purpose of sustainable offshore operations.

Alkanolamines as activators in no-clean flux systems: investigation of humidity robustness and solderability

This paper systematically investigates the humidity robustness and solderability of five alkanolamines used as activators in flux systems, and their effect was assessed along with the influence of soldering temperature. Electrochemical impedance spectroscopy and chronoamperometry techniques were used to obtain a better understanding of water adsorption, absorption, and protonation tendencies of alkanolamine candidates. Potentiodynamic polarization, hot plate spreading test, and wetting balance test were adapted for the etching ability and solderability evaluation. Thermal degradation of alkanolamine compounds was analyzed using thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FT-IR). The combined results indicate a strong water absorption and protonation of diethanolamine (DEA), triethanolamine (TEA), and triisopropanolamine (TIPA), rendering them not reliable and not feasible as activators. Poor solderability of alkanolamine-based fluxes was inferred based on their thermal degradation behavior and poor oxide removal ability under the soldering conditions.

Role of rare earth elements on the improvement of corrosion resistance of micro-alloyed steels in 3.5 wt.% NaCl solution

The effects of rare earth (RE) addition on the corrosion behavior of micro-alloyed steels in 3.5 wt.% NaCl solution were investigated elaborately through electrochemical tests and material characterization analyses. Results showed that the corrosion rate decreased after addition of RE elements. The RE elements did not alter the pitting nucleation mechanism, while the sensitivity of pitting propagation was reduced by decreasing the pitting density and pitting depth. In the long-term corrosion, preferential precipitation of RE corrosion products promoted the formation of protective rust layers and accelerated the co-deposition of these layers, which probably be favorable for the formation of compact rust layers. Moreover, the RE addition reduced the surface electrochemical activity and the adsorption tendency of Cl− on the metal surface. As a consequence, the resistance of electrochemical reactions (represented by Rp values in EIS tests) increased, resulting in a decrease of corrosion rate by RE addition.

Spatial variability in heavy metal concentration in urban pavement joints – a case study

Abstract. Heavy metals are known to be among one of the major environmental pollutants, especially in urban areas, and, as generally known, can pose environmental risks and direct risks to humans. This study deals with the spatial distribution of heavy metals in different pavement joints in the inner city area of Marburg (Hesse, Germany). Pavement joints, defined as the joint between paving stones and filled with different materials, have so far hardly been considered as anthropogenic materials and potential pollution sources in urban areas. Nevertheless, they have an important role as possible sites of infiltration for surface run-off accumulation areas and are therefore a key feature of urban water regimes. In order to investigate the spatial variability in heavy metals in pavement joints, a geospatial sampling approach was carried out on six inner city sampling sites, followed by heavy metal analyses via inductively coupled plasma–mass spectrometry (ICP–MS) and additional pH and organic matter analyses. A first risk assessment of heavy metal pollution from pavement joints was performed. Pavement joints examined consist mainly of basaltic gravel, sands, organic material and anthropogenic artefacts (e.g. glass and plastics), with an average joint size of 0.89 cm and a vertical depth of 2–10 cm. In general, the pavement joint material shows high organic matter loads (average 11.0 % by mass) and neutral to alkaline pH values. Besides high Al and Fe content, the heavy metals Cr, Ni, Cd and Pb are mainly responsible for the contamination of pavement joints. The identified spatial pattern of maximum heavy metal loads in pavement joints could not be attributed solely to traffic emissions, as commonly reported for urban areas. Higher concentrations were detected at run-off accumulation areas (e.g. drainage gutters) and at the lowest sampling points with high drainage accumulation tendencies. Additional Spearman correlation analyses show a clear positive correlation between the run-off accumulation value and calculated exposure factor (ExF; Spearman correlation coefficients (rSP) – 0.80; p<0.00). Further correlation analyses revealed different accumulation and mobility tendencies of heavy metals in pavement joints. Based on sorption processes with humic substances and an overall alkaline pH milieu, especially Cu, Cd and Pb showed a low potential mobility and strong adsorption tendency, which could lead to an accumulation and fixation of heavy metals in pavement joints. The presence of heavy metals in pavement joints poses a direct risk for urban environments and may also affect environments out of urban areas if drainage transports accumulated heavy metals. Finally, we encourage further research to give more attention to this special field of urban anthropogenic materials and potential risks for urban environments. Overall urban geochemical background values, and the consideration of run-off-related transport processes on pavements, are needed to develop effective management strategies of urban pavement soil pollution.

Removal of methylene blue and rose bengal dyes from aqueous solutions using 1-naphthylammonium tetrachloroferrate (III)

In this work, an ionic liquid (IL), 1-naphthylammonium tetrachloroferrate (III), was synthesized and characterized using different characterization techniques. The IL existed as solid at room temperature and hence it was explored as an adsorbent for the removal of methylene blue (MB) and rose bengal (RB) dyes from aqueous solutions. The adsorption capacity of the adsorbent at equilibrium was found to be 6.443 mg/g for MB and 20.70 mg/g for RB. Furthermore, the adsorption isotherms were fitted into Langmuir isotherm model indicating that the two dyes were homogenously adsorbed on the surface of the material and the adsorption kinetics followed pseudo-second-order kinetic model with R2 value above 0.99. In addition, density functional theory (DFT) calculation confirmed the experimental findings showing energy gap (ΔE) of 3.572 eV and 4.084 eV for MB and RB respectively, and after complexation, a shift of 1.261 eV was observed in MB compared to 0.484 eV in RB in basic medium, indicating higher tendency of MB adsorption. The adsorption energies exhibited a greater affinity for MB with 13.2 kcal/mol, while RB in acidic condition with a value of 20.2 kcal/mol and 2.806 Å binding distances for RB which is lower than the Van der Waals radii, 2.990 Å showing Lewis acid-base interaction.

Amorphous mesoporous matrix from metal-organic framework UiO-66 template with strong nucleophile substitution

The metal-organic framework (MOF) UiO-66 is made of zirconium clusters coordinated with 1,4-benzenedicarboxylate linkers that is stable in water and is highly tolerant to extremely acidic or basic environments. Conversely, the zirconium clusters are affine to nucleophiles so the crystalline structures of UiO-66 can be converted into amorphous derivatives. In a mineral acid solution both protons and coordinating nucleophile are present. This study for the first time revealed that it is the strong nucleophile instead of proton deteriorate the crystalline structures of UiO-66. Also, the so-produced amorphous mesoporous matrix, if not totally dissolved, can be applied as an efficient adsorbent. The noted adsorption capabilities of Cu(II) and nucleophiles by these amorphous mesoporous matrix did not correlate with the structural crystallinity or the internal surface area; conversely, the doped nucleophiles were noted to contribute to the adsorption tendencies towards Cu(II) and phosphate species via electrostatic interactions and hydrogen bonding, respectively. Conversion of sacrificing UiO-66 template to amorphous matrix can be applied as an effective way to fabricate specific adsorbent with resistance to extreme pH and strong nucleophile challenges.

Comparative analysis of TiO2 and Ag nanoparticles on xylan/chitosan conjugate matrix for wound healing application

Our present study evaluates the performance of wound dressing material fabricated by incorporating silver(Ag) and titanium dioxide(TiO2) nanoparticles(NPs) in xylan/chitosan-based conjugate matrix. The porous nanocomposites were examined for antimicrobial, cell attachment, swelling, protein adsorption, and cytotoxic studies. Nanocomposites exhibited potent antimicrobial response against both gram-negative and gram-positive strains of bacteria. Despite remarkable cellular response, a concentration-dependent cytotoxicity was observed in matrix with high Ag NPs content. Nanoparticles incorporated composites also tuned the pore size, swelling ratio, and protein adsorption tendency of scaffold making them feasible as wound dressing material.

Molecular dynamic simulation and experimental study of wettability alteration by hydrolyzed polyacrylamide for enhanced oil recovery: A new finding for polymer flooding process

Polymer flooding by hydrolyzed polyacrylamide (HPAM) is a well-known enhanced oil recovery (EOR) technique which is mainly applied to viscosify the pushing fluid and improve the mobility ratio; however, the role of this polymer on the rock wettability alteration, one of three main recovery mechanisms, has remained a topic of debate. In this study, the adsorption of hydrolyzed-polyacrylamide on the carbonate surface was investigated by molecular dynamic simulation considering a simple Young model based on the surface tensions of each phase to calculate the water contact angle and then continued by an experimental procedure after aging carbonate slices in the oil and polymer solutions. Dreiding and Universal force fields were selected for the simulation of water and HPAM boxes, respectively, to calculate non-bonding/bonding energies and surface tension for the water, polymer, and three-phase system including calcite rock. The polymer adsorbing decreased the final water contact angle to about 130 and 140° at the ambient and reservoir temperatures, respectively, to provide a moderately oil-wet state and a good agreement with the experimental results for the surface wettability alteration toward the water wetting. However, the theory and laboratory observations showed a different relation between the polymer adsorption and increasing temperature. Lennard-Jones potentials showed the polymer surface desorption at the increased kinetic energy of molecules due to the molecular distance whereas in the experiment condition the tendency of polymer adsorption on the calcite surface increased with temperature, probably because of ion exchange and thermal decarboxylation phenomenon. These findings make an opportunity to further molecular dynamic investigations of different polymers as a wettability modifier through the EOR process.