1,721,094 research outputs found
Solubility of benzene in copolymer aqueous solutions for the design of gas absorption unit operations
No full textIn this work, an amphiphilic block copolymer (ABC) aqueous solution is proposed as innovative green liquid for benzene recovery from polluted gas. This ABC has been selected among four commercially available copolymers, two thermosensitive ABC containing poly-ethylene oxide and poly-propylene oxide blocks-Pluronic (R) L62 and Pluronic (R) P123 - one non-thermosensitive ABC - poly(vinyl pyrrolidone)-polystyrene (PVP-PS) and one non-ionic surfactant - polyoxyethylene sorbitol monooleate (Tween 80 (R)). For each copolymer aqueous solution, benzene Henry's constant (H) has been experimentally calculated and the effects of temperature (4-90 degrees C) and copolymer concentration (4-20%) have been investigated. Experimental results at 20 degrees C and 4% copolymer concentration showed that the H values are in the range 50-280 atm, with a ranking PVP-PS 1100 atm) has been measured in P123 aqueous solution at 90 degrees C, corresponding to its critical point (i.e. phase separation and no micelles presence). As a result of its benzene H values, the P123 aqueous solution was found to be the most promising liquid for benzene recovery among those investigated, being effective for both operations of gas absorption (at low temperature) and solvent regeneration by thermal stripping (at high temperature)
Desorption of arsenic from exhaust activated carbons used for water purification
No full textThis work aims to the analysis of arsenic desorption from an exhaust activated carbon used for the purification of a natural water. This last was used to mimic the properties of common groundwater or drinking water. Different low-cost and harmless eluting solutions were considered, including distilled water, natural water, saline (NaCl, CaCl2 and NaNO3) and basic (NaOH) solutions. Experimental results showed that, for 1 g of activated carbon with arsenic loading close to the maximum value available for the model natural water (omega approximate to 0.1 mg/g), it is possible to recover more than 80% of the arsenic using 20 ml of 0.1 M sodium chloride solution. A temperature variation within 20 and 40 degrees C has scarce effect on desorption efficiency. A comparison between desorption data and adsorption isotherms data suggests that arsenic adsorption is actually a reversible process. Therefore, it is virtually possible to increase arsenic recovery efficiency close to 100% by increasing the NaCl concentration or the volume of the desorption solution, but a preliminary cost benefit analysis lead to consider a NaCl 0.1 M solution as an optimal solution for practical application
Theoretical investigation of the solubility of some antiemetic drugs
No full textA theoretical study using density functional theory (DFT) is carried out to compare and explain the observed solubility of four antiemetic molecules, namely chlorpromazine, haloperidol, ondansetron and metoclopramide.The COSMO-RS (conductor-like screening model for real solvents) method is used to study the interaction between hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) of the antiemetic drugs, and their molecular interactions with water (dipole moments, interaction and solvation energies). In addition, the AIM (Atoms in Molecules) method is used to deeply study the hydrogen bonding interaction of the antiemetic drug which was found the most soluble in water, namely the metoclopramide. In fact, results show that atom O42 makes two H-bonds with two different water-oxygen atoms (BCP59 and BCP60). One of them, have another H-bond (BCP62) with the hydrogen H27. This study confirms that two of the three H-bonds with water are more stable than the intramolecular interaction between O9 and H27 (BCP1). These H-bonds are likely responsible of the highest solubility of metoclopramide
Experimental study on single and competitive adsorption of benzene and toluene from model groundwater
No full textOn the effect of the coal ash pre-treatment as a mean to improve their sorptive behaviour toward heavy metals in wastewaters
No full textMagnetite nanoparticles for removal of heavy metals from aqueous solutions: Synthesis and characterization
No full textFe3O4 magnetic nanoparticles were synthesized by co-precipitation method. The structural characterization showed an average nanoparticle size of 8 nm. The synthesized Fe3O4 nanoparticles were tested for the treatment of synthetic aqueous solutions contaminated by metal ions, i.e. Pb(II), Cu(II), Zn(II) and Mn(II). Experimental results show that the adsorption capacity of Fe3O4 nanoparticles is maximum for Pb(II) and minimum for Mn(II), likely due to a different electrostatic attraction between heavy metal cations and negatively charged adsorption sites, mainly related to the hydrated ionic radii of the investigated heavy metals. Various factors influencing the adsorption of metal ions, e.g., pH, temperature, and contacting time were investigated to optimize the operating condition for the use of Fe3O4 nanoparticles as adsorbent. The experimental results indicated that the adsorption is strongly influenced by pH and temperature, the effect depending on the different metal ion considered
Adsorption of metallic ions from aqueous solutions onto activated carbons: a descriptive model
No full textIn this work, a model for the description of metallic ions adsorption onto activated carbon is presented. The model starts from an evaluation of ion speciation and considers the presence of both the acid-basic sites and nucleophilic/electrophilic active sites on the activated carbon. Moreover, the multi-component Langmuir model is considered. The model has been used to correlate available experimental data on the adsorption of As(V), Cd(II), Cr(III) and Cr(VI) ions on activated carbon. A good matching between experimental results and model predictions has been obtained for all the investigated conditions
Cd(II) removal from aqueous solutions by adsorption onto activated carbon
No full textThis paper documents the results of an experimental study on cadmium removal from model aqueous solutions by adsorption onto a granular activated carbon (GAC). Adsorption isotherms have been carried out at different pH, salinity and temperature levels. Cadmium adsorption is the highest at neutral pH levels while it strongly decreases by decreasing pH. Due to Cd(OH)2 precipitation, the adsorption becomes irrelevant in alkaline systems. On the contrary temperature and salinity have more limited effects on cadmium capture by the GAC
Experimental and theoretical investigation of the interaction of sulfonated graphene oxide with polyvinylalcohol/poly (4-styrenesulfonic) complex
No full textThe effect of sulfonated graphene oxide (SGO) on the interaction mechanism of polyvinyl alcohol and poly (4-styrene sulfonic acid) (PVA/PSS) matrix is investigated in this paper. Pure PVA/PSS, PVA/PSS/graphene oxide (GO) and PVA/PSS/SGO nanocomposites are prepared by the freeze-thaw method. The glutaraldehyde (GLA) is used as a crosslinking agent to improve the stability of the materials. The sulfonation of GO is confirmed by the Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence spectrometry (XRF) analyses. The fully exfoliation of GO is recognized using a transmission electronic microscopy (TEM). All the nanocomposites are characterized using FTIR, UV-Vis spectroscopy and scanning electron microscopy (SEM).
A theoretical molecular simulation of the nanocomposites systems is performed to elucidate the different energies associated with the interfacial interactions. A strong interaction energy is determined due to the presence of different functional groups within the systems. The hydrogen bonding of the OH, COOH, SO3H and C-O-C groups show a EH-bond energy for the PVA/PSS/SGO system (-735.39 kcal/mol) which is higher than the corresponding of PVA/PSS/GO (-686.86 kcal/mol). The effect of the sulfonated group is more significant than that of the carboxylic group, due to both the higher polarity and higher electronegativity of the sulfonic acid group
Fixed-bed CO2 adsorption onto activated carbons impregnated with [Emim][Gly] ionic liquid
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