Adsorption Capacity Of Salicylic Acid Research Articles

Adsorption of Pharmaceutical Aromatic Pollutants on Heat-Treated Activated Carbons: Effect of Carbonaceous Structure and the Adsorbent-Adsorbate Interactions.

Drugs are considered emerging pollutants from water sources and are therefore considered to be of high toxicological risk to aquatic fauna. Activated carbon adsorption is one of the methods approved by the Word Health Organization to remove pharmaceutical compounds from water in treatment plants due to its cost and easy implementation. This study presents the modification of a commercial activated carbon by heat treatment at 1073, 1173, and 1273 K. The impact of the physicochemical changes of the adsorbent on the adsorption capacity of salicylic acid and methylparaben, compounds derived from phenol, was studied. Finally, the adsorbate–adsorbent interactions are evaluated through immersion calorimetry. It is observed that at 1173 K, activated carbon increases its surface area by 29%. At higher temperatures, the surface area drops to 21%. In the activated carbon subjected to heat treatment at 1173 K, it increases the adsorption capacity of salicylic acid and methylparaben by 24 and 34%, respectively, compared to activated carbons subjected to higher temperatures. The interaction enthalpies (adsorbate–adsorbent interaction) have values between −12 and 5 J g–1.

Preparation of Ethylene Glycol Dimethacrylate (EGDMA)-Based Terpolymer as Potential Sorbents for Pharmaceuticals Adsorption.

Ethylene glycol dimethacrylate (EGDMA) is used as a crosslinker in poly(acrylonitrile (AN)-co-vinylbenzyl chloride (VBC)) to investigate the effect of long-chain crosslinker to the porosity of the terpolymer system. Poly(AN-co-EGDMA-co-VBC) is synthesized by using precipitation polymerization method and further hypercrosslinked by Friedel-Crafts reaction. FT-IR spectra of poly(AN-co-EGDMA-co-VBC) show that the absorption bands at ~1290 cm−1 that are assigned to the C–Cl vibrations are almost disappeared in hypercrosslinked (HXL) poly(AN-co-EGDMA-co-VBC) polymers, confirming that the hypercrosslinking reaction is successful. SEM images show that the morphologies of the polymers are retained through the hypercrosslinking reactions. Brunauer–Emmett–Teller (BET) analysis shows that hypercrosslinked polymers had a specific surface area up to 59 m2·g−1. The preliminary performance of the terpolymer adsorbent to capture polar analyte is evaluated by adsorbing salicylic acid and mefenamic acid from aqueous solution in a batch system. The maximum adsorption capacity of salicylic acid and mefenamic acid were up to 416.7 mg·g−1 and 625 mg·g−1, respectively, and the adsorption kinetic data obeyed pseudo-second-order rate equation.

Selective recognition of salicylic acid employing new fluorescent imprinted membrane functionalized with poly(amidoamine) (PAMAM)-encapsulated Eu(TTA)3phen

Selective fluorescent molecularly imprinted membrane (FMIM) for salicylic acid (SA) was successfully prepared by phase inversion technique with SA as template molecule, chitosan (CHI) as functional polymer, and Eu(TTA)3phen/PAMAM composed of Eu(TTA)3phen and the dendrimer (PAMAM) as the fluorophore, which was characterized by SEM, AFM, and XPS techniques. The introduction of the hydrophilic Eu(TTA)3phen/PAMAM into FMIM was able to improve the flux and the adsorption capacity of SA with good fluorescent stability. Among the FMIM, the FMIM2 prepared with 2.0% Eu(TTA)3phen/PAMAM in the cast membrane fluid was the optimal fluorescent imprinted membrane for selective detection of SA, which displayed a relatively wider linear range and lower limit of detection (LOD) (24 mg L−1). The imprinted FMIM2 could selectively detect the SA from complicated samples without obvious interference from analogues compared to the non-imprinted FNIM2. Moreover, the FMIM had promising recycling performance. It can be potentially used as an alternative imprinted membrane for selective detection and separation of trace SA in water.

Effects of the hydrophobicity of adsorbate on the adsorption of salicylic acid and 5-sulfosalicylic acid onto the hydrophobic-hydrophilic macroporous polydivinylbenzene/polymethylacrylethylenediamine IPN

Hydrophobic-hydrophilic macroporous polydivinylbenzene/polymethylacrylethylenediamine IPN (PDVB/PMAEM IPN) was synthesized indirectly through the strong forced compatibility. The effects of the hydrophobicity of adsorbate on the adsorption of salicylic acid and 5-sulfosalicylic acid onto the hydrophobic-hydrophilic PDVB/PMAEM IPN were investigated. PDVB/PMAEM IPN exhibited greater adsorption capacity of salicylic acid than that of 5-sulfosalicylic acid. The absolute values of ΔH, ΔG and ΔS of the adsorption of salicylic acid onto PDVB/PMAEM IPN were greater than those of 5-sulfosalicylic acid, indicating the adsorption of salicylic acid onto PDVB/PMAEM IPN was more welcome. Adsorption mechanism proved that greater adsorption capacity of salicylic acid onto PDVB/PMAEM IPN than that of 5-sulfosalicylic acid was attributed to the stronger hydrophobicity of salicylic acid.

Polar modified post-cross-linked resin and its adsorption toward salicylic acid from aqueous solution: Equilibrium, kinetics and breakthrough studies

A novel polar modified post-cross-linked resin PDMPA was synthesized, characterized and evaluated for adsorption of salicylic acid from aqueous solution. PDMPA was prepared by a suspension polymerization of methyl acrylate (MA) and divinylbenzene (DVB), a Friedel–Crafts reaction and an amination reaction. After characterization of the chemical and pore structure of PDMPA, the adsorption behaviors of salicylic acid on PDMPA were determined in comparison with the precursor resins. The equilibrium adsorption capacity of salicylic acid on PDMPA was much larger than the precursor resins and the equilibrium data were correlated by both of the Langmuir and Freundlich models. The pseudo-second-order rate equation fitted the kinetic data better than the pseudo-first-order rate equation, and the micropore diffusion model could characterize the kinetic data very well. The dynamic experimental results showed that the breakthrough point and saturated point of salicylic acid on PDMPA were 40.3 and 92.4BV (1BV=10mL) at a feed concentration of 995.8mg/L and a flow rate of 1.4mL/min, and the resin column could be regenerated by 16.0BV of a mixture desorption solvent containing 0.01mol/L of NaOH (w/v) and 50% of ethanol (v/v).

Removal of salicylic acid and carbamazepine from aqueous solution with Y-zeolites modified with extraframework transition metal and surfactant cations: Equilibrium and fixed-bed adsorption

A synthetic zeolite (Na+-Y; Si/Al∼2.8) was modified through incorporation of both a transition metal (Co2+, Ni2+ or Cu2+) and a surfactant (cetylpyridinium; CPY+) to develop adsorbents with tailored selectivity and uptake capacity for pharmaceutical and personal care products (PPCPs) present in water. Two PPCPs were targeted in this study, namely salicylic acid and carbamazepine, due to their reported recurrence in water sources. In general, the zeolite modifications increased the equilibrium salicylic acid adsorption capacities, from 0.03 up to 3.9mgg−1 in the 0.1–10ppm PPCP concentration range (pH range 6–11). The salicylic acid equilibrium adsorption capacities increased as follows: Ni2+<Na+<Co2+<Cu2+. A remarkable selectivity toward salicylic acid was evident in all cases, but the capacity for carbamazepine also varied upon modification of the zeolite. Fixed-bed adsorption studies were performed on (Cu2+, CPY+)-Y for single- and multi-component PPCP feeds at pH∼6 and ambient temperature, and indicated that the uptake was not limited by diffusion and that most of the bed depth was used efficiently. The multi-component tests revealed a ca. 55% increase in adsorption capacity for salicylic acid when compared against the single-component results.

Enhancing the photocatalytic degradation of salicylic acid by using molecular imprinted S-doped TiO2 under simulated solar light

Molecular imprinted polymer coated S-doped TiO2 (MIP/S-TiO2) nanocomposites were successfully synthesized by a surface molecular imprinting technique using p-phenylenediamine as the functional monomer and salicylic acid as the template molecule. The structure and properties of the catalysts were characterized by X-ray diffraction, scanning electron microscopy, and UV–vis diffuse reflectance spectra. Compared with TiO2 nanoparticles, the absorption edge of MIP/S-TiO2 nanocomposites was enhanced over the whole range of visible region. Moreover, MIP/S-TiO2 nanocomposites showed higher adsorption capacity for salicylic acid than for S-TiO2 nanoparticles. The rate constant for the photodegradation of salicylic acid over MIP/S-TiO2 nanocomposites was 1.7 times that of salicylic acid over S-TiO2 nanoparticles, which was attributed to the molecular recognition ability of MIP/S-TiO2 nanocomposites for the target molecules.

A novel adsorbent based on functionalized three-dimensionally ordered macroporous cross-linked polystyrene for removal of salicylic acid from aqueous solution

A novel polymeric adsorbent with three-dimensionally ordered macroporous (3DOM) structure was prepared. Poly(2-hydroxyethyl methacrylate) (PHEMA) was controllably grafted from the pore wall of 3DOM cross-linked polystyrene (3DOM CLPS-g-PHEMA) by surface-initiated atom-transfer radical polymerization (SI-ATRP) technique. Batch adsorption runs of salicylic acid from aqueous solution onto 3DOM CLPS-g-PHEMA were investigated as well as the relationship of the grafted amount with the adsorption capacity. When the grafted amount was 22.1%, the 3DOM CLPS-g-PHEMA exhibited the optimum adsorption capacity. Commercial macroporous resin XAD-4 was chosen as the comparison. Adsorption isotherm experimental results indicated that isotherms of salicylic acid adsorption onto 3DOM CLPS-g-PHEMA adsorbent could be represented by Langmuir and Freundlich models and the Freundlich model was shown to be the most suitable. The 3DOM CLPS-g-PHEMA exhibited a much higher adsorption capacity of salicylic acid than that of XAD-4, attributing to the special structure of 3DOM polymer and the grafted polymeric chains on the pore walls. The adsorption capacities increased with temperature increasing, and the isosteric enthalpy changes were calculated with a derivative Van’t Hoff equation. Kinetics studies showed that the salicylic acid uptake onto 3DOM CLPS-g-PHEMA followed the pseudo-second order model. In addition, the spent 3DOM CLPS-g-PHEMA could be regenerated by extracted with ethanol, the regenerated 3DOM CLPS-g-PHEMA also exhibited the high adsorption capacity. We envision that the novel 3DOM polymeric adsorption will play a significant role in developing a new generation adsorbent.

Synthesis, characterization and adsorption properties of diethylenetriamine-modified hypercrosslinked resins for efficient removal of salicylic acid from aqueous solution

We report an effective approach for tailoring the pore textural properties and surface polarity of a hypercrosslinked resin to enhance its adsorption capacity and selectivity for removing salicylic acid from aqueous solution. Four hypercrosslinked resins were synthesized by controlling the reaction time of the self Friedel–Crafts reaction of chloromethylated polystyrene-co-divinylbenzene, and then modified with diethylenetriamine to adjust their surface polarity. The resins were characterized with N2 adsorption for pore textural properties, Fourier transform infrared spectroscopy (FT-IR) for surface functional groups, chemical analysis for residual chlorine content and weak basic exchange capacity. Adsorption equilibrium, kinetics and breakthrough performance were determined for the removal of salicylic acid from aqueous solution on a selected resin HJ-M01. The equilibrium adsorption capacity of salicylic acid on HJ-M01 is significantly higher than that on its precursor HJ-11 and a few commercial adsorbents including AB-8, XAD-4 and XAD-7. The dynamic adsorption capacity of salicylic acid on HJ-M01 was found to be 456.4mg/L at a feed concentration of 1000mg/L and 294K. The used resin could be fully regenerated with 1% sodium hydroxide solution. The hypercrosslinked resins being developed were promising alternatives to commercial adsorbents for removing salicylic acid and other volatile organic compounds (VOCs) from aqueous solution.

Synthesis of the Water-Compatible P-Aminophenol Resin and its Adsorption for Salicylic Acid

A novel water-compatible hypercrosslinked resin modified by p-aminophenol was synthesized with chloromethylated polystyrene and p-aminophenol by Friedel-Crafts reaction. The objective of this work was to study the adsorption performances for salicylic acid onto p-aminophenol resin. The results showed that the adsorption capacity of salicylic acid onto p-aminophenol resin was superior to XAD-4 resin. It is seen that the maximum adsorption capacity is observed at pH of 3.0. It was found the adsorption dynamics obeyed the pseudo-first-order rate equation and the intra-particle diffusion was the rate-limiting step. The maximum adsorption capacity of salicylic acid for p-aminophenol resin was measured to be 283.7 mg/g with the equilibrium concentration at 404.6mg/L. The micropore structure, the pore diameter of p-aminophenol resin, the hydrogen bond between p-aminophenol resin and salicylic acid bring the larger adsorption capacity.