Adsorption Of Phenylalanine Research Articles

Modification of carbon sorbent by sequential adsorption of biologically active phenylalanine and salicylic acid

The sequential adsorption of phenylalanine and salicylic acid on a carbon sorbent was studied. The influence of modification conditions, including the sorbent/solution volume ratio, amino acid concentration, temperature and pH, on the adsorption parameters of phenylalanine, as well as the physicochemical properties of the resulting carbon sorbent sample, was established. The effect of sequential adsorption of phenylalanine and salicylic acid on the physicochemical characteristics of sorbents is shown.

Selectivity of Tryptophan and Phenylalanine Adsorption by Activated Coconut Carbon of Medical Assignment

Selectivity of Tryptophan and Phenylalanine Adsorption by Activated Coconut Carbon of Medical Assignment

Adsorption of Phenylalanine from Aqueous Solutions Using Activated Carbon from Sunflower Meal Functionalized with Sulfonic Groups.

The present work proposes the use of an agro-industrial residue from the sunflower crop as a feedstock to produce a low-cost adsorbent with a chemically modified surface bearing sulfonic groups. This modified low-cost adsorbent can be used for the removal of phenylalanine, and can also be applied in the process of obtaining a source of protein supplementation for patients with phenylketonuria. The functionalization of the adsorbent with sulfonic groups was adapted and presented advantages in terms of execution time, energy expenditure, number of reagents used and adsorbed amino acids. The produced adsorbent presented a surface area of 317.31 m2 g-1 with a predominance of micro- and mesopores, that influenced an approximate 30-fold reduction in adsorption equilibrium time. The optimization results indicated a higher adsorption capacity (39.64 mg g-1) in pH = 4; temperature of 25 °C and adsorbent dosage of 10 g L-1. The FTIR analyzes and the qualitative analysis of the elements present in the samples by EDS confirmed the introduction of sulfonic groups in the MPS500 coal. This work contributed to the understanding behind the adsorption of L-phenylalanine on charcoal surfaces functionalized with sulfonic groups, showing that they can be more selective for the adsorption of phenylalanine in a competitive system.

Selective adsorption of egg white hydrolysates onto activated carbon: Establishment of physicochemical mechanisms for removing phenylalanine

Previously, it was shown that activated carbon can remove phenylalanine from egg white hydrolysates to produce a low phenylalanine peptide ingredient that can be used by individuals suffering from phenylketonuria. However, the factors impacting the selective adsorption of phenylalanine and peptides to activated carbon is not fully understood, which is holding back the optimization of this process. In this research, two activated carbons with different morphologies and electrical characteristics were used to adsorb egg white hydrolysates with different degrees of hydrolysis. The selective adsorption behavior of the different constituents within the hydrolysates was studied to identify the nature of the adsorption mechanisms involved. The results showed that aromatic amino acids and components with higher molecular weight were preferentially adsorbed. Moreover, the main driving force for adsorption was hydrophobic attraction, followed by hydrogen bonding and electrostatic interactions. These results could facilitate the preparation of medical foods for patients with phenylketonuria.

The effect of a novel D-camphoric acid-based MOF on chiral separation

A new metal organic framework [Cu6(D-cam)8(TMDPY)4Cd2Na(OH)4] (D-cam = d-Camphoric acid, TMDPY = 4,4′-Trimethylenedipyridine, MOF 1) was synthesized for the first time under hydrothermal conditions. It has three different metal clusters that are connected by a D-cam to form a two-dimensional structure. The layers are connected by TMDPY to form a three-dimensional structure. We used this material to separate racemic phenylalanine by adsorption, indicating that it has a much higher adsorption effect on D-phe (d-phenylalanine) than L-phe (l-phenylalanine). The adsorption kinetics of the adsorption process was studied, which indicated that the adsorption of phenylalanine by MOF 1 accords with the Langmuir isotherm adsorption model. Finally, the ratio of L-phe to D-phe in the solution adsorbed by MOF 1 is about 9:1. It is further illustrated that MOF 1 has a good separation effect on phenylalanine.

Theoretical insight of alpha amino acid phenylalanine adsorption on pristine and decorated fullerenes

Abstract Fullerenes, with their extensive application potentials, have been receiving attention for their possible usage as drug delivery vehicles and devices for sensor technologies. In this work, the optimized molecular geometries, some diagnostic geometric parameters, electronic characteristics, natural bond orbital examinations and the interaction phenomena between C60, Si- or Al-doped C60 and phenylalanine amino acid molecule were investigated by the quantum mechanical calculations. It is observed that the impurity addition and using water as the solvent intensify the interaction between fullerene and amino acid system. These lead to various alterations in the electronic properties and NH stretching values of the clusters studied.

Removal of cyanobacterial amino acids in water treatment by activated carbon adsorption

Abstract The applicability of activated carbon for the adsorption of phenylalanine, arginine and aspartic acid from aqueous solution was evaluated in this study. These amino acids are plentiful in low-molecular weight algal organic matter produced by cyanobacteria, which is not satisfactorily removed by chemical coagulation. Because of this they may gravely disturb the water treatment process. Equilibrium adsorption of amino acids was studied on well-characterized activated carbons, Picabiol (PIC) and Filtrasorb (FTL), possessing different chemical and charge properties evaluated by Boehm titration. Adsorption experiments were conducted at various adsorbate initial concentrations, pH values and ionic strengths to elucidate the effect of solution properties on the amino acid removal. Distinct adsorption mechanisms were observed for individual amino acids depending on the pH and the type of carbon applied. Electrostatic interactions between functional groups of the adsorbents and arginine were deemed the predominant adsorption mechanism. The maximum arginine uptake was achieved through electrostatic attraction at pH 9 on PIC, which bears a higher number of acidic functionalities. Hydrogen bonds between protonated functionalities of adsorption participants were suggested as a possible explanation for the observed arginine adsorption on FTL in unfavourable conditions at pH 5 and 7, when electrostatic repulsion prevailed. Phenylalanine adsorption was dominated by hydrophobic interactions under all experimental conditions. Electrostatic interactions then caused the final differences in phenylalanine uptakes at particular pH values. Besides the direct hydrophobic interactions, phenylalanine removal was enhanced by intermolecular hydrophobic interactions leading to the formation of associates consisting of several phenylalanine molecules, which were then adsorbed as a unit. Insignificant adsorption of aspartic acid was observed on both carbons owing to its strong hydrophilicity. Generally, adsorption of amino acids decreased as the ionic strength of the solution increased. The added salt screened attractive electrostatic interactions, altered surface charge of the adsorbents or changed adsorbate solubility.

Phenylalanine Removal from Water by Fe3O4 Nanoparticles Functionalized with Two Different Surfactants

In the present study, the application for the removal of phenylalanine by using two nano sorbents, namely, cetyltrimethylammonium bromide –Coated and BKC (benzal-conium chloride)-Coated Fe3O4 nanoparticles was investigated. Solid-phase extraction (SPE) and ultra violet–visible spectroscopy were used for studying the removal ability of each nano-sorbent in this study. Scanning Electron Microscopy, X-ray diffraction and Fourier infrared were used to characterize the synthesized magnetite nanoparticles. Batch adsorption studies were carried out to study the effect of various parameters, such as contact time, solution pH and concentration of phenylalanine. The equilibrium adsorption data of phenylalanine onto Fe3O4 nanoparticles (non-functionalized sample), cetyltrimethylammonium bromide -Coated and BKC -Coated were analyzed using Freundlich and Langmuir adsorption isotherms. The results indicated that adsorption of phenylalanine increased with increasing solution pH and maximum removal of phenylalanine was obtained at pH=9.0. Correlation coefficient were determined by analyzing each isotherm. It was found that the Freundlich equation showed better correlation with the experimental data than the Langmuir.

Physicochemical and sorption properties of multi-walled carbon nanotubes decorated with silver nanoparticles

Abstract Multi-walled carbon nanotubes (CNTs) modified with silver nanoparticles were tested as adsorbents of l -phenylalanine amino acid. CNTs were impregnated with an aqueous solution of silver nitrate(V) in the amount necessary to obtain the Ag loading of 1, 3 and 5 wt.%. The materials were characterised by X-ray diffraction, transmission electron microscopy and low-temperature nitrogen adsorption. TEM and XRD data clearly revealed the presence of spherical Ag nanoparticles of the mean size ∼20 nm on the carbon nanotubes surface. The modification with silver was evidenced to strongly affect the textural properties of the support. l -Phenylalanine was adsorbed on the surface of the materials obtained from buffer solutions of pH 5.6 at 20 °C. The sorption capacities of the silver-modified multi-walled carbon nanotubes towards amino acid increased with increasing percentage content of silver. The process of l -phenylalanine adsorption onto the materials studied can be described by a Langmuir type isotherm. Thermogravimetric measurements of the samples after l -phenylalanine adsorption proved that for temperatures from the range ∼160–250 °C, the condensation of l -phenylalanine molecules takes place on the nanotubes surface leading to formation of peptides that desorb into the gas phase at ∼270 °C.

Facile Synthesis of Magnetic Nanoparticles Containing Mesoporous Carbon for the Adsorption of Phenylalanine

Facile Synthesis of Magnetic Nanoparticles Containing Mesoporous Carbon for the Adsorption of Phenylalanine

Application of Magnetite Nanoparticles in Phenylalanine Removal from Water Samples

The purpose of the current research is investigating the phenylalanine removal by using magnetic nanoparticles (Fe3O4) from water samples. The effect of pH, contact time and phenylalanine concentration on phenylalanine adsorption efficiency by magnetite nanoparticles are studied in a batch system. Transmission electron microscopy (TEM), X-ray Diffraction Patterns (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize the synthesized magnetite nanoparticles.

Chiral adsorption of phenylalanine by α-, β-cyclodextrin modified layered double hydroxides

The chiral adsorption of racemic phenylalanine (Phe) by carboxymethyl-α/β-cyclodextrin-intercalated Zn-Al layered double hydroxides (CM-α/β-CD-LDHs) has been studied. The adsorption isotherms of chiral excess adsorption and the total adsorption of Phe by these CM-α/β-CD-LDHs have been investigated. CM—CD-LDHs were found to be more suitable for chiral recognition of Phe than CM—CD-LDHs. Furthermore, the intraparticle diffusion model is successfully validated in this work. Intraparticle effective diffusivities (D eff ) of Phe in these CM-α/β-CD-LDHs macroparticles were determined from the homogeneous Fickian diffusion model at various temperatures.

Evaluation of the performance of an agricultural residue-based activated carbon aiming at removal of phenylalanine from aqueous solutions

Phenylalanine removal is a necessary step for production of protein hydrolysates appropriate for consumption by phenylketonuria patients. In this study, the feasibility of employing an agricultural residue as precursor material in the production of adsorbents for phenylalanine removal from model solutions was studied. The adsorbent was prepared by treatment of the residue (defective coffee press cake) with H3PO4 and activation at 350 °C. Batch adsorption studies were conducted at 25, 35 and 45 °C. Distinct mechanisms were observed for adsorption of phenylalanine onto the prepared adsorbent depending on the solution pH. Hydrophobic interactions between carbon rings at the adsorbent surface and phenyl rings of the adsorbate molecules was deemed the predominant mechanism. Adsorption kinetics was satisfactorily described by a pseudo-second-order model and Langmuir model provided the best-fit for equilibrium description. Maximum uptake capacity of phenylananine was comparable to values encountered in the literature for synthetic adsorbents. The results show that agricultural residues present potential as materials for production of adsorbents for phenylalanine removal from aqueous solutions.

Fabrication of centimeter-sized sphere of mesoporous silica with well-defined hollow nanosphere topology and its high performance in adsorbing phenylalanine

Large mesoporous silica spheres with centimeter-scale were synthesized for the first time via a multi-level self-assembly using an emulsion system of ethyl ether, tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) surfactant. Apart from the controllable morphology and size, the inorganic hybrid or organic functionalized self-molding mesoporous materials could also be synthesized through one-pot method, that is, the synthesis and functionalization and self-molding with special morphology of the mesoporous material were realized simultaneously. According to the analysis of SEM, TEM, XRD and N 2 adsorption–desorption, the obtained macroscopic spheres were composed of nanosized silica spheres, which possessed relatively ordered mesostructure. Moreover, the obtained macroscopic silica spheres could resist a pressure of 46 N cm −2. The adsorption of phenylalanine was performed to assess the performance of these macrospheres, in which the adsorption capacity of aminopropyl triethoxysilane (APTES) functionalized sample was up to 196 mg g −1, twice higher than the best value reported in the literature.

Molecularly Imprinted Polymer for Preparation and Adsorption of Phenylalanine

Molecular imprinting technology was employed to produce one kind of Phenylalanine ( Phe) molecularly imprinted polymers (MIP)by precipitation polymerization using Phe, anhydrous alcohol, acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile as template, porogen, functional monomer, cross-linker and initiator respectively. In this study, the polymerization conditions were optimized. The template on particle size and morphology of polymers were investigated in detail by scanning electron microscopy (SEM) and adsorption isotherm determination. The binding properties of Phe on imprinted polymers were evaluated in water by equilibrium rebinding experiments, and the maximum number of adsorption was 0.60 mmol/g. It is indicated that the existence of binding sites in imprinted polymers was proved and the binding sites showed good specific and selective capability to the template molecule Phe. So the polymers would be used to separate Phe from medicine and food.

Potential-Dependent Studies on the Interaction between Phenylalanine-Substituted Bombesin Fragments and Roughened Ag, Au, and Cu Electrode Surfaces

In this work, we report systematic surface-enhanced Raman spectroscopy (SERS) and generalized two-dimensional correlation analysis (G2DCA) studies of the structures of five specifically modified phenylalanine-substituted C-terminal bombesin 6-14 fragments (BN(6-14)). The fragments studied have all been tested as chemotherapeutic agents in cancer therapy, and they form amino acid sequences in bombesin: cyclo[d-Phe(6),His(7),Leu(14)]BN(6-14), [D-Phe(6),Leu-NHEt(13),des-Met(14)]BN(6-14), [D-Phe(6),Leu(13)-((R))-p-Cl-Phe(14)]BN(6-14), [D-Phe(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14), and [D-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14). We adsorbed these fragments onto roughened Ag, Au, and Cu electrode surfaces, using a potential range from -1.200 to 0.400 V, at physiological pH. We compared the adsorption mechanism of each fragment on these substrates, as well any changes observed with varying electrode potential, to determine the relationship between adsorption strength and geometry of each of the peptides wherever it was possible. For example, we showed that none of these fragments directly interact with the Ag, Au, and Cu surfaces via residues of Phe (phenylalanine) and Trp(8) (L-tryptophane at position 8 of the BN amino acid sequence) or by an amide bond, due to a very small shift in wavenumber of their characteristic vibrations. Specific interactions were recognized from the broadening, wavenumber shift, and increase in intensity of the W18 Trp(8) mode near 759 cm(-1) and decrease in nu(12) vibration frequency of the Phe residue. In general, more intense SERS bands were observed due to the Phe ring, compared with the Trp(8) ring, which suggested a preferential adsorption of phenylalanine over tryptophane. For [D-Tyr(6),beta-Ala(11),Phe(13),Nle(14)]BN(6-14), the data also suggest some interaction of a D-Tyr(6) residue (D-tyrosine at position 6). Finally, only slight rearrangements of these moieties on the substrates are observed with changes in electrode potential.

Direct synthesis of high quality cubic Ia3d mesoporous material under organosilane assisted

Cubic Ia3d mesoporous silica was synthesized through a novel and effective way for the first time, using cationic surfactant cetyltrimethylammonium bromide (CTAB) and silica as the raw material plus vinyltriethoxysilane (VTES) additive through a phase transition method. The organic additive VTES not only acted as the organic-functionalizing agent in the synthesis, but also influenced the interaction between the cationic surfactant and silica oligomers, which was proven to be crucial for the formation of cubic Ia3d structure. The optimal synthetic conditions were determined to spur the phase transition toward Ia3d structure, including the VTES/(SiO 2 + VTES) molar ratio of 0.176 and the HCl/(SiO 2 + VTES) of 0.24 as well as the aging time of sample (72 h). Moreover, the resulting vinyl-containing MCM-48 exhibited the higher capability than common MCM-48 in gaseous adsorption of phenol and liquid adsorption of phenylalanine (Phe), offering a new candidate for environment protection and pharmaceutical industry.

Adsorption of phenylalanine on layered double hydroxides: effect of temperature and ionic strength

In this work we report the adsorption of phenylalanine (Phe) on Magnesium Aluminum Layered Double Hydroxides (Mg–Al–CO3-LDH) at two different temperatures (298 and 310 K) and under two distinct ionic strength conditions (with and without the addition 0.1 M of NaCl). The adsorption isotherms exhibit the same profile in all conditions, and they only differ in the amount of removed Phe. At lower ionic strength, the isotherms are almost identical at both temperatures, except for the last points, where the increase in temperature causes a decrease in the amount of adsorbed Phe. An increase in ionic strength results in a decrease in Phe adsorption. The electrokinetic potential decreases as the amount of adsorbed Phe increases, and only positive values are observed. This indicates that the surface of the adsorbent is not totally neutralized and suggests that more Phe could be removed by adsorption. The presence of Phe on the solid is confirmed by FTIR spectra, which present the specific bands assigned to Phe. The hydrophobicity of the amino acid probably contributes to its extraction, thus enabling the removal of a great amount of Phe. In conclusion, LDH is potentially applicable in the removal of Phe from wastewater.

Adsorption of phenylalanine on single crystal rutile TiO 2(1 1 0) surface

The adsorption of the aromatic amino acid, phenylalanine on a TiO 2 rutile (1 1 0) single crystal surface has been investigated with photoemission and NEXAFS (near edge X-ray absorption fine structure) spectroscopy. The results indicate initial adsorption via the carboxylate group in a bidentate configuration with the phenyl ring oriented at approximately 25° to the surface normal. The amino group remains as NH 2. Subsequent layers of phenylalanine appear to adsorb as neutral molecules with H-bonding between NH 2 and C O groups.

Electrochemical quartz crystal nanobalance and chronocoulometry studies of phenylalanine adsorption on Au

The interfacial adsorption behaviour of the amino acid, phenylalanine (Phe), was studied at a polycrystalline Au surface in 0.05 M KClO 4 using cyclic voltammetry, chronocoulometry (CC) and electrochemical quartz crystal nanobalance (EQCN) frequency measurements. The frequency was observed to decrease with increasing concentration of Phe, indicating that the frequency measurements were following analyte adsorption directly. Both CC and EQCN frequency measurements showed a two-stage adsorption process, consistent with the molecule being adsorbed in the horizontal position at negative potentials, but rearranged to the more upright position at potentials more positive to the potential of zero charge. From the slopes at the onset of each of these two regions in plots of change in mass from the EQCN frequency measurements versus the surface charge density from CC measurements, the calculated molar mass corresponded to that of Phe displacing adsorbed water molecules for EQCN measurements made with small bulk concentrations of Phe (i.e., <1 × 10 −4 mol L −1). The adsorption process from CC measurements for Phe, described using the Henry adsorption isotherm, gave Gibbs energies of adsorption (Δ G ADS) ranging from −18 to −35 kJ mol −1 over the potential range of −0.6 to 0.6 V. The observed decrease in frequency of the EQCN measurements with additions of aliquots of amino acid and the substantial Δ G ADS values suggests that Phe adsorbs onto the surface via chemisorption. Surface concentrations (1.2 × 10 −10 mol cm −2) were in excellent agreement between the EQCN and CC measurements for small bulk concentrations of Phe (4.0 × 10 −5 mol L −1), in very good agreement with previously published results at the Au(1 1 1) surface. Thus, for small bulk concentrations of analyte, these electrochemical techniques complement one another to enhance our knowledge of the behaviour of thin organic films at electrode surfaces.