Hexavalent Chromium Removal and Reduction to Cr (III) by Polystyrene Tris(2-aminoethyl)amine

A commercially available chelating polymer, polystyrene tris(2-aminoethyl)amine, was used for the removal of chromium from aqueous solution. The influence of pH, contact time, adsorbent dosage and initial Cr (VI) concentration on adsorption was studied. The optimum pH for the removal of Cr (VI) was at pH 5, while optimum contact time and adsorbent dosage were 120 minutes and 10 g/L, respectively. Total chromium and Cr (VI) concentrations were analyzed by ICP-MS and UVVisible. Adsorption isotherms using Langmuir and Freundlich isotherm models revealed that the data fitted Langmuir isotherm model better than Freundlich with a maximum adsorption capacity of 312.27 mg/g. FTIR spectroscopy, Scanning electron microscopy (SEM) and Energy Dispersive Spectrometry (EDS) analyses were performed on the adsorbent before and after binding Cr (VI). All analyses confirmed the complexation of Cr (VI) to the adsorbent. Desorption experiments using KCl solution indicated 89.3% release of chromium, rendering this method of high potential for adsorbent regeneration.We wish to thank Professor Dr. Z. Abdeen for his valuable financial support which made this work possible. We also wish to thank the Aquatic and Aquaculture Research Laboratory at Al-Quds University for performing the ICP-MS analysis

Variation in the optical sensing properties of dithiocarbamate polymer microspheres as function of surface morphology

Three polymers with N-ethanolamino-, N-benzylamino-, and N-t-butylamino-dithiocarbamate groups were synthesized from polyvinylbenzylchloride. Each of the three polymers was incorporated in a hydrogel membrane (PVA) cross-linked with glutaraldehyde to form a sensing element. The latter was, then, evaluated for its optical sensing behavior by subjecting it to varying concentrations (1.0x10-5 up to 0.1 M) of metal ions (Zn2+, Cd2+, Pb2+, Hg2+,Ca2+, Mg2+, K+, Na+, Cr3+, Ni2+, Cu2+). Significant response was observed for the Hg2+ ions while the others showed negligible or no response. The turbidity absorbance increased consecutively from the dithiocarbamate polymer derived from N-t-butylamine towards that from ethanolamine as the concentration of the Hg2+ solution increased. The response time measured for the three polymer microspheres ranged between 2 and 30 minutes. The aminodithiocarbamate polymers were stable at normal temperatures (25ο - 40 ο C) and as pH was changed between 2 and 7. In addition, the polymers demonstrated excellent stability with time and a capacity of 3.967, 3.787, 3.355 mmol Hg2+ ions per gram of polymer for the N-ethanolamino-, N-benzylamino-, and N-t-butylamino-dithiocarbamate respectively. SEM and Eds analyses showed an increase in size of about 25% in the case of complexation with N-ethanolamino-, no size change with N-benzylamino-, and a 16.6% decrease in size with N-t-butylamino-dithiocarbamate.We are grateful to professor W.R.Seitz and his research group, of the University of New Hampshire (USA) for supplying us with the polymer polyvinylbenzylchloride.We are also grateful to professor M.Khamis of Al-Quds University for financial support for the SEM analyses

Analysis of phenolic and flavonoids of wild ephedra alata plant extractsby lc/pda and lc/ms and their antioxidant activity

Background: Ephedra is among Palestinian medicinal plants that are traditionally used in folkloric medicine for treating many diseases. Ephedra is known to have antibacterial and antioxidant effects. The goal of this study is to evaluate the antioxidant activity of different extracts from the Ephedra alata plant growing wild in Palestine, and to analyze their phenolic and flavonoid constituents by HPLC/PDA and HPLC/MS. Materials and Methods: Samples of the Ephedra alata plant grown wild in Palestine were extracted with three different solvents namely, 100% water, 80% ethanol, and 100% ethanol. The extracts were analyzed for their total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AA), as well as phenolic and flavonoids content by HPLC/PDA/MS. Results: The results revealed that the polarity of the extraction solvent affects the TPC, TFC, and AA of extracts. It was found that both TPC and AA are highest for plant extracted with 80% ethanol, followed by 100% ethanol, and finally with 100% water. TFC however was highest in the following order: 100% ethanol > 80% ethanol > water. Pearson correlation indicated that there is a significant correlation between AA and TPC, but there is no correlation between AA and TFC. Simultaneous HPLC-PDA and UHPLC-MS analysis of the ethanolic plant extracts revealed the presence of Luteolin-7-O-glucuronide flavone, Myricetin 3-rhamnoside and some other major polyphenolic compounds that share myricetin skeleton. Conclusion Ephedra alata extract is rich in potent falvonoid glycosidic compounds as revealed by their similar overlaid UV-Vis spectra and UHPLC-MS results. On the basis of these findings, it is concluded that Ephedra alata constitutes a natural source of potent antioxidants that may prevent many diseases and could be potentially used in food, cosmetics, and pharmaceutical products

Polyvinylbenzyl Tris-Aminodicarboxylate Microspheres for the Optical Sensing of Cu2+ Ions

In this work, a tris(2-aminoethyl)aminodicaboxylate functionality was substituted for the chloride of polyvinyl- benzyl chloride (PVBC) which was lightly cross-linked (2%) with divinyl benzene. The resulting derivatized po- lymer microspheres were embedded in a hydrogel matrix of poly vinyl alcohol cross-linked with glutaraldehyde to produce a sensing membrane. The latter responded selectively to Cu2+ solutions of different concentration ranges (1 × 10−4 M to 1 × 10−6 M). The response is based on the interaction between the metal cations and the negatively charged deprotonated dicarboxylate functional group, which led to neutralization of the charges. As a result, an increase in the turbidity of the sensing membrane occurred which is attributed to a change in the re- fractive index of the derivatized polymer microspheres relative to that of the hydrogel. The change in the turbid- ity of the sensing membrane was measured as absorbance using a conventional spectrophotometer. It was found that Cu2+ ions bind to the aminodicarboxylated-polymer with a formation constant, Kf, of 1 × 105 M−1. SEM, Eds and IR analyses were performed on the aminodicarboxylated microspheres and their Cu2+ complex.We are grateful to Professor W. R. Seitz and his research group, at the University of New Hampshire (USA) for their fruitful comments and for supplying us with the polyvinylbenzyl chloride microspheres. We are also grateful to the staff at the department of chemistry of An-Najah National University (PA), for their technical assistance

Effect of Geographical Region and Harvesting Date on Antioxidant Activity, Phenolic and Flavonoid Content of Olive Leaves

The effect of geographical region and harvesting date (seasonal change) on antioxidant activities (AA), total phenolic content (TPC) and total flavonoid content (TFC) of olive leaves obtained from different geographical regions of Palestine (north, middle, and south) at different maturation stages (June 2013, October 2013, and January 2014) was investigated in this study. Results revealed that both geographical region and maturation stage affect AA, TPC, and TFC of the olive leaves. Highest AA, TPC, and TFC were obtained for samples collected in June. TPC was found to be highest in north and lowest in south, while the highest AA, and TFC contents were alternating between north, middle, and south. During different maturation stages, TPC, TFC, and AA varied between 21.56 - 47.52 mg (GAE), 19.3 - 32.6 mg catechin equivalents, 318.53 – 1106.43 μmol FRAP equivalents per gram of dry olive leaves, respectively

Optical Sensing Properties of Dithiocarbamate-Functionalized Microspheres, Using a Polyvinylpyridine-Polyvinylbenzyl Chloride Copolymer

In this study, a new modified optical chemical sensor based on swellable polymer microspheres is developed using a 5% copolymer of polyvinylpyridine-polyvinyl-benzyl chloride microspheres functionalized as the corresponding dithiocarbamate. This sensor demonstrated significant enhancements in sensitivity, dynamic range and response time. These improvements are related to the presence of pyridine in the polymer backbone, which is believed to increase the space between the groups, thus decreasing steric hindrance, and hence increasing substitution of the dithiocarbamate group. The hydrophilicity of pyridine also allows free movement of the solvent and analyte to and from the inside of the microspheres. These dithiocarbamate-derivatized polymer microspheres were embedded in a hydrogel matrix of polyvinylalcohol cross-linked with glutaraldehyde. This sensor responded selectively to Hg2+ solutions of different concentrations (1 × 10−5 M to 0.1 M). The observed turbidity measured as absorbance varied between 1.05 and 1.75 units at a wavelength of 700 nm. The response is based on the interaction between the metal cations with the negative charges of the deprotonated dithiocarbamate functional group, which led to neutratization of the charges and thus to polymer shrinking. As a result, an increase in the turbidity of the sensing element due to a change in the refractive index between the hydrogel and the polymer microspheres occured. The changes in the turbidity of the sensing element were measured as absorbance using a conventional spectrophotometer

Spectrophotometric Determination of Cu2+ Metal Ions via Complex Formation with Carboxylated Tris(2-aminoethyl)amine

An aminopolycarboxylic acid chelating agent; tris(2-aminoethyl)aminehexaacetic acid (TAHA) was prepared and characterized. TAHA formed stable complexes with Cu(II) ions and other metal ions at pH 10. The complexation behavior was studied by spectrophotometry at the complex maximum wavelength. Mixtures of Cu(II) and other metal ions (M2+; Ca2+, Co2+, Ni2+, Cd2+)were titrated with TAHA at pH 10. The stoichiometry of ligand - to - metal was found to be 1:1. The stability constant of Cu(II)–TAHA complex was determined to be 1.86×105 by using the continuous variation method. Beer’s law was obeyed over the concentration range 3.0×10–4 M – 1.2×10–2 M for Cu(II) solution. The results of the quantitative determination of Cu(II) gave LOD and LOQ values of 7.285×10–6 M and 2.428×10–5 M respectively. The percent relative standard deviation (%RSD) for five replicate samples was found to be 1.088% and 4.804% for Cu(II) concentrations of 1.2×10–2 M and 3.0×10–4 M respectively

Spectrophotometric Determination of Cu2+ Metal Ions via Complex Formation with Carboxylated Tris(2-aminoethyl)amine

An aminopolycarboxylic acid chelating agent; tris(2-aminoethyl)aminehexaacetic acid (TAHA) was prepared and characterized. TAHA formed stable complexes with Cu(II) ions and other metal ions at pH 10. The complexation behavior was studied by spectrophotometry at the complex maximum wavelength. Mixtures of Cu(II) and other metal ions (M2+; Ca2+, Co2+, Ni2+, Cd2+)were titrated with TAHA at pH 10. The stoichiometry of ligand - to - metal was found to be 1:1. The stability constant of Cu(II)–TAHA complex was determined to be 1.86×105 by using the continuous variation method. Beer’s law was obeyed over the concentration range 3.0×10–4 M – 1.2×10–2 M for Cu(II) solution. The results of the quantitative determination of Cu(II) gave LOD and LOQ values of 7.285×10–6 M and 2.428×10–5 M respectively. The percent relative standard deviation (%RSD) for five replicate samples was found to be 1.088% and 4.804% for Cu(II) concentrations of 1.2×10–2 M and 3.0×10–4 M respectively

Spectrophotometric Determination of Cu2+ Metal Ions via Complex Formation with Carboxylated Tris(2-aminoethyl)amine

An aminopolycarboxylic acid chelating agent; tris(2-aminoethyl)aminehexaacetic acid (TAHA) was prepared and characterized. TAHA formed stable complexes with Cu(II) ions and other metal ions at pH 10. The complexation behavior was studied by spectrophotometry at the complex maximum wavelength. Mixtures of Cu(II) and other metal ions (M2+; Ca2+, Co2+, Ni2+, Cd2+) were titrated with TAHA at pH 10. The stoichiometry of ligand - to - metal was found to be 1:1. The stability constant of Cu(II)–TAHA complex was determined to be 1.86×105 by using the continuous variation method. Beer’s law was obeyed over the concentration range 3.0×10–4 M – 1.2×10–2 M for Cu(II) solution. The results of the quantitative determination of Cu(II) gave LOD and LOQ values of 7.285×10–6 M and 2.428×10–5 M respectively. The percent relative standard deviation (%RSD) for five replicate samples was found to be 1.088% and 4.804% for Cu(II) concentrations of 1.2×10–2 M and 3.0×10–4 M respectively

ANALYSIS OF PHENOLIC AND FLAVONOIDS OF WILD EPHEDRA ALATA PLANT EXTRACTS BY LC/PDA AND LC/MS AND THEIR ANTIOXIDANT ACTIVITY

Background: Ephedra is among Palestinian medicinal plants that are traditionally used in folkloric medicine for treating many diseases. Ephedra is known to have antibacterial and antioxidant effects. The goal of this study is to evaluate the antioxidant activity of different extracts from the Ephedra alata plant growing wild in Palestine, and to analyze their phenolic and flavonoid constituents by HPLC/PDA and HPLC/MS. Materials and Methods: Samples of the Ephedra alata plant grown wild in Palestine were extracted with three different solvents namely, 100% water, 80% ethanol, and 100% ethanol. The extracts were analyzed for their total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AA), as well as phenolic and flavonoids content by HPLC/PDA/MS. Results: The results revealed that the polarity of the extraction solvent affects the TPC, TFC, and AA of extracts. It was found that both TPC and AA are highest for plant extracted with 80% ethanol, followed by 100% ethanol, and finally with 100% water. TFC however was highest in the following order: 100% ethanol > 80% ethanol > water. Pearson correlation indicated that there is a significant correlation between AA and TPC, but there is no correlation between AA and TFC. Simultaneous HPLC-PDA and UHPLC-MS analysis of the ethanolic plant extracts revealed the presence of Luteolin-7-O-glucuronide flavone, Myricetin 3-rhamnoside and some other major polyphenolic compounds that share myricetin skeleton. Conclusion Ephedra alata extract is rich in potent falvonoid glycosidic compounds as revealed by their similar overlaid UV-Vis spectra and UHPLC-MS results. On the basis of these findings, it is concluded that Ephedra alata constitutes a natural source of potent antioxidants that may prevent many diseases and could be potentially used in food, cosmetics, and pharmaceutical products