Synthesis and Characterization of a Nanosilica-Cysteine Composite for Arsenic(III) Ion Removal.

This article describes the synthesis of nanosilica-cysteine composite (SiO2-Cys) and its application as a sorbent for arsenic(III) removal from different aqueous media. Attenuated total reflectance-Fourier-transform infrared spectroscopy, scanning and transmission electron microscopy, X-ray diffraction, and thermogravimetric analysis were applied to characterize SiO2-Cys. Using the batch technique, sorption of As(III) ion by SiO2-Cys was studied, and the effects of pH, sorbent dosage, temperature, initial concentration, and contact time were all taken into consideration. According to kinetic studies, the pseudo-second-order equation adequately described the sorption of the As(III) ion. The spontaneity of the sorption process on SiO2-Cys is suggested by the negative values of Gibbs free energy (G°). Positive values of enthalpy (ΔH°) indicate the endothermic adsorption process and the positive values of entropy (ΔS°) for As(III) ions adsorption imply that the adsorption involves increasing randomness. The Langmuir model, which has a maximum sorption capacity for SiO2-Cys of (66.67 mg/g) at 25°C, provided a better fit to the sorption isotherm.

Synthesis and Characterization of Chelating Hyperbranched Polyester Nanoparticles for Cd(II) Ion Removal from Water.

Chelating hyperbranched polyester (CHPE) nanoparticles have become an attractive new material family for developing high-capacity nanoscale chelating agents with highly branched structures and many functional groups in the main chains and end groups that can be used to remove heavy metals from water. In this study, a hyperbranched polyester with a particle size of 180-643 nm was synthesized with A2+B3 interfacial polymerization, using dimethylmalonyl chloride as the difunctional monomer (A2) and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) as the trifunctional monomer (B3). FTIR and NMR were used to characterize the CHPE and confirm the structure. The CHPE nanoparticles were generally considered hydrophilic, with an observed swelling capacity of 160.70%. The thermal properties of the CHPE nanoparticles were studied by thermal gravimetric analysis (TGA) with 1% mass loss at temperatures above 185 °C. The XRD of the CHPE nanoparticles showed a semi-crystalline pattern, as evident from the presence of peaks at positions ~18° and 20°. The nature of the surface of the CHPE was examined using SEM. Batch equilibrium was used to investigate the removal properties of the CHPE nanoparticles towards Cd(II) ions as a function of temperature, contact time, and Cd(II) concentration. The Cd(II) ion thermodynamics, kinetics, and desorption data on the CHPE nanoparticles were also studied.

Comparison of Jordanian and standard diatomaceous earth as an adsorbent for removal of Sm(III) and Nd(III) from aqueous solution.

In this study, Jordanian diatomaceous earth (JDA) and commercial diatomaceous earth (standard diatomaceous earth, SDA) were used for adsorption of samarium (Sm)(III) and neodymium (Nd)(III) ions from aqueous solutions using batch technique as a function of initial concentration of metal ions, adsorbent dosage, ionic strength, initial pH solution, contact time, and temperature. Both adsorbents were characterized by Fourier transform infrared (FTIR), X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area, and cation exchange capacity (CEC). Maximum metal ion uptake was observed after 100 min of agitation, and the uptake has decreased with increasing temperature and reached a maximum at pH ≈ 5. Different types of adsorption isotherms and kinetic models were used to describe the Nd(III) and Sm(III) ion adsorption. The experimental data fitted within the following isotherms in the order Langmuir > Dubinin-Radushkevich (DR) > Freundlich and the pseudo-second-order kinetic model based on their coefficient of determination (R2), chi-square (χ2), and error function (Ferror%) values. Maximum adsorption uptakes, according to the Langmuir model, were obtained as 188.679 mg/g and 185.185 mg/g for Sm(III) and 169.492 mg/g and 149.254 mg/g for Nd(III) by JDA and SDA, respectively. The results of thermodynamic parameters showed that the adsorption of Sm(III) and Nd(III) ions onto JDA and SDA is a feasible, spontaneous, exothermic, and entropy driven. The best recovery for Sm(III) and Nd(III) was obtained when the 0.05 M EDTA + 0.05 M H3PO4 mixture was used as an eluent.

Purification and biochemical characterization of photo-active membrane protein bacteriorhodopsin from Haloarcula marismortui, an extreme halophile from the Dead Sea.

Bacteriorhodopsin (BR) is an exciting photo-active retinal protein with many potential industrial applications. In this study, BR from the extremely halophilic archaeon Haloarcula marismortui (HmBR) was purified successfully using aqueous two phase extraction method. Absorption spectroscopy analysis showed maximum absorption peak of HmBR retinal protein (λmax) at 415 nm. The purified HmBR was visualized by SDS-PAGE, with a subunit molecular mass of 27 kDa, and its identity was confirmed by resonance Raman spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The effect of pH and salt concentration on the absorption spectrum of HmBR was evaluated. Red-shifted in λmax of HmBR was recorded at acidic condition (pH 5) and HmBR showed remarkable optical activity under high salinity condition. The photoelectric activity of HmBR was evaluated by measuring the DC-voltage generated from HmBR coated on indium tin oxide (ITO) glass when light illumination was applied.

Adsorption of uranium(VI) and thorium(IV) by insolubilized humic acid from Ajloun soil - Jordan.

Humic acid from Ajloun soil has been extracted and insolubilized. The insolubilized humic acid (NaIHA) was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermal gravimetric analysis, X-ray diffraction and differential scanning calorimetry. Adsorption of U(VI) and Th(IV) by NaIHA was studied using batch technique at different temperatures (25.0, 35.0 and 45.0 °C) and at different pH values (1.00, 2.00 and 3.00). It was found that NaIHA has higher uptake for Th(IV) than U(VI), and that the metal ion uptake by NaIHA increased with pH and reached a maximum at pH = 3. The kinetic studies were done, and showed that the equilibrium time for each metal ion occurs at 6 h to achieve maximum uptake level. Adsorption data were evaluated according to the Pseudo second-order reaction kinetic. The metal ions uptake properties by the NaIHA fit Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. Thermodynamic functions, ΔG°, ΔH° and ΔS° were determined for each metal ion. The positive values of ΔG° indicate that adsorption process is not highly favorable, while ΔH° values indicated that this process is endothermic. On the other hand, the process has positive entropy which means that the adsorption process increases the disorder of the system and it is entropy driven. Column experiments were used for the determination of metal ion loading capacity and desorption studies. The uptake capacities in column technique of U(VI) and Th(IV) ions are 2.63 and 4.85 mg metal ion/g NaIHA respectively. Recovery of U(VI) and Th(IV) ions was carried out by treatment of loaded insolubilized humic acid with 0.1 M and 1.0 M HNO3, the best recovery for U(VI) and Th(IV) ions were obtained when 1.0 M HNO3 was used.

Characteristics of organosulphur compounds adsorption onto Jordanian zeolitic tuff from diesel fuel.

The removal of organosulphur compounds (ORS) from diesel fuel is an important aspect of Jordanian's effort to reduce air pollution. Currently, the total sulphur content in Jordanian diesel fuel is 12,000 ppmw (1.2%, wt/wt), but Jordanian government has recently introduced new restrictions that will reduce this level gradually to internationally acceptable levels. The zeolitic tuff (ZT), from Tlul Al-Shahba region, was characterised using various analytical techniques. It was found that the Freundlich model fitted the adsorption isotherms more accurately than the Langmuir model; indicating that the ZT had a heterogeneous surface. The Langmuir adsorption capacity values for the three particle size ranges (100-200), (300-400), and (500-600) microm were 7.15, 6.32, and 5.52 mg/g and the column capacities were 4.45, 2.57, and 1.92 mg/g, respectively. The spent ZT was regenerated by washing with n-heptane with an efficiency of 81.5%. Two adsorption mechanisms were investigated. One is that the interaction of thiophene with the Brønsted site of the ZT through S atoms; the other is via C-S bond cleavage in thiophene-derived carbocations to form unsaturated fragments on the Brønsted acid sites.

The influence of using Jordanian natural zeolite on the adsorption, physical, and mechanical properties of geopolymers products.

Geopolymers consist of an amorphous, three-dimensional structure resulting from the polymerization of aluminosilicate monomers that result from dissolution of kaolin in an alkaline solution at temperatures around 80 degrees C. One potential use of geopolymers is as Portland cement replacement. It will be of great importance to provide a geopolymer with suitable mechanical properties for the purpose of water storage and high adsorption capacity towards pollutants. The aim of this work is to investigate the effect of using Jordanian zeolitic tuff as filler on the mechanical performance and on the adsorption capacity of the geopolymers products. Jordanian zeolitic tuff is inexpensive and is known to have high adsorption capacity. The results confirmed that this natural zeolitic tuff can be used as a filler of stable geopolymers with high mechanical properties and high adsorption capacity towards methylene blue and Cu(II) ions. The XRD measurements showed that the phillipsite peaks (major mineral constituent of Jordanian zeolite) were disappeared upon geopolymerization. The zeolite-based geopolymers revealed high compressive strength compared to reference geopolymers that employ sand as filler. Adsorption experiments showed that among different geopolymers prepared, the zeolite-based geopolymers have the highest adsorption capacity towards methylene blue and copper(II) ions.

Adsorption of Cu(II) and Ni(II) on solid humic acid from the Azraq area, Jordan.

Isotherms of adsorption of Cu(II) and Ni(II) onto solid Azraq humic acid (AZHA) were studied at different pH (2.0-3.7) values and 0.1 M NaClO4 ionic strength. The Langmuir monolayer adsorption capacity was found to range from 0.1 to 1.0 mmol metal ion/g AZHA, where Cu(II) has higher adsorptivity than Ni(II). The previously reported NICA-Donnan parameters for sorption of Cu(II) on HA fit the amount of Cu(bound) determined in the present study at pH 3.7 but underestimates those at pH values of 3.0, 2.4, and 2.0. The contribution of low affinity sites to binding of metal ions increases with decreasing pH and increasing metal ion loading. The aggregation of HA, which is facilitated by decreasing pH and increasing metal loading, may increase the ability of low-affinity sites to encapsulate metal ions. The binding of Ni(II) to HA exhibits less heterogeneity and less multidentism than that of Cu(II). AZHA loaded with Cu(II) and Ni(II) was found to be insoluble in water with no measurable amount of desorbed metal ions.