Initial Silver Ion Concentration Research Articles

STUDY OF SILVER ADSORPTION ON CELLULOSE-BASED BIOSORBENTS

The survey aimed to investigate the adsorption properties of cellulose-based materials derived from cereal by-products towards Ag+ ions in water solutions, and to shed light on the mechanism of adsorption. Cellulose was isolated from rice and einkorn husks using alkali and bleaching treatments. Untreated einkorn husks and commercial cellulose served as reference samples. Characterization techniques included XRD, FTIR, SEM, and low-temperature nitrogen adsorption, with surface elemental composition analyzed by XPS. The study examined how contact time, initial silver ion concentration, pH, and temperature affected adsorption. The adsorption process was modeled using pseudo-second-order and Langmuir models, and thermodynamic parameters were evaluated. All materials showed potential as effective Ag+ ion adsorbents, indicating their suitability for creating silver-modified catalytic materials.

Green Synthesis and the formation kinetics of silver nanoparticles in aqueous Inula Viscosa extract

In this study, we present the production of silver nanoparticles in aqueous Inula Viscosa extract by the green synthesis approach at room temperature. The structural, and morphological properties as well as formation kinetics of the synthesized silver nanoparticles were characterized by UV–Vis, DLS, STEM, XRD, Raman, and FTIR measurements. Mono-dispersed and very stable silver nanoparticles with a size of 15 ± 5 nm and face-centered cubic crystal structure were synthesized in aqueous Inula Viscosa extract. The kinetic studies of silver nanoparticles formation in Inula Viscosa extract show that silver nanoparticle formation reaction reached an equilibrium within 24 h and fit in the first-order reaction kinetics. The results clearly show that the size of fabricated nanoparticles is independent of the dynamical formation process since the reaction time and initial silver ion concentration are not affected by the size and morphology of the produced particles.

Effect of nickel on the adsorption of silver ions over activated carbon

PurposeThe disposal of wastewater containing silver is an environmental concern. Due to the toxicity of silver, treatment of such wastewater is necessary. Real wastewater contains a complex matrix of pollutants. The purpose of this paper is to study the adsorption behavior of silver in single and binary systems (with nickel) onto granular activated carbon.Design/methodology/approachThe effect of silver ions concentration and the mass of adsorbent on the adsorption behavior were analyzed. Five two-parameter isotherms (Langmuir, Elovich, Freundlich, Dubinin–Radushkevich and Temkin) were applied to investigate the adsorption mechanism. Both linear and nonlinear regressions were tested for the first three isotherms. The experimental data were also fitted to Redlich–Petersons, Sips and Toth models.FindingsA direct relationship between the initial silver ion concentration and its adsorption capacity was observed, whereas an inverse relationship between the adsorbent mass and the adsorption capacity was documented. The Langmuir model was found to best-fit the data indicating monolayer adsorption behavior. The maximum uptake was 2,500 mg/g in the single adsorption system. This value decreased to 909 mg/g in the binary system. The adsorption was found to have an exothermic chemical nature.Originality/valueThe study of the silver adsorption in a single system is inaccurate. Real wastewater contains a complex matrix of pollutants. This research gives a clear insight into the adsorption behavior in binary systems.

Kinetic, Isotherm, and Thermodynamic Studies for Ag(I) Adsorption Using Carboxymethyl Functionalized Poly(glycidyl methacrylate).

Industrial wastewater contains large amounts of silver ions. Here, a new adsorbent was synthesized by functionalizing poly(glycidyl methacrylate) with carboxymethyl groups. The adsorbent was used to recover Ag(I) in wastewater. Fourier transform infrared spectroscopy, zeta potential, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the adsorbent. The experimental parameters affecting the adsorption are solution pH, contact time, and initial silver ion concentration. The optimum pH for adsorption of Ag(I) is pH 4. The maximum adsorption capacity at pH 4 is 157.05 mg/g, and the adsorption reaches equilibrium at 300 min. The kinetics and isotherms of the adsorption process were described by pseudo second-order, Langmuir and D-R models, respectively. The adsorption process was a single layer chemical adsorption, exothermic, feasible, and spontaneous. The adsorption mechanism is electrostatic or chelation. The adsorbent selectively absorbed Ag(I) from coexisting ions (Cu2+, Ni2+, Co2+, Zn2+). Finally, the removal rate of silver ions decreased from 79.29% to 65.01% after four repetitive experiments, which proved that the adsorbent had good reusability. The adsorbent has great potential benefit in removing Ag(I).

High removal capacity of silver ions from aqueous solution onto Halloysite nanotubes

The adsorption of silver ions onto Halloysite nanotubes (HNTs) was investigated in aqueous solution in a batch system. The natural HNTs used as adsorbent in this work were initially characterized by TEM. The amounts of the silver ions adsorbed onto HNTs were influenced by initial silver ion concentration, temperature, pH, contact time and adsorbent dose.Adsorption increased with increasing initial silver ion concentration, initial pH, and temperature. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were considered to evaluate the rate parameters. The adsorption followed pseudo-second-order kinetic model with correlation coefficients greater than 0.999. The experimental isotherm data were analyzed using the Langmuir, Freundlich and Temkin equations. The Langmuir isotherm model showed significant fit to the equilibrium adsorption data and the maximum adsorption capacity of 109.79mgg−1 (99.8% removal) of silver ions was achieved. The thermodynamic parameters of activation such as Gibbs free energy, enthalpy and entropy were also evaluated. The results indicate that HNTs could be employed as effective nanoadsorbent for the removal of heavy metal ions.

Biosorption of Ag(I) from Aqueous Solution by <i>Bacillus licheniformis</i> Strain R08

Biosorption of heavy metals is an effective technology for the treatment of industrial wastewater. In this paper, Bacillus licheniformis R08 was used as biosorbent for Ag+. The physic-chemical properties of biosorption of silver by Bacillus licheniformis R08 were studied. Experimental parameters, including pH, temperature, biosorption time, initial silver ion concentration and biomass concentration were optimized. Under the optimized conditions, the silver biosorption capacity and biosorption efficiency could reach 73.6mg×g-1 and 73.6%, respectively. Equilibrium isotherms of biosorption by R08 were fitted by Langmuir equation and the theoretical maximum biosorption capacity was 136 mg×g-1. FTIR results showed that-CO-NH and -COO- groups of R08 cell were confirmed to be the main active groups that could combine with silver ions.

Adsorption of silver from aqueous solution onto raw vermiculite and manganese oxide-modified vermiculite

In this work, the manganese oxide-modified vermiculite (Mn-MV) was prepared from raw vermiculite (RV) and characterized chemically and morphologically. The adsorption surface of RV was increased about 10 times after the modification due to the increase in negative charge onto the sorbent surface. The adsorption performance of RV and Mn-MV sorbents in the removal of silver (Ag(I)) ions from aqueous solution was examined using batch method. The effects of initial pH of solution, contact time, adsorbent concentration, initial silver ion concentration, modifying agent concentration and temperature of solution on the adsorption efficiency were investigated systemically. The maximum adsorption capacity of RV and Mn-MV sorbents was found as 46.2 and 69.2mgg−1, respectively. The calculated adsorption energy (9.6kJmol−1) from the Dubinin–Radushkevich (D–R) model indicated that the adsorption process onto modified sorbent was taken place mainly by chemical ion exchange. A 95% portion of the Ag(I) ions adsorbed was desorbed successfully from the sorbent surface by using 0.5M 10mL HCl. The Mn-MV sorbent had good reusability performance after 10 adsorption–desorption cycles. The calculated thermodynamic parameters showed that the adsorption of Ag(I) onto Mn-MV sorbent process was feasible, spontaneous and exothermic. The kinetic evaluation also suggested that the adsorption process followed well the pseudo-second-order kinetic model.

Controlled Preparation and Reactive Silver-Ion Sorption of Electrically Conductive Poly(N-butylaniline)-Lignosulfonate Composite Nanospheres

Electroconductive poly(N-butylaniline)-lignosulfonate (PBA-LS) composite nanospheres were prepared in a facile way by in situ, unstirred polymerization of N-butylaniline with lignosulfonate (LS) as a dispersant and dopant. The LS content was used to optimize the size, structure, electroconductivity, solubility, and silver ion adsorptive capacity of the PBA-LS nanospheres. Uniform PBA-LS10 nanospheres with a minimal mean diameter of 375 nm and high stability were obtained when the LS content was 10 wt %. The PBA-LS10 nanospheres possess an increased electroconductivity of 0.109 S cm(-1) compared with that of poly(N-butylaniline) (0.0751 S cm(-1)). Furthermore, the PBA-LS10 nanospheres have a maximal silver-ion sorption capacity of 815.0 mg g(-1) at an initial silver ion concentration of 50 mmol L(-1) (25 °C for 48 h), an enhancement of 70.4% compared with PBA. Moreover, a sorption mechanism of silver ions on the PBA-LS10 nanospheres is proposed. TEM and wide-angle X-ray diffraction results showed that silver nanoparticles with a diameter size range of 6.8-55 nm was achieved after sorption, indicating that the PBA-LS10 nanospheres had high reductibility for silver ions.

Recovery of silver from wastewater coupled with power generation using a microbial fuel cell

A cost-effective microbial fuel cell (MFC) system was developed in order to recover silver metal from silver ion containing wastewaters. After 8h reaction, silver metal recovery efficiencies as high as 99.91±0.00%–98.26±0.01% were achieved. The initial concentrations were from 50ppm to 200ppm with a load resistor of 1000Ω. In the batch-fed cathode and continuous-fed anode system with an initial silver concentration of 200ppm, discharge curves display the production of both silver metal and electric energy at a rate of 69.9kg silver per KWh energy output. The maximum power of about 4.25W/m2, maximum voltage of 0.749V, maximum current density of 5.67A/m2, and a fill factor of 0.626 were achieved at 1000ppm initial silver ion concentration.

Silver nanostructures via cementation on copper: a comparison between experimental data and statistical design model

AbstractSilver nanostructures have been precipitated successfully from acidic solutions of silver ions via cementation on copper sheets. The experimental parameters that have been studied are time, temperature of reaction, pH and initial silver ion concentration. XRD analysis showed that precipitated silver particles werecomposed mainly of metallic silver. No other phases such as silver oxide, sulfide or sulfate could be detected. SEM investigations confirmed that silver nanostructures were deposited mainly in the form of nanoparticles, dendrites or nanorods as the parameters varied. The average silver nanoparticle size that could be obtained by optimizing the experimental conditions of cementation process was about 60 nm. This value was in agreement with that obtained from application of factorial design under the same conditions. Copyright © 2010 John Wiley & Sons, Ltd.

Superhydrophobic surface created by the silver mirror reaction and its drag-reduction effect on water

Stable superhydrophobic silver films were fabricated on glass substrates by using the silver mirror reaction. The water contact angle (CA) on the obtained silver surface was 154°, and a water droplet could easily roll off. Both the CA and surface roughness could be tailored by altering the initial silver ion concentration. The movement of a superhydrophobic ball on the surface of water was also investigated and compared with that of a superhydrophilic ball. The results suggested that the superhydrophobic coating on the ball repulsed water and provided extra supporting force, leading to a faster movement on the surface of water. We hope that our findings would improve the understanding of superhydrophobic properties and be useful in further research on drag-reducing materials.

Superhydrophobic properties of silver-coated films on copper surface by galvanic exchange reaction

Hydrophobic properties of thin nanostructured silver films produced by galvanic exchange reaction on a copper surface were studied after passivation with stearic acid. The morphology of the silver films was controlled by varying the concentration of silver nitrate in the solution. Water contact angle as high as 156° and contact angle hysteresis as low as 5° were achieved for samples obtained with initial silver ion concentration of 24.75 mM in the solution. However, a strong dependence of contact angle and contact angle hysteresis on the fractal-like morphology of the silver films was observed with the variation of silver ion concentration.

Preparation of silver nanocomposites stabilized by an amphiphilic block copolymer under ultrasonic irradiation

Silver nanoparticles were synthesized by using amphiphilic block copolymer Polyacrylonitrile- block-poly(ethylene glycol)- blcok-Polyacrylonitrile (PAN- b-PEG- b-PAN, PEA) based on the flexibility of the copolymer chains and the complex effect of –CN in the polyacrylonitrile with Ag + ion and Ag under ultrasonic irradiation. The product was characterized by X-ray Diffraction (XRD), Fourier Transfer Infrared Spectrometer (FTIR), Transmission Electron Microscope (TEM), UV–Vis spectrum and Thermal Gravity Analysis (TGA). The results revealed that the size and size distribution of the resulting silver nanoparticles prepared basing on the copolymer were strongly dependent on the initial concentration of the silver ion solution and the irradiation conditions. Low initial silver ion concentration allowed for yielding silver nanoparticles with a small size and the size of the silver nanoparticles increased with increasing of silver ion concentration. The silver crystal was polycrystalline with a cubic structure, as confirmed by XRD. This work provides a simple route for the in situ synthesis of Ag nanoparticles.

Reaction of hypohalous acids with 2-halogenopropenes. Exchange of halogen atoms. Part II

2-Chloropropene reacts with [36Cl]hypochlorous acid in the presence of excess of silver ion to form chloroacetone (85%) and 2,3-dichloropropene (15%) both with a much reduced specific activity. The radioactivity in the 2,3-dichloropropene was shown to be exclusively in the 3-chloro-substituent. The loss of activity was decreased as the initial silver-ion concentration was increased. Similar exchange occurred in the reaction of 2-bromopropene with [82Br]hypobromous acid and the reaction of hypochlorous acid with 2-bromopropene produced bromoacetone as well as chloroacetone. Addition of halide ion to [36Cl]hypochlorous acid containing excess of silver ion showed the expected variation with silver ion of the radioactivity formed in solution which also decreased in the order Cl– > Br– > l–.