Biosorption of As (III) by Non-living Biomass of an Arsenic-Hypertolerant Bacillus cereus Strain SZ2 Isolated from a Gold Mining Environment: Equilibrium and Kinetic Study

The ability of non-living biomass of an arsenic-hypertolerant Bacillus cereus strain SZ2 isolated from a gold mining environment to adsorb As (III) from aqueous solution in batch experiments was investigated as a function of contact time, initial As (III) concentration, pH, temperature and biomass dosage. Langmuir model fitted the equilibrium data better in comparison to Freundlich isotherm. The maximum biosorption capacity of the sorbent, as obtained from the Langmuir isotherm, was 153.41 mg/g. The sorption kinetic of As (III) biosorption followed well the pseudo-second-order rate equation. The Fourier transform infrared spectroscopy analysis indicated the involvement of hydroxyl, amide and amine groups in As (III) biosorption process. Field emission scanning electron microscopy–energy dispersive X-ray analysis of the non-living B. cereus SZ2 biomass demonstrated distinct cell morphological changes with significant amounts of As adsorbed onto the cells compared to non-treated cells. Desorption of 94 % As (III) was achieved at acidic pH 1 showing the capability of non-living biomass B. cereus SZ2 as potential biosorbent in removal of As (III) from arsenic-contaminated mining effluent.     

Removal of La(III) by amino-phosphonic acid functionalized polystyrene microspheres prepared via electron beam irradiation

A new aminophosphonic acid chelating resin was successfully prepared via electron beam irradiation grafting combined with chemical modification and used for the efficient removal of La(III). Firstly, glycidyl methacrylate (GMA) was grafted to polystyrene microspheres (PS) via electron beam co-radiation to obtain PS-PGMA microspheres, then followed by the amination with diethylenetriamine (DETA) to formed PS-PGMA-DETA (PGD) microspheres through nucleophilic substitution between amino and epoxy group, and finally PS-PGMA-DETA-PA (PGDP) microspheres was obtained by phosphorylation with phosphorous acid (PA). The obtained chelating resin absorbent was characterized by Fourier-transform infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), which demonstrated that the millimetric aminophosphonic acid chelating resin were successfully prepared with well-defined morphology and enhanced thermal stability. The X-ray photoelectron spectroscopy (XPS) characterization results confirmed a possible adsorption mechanism, which is mainly based on the chelation and coordination of N and O in PDGP with La(III) in the solution. A series of parameters were taken into account in the adsorption experiment, such as absorbed dose, GMA concentration, dosage of PGDP, pH, contact time, temperature, and the initial concentrations of La(III). The maximum adsorption capacity obtained from the research can be achieved 288.69 mg/g at 298.15 K, pH = 6. The kinetic sorption for for La(III) fitted the type 1 pseudo-second-order (R² = 0.9981), which revealed that the La(III) are chemisorbed on the surface of the PGDP. It was concluded that the La(III) adsorption conformed to the Freundlich equation, indicating a multilayer adsorption process. Thermodynamic data indicated that the La(III) uptake process was a spontaneous and endothermic. In addition, this research provided a new irradiation grafting method for rare earth ions removal.     

Synthesis,spectroscopic and thermal studies of 2,3-naphthalenedicarboxylates of rare earth elements

The complexes of rare earth elements with 2,3-naphthalenedicarboxylic acid of the formula: Ln₂(C₁₂H₆O₄)₃·nH₂O, where Ln = La(III)-Lu(III) and Y(III); n = 3 for La(III), Ce(III); n = 6 for Pr(III)-Yb(III) and Y(III) and n = 5 for Lu(III) have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis (TG, DTG, DTA and TG-FTIR) and X-ray analysis. They are sparingly soluble in water and stable at room temperature. During heating in air atmosphere, they lose all water molecules in several steps, generally in two or three steps, except for the La(III) and Ce(III) complexes which lose all water molecules in one step. The anhydrous compounds are stable up to about 773 K and then decompose to corresponding oxides. The thermal decomposition is connected with the release of water molecules (443 K), carbon dioxide (713 K) and hydrocarbons.     

Biosorption kinetics, thermodynamics and isosteric heat of sorption of Cu(II) onto Tamarindus indica seed powder

Biosorption of Cu(II) by Tamarindus indica seed powder (TSP) was investigated as a function of temperature in a batch system. The Cu(II) biosorption potential of TSP increased with increasing temperature. The rate of the biosorption process followed pseudo second-order kinetics while the sorption equilibrium data well fitted to the Langmuir and Freundlich isotherm models. The maximum monolayer Cu(II) biosorption capacity increased from 82.97 mg g(-1) at 303 K to 133.24 mg g(-1) at 333 K. Thermodynamic study showed spontaneous and endothermic nature of the sorption process. Isosteric heat of sorption, determined using the Clausius-Clapeyron equation increased with increase in surface loading showing its strong dependence on surface coverage. The biosorbent was characterized by scanning electron microscopy (SEM), surface area and porosity analyzer, X-ray diffraction (XRD) spectrum and Fourier transform infrared (FTIR) spectroscopy. The results of FTIR analysis of unloaded and Cu(II)-loaded TSP revealed that -NH(2), -OH, -C=O and C-O functional groups on the biosorbent surface were involved in the biosorption process. The present study suggests that TSP can be used as a potential, alternative, low-cost biosorbent for removal of Cu(II) ions from aqueous media.     

Antioxidant,Anti-inflammatory and Biosorption Properties of Starch Nanocrystals In Vitro Study: Cytotoxic and Phytotoxic Evaluation

This study aimed to investigate the antioxidant, anti-inflammatory and biosorption properties of starch nanocrystals (SNC). The characterization of synthesized SNC was done using various analytical techniques like microscopic and spectroscopic analysis. The antioxidant property was determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and metal ion chelating assay. SNC showed the highest scavenging activity of 70.03?±?0.74% at 100 µg/mL concentration. Protein denaturation assay and proteinase inhibitory assay depicted the anti-inflammatory property of SNC. The results revealed that the maximum inhibition activity was found at 100 µg/mL with 72.71% inhibition. The maximum removal efficiency was found to be 83.42% at pH 2.0 with 0.15 g biosorbent. As the pH increases, biosorption capacity of SNC were reduced from 8.17 to 6.30 mg/g and the efficiency of the dye removal was decreased from 80.95 to 36.01%. The shape of synthesized SNC was spherical nanoplatelets and it shows agglomeration. The Langmuir isotherm model is best suited for the biosorption experiments with the R2 value of 0.986. SNC were subjected to cytotoxic and phytotoxic evaluation. Cell viability and phytotoxic assays proves the non-toxic nature of the SNC.

     

Highly ordered mesoporous La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 as a very efficient nanocatalyst for green aerobic oxidative coupling of thiols to disulfides

Selective aerobic oxidative coupling of thiols that are catalyzed by La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 (SBA-15@Glp–La; SBA = Santa Barbara amorphous) was studied. Using SBA-15@Glp–La, the complete conversion was achieved at room temperature in the presence of air without producing any over-oxidized yields. SBA-15@Glp–La was prepared by post-grafting technique. 5-Oxopyrrolidine-2-carboxylic acid (Glp) condensation followed by La(III) impregnation caused this La(III)-grafted 5-oxopyrrolidine-2-carboxylic acid (Glp) to immobilize on SBA-15. This SBA-15@Glp–La catalyst shows excellent catalytic activity in the selective aerobic oxidative coupling of thiols. Effects of amount of the catalyst, polarity of the solvent, effects of substrate, and catalyst reusability were investigated. It has been observed that seven repetitive reaction cycles did not cause any appreciable loss in the catalytic activity of this catalyst. The catalyst characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy, inductively coupled plasma, elemental mapping, and N₂ adsorption–desorption is reported. The procedure developed is heterogeneous and environmentally benign.     

Norfloxacin La(III)-based complex: synthesis,characterization, and DNA-binding studies

A La(III) complex, [La^IIICl₂(NOR)₂]Cl (2), containing norfloxacin (NOR) (1), a synthetic fluoroquinolone antibacterial agent, has been synthesized and characterized by elemental analysis, IR, UV–vis spectra and ¹H NMR spectroscopy, and molar conductance measurements. The interaction between 2 and CT-DNA was investigated by steady-state absorption and fluorescence techniques in different pH media, and showed that 2 could bind to CT-DNA presumably via non-intercalative mode and the La(III) complex showed moderate ability to bind CT-DNA compared to other La(III) complexes. The binding site number n, and apparent binding constant K_A, corresponding thermodynamic parameters ΔG^#, ΔH^#, ΔS^# at different temperatures were calculated. The binding constant (K_A) values are 0.23 ± 0.05, 0.56 ± 0.05, and 0.18 ± 0.08 × 10⁵ L mol^?1 for pH 4, 7, and 11, respectively. It was also found that the fluorescence quenching mechanism of CT-DNA by La(III) complex was a static quenching process.     

Electroanalytical Determination of Arsenic(III) and Total Arsenic in 1 mol L−1 HCl Using a Carbonaceous Electrode Without a Reducing Agent

Abstract

Arsenic(V) [As(V)] was reduced to As(0) at pH 0.0 and As(III) at pH 4.5 on a carbon-paste electrode modified with hematite, which allowed their selective determination. Arsenic(V) suffered interference from copper (Cu) and bismuth (Bi). Arsenic(III) was almost free of them. Humic acid did not affect the signal of As(V) but increased the signal of As(III). Arsenic was preconcentrated at ?0.8 V for 100 s. The response was linear up to 70 µg L^?1 for As(V) and 50 µg L^?1 for As(III). The limits of detection were 2 µg L^?1 and 5 µg L^?1 respectively. This method was applied to drinking water and compost lixiviate.     

Biosorption of Ni(II) from electroplating wastewater by modified (Eriobotrya japonica) loquat bark

Biosorption of nickel ions from aqueous solutions by modified loquat bark waste (MLB) has been investigated in a batch biosorption process. The biosorbent MLB was characterized by FTIR analysis. The extent of biosorption of Ni(II) ions was found to be dependent on solution pH, initial nickel ions concentration, biosorbent dose, contact time, and temperature. The experimental equilibrium biosorption data were analyzed by three widely used two-parameters Langmuir, Temkin and Freundlich isotherm models. Langmuir and Temkin isotherm models provided a better fit with the experimental data than Freundlich isotherm model by high correlation coefficients R². The maximum adsorption capacity was 27.548 mg/g of Ni(II) ions onto MLB. The thermodynamic analysis indicated that the biosorption behavior of nickel ions onto MLB biosorbent was an endothermic process, resulting in higher biosorption capacities at higher temperatures. The negative values of ΔG° (−5.84 kJ/mol) and positive values of ΔH° (13.33 kJ/mol) revealed that the biosorption process was spontaneous and endothermic. Kinetic studies showed that pseudo-second order described well the biosorption experimental data. The modified loquat bark (MLB) was successfully used for the biosorption of nickel ions from synthetic and industrial electroplating effluents.     

Identification of Saturating Solid Phases in the System Ce2(SO4)3-H2O from the Solubility Data

Saturating solid phases, Ce₂(SO₄)₃·hH₂O, with hydrate numbers h equal to 12, 9, 8, 5, 4 and 2, have been identified by critical evaluation of the solubility data in the system Ce₂(SO₄)₃—H₂O over the temperature range 273–373 K. The results are compared with the respective TG—DTA—DSC and X-ray data. The solubility smoothing equations, transition points and solution enthalpy estimators of the identified hydrates are given. The stable equilibrium solid phases are concluded to be only Ce₂(SO₄)₃·9H₂O at 273–310 K, Ce₂(SO₄)₃·4H₂O at 310–367 K and Ce₂(SO₄)₃·2H₂O at 367–373 K. Divergencies of up to 185% in the reported solubility data are mainly due to a variety of metastable equilibria involved in the close crystallization fields, and incorrect assignments of the saturating solid phases. Since a similar variety of the hydrate numbers exists for the analogous La(III) system, it most probably also occurs for the corresponding Pu(III), Np(III) and U(III) systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Assessment of copper(II) biosorption from aqueous solution by agricultural and industrial residues

In this study, newspaper scraps (NS) and maize spatha (MS) treated in turn by HNO₃ and MeOH were evaluated for the biosorption of Cu²⁺ ions, on the basis of batch experiments. The effects of several parameters were investigated, including contact time, solution pH, shaking speed, biosorbent dosage and ionic strength. Under optimal conditions, the maximum sorption capacities (Q_max) were (60.386 ± 0.006) and (44.90 ± 0.02) μmol Cu²⁺ per g of sorbent, respectively, for NS and MS chemically treated with HNO₃. The optimal parameters were pH: 5, contact time: 40 min and shaking speed: 100 rpm for NS, while for MS the same parameters were pH 5, 20 min and 150 rpm, respectively. It was found that Cu²⁺ biosorption is disfavored by an increase in ionic strength and by the presence of some interfering cations. The experimental data obtained with NS best matched the Langmuir’s sorption model (R² = 0.994) while the Temkin model best described biosorption on MS (R² = 0.987). The biosorption of Cu²⁺ on both materials followed pseudo-second order kinetics, and the desorption of Cu²⁺ ions was effective in 0.01 M HCl solution.     

Construction and characterization of nano iron complex ionophore for electrochemical determination of Fe(III) in pure and various real water samples

Electrochemical methods represent an important class of widely used techniques for the detection of metal ions. The unique chemical and physical properties of nanoparticles make them extremely suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. This study focused on the synthesis of a nano‐Fe(III)–Sud complex and its characterization using various spectroscopic and analytical tools, optimized using the density functional theory method, screened for antibacterial activity and evaluated for possible binding to DNA using molecular docking study. Proceeding from the collected information, nano‐Fe(III)–Sud was used further for constructing carbon paste and screen‐printed ion‐selective electrodes. The proposed sensors were successfully applied for the determination of Fe(III) ions in various real and environmental water samples. Some texture analyses of the electrode surface were conducted using atomic force microscopy. At optimum values of various conditions, the proposed electrodes responded towards Fe(III) ions linearly in the range 2.5 × 10^?9–1 × 10^?2 and 1.0 × 10^?8–1 × 10^?2 M with slope of 19.73 ± 0.82 and 18.57 ± 0.32 mV decade^?1 of Fe(III) ion concentration and detection limit of 2.5 × 10^?9 and 1.0 × 10^?8 M for Fe(III)–Sud‐SPE (electrode I) and Fe(III)–Sud‐CPE (electrode II), respectively. The electrode response is independent of pH in the range 2.0–7.0 and 2.5–7.0, with a fast response time (4 and 7 s) at 25°C for electrode I and electrode II, respectively. Moreover, the electrodes also showed high selectivity and long lifetime (more than 6 and 3 months for electrode I and electrode II, respectively). The electrodes showed good selectivity for Fe(III) ions among a wide variety of metal ions. The results obtained compared well with those obtained using atomic absorption spectrometry.     

New complexes of lanthanide Ln(III), (Ln = La, Sm, Gd, Er) with Schiff bases derived from 2-furaldehyde and phenylenediamines

Some new Schiff bases derivates from 2-furaldehyde and phenylenediamines (L^1-3) and their complexes with lanthanum (La), samarium (Sm), gadolinium (Gd) and erbium (Er) have been synthesized. These complexes with general formula [Ln(L^1-3)₂(NO₃)₂]NO₃·nH₂O (Ln = La, Sm, Gd, Er) were characterized by elemental analysis, UV-Vis, FT-IR and fluorescence spectroscopy, molar conductivity and thermal analysis. The metallic ions were found to be eight coordinated. The emission spectra of these complexes indicate the typical luminescence characteristics of the Sm(III), La(III), Er(III) and Gd(III) ions.     

Study on the characterization of lead (II) biosorption by fungus <Emphasis Type="Italic">Aspergillus parasiticus</Emphasis>

The lead (II) biosorption potential of Aspergillus parasiticus fungal biomass has been investigated in a batch system. The initial pH, biosorbent dosage, contact time, initial metal ion concentrations and temperature were studied to optimize the biosorption conditions. The maximum lead (II) biosorption capacity of the fungal biosorbent was found as 4.02 × 10⁻⁴ mol g⁻¹ at pH 5.0 and 20°C. The biosorption equilibrium was reached in 70 min. Equilibrium biosorption data were followed by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. In regeneration experiments, no significant loss of sorption performance was observed during four biosorption-desorption cycles. The interactions between lead (II) ions and biosorbent were also examined by FTIR and EDAX analysis. The results revealed that biosorption process could be described by ion exchange as dominant mechanism as well as complexation for this biosorbent. The ion exchange mechanism was confirmed by E value obtained from D-R isotherm model as well.     

Utilization of anion exchange resin Spectra/Gel for separation of arsenic from water

Arsenic in drinking water is one of the most challenging health hazards facing mankind today. Arsenic is a naturally occurring carcinogen and creates epidemiological problems through chronic ingestion from drinking water. Arsenic is present in water primarily as As(III) or As(V). Removal of both As(III) and As(V) from water by adsorption on strong base anion-chloride has been studied. Arsenic concentration was measured by Inductively Coupled Argon Plasma (ICP) analysis. The resin was regenerated and the adsorbed arsenic fractions were eluted by using 2 M NaCl. The effect of different parameters that influence adsorption process, such as relative arsenic and resin concentrations, retention time, and pH, were investigated. Results obtained revealed that As(III) was poorly adsorbed, whereas As(V) was successfully retained on the resin. The adsorption process was optimized by using 1 g resin for 16 ppm As(V) at pH 9 for 30 min. The removal efficiency of As(V) was 99.2%.     

Magneto-structural correlation and low temperature heat capacity of a Mn (III) quadridentate Schiff-base coordination compound

A new Mn (III) Schiff-base coordination compound, [Mn(L)(NCS)]₂ (H₂L = N,N′-bis(5-chlorosalicylidene)-1,2-diaminoethane), has been synthesized and characterized structurally and magnetically. The target compound is a phenoxo-bridged dimeric compound with the isothiocyanate coordinating in a usual bent mode. A magnetic susceptibility study reveals that the target compound exhibits antiferromagnetic intra-dimer coupling between Mn (III) ions. The low temperature heat capacity of the compound over the temperature range (2 to 300) K has been measured using the heat capacity option of a Quantum Design Physical Property Measurement System (PPMS). The thermodynamic functions in the experimental temperature range have been determined by curve fitting. The standard entropy and enthalpy of the as-prepared compound at T = 298.15 K have been calculated to be (924.52 ± 10.17) J · K⁻¹ · mol⁻¹ and (133.47 ± 1.47) kJ · mol⁻¹, respectively.     

Performance of Pleurotus ostreatus Mushrooms and Spent Substrate for the Biosorption of Cd(II) From Aqueous Solution

The capacities of Pleurotus ostreatus mushroom and spent substrate were evaluated for the biosorption of cadmium (II) from aqueous solution in order to select the most efficient material for bioremediation. The optimum sorption conditions were optimized, including the pH of the aqueous solution, contact time, biomass dosage, initial metal concentration, and temperature. The sorption of cadmium on both biosorbents was also evaluated by several kinetic, equilibrium, and thermodynamic models. The possible heavy metal biosorption mechanisms were evaluated through point of zero charge (pH_pzc), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). Based on the results of column studies, the effectiveness of the P. ostreatus spent substrate was confirmed as a biosorbent for Cd(II) removal from aqueous solutions.     

Lanthanide complex of 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldehyde-(isonicotinoyl) hydrazone: crystal structure and DNA-binding properties

A Schiff-base ligand derived from 1-phenyl-3-methyl-4-formyl-2-pyrazolin-5-one (PMFP) and isoniazid was prepared and its La(III) complex was characterized by X-ray single crystal diffraction. The La(III) is nine-coordinate in a space group P2₁/n. DNA-binding was investigated by UV-Vis, fluorescence titration, ethidium bromide displacement experiments, and viscosity measurements, which indicated that the ligand and La(III) complex strongly binds to calf thymus DNA presumably via groove binding and intercalation. The intrinsic binding constants of the ligand and La(III) complex were 0.86?×?10⁵ and 2.46?×?10^5?mol?L^?1, respectively. Antioxidant data from hydroxyl radical scavenging experiments in vitro suggest that the La(III) complex possesses higher scavenging ratio than the free ligand, metallic salt, and some standard antioxidants like mannitol.     

Synthesis and cytotoxicity study of gold(III) porphyrin complexes and their derivative in breast cancer cells

Gold(III) [Au(III)] complexes exhibit potential anticancer activities. A series of Au(III) porphyrin complexes containing different meso-substituent groups (phenyl, methoxyphenyl, butyloxyphenyl, octyloxyphenyl, and decyloxyphenyl) was synthesized. The synthesized compounds were characterized using mass spectrometry, infrared spectroscopy, UV–visible and fluorescence spectroscopy, and electron paramagnetic resonance spectroscopy. Moreover, the in vitro cytotoxicity of these Au(III) porphyrin complexes was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide surrogate viability assay on an MCF7 human breast cancer cell line. The Au(III) complexes with 5,10,15,20-tetraphenylporphyrin (AuTPP) and 5,10,15,20-tetrakis(4-methyloxyphenyl)porphyrin (AuTOMPP) demonstrated high anticancer activity with IC₅₀ values against MCF7 cells at 4.30 and 25.35 µM, respectively. The toxicity of the Au(III) porphyrin complexes against the LLC-MK2 rhesus monkey kidney epithelial cell line, a representative normal cell line, was investigated. All the tested Au(III) porphyrin complexes were non-cytotoxic in LLC-MK2 cells. For AuTPP, more than 80% LLC-MK2 cell viability was observed at concentrations lower than 5 μM.