Facile Synthesis of Magnetic Iron-Based Nanoparticles from the Leach Solution of Hyperaccumulator Plant Pinus brutia for the Antibacterial Activity and Colorimetric Detection of Ascorbic Acid.

It has been well known that metallic nanoparticles with striking properties possess wide application prospects in the processes of colorimetric detection, catalysis, disease diagnosis and treatment, energy, wastewater treatment, remediation, and antibacterial activity in recent years. Herein, iron-based nanoparticles (FeNPs), metallic nanoparticles, were synthesized via a facile chemical reduction method using a hyperaccumulator plant. Also, their use in antibacterial activity applications and colorimetric ascorbic acid (AA) detection was investigated. It was observed that FeNPs presented high antibacterial potency against Gram-positive bacteria of Listeria monocytogenes and Staphylococcus aureus and also Gram-negative bacteria of Escherichia coli(O157: H7), E. coli(ATCC 25922), Salmonella enteritidis, and Salmonella typhimurium. Moreover, it was found that FeNPs exhibited superior peroxidase-like activity to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue color product, oxidized TMB (oxTMB), in the presence of H2O2. The colorimetric AA detection could be carried out by making the solution color lighter owing to the antioxidant property of AA. The quantitative detection of AA could be performed simply, selectively, and sensitively with FeNPs with a detection limit (LOD) of 0.5462 µM in a linear range of 30-200 µM.

Efficient decolourization of malachite green with biosynthesized iron oxide nanoparticles loaded carbonated hydroxyapatite as a reusable heterogeneous Fenton-like catalyst.

In this study, iron oxide nanoparticles (IO-NPs) with a mean diameter of 102.85 nm were firstly synthesized via a facile green route using Ulva spp. aqueous extract as a bioreductant agent. Then, IO-NPs were loaded into carbonated hydroxyapatite (c-Hap) and the final product was named as the iron oxide nanoparticles loaded carbonated hydroxyapatite (IO-NPs-Lc-Hap). Subsequently, IO-NPs-Lc-Hap was characterized by FT-IR, SEM, XRD and EDX analysis methods. MG colour removal efficiencies of Ulva spp., Hap, IO-NPs and IO-NPs-Lc-Hap materials were also evaluated by adsorption and/or Fenton-like reaction methods. IO-NPs-Lc-Hap with the highest decolourization capacity was chosen as a heterogeneous Fenton-like catalyst for Malachite Green (MG). For Fenton-like decolourization of MG, the optimum H2O2 concentration, initial dye concentration and catalyst concentration were determined to be 30 mM, 100 mg/L and 1.0 g/L, respectively. At these optimum conditions, 100% decolourization efficiency and 33.3% COD removal were obtained. On the other hand, 94% decolourization efficiency and 42% COD removal were achieved for the real textile wastewater at the obtained optimum conditions. The experimental decolourization reaction rate for MG was determined as -rd = 0.0779 [(mg dye0.3) (g cat-0.3) (min-1)] × qt0.7. Also, the catalyst had high decolourization efficiencies at the end of six sequence usages.

Investigation of nickel(II) biosorption on Enteromorpha prolifera: optimization using response surface analysis.

In this study, the biosorption of nickel(II) ions on Enteromorpha prolifera, a green algae, was investigated in a batch system. The single and combined effects of operating parameters such as initial pH, temperature, initial metal ion concentration and biosorbent concentration on the biosorption of nickel(II) ions on E. prolifera were analyzed using response surface methodology (RSM). The optimum biosorption conditions were determined as initial pH 4.3, temperature 27 degrees C, biosorbent concentration 1.2 g/L and initial nickel(II) ion concentration 100 mg/L. At optimum biosorption conditions, the biosorption capacity of E. prolifera for nickel(II) ions was found to be 36.8 mg/g after 120 min biosorption. The Langmuir and Freundlich isotherm models were applied to the equilibrium data and defined very well both isotherm models. The monolayer coverage capacity of E. prolifera for nickel(II) ions was found as 65.7 mg/g. In order to examine the rate limiting step of nickel(II) biosorption, such as the mass transfer and chemical reaction kinetics, the intraparticle diffusion model, external diffusion model and the pseudo second order kinetic model were tested with the experimental data. It was found that for both contributes to the actual biosorption process. The pseudo second order kinetic model described the nickel(II) biosorption process with a good fitting.

Low cost removal of reactive dyes using wheat bran.

In this study, the adsorption of Reactive Blue 19 (RB 19), Reactive Red 195 (RR 195) and Reactive Yellow 145 (RY 145) onto wheat bran, generated as a by-product material from flour factory, was studied with respect to initial pH, temperature, initial dye concentration, adsorbent concentration and adsorbent size. The adsorption of RB 19, RR 195 and RY 145 onto wheat bran increased with increasing temperature and initial dye concentration while the adsorbed RB 19, RR 195 and RY 145 amounts decreased with increasing initial pH and adsorbent concentration. The Langmuir and Freundlich isotherm models were applied to the experimental equilibrium data depending on temperature and the isotherm constants were determined by using linear regression analysis. The monolayer covarage capacities of wheat bran for RB 19, RR 195 and RY 145 dyes were obtained as 117.6, 119.1 and 196.1 mg/g at 60 degrees C, respectively. It was observed that the reactive dye adsorption capacity of wheat bran decreased in the order of RY 145>RB 19>RR 195. The pseudo-second order kinetic and Weber-Morris models were applied to the experimental data and it was found that both the surface adsorption as well as intraparticle diffusion contributed to the actual adsorption processes of RB 19, RR 195 and RY 145. Regression coefficients (R2) for the pseudo-second order kinetic model were higher than 0.99. Thermodynamic studies showed that the adsorption of RB 19, RR 195 and RY 145 dyes onto wheat bran was endothermic in nature.

Biosorption of Acid Blue 290 (AB 290) and Acid Blue 324 (AB 324) dyes on Spirogyra rhizopus.

In this study, the biosorption of Acid Blue 290 and Acid Blue 324 on Spirogyra rhizopus, a green algae growing on fresh water, was studied with respect to initial pH, temperature, initial dye concentration and biosorbent concentration. The optimum initial pH and temperature values for AB 290 and AB 324 biosorption were found to be 2.0, 30 degrees C and 3.0, 25 degrees C, respectively. It was observed that the adsorbed AB 290 and AB 324 amounts increased with increasing the initial dye concentration up to 1500 and 750 mg/L, respectively. The Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models were applied to the experimental equilibrium data and the isotherm constants were determined by using Polymath 4.1 software. The monolayer coverage capacities of S. rhizopus for AB 290 and AB 324 dyes were found as 1356.6 mg/g and 367.0 mg/g, respectively. The intraparticle diffusion model and the pseudo-second order kinetic model were applied to the experimental data in order to describe the removal mechanism of these acidic dyes by S. rhizopus. The pseudo-second order kinetic model described very well the biosorption kinetics of AB 290 and AB 324 dyes. Thermodynamic studies showed that the biosorption of AB 290 and AB 324 on S. rhizopus was exothermic in nature.

Biosorption of Acid Red 274 (AR 274) on Enteromorpha prolifera in a batch system.

The biosorption of Acid Red 274 (AR 274) dye on Enteromorpha prolifera, a green algae grown on Mersin costs of the Mediterranean, Turkey, was studied as a function of initial pH, temperature, initial dye and biosorbent concentration. The experiments were conducted in a batch manner. The Langmuir and Freundlich isotherms were used for modelling the biosorption equilibrium. At optimum temperature 30 degrees C and initial pH 2.0-3.0, the Langmuir isotherm fits best to the experimental equilibrium data with a maximum monolayer coverage of 244 mg/g. The equilibrium AR 274 concentration of the exit stream of a single batch was also obtained by using the experimental equilibrium curve and operating line graphically. The pseudosecond-order kinetic model and Weber-Morris model were applied to the experimental data and it was found that both the surface adsorption as well as intraparticle diffusion contribute to the actual adsorption process. The biosorption process follows a pseudosecond-order kinetics and activation energy was determined as -4.85 kJ/mol. Thermodynamic studies showed that the biosorption of AR 274 on E. prolifera is exothermic and spontaneous in nature.

Comparative study of the biosorption of Pb(II), Ni(II) and Cr(VI) ions onto S. cerevisiae: determination of biosorption heats.

In this study, the biosorption of Pb(II), Ni(II) and Cr(VI) ions onto inactive Saccharomyces cerevisiae was investigated as a function of initial pH, initial metal ion concentration and temperature. The Langmuir model was applied to experimental equilibrium data of Pb(II), Ni(II) and Cr(VI) biosorption depending on temperature and the maximum metal ions uptake at optimum biosorption temperature of 25 degrees C, were found to be 270.3, 46.3 and 32.6 mgg(-1), respectively. Using the Langmuir constant, b values obtained at different temperatures, the biosorption heats of Pb(II), Ni(II) and Cr(VI) were determined as -1.125, -1.912 and -2.89 kcalmol(-1), respectively. The results indicated that the biosorption of Pb(II), Ni(II) and Cr(VI) ions to S. cerevisiae is by the physical adsorption and has an exothermic nature.