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.