A comprehensive study on the adsorption-photocatalytic processes using CoFe2O4/SiO2/MnO2 magnetic nanocomposite as a novel photo-catalyst for removal of Cr (VI) under simulated sunlight: Isotherm, kinetic and thermodynamic studies.

Purpose: The present study aimed to investigate the efficiency of CoFe2O4/SiO2/flower-like MnO2 nanoparticles as a catalyst for Cr (VI) adsorption-photocatalytic processes. Methods: The magnetic nanocomposite used was first synthesized and then characterized using TEM, SEM, EDX, XRD, FTIR, XRF and BET advanced techniques. The removal of the Cr (VI) was performed through a batch adsorption approach and the effects of sample pH (A; 2-6), initial chromate concentration (B; 50-100 ppm) and adsorbent weight to sample volume ratio (C; 1-3 mg ml-1), hole scavenger (0.1 -0.3%w/v) and time (E; 30-60 min), to evaluate the individual and interactive effects under ultraviolet light conditions, were also studied by the central composite design in the photocatalytic process of adsorption. Results: The adsorption-photocatalytic performance of the CoFe2O4/SiO2/MnO2 composite was high in which 98.1% of Cr(VI) after 30 min of photocatalytic treatment in optimum conditions (i.e. pH = 3, catalyst concentration = 2 mg L-1, Cr(VI) concentration = 200 mg L-1, and hole scavenger concentration = 0.4% (w/ v), At laboratory temperature, speed = 400 rpm, under UV radiation).Under optimum conditions, Cr(VI) reductive followed pseudo-second-order kinetics and followed the Langmuir and Temkin isotherms, also, positive value of ΔH° indicates endothermic nature. Conclusions: The results showed that the synthesized CoFe2O4/SiO2/MnO2 magnetic nanocomposite holds a great potential for use as a photocatalyst to remove Cr (VI) in adsorption reactions. It can be used as an effective catalyst in the eradication of Cr (VI) wastewater. Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-021-00763-1.

Gel electro-membrane extraction of propranolol and atenolol from blood serum samples: Effect of graphene-based nanomaterials on extraction efficiency of gel membrane.

In this work, gel electro-membrane extraction (G-EME) method is suggested for extraction and determination of propranolol and atenolol in complex biological samples. An in-house membrane based on agarose was used as green and biodegradable gel membrane. Essential chemical parameters that influence on extraction efficiency were tested, optimized and evaluated via a central composite design (CCD) and response surface methodology (RSM). Optimal conditions for extraction of drugs from the 7.0 mL sample were as follows: 3% (w/v) agarose with 0.1% (v/v) acetic acid functioning as membrane, voltage: 50 V; pH of the donor phase (DP): 8.1; pH of the AP: 3.3; extraction time: 35.9 min. Under these conditions, the acceptable normalized extraction recoveries were obtained such as 71.9 ± 5.4% that were in good agreement with the predicted values (i.e., 73.1 ± 0.9%). Limits of detection (LODs) for propranolol and atenolol were 5.0 ng mL-1 and 7.5 ng mL-1, respectively. Moreover, for the first time, the effect of presence of four graphene-based nanomaterials such as graphene (G), graphene oxide (GO), three-dimensional nitrogen doped graphene oxide (3D-ND-GO) and high nitrogen doped graphene oxide (HND-GO) in agarose gel membrane on extraction efficiency, was investigated. The results showed that in presence of these nanomaterials, the normalized recovery depressed significantly due to increasing of electric current and electroendosmosis (EEO) phenomenon. Eventually, the proposed method was applied to quantify basic drugs in real plasma samples with relative recoveries in the range of 85.7-97.5%, indicating good reliability of the assay.

Modified nickel ferrite nanocomposite/functionalized chitosan as a novel adsorbent for the removal of acidic dyes.

As a new type of magnetic adsorbent, a nickel ferrite nanocomposite modified by functionalized chitosan was developed to remove methyl orange and Congo red from aqueous solutions. This new adsorbent was characterized and utilizing batch adsorption approach, the mechanism of methyl orange and Congo red removal were probed. Following that the study on pertinent parameters which could influence the efficiency of the dyes removal, i.e. pH of the solution, initial dye concentration, dose of the adsorbent, and contact time were accomplished in order to arrive their optimized values by using response surface methodology. In addition, kinetics and isotherm studies were conducted on the developed system. Langmuir model was used to probe adsorption isotherm, acquiring adsorption capacity of 551.2 and 274.7 mg g-1 for methyl orange and Congo red, respectively. Both of methyl orange and Congo red adsorption kinetics obeyed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step and only 5 min was required to remove 50% of dyes. The fitting of experimental data was fulfilled with intra-particle diffusion reaching to conclusion that the adsorption kinetic could be controlled simultaneously by film diffusion and intra-particle diffusion. Furthermore, the desorption studies of dyes showed that the adsorbent is reusable.

A new and highly selective turn-on fluorescent sensor with fast response time for the monitoring of cadmium ions in cosmetic, and health product samples.

Cadmium (Cd) which is an extremely toxic could be found in many products like plastics, fossil fuel combustion, cosmetics, water resources, and wastewaters. It is capable of causing serious environmental and health problems such as lung, prostate, renal cancers and the other disorders. So, the development of a sensor to continually monitor cadmium is considerably demanding. Tetrakis(4-nitrophenyl)porphyrin, T(4-NO2-P)P, was synthesized and used as a new and highly selective fluorescent probe for monitoring cadmium ions in the "turn-on" mode. There was a linear relationship between fluorescence intensity and the concentration of Cd(II) in the range of 1.0×10(-6) to 1.0×10(-5)molL(-1) with a detection limit of 0.276µM. To examine the most important parameters involved and their interactions in the sensor optimization procedure, a four-factor central composite design (CCD) combined with response surface modeling (RSM) was implemented. The practical applicability of the developed sensor was investigated using real cosmetic, and personal care samples.

Cd-Cysteine Nanorods as a Fluorescence Sensor for Determination of Fe (III) in Real Samples.

A new Cd-Cysteine complex nanorods (Cd-Cys NRs) were synthesized in one step at room temperature, and its morphology, structure and spectral properties were characterized by transmission electron microscopy (TEM), elemental analysis (EA), X-Ray diffraction (XRD), solid state and normal UV-Vis, Fourier transform infrared (FTIR) and spectrofluorometry. The developed Cd-Cys NRs were used as a fluorescence sensor for detection of Fe (III) in different aqueous matrices. The selectivity and sensitivity of the fabricated nano-sensor based on its fluorescence quenching in the presence of Fe (III) were probed according to the Stern-Volmer equation. The detection limit of the method was in micro-molar per liter range. Cd-Cys NRs response tested in different complex samples such as Rosemary plant leaves, exhibited a well-defined response. Anticoagulation measurements were performed to evaluate their blood biocompatibility.