Novel Polymer-Bentonite Sorbent for Recovery of Antioxidant Polyphenols from Cornus mas L. through Integrated Process Extraction/Adsorption: Optimization of Extraction Parameters by Response Surface Methodology

Here, ultrasound-assisted extraction with ultrasonic probe of total polyphenolic content from leaves of cornelian cherry (Cornus mas L.) was studied. Batch adsorption was carried out to concentrate polyphenol extract using bentonite/2-(dimethyl amino) ethyl methacrylate composite adsorbent. The extraction was optimized through face central composite design combined with response surface methodology. It was found that bentonite/2-(dimethyl amino) ethyl methacrylate composite exhibits significant adsorption capacity (2407.50 mg-GAE/g-bentonite/2-(dimethyl amino) ethyl methacrylate composite) for polyphenols in cornelian cherry leaves. It was observed that pH was the crucial factor and highest adsorption capacity was obtained at pH 10. © 2016, Copyright © Taylor & Francis Group, LLC

Environmental aspects of direct methanol fuel cell: Experimental detection of methanol electro-oxidation products

This study deals with the experimental investigation of compositional changes of various liquid/gas streams during mid-term (3 h) continuous operation of an active direct methanol fuel cell (DMFC). A test system is equipped with various sensors and with sampling ports to collect liquid samples to measure off-line methanol, formaldehyde, and formic acid concentrations by means of high pressure liquid chromatography (HPLC) and UV spectroscopy. Initially, polarization study is performed to select suitable operating ranges to be considered in an experimental plan according to which runs are performed to collect process data from the system. Then, the experimental data is fitted using regression analysis for the statistical evaluation of the impacts of operating variables on the compositions of methanol tank solution and cathode gas by means of response surface plots. The cathode gas composition is further discussed in the context of methanol crossover and catalytic chemical reactions on the cathode side. Experiments show that methanol, formaldehyde, and formic acid concentrations may exceed their safe limits of exposure depending on the operating conditions. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1847–1855, 2017. © 2017 American Institute of Chemical Engineers Environ Pro

A novel approach for olive leaf extraction through ultrasound technology : Response surface methodology versus artificial neural networks

Response surface methodology (RSM) and artificial neural network (ANN) were used to evaluate the ultrasound-assisted extraction (UAE) of polyphenols from olive leaves. To investigate the effects of independent parameters on total phenolic content (TPC) in olive leaves, pH (3–11), extraction time (20–60 min), temperature (30–60 °C) and solid/solvent ratio (500 mg/10–20 mL) were selected. RSM and ANN approaches were applied to determine the best possible combinations of these parameters. Box-Behnken design model was chosen for designing the experimental conditions through RSM. The second-order polynomial models gave a satisfactory description of the experimental data. Experimental parameters and responses were used to train the multilayer feed-forward networks with MATLAB. ANN proved to have higher prediction accuracy than that of RSM. © 2014, Korean Institute of Chemical Engineers, Seoul, Korea

Pulsed ultrasound-assisted extraction of natural antioxidants from mandarin (Citrus deliciosa Tenore) leaves: Experimental and modeling study

Pulsed ultrasound-assisted extraction (PUAE) of flavonoids and polyphenols from mandarin (Citrus deliciosa Tenore) leaves was examined. The response surface methodology (RSM) via face-centered central composite design (FCCD) was used to investigate the effects of extraction time (15–75 min), output amplitude (30–70%), and pH (4–10) to optimize the extraction process. The total phenolic material (TPM) and the total flavonoid material (TFM) and also the consumed energy of horn were measured as responses. Additionally, calorimetric calculations were done to evaluate the ultrasound energy dissipated into the solution. The calculated quadratic models were highly significant (p < 0.0001) for all the parameters studied with high correlation coefficients (R2) of 0.9722, 0.9805, and 0.9983. The results of the present study suggest that 65 min, 68.72 min, 15.00 extraction time, 61%, 59%, and 30% of ultrasound amplitude and 4, 6.7, and 4 pH of solution should be considered as optimal extraction conditions to get the optimum TPM (37.845 mg-GAE/g-DL), TFM (10.709 mg-CE/g-DL), and energy consumption (6130.275 Joule) for PUAE of mandarin leaves, respectively. © 2018 Taylor & Francis.Istanbul ÜniversitesiThe authors wish to thank for the support of the Research Fund of Istanbul University. The project number is 22959

Evaluation of 2,4-D removal via activated carbon from pomegranate husk/polymer composite hydrogel: Optimization of process parameters through face centered composite design

A new type of polymer composite hydrogel was prepared by introducing activated carbons from pomegranate husk into poly ((2-dimethylamino) ethyl methacrylate) network. The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution was studied with respect to pH of the media, initial 2,4-D concentration and activated carbon content into the polymeric network. Face centered composite design (FCCD) through response surface methodology (RSM) was used for designing the experiments as well as for studying the effects of the process parameters. A quadratic model and a two factor interaction design model were developed for the removal of 2,4-D and adsorption capacity, respectively. The optimum pH of the pesticide solution, activated carbon content into the polymeric network and initial concentration of 2,4-D were found as 3, 2.5 wt% and 100mg/L. 63.245% and 68.805 (mg/g) for the removal of 2,4-D and adsorption capacity were obtained by using Simplex optimization method. Furthermore, the surface characteristics of the adsorbent prepared under optimized conditions were examined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). © 2015, Korean Institute of Chemical Engineers, Seoul, Korea

Study on Optimum Extraction Conditions for Olive Leaf Extracts Rich in Polyphenol and Flavonoid

Ultrasound-assisted extraction (UAE) of polyphenols and flavonoids from olive leaves was investigated. The effects of temperature (27?37°C), solvent concentration (10?70% ethanol (EtOH), v/v) and time (30?60 min) were determined by both experimental and Response Surface Methodology (RSM) techniques. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. For total phenolic content (TPC), 43.8252 mg-GAE/g dried leaf was predicted at the optimum conditions (34.18°C, 43.61% (v/v) of EtOH, and 59.99 min). In case of total flavonoid content (TFC), 31.9920 mg-CE/g dried leaf was calculated at the optimum conditions (34.44°C, 70% (v/v) of EtOH, and 60 min). © , Copyright © Taylor & Francis Group, LLC

A Green Valorisation Approach Using Microwaves and Supercritical CO 2 for High-Added Value Ingredients from Mandarin (Citrus deliciosa Tenore) Leaf Waste

The present study aims to increase the efficiency of a resource from waste to health by valorisation of it through cleaner, eco-friendly and less energy-consuming technical processes such as microwave-asissted (MAE) and supercritical fluid (SFE) extractions. On the other hand, optimization of the processes have been applied utilizing multivariate statistic technique such as Response surface Methodology (RSM) in order to consider any possible interaction between variables with less number of experiments as well as to model a response affected by several variables. The outcome of the present study indicates that the optimum conditions for MAE were 275 W of microwave power together with 2 g mandarin leaf for 45 s; regarding SFE, 50 °C, 200 bar and 0.39 mL/min was found as the optimal condition to obtain the maximum yields of each dependent variable such as total phenolic material (TPM) and total flavonoid material (TFM), respectively. Additionally, antioxidant activity values measured by several methods such as cupric ion reducing antioxidant capacity (CUPRAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2?-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) were correlated positively with both TPM and TFM in the leaf extracts. Furthermore, scanning electron microscope (SEM) images indicated cell wall disruption in all the treatement groups compared to untreated samples. © 2017, Springer Science+Business Media B.V.Acknowledgements The authors wish to thank for the support of the Research Fund of Istanbul University (Bilimsel Araştirma Projeleri Birimi, Istanbul Üniversitesi). Project number is 41685

Isolation of naproxen from wastewater using carbon-based magnetic adsorbents

Naproxen is one of the mostly used drugs worldwide and is most abundant in wastewater. This study aims to adsorb naproxen from wastewater using magnetically modified carbon-based adsorbents. These adsorbents have very large specific area for naproxen adsorption, and magnetite modification provides easy separation and regeneration. The co-precipitation method was used for magnetic modification. Adsorption process was carried out in batches. The effect of adsorption variables was investigated. Langmuir, Freundlich, and Dubinin–Radushkevich isotherms were applied to the equilibrium data. The maximum adsorption capacities of adsorbents from Langmuir isotherm were found as 20.75 mg/g for magnetic multi-wall carbon nanotubes and 87.79 mg/g for magnetic activated carbon. Pseudo-first-order kinetic model, pseudo-second-order kinetic model, intra-particle diffusion model, and Bangham model were used for determination of adsorption mechanisms. The rate-limiting step is electron exchange between the adsorbent and adsorbate. Both film diffusion and intra-particle diffusion occur while the adsorption process. ?G°, ?S°, and ?H° were calculated for the process. © 2015, Islamic Azad University (IAU)

Isolation of naproxen from wastewater using carbon-based magnetic adsorbents

Naproxen is one of the mostly used drugs worldwide and is most abundant in wastewater. This study aims to adsorb naproxen from wastewater using magnetically modified carbon-based adsorbents. These adsorbents have very large specific area for naproxen adsorption, and magnetite modification provides easy separation and regeneration. The co-precipitation method was used for magnetic modification. Adsorption process was carried out in batches. The effect of adsorption variables was investigated. Langmuir, Freundlich, and Dubinin-Radushkevich isotherms were applied to the equilibrium data. The maximum adsorption capacities of adsorbents from Langmuir isotherm were found as 20.75 mg/g for magnetic multi-wall carbon nanotubes and 87.79 mg/g for magnetic activated carbon. Pseudo-first-order kinetic model, pseudo-second-order kinetic model, intra-particle diffusion model, and Bangham model were used for determination of adsorption mechanisms. The rate-limiting step is electron exchange between the adsorbent and adsorbate. Both film diffusion and intra-particle diffusion occur while the adsorption process. Delta GA degrees, Delta SA degrees, and Delta HA degrees were calculated for the process

Highly efficient recovery of biophenols onto graphene oxide nanosheets: Valorisation of a biomass

In this study, graphene oxide (GO) nanosheets were evaluated for the recovery of biophenols from an agricultural biomass, olive leaf. Modified Hummer's method was used to synthesize GO by natural oxidation of graphite. The adsorbent was characterized by several novel analysis methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). On the other hand, optimization of the adsorption process was applied utilizing multivariate statistic technique such as Response Surface Methodology (RSM) in order to consider any possible interaction between variables with less number of experiments as well as to model a response affected by several variables. The outcome of the present study indicates that the optimum conditions for the adsorption of were 4.57/10 of pH together with 24.62/30 °C of temperature and 3 mg of GO to achieve the maximum yields of each dependent variable such as total biophenol content (TBC) and the most prevalent compound, oleuropein (OC). The verification of the calculated models was held by several error function analysis. © 2017 Elsevier B.V