Decoration of carbon nanotubes in the substrate or selective layer of polyvinyl alcohol/polysulfone thin-film composite membrane for nanofiltration applications

Nanofiltration (NF) membranes demonstrate considerable promise for desalinating saline water and wastewater containing mineral salts to overcome the lack of fresh water and improve drinking water quality. This research work aims to detect the influence of carbon nanotubes (CNTs) on the filtration performance of polyvinyl alcohol (PVA)/polysulfone (PSf) thin-film composite NF membranes. For this purpose, CNTs were incorporated in the PSf substrate/PVA selective layer to fabricate a thin-film composite (TFC) with nanocomposite substrate (nTFC) and a thin-film nanocomposite (TFN) membranes, respectively. To fabricate TFC membranes, PSf substrates with different concentrations (16–20 wt%) were made using the phase inversion technique. Then, the selective layer of PVA was formed on the PSf support through cross-linking with glutaraldehyde during dip-coating. The membranes’ NF performance was assessed by filtration of NaCl and Na2SO4 solutions at a relatively low pressure of 0.3 MPa. The salt rejection of all prepared membranes followed the sequence of Na2SO4 > NaCl, indicating the characteristics of negatively charged membranes. By embedment of 0.05 wt% CNT in the PSf substrate/PVA selective layer, the rejections of over 43% for NaCl and over 80% for Na2SO4 were obtained, which is higher than that of TFC-16 as a control membrane (18.1% for NaCl and 74.7% for Na2SO4). Furthermore, in the presence of CNTs, the permeance and fouling resistance of the nTFC and TFN membranes have been improved compared to the TFC-16 membrane

Topological Wiener indices and polynomials of C84 fullerene nanocage

Griffith Sciences, School of Information and Communication TechnologyNo Full Tex

Toxicity of Zn-Fe Layered Double Hydroxide to Different Organisms in the Aquatic Environment

The application of layered double hydroxide (LDH) nanomaterials as catalysts has attracted great interest due to their unique structural features. It also triggered the need to study their fate and behavior in the aquatic environment. In the present study, Zn-Fe nanolayered double hydroxides (Zn-Fe LDHs) were synthesized using a co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption analyses. The toxicity of the home-made Zn-Fe LDHs catalyst was examined by employing a variety of aquatic organisms from different trophic levels, namely the marine photobacterium Vibrio fischeri, the freshwater microalga Pseudokirchneriella subcapitata, the freshwater crustacean Daphnia magna, and the duckweed Spirodela polyrhiza. From the experimental results, it was evident that the acute toxicity of the catalyst depended on the exposure time and type of selected test organism. Zn-Fe LDHs toxicity was also affected by its physical state in suspension, chemical composition, as well as interaction with the bioassay test medium

Toxicity of Zn-Fe Layered Double Hydroxide to Different Organisms in the Aquatic Environment

The application of layered double hydroxide (LDH) nanomaterials as catalysts has attracted great interest due to their unique structural features. It also triggered the need to study their fate and behavior in the aquatic environment. In the present study, Zn-Fe nanolayered double hydroxides (Zn-Fe LDHs) were synthesized using a co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption analyses. The toxicity of the home-made Zn-Fe LDHs catalyst was examined by employing a variety of aquatic organisms from different trophic levels, namely the marine photobacterium Vibrio fischeri, the freshwater microalga Pseudokirchneriella subcapitata, the freshwater crustacean Daphnia magna, and the duckweed Spirodela polyrhiza. From the experimental results, it was evident that the acute toxicity of the catalyst depended on the exposure time and type of selected test organism. Zn-Fe LDHs toxicity was also affected by its physical state in suspension, chemical composition, as well as interaction with the bioassay test medium

Modeling Preparation Condition and Composition–Activity Relationship of Perovskite-Type La_<i>x</i>Sr_1–<i>x</i>Fe_<i>y</i>Co_1–<i>y</i>O₃ Nano Catalyst

In this paper, an artificial neural network (ANN) is first applied to perovskite catalyst design. A series of perovskite-type oxides with the La_<i>x</i>Sr_1–<i>x</i>Fe_<i>y</i>Co_1–<i>y</i>O₃ general formula were prepared with a sol–gel autocombustion method under different preparation conditions. A three-layer perceptron neural network was used for modeling and optimization of the catalytic combustion of toluene. A high <i>R</i>² value was obtained for training and test sets of data: 0.99 and 0.976, respectively. Due to the presence of full active catalysts, there was no necessity to use an optimizer algorithm. The optimum catalysts were La_0.9Sr_0.1Fe_0.5Co_0.5O₃ (<i>T</i>_c = 700 and 800 °C and [citric acid/nitrate] = 0.750), La_0.9Sr_0.1Fe_0.82Co_0.18O₃ (<i>T</i>_c = 700 °C, [citric acid/nitrate] = 0.750), and La_0.8Sr_0.2Fe_0.66Co_0.34O₃ (<i>T</i>_c = 650 °C, [citric acid/nitrate] = 0.525) exhibiting 100% conversion for toluene. More evaluation of the obtained model revealed the relative importance and criticality of preparation parameters of optimum catalysts. The structure, morphology, reducibility, and specific surface area of catalysts were investigated with XRD, SEM, TPR, and BET, respectively