Enhancement in pervaporative performance of PDMS membrane for separation of styrene from wastewater by hybridizing with reduced graphene oxide

Polydimethylsiloxane (PDMS) Membrane for Separation of Soluble Toluene by Pervaporation Process

A commercial polydimethylsiloxane (PDMS) membrane was employed to separate the soluble toluene compounds (C₇H₈) from an aqueous solution via the pervaporation (PV) process. The performance and the efficacy of the PDMS PV membrane were evaluated through the estimation of the permeation flux and separation factor under various operating parameters. The response surface method (RSM) built in the Minitab-18 software was used for the design of the experiment in this study, and the responses of the permeation flux and the separation factor were analyzed and optimized based on the operating conditions. A nonlinear regression analysis was applied to the experimental output and input, and as a result, a quadratic equation model with parameters interactions was obtained as mathematical expressions to predict the permeation flux and separation factor. At the optimal conditions of temperature 30 °C, initial toluene concentration 500 ppm, and feed flowrate 3.5 L/min, the toluene permeation flux and separation factor were 125.855 g/m²·h and 1080, respectively. The feed concentration was the most impactful and significant in the improvement of the permeation flux and separation factor of the PDMS membrane.

Production of magnetic sodium alginate polyelectrolyte nanospheres for lead ions removal from wastewater

Polyelectrolyte composite nanospheres are relatively new adsorbents which have attracted much attention for their efficient pollutant removal and reuse performance. A novel polyelectrolyte nanosphere with magnetic function (SA@AM) was synthesized via the electrostatic reaction between the polyanionic sodium alginate (SA) and the surface of a prepared terminal amino-based magnetic nanoparticles (AMs). SA@AM showed a size of 15-22 nm with 6.85 emu·g^-1 of magnetization value, exhibiting a high adsorption capacity on Pb(II) ions representing a common heavy metal pollutant, with a maximum adsorption capacity of 105.8 mg g^-1. The Langmuir isotherm adsorption fits the adsorption curve, indicating uniform adsorption of Pb(II) on the SA@AM surfaces. Repeated adsorption desorption experiments showed that the removal ratio of Pb(II) by SA@AM was more than 76%, illustrating improved regeneration performance. These results provide useful information for the production of bio-based green magnetic nano scale adsorption materials for environmental remediation applications.

Ceramic-Polymer Composite Membranes for Water and Wastewater Treatment: Bridging the Big Gap between Ceramics and Polymers

Clean water supply is an essential element for the entire sustainable human society, and the economic and technology development. Membrane filtration for water and wastewater treatments is the premier choice due to its high energy efficiency and effectiveness, where the separation is performed by passing water molecules through purposely tuned pores of membranes selectively without phase change and additional chemicals. Ceramics and polymers are two main candidate materials for membranes, where the majority has been made of polymeric materials, due to the low cost, easy processing, and tunability in pore configurations. In contrast, ceramic membranes have much better performance, extra-long service life, mechanical robustness, and high thermal and chemical stabilities, and they have also been applied in gas, petrochemical, food-beverage, and pharmaceutical industries, where most of polymeric membranes cannot perform properly. However, one of the main drawbacks of ceramic membranes is the high manufacturing cost, which is about three to five times higher than that of common polymeric types. To fill the large gap between the competing ceramic and polymeric membranes, one apparent solution is to develop a ceramic-polymer composite type. Indeed, the properly engineered ceramic-polymer composite membranes are able to integrate the advantages of both ceramic and polymeric materials together, providing improvement in membrane performance for efficient separation, raised life span and additional functionalities. In this overview, we first thoroughly examine three types of ceramic-polymer composite membranes, (i) ceramics in polymer membranes (nanocomposite membranes), (ii) thin film nanocomposite (TFN) membranes, and (iii) ceramic-supported polymer membranes. In the past decade, great progress has been made in improving the compatibility between ceramics and polymers, while the synergy between them has been among the main pursuits, especially in the development of the high performing nanocomposite membranes for water and wastewater treatment at lowered manufacturing cost. By looking into strategies to improve the compatibility among ceramic and polymeric components, we will conclude with briefing on the perspectives and challenges for the future development of the composite membranes.