Ultrasonic Pretreated Sludge Derived Stable Magnetic Active Carbon for Cr(VI) Removal from Wastewater

Abstract

A stable magnetic carbon was synthesized using activated sludge as the carbon precursor. The ultrasonic pretreatment was used to destroy the cells in the activated sludge and to release the soluble carbon source, which was responsible for the improved stability of the synthesized magnetic carbon. 800 W was demonstrated as the optimized ultrasonication power for the pretreatment of activated sludge. Then, the carbonization parameters, such as pyrolysis temperature, heating rate, and dwell time were optimized as 800 °C, 10 °C/min, and 60 min, respectively. To be more specific, this activated sludge derived magnetic carbon can reduce almost all the hexavalent chromium (Cr(VI)) (2.0 mg/L) in 10 min and has a maximum capacity as high as 203 mg/g. The iron release rate of the synthesized activated sludge derived magnetic carbon was decreased, which improved the electron utilization of zerovalent iron (ZVI). This composite was demonstrated to have a good stability and recyclability as well. Finally, the Cr(VI) removal mechanisms were clarified under the acidic and the natural conditions.

Significantly Enhanced Uranium Extraction from Seawater with Mass Produced Fully Amidoximated Nanofiber Adsorbent

“…The K d calculated with different amount of PIDO NF adsorbent (15,30, and 60 mg) in 5 L of 8 ppm uranium spiked seawater are 2.84 × 10 5 , 1.92 × 10 5 , and 2.42 × 10 5 for the V/m ratios of 3.3 × 10 5 , 1.6 × 10 5 , and 8.3 × 10 4 , respectively. The K d calculated with different amount of PIDO NF adsorbent (15,30, and 60 mg) in 5 L of 8 ppm uranium spiked seawater are 2.84 × 10 5 , 1.92 × 10 5 , and 2.42 × 10 5 for the V/m ratios of 3.3 × 10 5 , 1.6 × 10 5 , and 8.3 × 10 4 , respectively.…”

“…[43] In a highly alkaline environment, uranyl ions form negatively charged complex anions, such as (UO 2 ) 3 (OH) 8 2− , (UO 2 ) 3 (OH) 10 4− and UO 2 (OH) 3− etc., [44] which leads to a decrease of adsorption efficiency. Figure 3d illustrates adsorption kinetics by different contents of PIDO NF adsorbents (15,30, and 60 mg, corresponding to solution volume to adsorbent mass ratio (V/m) of 3.3 × 10 5 , 1.6 × 10 5 , and 8.3 × 10 4 , respectively) in 5 L of uranium (8 ppm) spiked seawater, which is collected from coastal water near the Boundary Island of South China Sea. Compared with the survey spectrum of PIDO, the spectrum of PIDO-U clearly shows a new strong U 4f double peak ( Figure 3b).…”

“…[3] The oceans hold ≈4.5 billion tons of uranium, [4] making them a potential huge resource to support nuclear power production for hundreds of years. [10][11][12][13][14][15][16] Among these technologies, the adsorption approach, particularly by using fiber-based adsorbents, is recognized as the most feasible process in terms of practicality, processability, cost, and environmental concerns. In the last decades, researchers worldwide have tried various methods to recover uranium from seawater and aqueous solution, such as coprecipitation, [6] ion-exchange, [7] adsorption via porous organic polymers, [8,9] and organic-inorganic hybrid adsorbents.…”

Solid‐Waste‐Derived Carbon Dioxide‐Capturing Materials

“…[52][53][54][55][56] Currently,t he main focus of research is on how to improve their captureability and selectivity for CO 2 . [52][53][54][55][56] Currently,t he main focus of research is on how to improve their captureability and selectivity for CO 2 .…”

Friction and Mechanical Properties of Highly Filled Polybenzoxazine Composites: Nanosilica Particle Size and Surface Treatment

“…Nowadays, highly filled nanocomposites have gained much attention due to their broad range of applications such as those reports on epoxy/flattened double walled carbon nanotubes, poly( N ‐isopropylacrylamide)‐nanoclay in bioinspired materials, bismaleimide/multiwalled carbon nanotube sheet for conductor, polybenzoxazine filled with ZrO 2 nanoparticles, and nanosilica as friction materials . Dueramae et al.…”