Activated Carbons from Hydrochars Prepared in Milk

Optimizing Al and Fe Load during HTC of Water Hyacinth: Improvement of Induced HC Physicochemical Properties

Nowadays, several alternatives have been proposed to increase the porosity and/or modify the surface groups of hydrochars from biomasses as well as to develop additional features on them. These alternatives can include specific modifications for the process, as previous steps or as postreatments, and the wide variety of forms in which they can be made can substantially affect the product distribution and properties. In this study, the hydrothermal carbonization process of an invasive floating plant (Water hyacinth) has been modified by introducing different amounts of iron (FeCl3) and aluminium alloy (shaving scrap waste) during the hydrothermal reaction. The effects on process reactivity, phase distribution, and physicochemical properties of the samples obtained were studied by means of different characterization techniques such as thermogravimetry (TG-DTG), physical adsorption/desorption of N2 at −196 °C, FT-IR spectroscopy, and scanning electron microscopy (SEM). In the case of iron-catalyzed reactions, the magnetite formation and magnetic behavior of the prepared hydrochars after a pyrolytic treatment was also estimated. The results obtained indicate that the porosity of the hydrochars was clearly improved to different extents by the addition of Al or Fe during direct synthesis. In addition, porous carbons with a moderate magnetic character were obtained.

Activated Carbon and Carbon Quantum Dots/Titanium Dioxide Composite Based on Waste Rice Noodles: Simultaneous Synthesis and Application in Water Pollution Control

To achieve the full utilization of waste rice noodle (WRN) without secondary pollution, activated carbon (AC) and carbon quantum dots/titanium dioxide (CQDs/TiO2) composite were simultaneously synthesized by using WRN as raw material. Both of the two materials showed potential applications in water pollution control. The AC based on WRN displayed a porous spherical micro-morphology, which could absorb heavy metal elements like Pb(II) and Cr(VI) efficiently, with a maximum equilibrium uptake of 12.08 mg·g−1 for Pb(II) and 9.36 mg·g−1 for Cr(VI), respectively. The adsorption of the resulted AC could match the Freundlich adsorption isotherm and the pseudo-second-order kinetics mode. On the other hand, the CQDs/TiO2 composite based on WRN displayed a high efficient photocatalytic degradation effect on various water-soluble dyes such as methylene blue, malachite green, methyl violet, basic fuchsin, and rhodamine B under visible light irradiation, which showed better photocatalytic performance than commercial TiO2. The introduction of CQDs based on WRN to TiO2 could result in efficient electron-hole pair separation and enable more photogenerated electrons to reduce O2 and more photogenerated holes to oxidize H2O or OH−, which could cause stronger abilities in producing O2·− and ·OH radical and better photocatalytic activity.