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Cellulose aerogels were synthesized to be used for urea adsorption and targeting a fast adsorption rate and high adsorption capacity. This kind of urea adsorbent was synthesized by a sol–gel method in a simple NaOH/urea aqueous solution system. The aerogels were characterized by FT-IR spectroscopy, XRD, SEM, and N2 adsorption/desorption techniques and their adsorption properties were evaluated. The results showed that the aerogels comprised an ultralight mesoporous material with a large specific surface area and a porous three-dimensional network structure. The adsorption process followed the Freundlich model and the pseudo-first-order kinetic model. The synthesized aerogels had a superior adsorption capacity and a fast adsorption rate, and adsorption equilibrium could be reached within 60 min under the human physiological temperature. Therefore, this aerogel type of absorbent has potential applications for the adsorption of urea in dialysate. [ABSTRACT FROM AUTHOR]

Waste toner with high carbon content has the potential to become a carbon material, but its utilization is limited due to the low carbonization yield. In this work, a carbon-based solid acid was prepared by carbonization and sulfonation of waste toner with the aid of sulfuric acid. The characterization of its structure and the evaluation of its properties revealed that sulfuric acid played three roles in the process of carbon-based solid acid prepared from waste toner (WT-CSA). Specifically, this method not only solved the problem of low yield of carbon precursor (CP) obtained by carbonization of waste toner but also introduced thiophene sulfur into the aromatic carbon flakes during the carbonization process. Moreover, thiophene sulfur makes the sulfonation easier, thus increasing the density of –SO3H. In addition, the activity and cyclic stability of the catalyst were evaluated by cellulose hydrolysis. The results show that the catalyst exhibits excellent hydrolytic activity and hydrothermal stability. [ABSTRACT FROM AUTHOR]