Upcycling spent brewery grains through the production of carbon adsorbents: application to the removal of carbamazepine from water

Spent brewery grains, a by-product of the brewing process, were used as precursor of biochars and activated carbons to be applied to the removal of pharmaceuticals from water. Biochars were obtained by pyrolysis of the raw materials, while activated carbons were produced by adding a previous chemical activation step. The influence of using different precursors (from distinct fermentation processes), activating agents (potassium hydroxide, sodium hydroxide, and phosphoric acid), pyrolysis temperatures, and residence times was assessed. The adsorbents were physicochemically characterized and applied to the removal of the antiepileptic carbamazepine from water. Potassium hydroxide activation produced the materials with the most promising properties and adsorptive removals, with specific surface areas up to 1120 m2 g-1 and maximum adsorption capacities up to 190 ± 27 mg g-1 in ultrapure water. The adsorption capacity suffered a reduction of < 70% in wastewater, allowing to evaluate the impact of realistic matrices on the efficiency of the materials.publishe

A Systematic in Situ Infrared Study of the Electrooxidation of C3 Alcohols on Carbon-Supported Pt and Pt-Bi Catalysts

International audienceThe electrooxidation of C3 alcohols (1-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol, and glycerol) has been studied in alkaline medium on Pt/C and Pt9Bi1/C catalysts by cyclic voltammetry and in situ FTIR spectroscopy. Both catalysts were synthesized with metal particle sizes below 5 nm and were characterized by TGA, AAS, and XRD. The modification of Pt by 10 at. % of Bi decreases the oxidation onset potentials of C3 alcohols down to ca. 200 mV. In situ FTIR spectroscopy measurements indicated clearly that the presence of Bi also led to avoid the C-C bond cleavage during alcohol electrooxidation reactions and, hence, to favor the formation of value-added C3 compounds. Moreover, with respect to a Pd-based catalyst, Pt9Bi1/C presented much higher electrocatalytic activity at low potentials. Systematic evaluation of the positions and intensity changes of absorption bands as a function of the electrode potential allowed determining reaction pathways of electrooxidation of C3 alcohols. It has been shown not only that the secondary alcohol groups are more reactive than the primary ones but also that in the case of glycerol steric limitations due to the presence of two primary alcohol groups could be responsible of the higher oxidation onset potential. At potentials above 0.6 V, the linear 1-propanol bearing a single primary alcohol group leads to the highest activity due to lower steric hindrance of the surface compared with the other alcohols studied

Oxidation of Glycerol with Oxygen Molecules as the Oxidant over Activated Clay Material Catalysts

Abstract Interest in glycerol oxidation to more useful products has risen significantly over the years. This has led to the development of several catalysts some of which are scarce, uneconomical and environmentally unfriendly. In this research, two catalysts prepared from red earth - ‘A1’ (calcined at 500°c) and ‘A2’ (calcined at 500°c and dealuminated) were characterized using x-ray fluorescence (XRF) and used to oxidize glycerol with O2 molecules for 240 mins. The XRF results showed that Al 2 O 3 (31.3%), SiO 2 (47.9%) and Fe 2 O 3 (16.05%) were the predominant components in ‘A1’ while ‘A2’ showed a marked significant difference in Al 2 O 3 (19.4%), SiO 2 (72.1 %) and Fe 2 O 3 (0 %). The selectivities of the oxidation products with A1 were 18.8 % glyceric acid (GLA), 13.1 % lactic acid (LCA), 1.66 % oxalic acid (OXA) and 1.24 % formic acid (FMA), while for A2 they were (20.4%) GLA and (17%) LCA. 88.1% glycerol was converted but selectivity towards any of the products was low