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This study reports that the C2–C2 aldolization in ethanol conversion to C4 products, particularly butadiene, can be catalyzed by silica-supported LaMnO3 catalysts. The concentration and strength of Mn4+ was discovered to be related to the particle size of supported LaMnO3: the smaller the particle size is, the higher the concentration and acidity of Mn4+ are. The presence of high concentration and acidity of Mn4+ of small LaMnO3 particles concurrently increases the amount of weak basic nonstoichiometric oxygen, with which the surface concentration of Lewis acid–base adducts can be elevated. The Mn4+/nonstoichiometric oxygen pair is intrinsically active in C2–C2 aldolization, and the concentration of the paired site is positively correlated to the selectivity of C4 products. By coreacting ethanol with its evolved intermediates, that is, acetaldehyde and crotonaldehyde, we discovered the aldol condensation of acetaldehyde molecules to be rate-limiting. Accordingly, a plausible mechanism of aldolization of acetaldehyde molecules into C4 products mediated by the Mn4+/nonstoichiometric oxygen adduct of LaMnO3 was established.

Low-cost adsorbents, e.g., cow manure-based carbon, provide alternatives to remove veterinary antibiotic sulfamethazine (SMT) from contaminated water bodies. In this study, the chemical structures and compositions of cow manure (CM) carbonized at 400, 600, and 800°C (CM400, CM600, and CM800) were examined using elemental analyzer (EA), Brunauer-Emmett-Teller, and spectroscopic techniques. Adsorptions of SMT on CM samples were conducted as functions of pH, hydrophobicity, and ionic strengths. Results of EA and spectroscopic analyses suggested that the raw CM and CM400 samples contained the highest amounts of O-containing groups and aliphatic domains. Amounts of such two chemical groups decreased as carbonization temperatures increased. The specific surface areas and total pore volumes of CM samples increased significantly when the carbonization temperatures exceeded 600°C. SMT adsorption on CM samples could be described essentially by the pseudo-second-order kinetic, intra-particle diffusion, and Freundlich isotherm models. Low pH and ionic strength were favorable for SMT adsorption in CM samples, particularly for the CM800, because a strong p ? -p electron donor-acceptor interaction (p ? -p EDA) was formed between SMT and CM surfaces enriched with hydrophobic domains. Further, the high adsorption affinity of SMT to the CM600 and CM800 samples was attributed in part to their larger surface areas and total pore volumes. Generally, CM-based materials carbonized [600°C showed relatively stable structures and exhibited strong aromatic properties. Moreover, maximum adsorption capacities of SMT on the CM800 sample (37-39 mM/kg) were significantly higher than those of other common adsorbents (0.02-35.93 mM/kg).