Adsorption Behavior Of Amino Acids On Mg-Al-CO₃-hydrotalcite, Covalent Triazine-Porous Materials, Titanate Nanotubes And Activated Carbon From Aqueous Solutions

Micro-dissolved organic nitrogen (DON) is drawing attention in drinking water treatment for its potential threaten to human health as the precursors of carcinogenic and cytotoxicity disinfection byproducts (DBPs), such as Haloacetonitriles(HANs), Nitroamines and Halonitromethanes(HNMs). Amino acids are important composition of DON and they are also known precursors to regulated and unregulated disinfection byproducts. Hence, understanding and controlling the incidence of N-DBPs is a contemporary challenge to the drinking water industry. Adsorption technique with high removal efficiency and easy operation has been widely used to remove the aqueous organic pollutants. In addition, the studies on the interfacial chemistry of amino acids can not only contribute to a better understanding for the adsorption of proteins or enzymes on solid materials but also provide sufficient theoretic guides for the practical process.In this study, three representative amino acids—Phenylalanine, Lysine and Glutamic acids, were selected as adsorbate. And the three Amino acids adsorption on Mg-Al-CO3-hydrotalcite, Covalent Triazine-based Framework (CTFs), Titanate Nanotube (TNT) were previously investigated. It is our intent to the general understanding of interactions between amino acids and nanomatericals. The crystal morphology and surface electrical of three nanomatericals were characterized by elemental analysis, X-ray diffraction analysis(XRD), specific surface area and pore size analysis(BET), Zeta potential measurement, thermal gravimetric analysis(TG), transmission electron microscopy (TEM). And the adsorption isotherms were used to investigate the amino acids in materials surface adsorption mechanism. The adsorption controlling factors were discussed by sorption kinetics experiments. The effects of various aqueous chemistry conditions (pH and ionic strength) on adsorption were also examined.According to the above studies, we have come to the following conclusions. Hydrophobic was the main factors in the adsorption of phenylalanine on CTFs and AC. The changes of ionics strength makes no different in the adsorption of phenylalanine on AC and CTFs. Phenylalanine adsorption on AC and CTFs was observed to be pH dependent with maximum adsorption near the isoelectric point of the amino acid. In the adsorption of lysine on TNT and AC, the electrostatic interactions and molecular sieve adsorption effect play a major role. Just like the adsorption of phenylalanine, the adsorption of lysine on TNT and AC get the maximum adsorption near the lysine’ isoelectric point. The main force of glutamic acid adsorption on AC is static electricity force. And the amount of adsorption is increased as the pH rises. The same to the lysine adsorption on AC, the adsorption capacity of Glutamic acid on AC reduced when the electrolyte solution was added in.Compared with the adsorbent AC, Mg-Al-CO3-hydrotalcite shows a significantly higher adsorption capacity, in the adsorption of phenylalanine and glutamic acid. When the electrolyte solution increases, the adsorption amounts of lysine and glutamate acids on Mg-Al-CO3-hydrotalcite will reduce.