Effective and selective adsorption of methyl tert-butyl ether on ZSM-5 zeolite: a comparative study.

The extensive use of methyl tert-butyl ether (MTBE) as a gasoline additive has caused serious environmental problems that need to be addressed urgently. The feasibility of remediation of MTBE-contaminated groundwater by ZSM-5 zeolite with SiO2/Al2O3 ratio of 50/130/360 was explored. The SiO2/Al2O3 ratio had a great influence on the physicochemical properties and structure, as well as the adsorption and mass transfer of MTBE on ZSM-5. The adsorption of MTBE on zeolites with SiO2/Al2O3 ratios of 50 and 130/360 followed the Langmuir and Freundlich models, respectively, and was controlled by different mass transfer processes. The morphology and adsorption capacity of ZSM-5 (50) and ZSM-5 (130) differed significantly, while the differences between ZSM5-(130) and ZSM-5 (360) were less pronounced. ZSM-5 (360) had higher adsorption capacity and adsorption efficiency for MTBE, and the larger BET surface area, pore volume and stronger hydrophobicity were the key factors to promote MTBE adsorption. Compared to activated carbon (AC), ZSM-5 (360) was more effective for MTBE removal at low concentrations (≤200 mg·L-1) and had the advantage of selective adsorption of MTBE with the addition of BTEX. In column adsorption, decreasing the concentration had opposite effects on MTBE removal by ZSM-5 and AC. At 5-10 mg·L-1, ZSM-5 (360) column reduced effluent concentration and improved bed utilization and removal efficiency.

Revealing the interaction forms between Hg(II) and group types (-Cl, -CN, -NH2, -OH, -COOH) in functionalized Poly(pyrrole methane)s for efficient mercury removal.

To explore the impact of different functional groups on Hg(II) adsorption, a range of poly(pyrrole methane)s functionalized by -Cl, -CN, -NH2, -OH and -COOH were synthesized and applied to reveal the interaction between different functional groups and mercury ions in water, and the adsorption mechanism was revealed through combined FT-IR, XPS, and DFT calculations. The adsorption performance can be improved to varying degrees by the incorporation of functional groups. Among them, the oxygen-containing functional groups (-OH and -COOH) exhibit stronger affinity for Hg(II) and can increase the adsorption capacity from 180 mg g-1 to more than 1400 mg g-1 at 318 K, with distribution coefficient (Kd) exceeding 105 mL g-1. The variations in the capture and immobilization capabilities of functionalized poly(pyrrole methane)s predominantly stem from the unique interactions between their functional groups and mercury ions. In particular, oxygen-containing -OH and -COOH effectively capture Hg(OH)2 through hydrogen bonding, and further deprotonate to form the -O-Hg-OH and -COO-Hg-OH complexes which are more stable than those obtained from other functionalized groups. Finally, the ecological safety has been fully demonstrated through bactericidal and bacteriostatic experiments to prove the functionalized poly(pyrrole methane)s can be as an environmentally friendly adsorbent for purifying contaminated water.

Alpha-Melanocyte-Stimulating Hormone-Mediated Appetite Regulation in the Central Nervous System.

Understanding the complex action mechanism of appetite regulation peptides can significantly impact therapeutic options in the treatment of obesity and other metabolic diseases. Hypothalamic alpha-melanocyte-stimulating hormone (α-MSH) is an anorexigenic peptide, closely related to the occurrence of obesity, playing a central role in food intake and energy expenditure. In the central nervous system, α-MSH is cleaved from proopiomelanocortin and then released into different hypothalamic regions to act on melanocortin 3/4 receptor-expressing neurons, lowering food intake, and raising energy expenditure via appetite suppression and sympathetic nervous system. Furthermore, it can increase the transmission of some anorexigenic hormones (e.g., dopamine) and interact with other orexigenic factors (e.g., agouti-related protein, neuropeptide Y) to influence food reward rather than merely feeding behavior. Therefore, α-MSH is a critical node of the hypothalamus in transmitting appetite suppression signals and is a key component of the central appetite-regulating circuits. Herein, we describe the role of α-MSH in appetite suppression in terms of specific receptors, effector neurons, sites of action, and the interaction with other appetite-relative peptides, respectively. We focus on the role of α-MSH in obesity. The status of research on α-MSH-related drugs is also discussed. With the intention of illuminating a new approach for targeting α-MSH in the hypothalamus as a strategy to manage obesity, we hope to further understand the direct or indirect mechanisms by which α-MSH exerts its appetite-regulating effects.