[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Recently sulfate radical-based advanced oxidation processes (SR-AOPs) attract increasing attention due to their capability and adaptability in decontamination. The couple of cobalt and peroxymonosulfate (PMS) is an efficient way to produce reactive sulfate radicals. This article reviews the state-of-the-art progress on various heterogeneous cobalt-based catalysts for PMS activation, including cobalt oxides, cobalt-ferrite and supported cobalt by diverse substrates. We summarize the intrinsic properties of these catalysts and their fundamental behaviors in PMS activation, as well as synthetic approaches. In addition, influencing factors and synergistic techniques of Co/PMS systems in organic degradation and possible environmental applications are also discussed. Finally, we propose perspectives on challenges related to cobalt-based catalysts, heterogeneous Co/PMS systems and their potential applications in practical environmental cleanup.

Cobalt-catalyzed sulfate radical-based advanced oxidation: A review on heterogeneous catalysts and applications

C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

3d Transition Metals for C-H Activation.

Metal oxide-based resistive-type gas sensors are solid-state devices which are widely used in a number of applications from health and safety to energy efficiency and emission control. Nanomaterials such as nanowires, nanorods, and nanoparticles have dominated the research focus in this field due to their large number of surface sites facilitating surface reactions. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can have drastic effects on gas sensor performance, especially the selectivity. Recently, these effects have been amplified by designing heterojunctions on the nano-scale. These designs have evolved from mixed commercial powders and bi-layer films to finely-tuned core–shell and hierarchical brush-like nanocomposites. This review details the various morphological classes currently available for nanostructured metal-oxide based heterojunctions and then presents the dominant electronic and chemical mechanisms that influence the performance of these materials as resistive-type gas sensors. Mechanisms explored include p–n and n–n potential barrier manipulation, n–p–n response type inversions, spill-over effects, synergistic catalytic behavior, and microstructure enhancement. Tables are presented summarizing these works specifically for SnO2, ZnO, TiO2, In2O3, Fe2O3, MoO3, Co3O4, and CdO-based nanocomposites. Recent developments are highlighted and likely future trends are explored.

Nanoscale metal oxide-based heterojunctions for gas sensing: A review

Polycyclic Hydrocarbons Vol. 1. Pp. xxvi + 487. 126S. (With a chapter on carcinogenesis by Regina Schoental.) Vol. 2. Pp. lvii + 487. 140s. By E. Clar. (London and New York: Academic Press; Berlin: Springer-Verlag, 1964.)

Polycyclic Aromatic Hydrocarbons

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Synthesis of spinel cobalt ferrite magnetic nanoparticles (MNPs) with average sizes in the range 40–50 nm has been achieved using a combined sonochemical and co-precipitation technique in aqueous medium without any surfactant or organic capping agent. The nanoparticules form stable dispersions in aqueous or alcoholic medium. The uncapped nanoparticles were utilized directly as a reusable catalyst for Knoevenagel reaction in aqueous ethanol (1:3). Compartmentation and recovery of the catalyst from reaction medium was done with the aid of an external magnet. High yield of corresponding Knoevenagel products were obtained within a very short time in presence of just 5 mol% of the catalyst at 50 °C.

Synthesis of highly stable CoFe2O4 nanoparticles and their use as magnetically separable catalyst for Knoevenagel reaction in aqueous medium

Iodine as an extremely powerful catalyst for the acetylation of alcohols under solvent-free conditions

Porous carbon with high surface area was synthesized from different tea precursors under thermochemical condition in presence of phosphoric acid as activating agent. The synthetic procedure was optimized under different condition of acid impregnation ratio, heating temperature, dwelling time, etc. Pore morphology, surface properties, crystalline nature and thermal stability of porous carbon (PC) were assessed by using BET, SEM, FTIR, XRD and TGA analysis. Under optimized synthetic condition, the maximum surface area of the carbon material was found to be 2054.49 m2 g−1 with a total pore volume of 1.747 cm3 g−1. Adsorption characteristics of the PC for removal of a cationic dye (methylene blue) and an anionic dye (eosin yellow) were investigated spectrophotometrically as a function of initial dye concentration and contact time, adsorbent dosage, solution pH and temperature, etc. The PC was found to be equally efficient for removal of both the dyes from aqueous solutions at neutral pH with adsorption performance of greater than 99%. The equilibrium adsorption data of both the dyes could be described well by the Langmuir isotherm equation. The maximum adsorption capacity for methylene blue and eosin yellow was found to be 402.25 mg g−1 and 400 mg g−1, respectively. The adsorption kinetics in case of both the dyes follows a pseudo-second-order pathway. Investigations on thermodynamic parameters in the temperature range of 303–323 K revealed that the adsorption process is spontaneous and endothermic in nature.

Adsorption of methylene blue and eosin yellow using porous carbon prepared from tea waste: Adsorption equilibrium, kinetics and thermodynamics study

Activated carbon (MTLAC) and sulfonic acid modified activated carbon (MTLAC-SA) were prepared from a low cost agricultural waste material matured tea leaf (MTL). BET surface area of MTLAC and MTLAC-SA was found to be 1313.4 m2/g and 1169.3 m2/g respectively. Synthesized materials were applied for adsorption of both anionic and cationic dyes. Rhodamine B (RhB), methylene blue (MB), brilliant green (BG), crystal violet (CV) and orange G (OG) were taken as the model dye. After modification, the activated carbon showed enhanced adsorption capacity for adsorption of cationic dyes. The effect of various parameters such as pH, initial dye concentration, adsorbent dose, ionic strength on adsorption process was investigated. A slight increase in adsorption capacity was observed with increase in concentration of existing ion. The equilibrium adsorption data were best described by Langmuir model. The maximum adsorption capacity for RhB and OG using MTLAC-SA (MTLAC) was found to be 757.6 (398.4) mg/g and 105.7 (318.5) mg/g respectively. The adsorption kinetics was best fitted with pseudo second order kinetic model. The thermodynamic study illustrated that the adsorption process is endothermic and spontaneous in nature.

Prodeep Phukan

Papers

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Synthesis of highly stable CoFe2O4 nanoparticles and their use as magnetically separable catalyst for Knoevenagel reaction in aqueous medium

Iodine as an extremely powerful catalyst for the acetylation of alcohols under solvent-free conditions

Adsorption of methylene blue and eosin yellow using porous carbon prepared from tea waste: Adsorption equilibrium, kinetics and thermodynamics study

Enhanced adsorption of cationic dyes using sulfonic acid modified activated carbon