Synthesis and characterizations of conocarpus- and azadirachta-derived activated carbons as wastewater recycling material.

Water being the most important fluid supporting the life as well as industry is getting sparse and polluted day by day. Activated carbon (AC) can be utilized in various applications of significant environmental impact and sustainable living such as carbon dioxide sensing and capturing, air purification, and water recycling. However, in the wake of the recent corona pandemic which resulted in global lockdown and took the entire world by shock, a cost-effective and simple synthesis of such a useful material remains dire need of time. Therefore, this paper describes a simple and cost-effective synthesis of activated carbon (AC) of high porosity and surface area derived from the pruning of conocarpus and azadirachta trees. In reference to the study under consideration, alongside numerous others, a furnace was employed to synthesize activated carbon. However, our approach utilized a more conventional methodology wherein the environmental parameters were not optimized. In furnace-based procedures, factors such as temperature, pressure, and humidity are meticulously regulated, contrasting with the conventional methodologies where such parameters lack optimal control. Consequently, employing a furnace does not constitute a cost-effective approach for the physical activation of organic samples thus proving a furnace is not imperative for physical activation. The synthesis was carried out by physical activation in the form of carbonization followed by chemical activation with potassium hydroxide (KOH). The influence of activated carbon from each pruning over filtration of water containing industrial dye was investigated. Activation temperature and impregnation ratio of 600-800 °C and 1:5 were selected respectively. X-ray diffraction patterns (XRD) for all AC samples indicted the appearance of broad peaks at 2θ value of 20-30° which confirms the presence of carbon in the sample. The physical morphology arrangement by SEM analysis showed uneven arrangement of pores of conocarpus which indicated higher iodine number and hence higher adsorption capacity of 442.13 mg/g.

Formylation of Amines by CO2 Hydrogenation Using Preformed Co(II)/Nickel(II) Complexes.

Preparation of formamides by CO2 hydrogenation requires an efficient catalyst and temperatures around 100 °C or higher, but most catalysts reported so far incorporate rare and toxic precious metals. Five cobalt(II) or nickel(II) complexes with dmpe or PNN (dmpe = 1,2-bis(dimethylphosphino)ethane; PNN = [(2-(di-tert-butylphosphinomethyl)-6-diethylaminomethyl)pyridine) have been evaluated as precatalysts for the hydrogenation of CO2 to prepare formamides from the corresponding secondary amines. The most active catalyst for these reactions was found to be [NiCl2(dmpe)] in DMSO, producing dimethylformamide (DMF) from CO2, H2, and dimethylamine in up to 6300 TON, the highest activity reported for this reaction with an abundant metal-phosphine complex.

Catalytic Formylation of Primary and Secondary Amines with CO2 and H2 Using Abundant-Metal Catalysts.

Catalytic hydrogenation of CO2 is an efficient and selective way to prepare formic acid derivatives, but most of the highly active catalysts used for this purpose require precious metals. In this study, in situ abundant-metal complexes have been evaluated as potential catalysts for CO2 hydrogenation to prepare formamides, including N-formylmorpholine, 2-ethylhexylformamide, and dimethylformamide, from the corresponding amines. From these initial screening results, the most active catalysts for these reactions were found to be MX2/dmpe in situ catalysts (M = Fe(II), Ni(II); X = Cl-, CH3CO2-, acac-; dmpe = 1,2-bis(dimethylphosphino)ethane) in DMSO. The optimal reaction conditions were found to be 100-135 °C and a total pressure of 100 bar. Morpholine was formylated with a TON value of up to 18000, which is the highest TON for the hydrogenation of CO2 to formamides using any abundant-metal-phosphine complex. With an appropriate selection of catalyst and reaction conditions, >90-98% conversion of amine to formamide could be achieved.