Abstract
Activated charcoal was prepared from Acrocomia aculeata (macaúba) endocarp by ZnCl2 activation. The charcoal was used for the adsorptive purification of pretreated crude glycerol (CG) and potassium dihydrogen phosphate (KH2PO4 or KDP) was formed by the addition of H3PO4 to the crude glycerol containing KOH, which was used as catalyst in the production of biodiesel and glycerol. The KH2PO4 was isolated and purified by recrystallization from aqueous solution. The KH2PO4 was characterized by X-Ray diffraction (XRD), thermal analysis (TGA/DTA) and spectrophotometry in the infrared region – FTIR. From 216.0 g of crude glycerol, 20.1038 g of purified KH2PO4 was obtained. The KH2PO4 was used in a simple, regioselective, green method as a selective base for the methylation of the salicylic acid (SA) carboxylate group using DMS as the methylating agent in the production of MS at reflux temperature (90 oC). The present method has a short reaction time, and it is simple with excellent yields of MS. In this process, DMS was used in excess because it has been shown to be an excellent eco-friendly, aprotic solvent for the SN2 mechanism. The reuse of organic waste was accompanied by the transformation of DMS into the K2SO4 drying agent and H3PO4 into KH2PO4, a source of potassium and phosphate in fertilizers. This reaction is the first example of the use of KH2PO4 as a useful selective base for methylation, and the present method obeys the reduce-reuse-recycle (RRR) principle for the development of a green protocol. Microbial susceptibility tests were accomplished by adding suspensions of microorganisms and spreading them on the surfaces of the Mueller Hinton and YPMD agar culture media, in which there were central wells containing 60 µL of pure MS, which inhibited the growth of Escherichia coli, Proteus mirabilis, Sporothrix sp, Rhodotorula mucilaginosa, Galactomyces geotrichum, Candida orthopsilosis and Candida akabanensis.