Degradation of diethyl phthalate and Di (2-ethylhexyl) phthalate using chemical and microbial methods

Abstract

Phthalates are alkyl aryl esters of 1, 2-benzene dicarboxylic acid, with a broad range of applications, especially as plasticizers. They disrupt endocrine and have recently been implicated in obesity. The chemical method for the degradation of phthalates involved the synthesis of silicon ironic hydroxide (Si-FeOOH) used in conjunction with an improvised catalytic reactor transmitting at an ultraviolet wavelength of 365 nm. 100 ppm of fungi solution (Fusarium oxysporumsp) was used with a shaking incubator in the dark for 28 hours to remediate aqueous solution containing 0.2, 0.4, 0.6, 0.8, and 1.0 mg/L of diethyl phthalate (DEP) and di (2-ethylhexyl) phthalate (DEHP). Si-FeOOH showed infrared peaks at 3310.17 cm^-1, 1086.66 cm^-1 and 442.64 cm^-1 which corresponds to O-H, Fe-O-Si and Si-O vibrational frequencies. These peaks were suggestive and confirmation of the synthesized compound. The parent phthalates showed infrared peaks for C=O_ester, C-O_ester and C=C_aromatic at 1728.94, 1124.78, and 1600.43cm^-1 (DEP), and 1738.01, 1123.01, and 1600.24cm^-1 (DEHP). However, for the degraded DEP aqueous solution and DEHP aqueous solution, the functional groups were significantly absent which were indication of complete degradation. The HPLC gave peaks at early retention time between 3.50 – 3.57 minutes for un-degraded DEP, and 2.21 - 2.23 minutes for un-degraded DEHP. However, for the degraded phthalate esters, there are no peaks at this retention times which were also suggestive of successful phthalates degradation. This showed that these chemical and microbial methods were effective in the degradation of diethyl phthalate (DEP) and di (2-ethylhexyl) phthalate (DEHP) in aqueous media.

Keywords: Diethyl phthalate; di (2-ethylhexyl) phthalate; Synthesis, Chemical and microbial degradation