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Dipyrone (DIPY), an analgesic drug, is very quickly hydrolyzed to 4-methylaminoantipyrine (4-MAA) in an acidic solution. Batch study was conducted to compare the performance of different oxidation processes such as Fenton (FP), photo-Fenton (PFP), UV/H 2 O 2 photolysis (UVP), and UV/TiO 2 photocatalysis (UVPC) for removal of 4-MAA from aqueous solution. The degradation efficiency was evaluated in terms of total organic carbon (TOC) reduction and enhancement of biodegradability. Maximum 4-MAA removals of 94.1, 96.4, 74.4, and 71.2% were achieved in FP, PFP, UCP, and UVPC, respectively, against mineralization of 49.3, 58.2, 47, and 24.6%. The proposed mechanisms suggest that the cleavage of three methyl moieties followed by pyrazolinone ring breakage led to formation of various intermediates with low errors (−0.88 to 0.11 g/mol). The intermediates primarily were hydroxylated and carboxylic derivatives. BOD 5 to COD (BOD, biochemical oxygen demand; COD, chemical oxygen demand) ratio of ≥0.4 resulted from DIPY decomposition in all processes with highest improvement in PFP (BOD 5 /COD ≈ 1.5). The collapse of iron(III)-chelates under UV irradiation gave higher biodegradability.

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In the present work, corn starch was grafted with oleic acid in the presence of redox initiators. Starch nanocrystals (SNCs) were synthesized using acid hydrolysis method and nanocomposite films were prepared by incorporation of SNCs into polyvinyl alcohol/starch (PVA/S) and PVA/grafted starch (PVA/GS) matrix, separately. It was observed that SNCs exhibited a platelet-like shape and in the size range of 200 nm. The increased crystallinity of SNCs indicated the removal of the amorphous and waxy region after acid hydrolysis of starch. Scanning electron micrographs of nanocomposite films showed good dispersion of SNCs within the PVA/GS matrix compared to the PVA/S matrix. The tensile strength of the nanocomposite films increased significantly with the reinforcement of SNCs into PVA/S matrix. Water uptake (%) of PVA/GS nanocomposite film decreased by 38.25% compared to the PVA/S nanocomposite film. Reinforcement of SNCs with PVA/S matrix improved the biodegradability of the films and was higher than PVA/S film. PVA/S nanocomposite film showed 32.4% weight loss after 120 days of soil burial degradation test. Thus, the obtained nanocomposite films can provide a potential alternative to the synthetic and nondegradable packaging films used worldwide.

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