Toxicity of aqueous mixture of phenol and chlorophenols upon photosensitized oxidation initiated by sunlight or vis-lamp

Abstract

It is well established that aquatic wildlife in marine and freshwater of the European Union is exposed to natural and synthetic endocrine disruptor compounds (EDCs) which are able to interfere with the hormonal system causing adverse effects on the intact physiology of organisms. The traditional wastewater treatment processes are inefficient on the removal of EDCs in low concentration. Moreover, not only the efficiency of treatment must be considered but also toxicological aspects. Taking into account all these aspects, the main goal of the study was to investigate the photochemical decomposition of hazardous phenolic compounds under simulated as well as natural sunlight from the toxicity point of view. The studies were focused on photodegradation of 2,4-dichlorophenol as well as mixture of phenol, 2-chlorophenol and 2,4-dichlorophenol. Photosensitized oxidation process was carried out in homogeneous and heterogeneous system. V. fischeri luminescence inhibition was used to determine the changes of toxicity in mixture during simulated and natural irradiation. The photodegradation was carried out in three kinds of water matrix; moreover, the influence of presence of inorganic matter on the treatment process was investigated. The experiments with natural sunlight proved applicability of photosensitive chitosan for visible-light water pollutant degradation. The results of toxicity investigation show that using photosensitive chitosan for visible-light, the toxicity of reaction mixture towards V. fischeri has significantly decreased. The EC 50 was found to increase over the irradiation time; this increase was not proportional to the transformation of the parent compounds.

Optimization of Heterogeneous Photosensitized Oxidation for Winery Effluent Treatment

“…Regarding BOD 5 , the photosensitized oxidation treatment allowed a reduction in this parameter for both pH 8.7 and 6.0 while allowing for compliance with Portuguese legislation for this parameter of water reuse for irrigation (10 mg O2 /L) [30] to a pH of 6.0. On the other hand, results for toxicity levels show an improvement in these levels for experiments carried out at pH 8.7 and 4.0 when compared with the initial effluent, agreeing with the study by Foszpa ńczyk et al [40], where toxicity levels decreased after 180 min of photosensitized oxidation treatment. In another work, Foszpa et al [16] studied the removal and toxicity levels of 10 aqueous contaminants, including phenolic compounds and parabens.…”

Heterogeneous Oxidation of Phenolic Compounds with Photosensitizing Catalysts Incorporated into Chitosan

“…According to the quenching constant determined in the acetone solution, 2,4,6-TCP and 2,4-DCP should have been oxidized by 1 O 2 the fastest. This trend was observed in the aqueous solution of 2,4-DCP and 2,4,6-TCP compounds in the undissociated form [27]. However, in the buffered solution, these compounds were predominantly in dissociated form, which was probably the reason that this correlation was not observed.…”

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“…Phenol is a general protoplasmic poison with corrosive local effects that denature proteins. Poisoning with phenol compounds may occur by ingestion, inhalation and absorption through skin [41]. Acute poisoning can cause strict gastrointestinal disturbances, kidney malfunction, and circulatory system failure and also lung edema.…”

“…Deadly doses can be absorbed through the skin. Key organs injured by chronic exposure to phenol consist of spleen, pancreas and kidneys [3,41]. This review addresses the incidence and fate of chlorophenolic compounds in the environment with emphasis on the role of sorption processes.…”