Dynamic Tracking of Highly Toxic Intermediates in Photocatalytic Degradation of Pentachlorophenol by Continuous Flow Chemiluminescence

Abstract

Photocatalytic degradation is a powerful technique for the decomposition of pollutants. However, toxic intermediates might be generated which have become a great concern recently. In the present work, a continuous flow chemiluminescence (CFCL) method was developed for dynamic monitoring of toxic intermediates generated in the photocatalytic degradation of pentachlorophenol (PCP). Among the main intermediates, tetrachloro-1,4-benzoquinone (TCBQ) and trichlorohydroxy-1,4-benzoquinone (OH-TrCBQ) showed higher or similar toxicity to PCP. As both TCBQ and OH-TrCBQ can produce chemiluminescence (CL) in the presence of HO, a CFCL system was established for the dynamic tracking of the two toxic intermediates. A PCP/TiO suspension was irradiated in a photoreactor, pumped continuously into a detection cell, and mixed with HO to produce CL. The time-dependent CL response displayed two distinctive peaks at pH 7, which were attributed to the generation of OH-TrCBQ and TCBQ, respectively, by comparing with their changes measured by high-performance liquid chromatography (HPLC). Furthermore, the CL response curve of PCP/TiO suspension showed a pattern very similar to their bacteria inhibition. Therefore, the CFCL could be used as a simple and low-cost method for online monitoring of TCBQ and OH-TrCBQ to ensure complete removal of not only PCP but also highly toxic degradation intermediates.

Chemiluminescence as a New Indicator for Monitoring Hydroxylated Intermediates in Persulfate-Based Advanced Oxidation Processes

“…The results were in good agreement with those obtained by the LC-MS method (Table S1). Moreover, the detection limits of earlier reported methods for the hydroxylated intermediates were between 0.5 and 0.05 μM. − Therefore, it was concluded that the proposed method was a sensitive method.…”

Visible-light photocatalysis by carbon-nano-onion-functionalized ZnO tetrapods: degradation of 2,4-dinitrophenol and a plant-model-based ecological assessment

“…Wastewater is mostly produced from the emissions of a wide range of organic contaminants, which are widespread in industrial, agricultural, and household applications 2,3 . The removal of organic pollutants from wastewater is currently a primary challenge to circumvent the world's water crisis, owing to their high resistance to biodegradation 4 . 2,4-Dinitrophenol (DNP) has been known as a priority pollutant because of its mutagenic and carcinogenic nature and bioaccumulation 5 .…”

“…Current research on photocatalytic water remediation is focused on the development of sustainable materials and the improvement in the degradation efficiency towards targeted pollutants, but it does not include the elimination of possible risk of environmental assessment 37,38 . Even after the complete degradation of organic pollutants, acute toxicity has been observed owing to the generation of toxic byproducts 4 . Therefore, the determination of the concentration of DNP in treated water may not be sufficient, and an accurate environmental risk assessment is highly desirable to evaluate the overall efficiency of wastewater treatments.…”

Efficient Photocatalytic Fuel Cell via Simultaneous Visible-Photoelectrocatalytic Degradation and Electricity Generation on a Porous Coral-like WO3/W Photoelectrode

“…Compared to photocatalysis, photoelectrocatalysis (PEC) has been used as an effective way to remove organic pollutants and produce H 2 because of the rapid separation of photoelectrons from holes under the bias voltage. − The photogenerated electrons can be rapidly transferred to the cathode to form a photocurrent or drive reduction reactions such as H 2 generation and CO 2 reduction, − and the holes left on the anode are used for oxidative degradation of POPs. − Thus, a new photocatalytic fuel cell (PFC) based on the entire process can be constructed for simultaneous electricity generation and pollutant degradation. − …”