Diphenylarsinic acid contaminated soil remediation by titanium dioxide (P25) photocatalysis: Degradation pathway, optimization of operating parameters and effects of soil properties

Abstract

Diphenylarsinic acid (DPAA) is formed during the leakage of arsenic chemical weapons in sites and poses a high risk to biota. However, remediation methods for DPAA contaminated soils are rare. Here, the photocatalytic oxidation (PCO) process by nano-sized titanium dioxide (TiO 2 ) was applied to degrade DPAA in soil. The degradation pathway was firstly studied, and arsenate was identified as the final product. Then, an orthogonal array experimental design of L 9 (3) 4 , only 9 experiments were needed, instead of 81 experiments in a conventional one-factor-at-a-time, was used to optimize the operational parameters soil:water ratio, TiO 2 dosage, irradiation time and light intensity to increase DPAA removal efficiency. Soil:water ratio was found to have a more significant effect on DPAA removal efficiency than other properties. The optimum conditions to treat 4 g soil with a DPAA concentration of 20 mg kg −1 were found to be a 1:10 soil: water ratio, 40 mW cm −2 light intensity, 5% TiO 2 in soil, and a 3-hour irradiation time, with a removal efficiency of up to 82.7%. Furthermore, this method (except for a change in irradiation time from 3 to 1.5 h) was validated in nine different soils and the removal efficiencies ranged from 57.0 to 78.6%. Removal efficiencies were found to be negatively correlated with soil Contents lists available at ScienceDirectScience of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n v electrical conductivity, organic matter content, pH and total phosphorus content. Finally, coupled with electron spin resonance (ESR) measurement, these soil properties affected the generation of OH• by TiO 2 in soil slurry. This study suggests that TiO 2 photocatalytic oxidation is a promising treatment for removing DPAA from soil.

Diverse biotechnological applications of multifunctional titanium dioxide nanoparticles: An up‐to‐date review

“…It has also been observed that all the parameters mentioned above result in the removal efficacy of 82.7% of the DPAA. It has been reported that the DPAA is not completely converted by TiO 2 NPs, rather its inorganic arsenic products are adsorbed by these NPs, hence playing crucial role in eradicating DPAA pollution [ 126 ].…”

An Overview of Chemical Oxidation Based Remediation technologies for Non-Aqueous Phase Liquids Removal from Soil

“…In addition, using artificial solar light on the photocatalytic process can be efficient. In another study, Wang et al (2016a) investigated the photocatalytic oxidation pathway of diphenylarsinic acid (DPAA) contaminated soil by nano-sized titanium dioxide (TiO2).…”

Enhanced Photocatalytic Properties of Surfactants Modified ZnO Particles Synthesized Directly via Sonochemistry Technique

“…Unfortunately, the limited-application of TiO 2 is due to its large band gap (3.2 eV) and low quantum yield in visible light region. [8,[18][19] Compared with TiO 2 , ZnO has been proposed as the promising photocatalyst to replace TiO 2 because of its same band gap energy, but shows higher absorption efficiency of the solar spectrum, special optical, strong oxidation activity and electrical properties and low electron affinity. Thus, it has drawn dominant interests in recent years.…”

“…The efficiency of photodegradation of organic pollutants primarily depends on the adsorbability for the pollutant and the quantum efficiency of the catalyst. Unfortunately, the limited‐application of TiO 2 is due to its large band gap (3.2 eV) and low quantum yield in visible light region [8,18–19] . Compared with TiO 2 , ZnO has been proposed as the promising photocatalyst to replace TiO 2 because of its same band gap energy, but shows higher absorption efficiency of the solar spectrum, special optical, strong oxidation activity and electrical properties and low electron affinity.…”