Arsenite to Arsenate Oxidation and Water Disinfection via Solar Heterogeneous Photocatalysis: A Kinetic and Statistical Approach

Abstract

Arsenic (As) poses a threat to human health. In 2014, more than 200 million people faced arsenic exposure through drinking water, as estimated by the World Health Organization. Additionally, it is estimated that drinking water with proper microbiological quality is unavailable for more than 1 billion people. The present work analyzed a solar heterogeneous photocatalytic (HP) process for arsenite (AsIII) oxidation and coliform disinfection from a real groundwater matrix employing two reactors, a flat plate reactor (FPR) and a compound parabolic collector (CPC), with and without added hydrogen peroxide (H2O2). The pseudo first-order reaction model fitted well to the As oxidation data. The treatments FPR–HP + H2O2 and CPC–HP + H2O2 yielded the best oxidation rates, which were over 90%. These treatments also exhibited the highest reaction rate constants, 6.7 × 10−3 min−1 and 6.8 × 10−3 min−1, respectively. The arsenic removal rates via chemical precipitation reached 98.6% and 98.7% for these treatments. Additionally, no coliforms were detected at the end of the process. The collector area per order (ACO) for HP treatments was on average 75% more efficient than photooxidation (PO) treatments. The effects of the process independent variables, H2O2 addition, and light irradiation were statistically significant for the AsIII oxidation reaction rate (p < 0.05).

Progress of photocatalytic oxidation–adsorption synergistic removal of organic arsenic in water

“…The current results of the TiO 2 nonhomogeneous photocatalytic work are consistent with TRL = 5 (ongoing pilot-scale application) and even beyond the device diffusion of TRL = 5, suggesting that the TiO 2 photocatalytic work has found suitable experimental conditions and is scalable if space is available. This is critical for achieving scale-up factors for large plant designs (Silerio-V azquez et al, 2022). TiO 2 has a dual function in purifying arsenic from water: as an adsorbent and a photocatalyst in the presence of sunlight or ultraviolet radiation and as an adsorbent only in the absence of such radiation (Xu et al, 2007).…”

Advanced Oxidation Process: Applications and Prospects

“…The study provides important suggestions concerning the suitability of NO and NO 2 as test molecules, with NO being more suitable. Silerio-Vázquez et al [16] analyzed a solar heterogeneous photocatalytic (HP) process for arsenite (AsIII) oxidation and coliform disinfection from a real groundwater matrix employing two reactors-a flat-plate reactor (FPR) and a compound parabolic collector (CPC)-with and without added hydrogen peroxide (H 2 O 2 ). Arouca et al [17] evaluated the effectiveness of white-light photolysis (WLP) via an advanced oxidation process (AOP) for removing polycyclic aromatic hydrocarbons (PAHs) from proximity firefighting protective clothing (PFPC), while maintaining the integrity of the fabric fibers.…”