Photocatalytic Reduction and Crystallization Hybrid System for Removal and Recovery of Lead (Pb)

Abstract

The heavy metal lead (Pb) is toxic to humans, animals, and plants and shows persistence and is nondegradable in aquatic media. A novel method has been proposed using photocatalysis (PC) and reduction crystallization (RC) for efficient removal and recovery of lead (Pb) from the aqueous phase. Using photocatalysis, maximum removal of lead ions (Pb 2+ ) was 79.6% under optimized conditions (2 g L −1 TiO 2 , pH 5.3, and 35 W cm −2 UV light intensity). However, reduction crystallization removed 90% lead ions (Pb 2+ ) using hydrazine hydrate as a reduction agent with optimized parameters (pH 10 and temp 80 °C). To achieve maximum removal as well as recovery of toxic lead, both methods, photocatalysis and reduction crystallization, were combined, removing 98.2% of lead ions (Pb 2+ ) from the aqueous phase. The recovered precipitates and photocatalysts (TiO 2 ) were analyzed using scanning electron microscopy−energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) techniques after applying processes at optimized conditions. The EDS spectrum showed that the recovered precipitates and TiO 2 contained the lead (Pb) element. The XRD peak analysis showed that precipitates contained lead having the crystallite size of around 90 nm, whereas the XRD spectrum of recovered titanium dioxide indicated additional peaks at specific angles, showing lead deposition on the TiO 2 surface. The rate of photocatalytic removal of lead ions (Pb 2+ ) followed the Langmuir−Hinshelwood equation of the first order.

The photocatalytic process in the treatment of polluted water

“…An intimately linked photocatalysis and biodegradation (ICPB) system comprised of Fe 3+ /g-C 3 N 4 and biofilm were developed for the treatment of synthetic household wastewater containing SMX. Qidi Liu Jun Hou (Kumar et al 2020) was the researcher in this study. The results showed that this ICPB system could remove 96.27% of SMX and 86.57% of COD simultaneously, which was superior to photocatalysis alone (SMX 100%, COD 4.2%) and solo biodegradation (SMX 42.21%, COD 95.1%).…”

Recent Development of Photocatalytic Application Towards Wastewater Treatment

“…Lead is the most toxic metal, often considered a primary pollutant. The presence of this metal in water bodies mainly relies on different processing industries, such as the battery industry, antiknocking agent-tetraethyl-lead manufacturing, metal plating and finishing industry, and ceramic/glass industry [84]. Lead accumulation in the human body, beyond its permissible limit (0.05 mg/L), can create several diseases anemia, kidney malfunction, brain tissue damage, and death in severe cases.…”

USE OF PHOTOCATALYSIS FOR THE REMOVAL OF Fe AND Cu

“…Con este volumen, el costo total de fabricación fue de 2,8 M$/año con un costo de producción de $127 por unidad. Asimismo, Kumar et al, (2021) aplicaron un sistema híbrido de reducción y cristalización fotocatalítica para la eliminación y recuperación de plomo. Los resultados demostraron que, usando fotocatálisis, la eliminación máxima de iones de plomo fue del 79.6% en condiciones optimizadas con dosis de 2 g/L TiO2, pH 5.3 y 35 W/cm 2 de intensidad de luz UV, mientras que la cristalización por reducción eliminó el 90% de los iones de plomo utilizando hidrato de hidracina como agente reductor con parámetros optimizados de pH 10 y temperatura a 80 °C.…”