The effectiveness and feasibility of ball-milled powdered activated carbon (BPAC) for removal of organic pesticides in conventional drinking water treatment process

Wei Li; Congjian Dong; Zijing Hao; Xinyi Wu; Donghai Ding; Jinming Duan

doi:10.1016/j.chemosphere.2024.142229

The effectiveness and feasibility of ball-milled powdered activated carbon (BPAC) for removal of organic pesticides in conventional drinking water treatment process

Chemosphere. 2024 May 7:359:142229. doi: 10.1016/j.chemosphere.2024.142229. Online ahead of print.

Authors

Wei Li¹, Congjian Dong², Zijing Hao², Xinyi Wu², Donghai Ding³, Jinming Duan⁴

Affiliations

¹ Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, 13 Yanta Road, Xi'an, 710055, China. Electronic address: liwei@xauat.edu.cn.
² Key Laboratory of Northwest Water Resources, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, 13 Yanta Road, Xi'an, 710055, China.
³ College of Materials Science and Engineering, Xi'an University of Architecture and Technology, 13 Yanta Road, Xi'an, 710055, China.
⁴ Centre for Water Management and Reuse, UniSA STEM, University of South Australia, Mawson Lakes Campus, SA, 5095, Australia. Electronic address: Jinming.Duan@unisa.edu.au.

PMID: 38723688
DOI: 10.1016/j.chemosphere.2024.142229

Abstract

In the conventional drinking water treatment process (CDWTP), powdered activated carbon (PAC) is commonly used for removing organic pesticides, or other organic contaminants. However, the hydraulic retention time (HRT) in CDWTP is insufficient for fulfilling PAC adsorption equilibrium to realize its full capacity. This study examined the adsorption kinetics, adsorption thermal dynamics, and removal efficiency for six organic pesticides using the ball-milled PAC (BPAC) with varying particle sizes in CDWTP. Based on the experiments with the pesticides of atrazine, diazinon, dimethoate, fenitrothion, isoproturon and thiometon, the results indicated that as the particle size reduced from around 38 μm for the commercial PAC to 1 μm for the BPAC, the adsorption rates for hydrophobic pesticides increased up to twentyfold. Diffusional adsorption from the bulk solution to the external PAC surface is the most likely predominant mechanism. This could allow a sufficient pesticides' adsorption within the limited HRT and to achieve a great depth removal of these toxic compounds. However, the addition of BPAC with a diameter of 1 μm was observed to significantly increase residual particles in treated water after the conventional treatment process. With a further systematic evaluation of both adsorption rate and particle penetration, a particle size of around 6 μm BPAC was considered a practical compromise between the adsorption rate and particle penetration for real application. Results from five surface waters of different water quality indicated that, compared to commercial PAC, application of 6 μm BPAC could achieve up to a 75% reduction in adsorbent dosage while maintaining around the same pesticide removal efficiencies. Additionally, thermodynamic analyses suggest that adsorption of these pesticides could be enthalpically or entropically driven depending on the degree of pesticide hydrophobicity.

Keywords: Ball-milled PAC; Conventional drinking water treatment; Pesticides; Powdered activated carbon.