Low-cost poly(vinyl formal) for heavy metal removal from water of a polluted river

Francisca Villanueva-Flores,Laura A Palomares

doi:10.2166/wrd.2022.077

Abstract

Abstract Heavy metal pollution in drinking water is a serious health risk, particularly in developing countries. Membranes of poly(vinyl formal) (PFA) were synthesized to explore their use for heavy metal removal from water samples from the polluted Mexican river ‘Atoyac.’ A single incubation step with PFA membranes for 24 h was sufficient to reduce lead, iron, manganese, arsenic, and thallium concentrations to acceptable levels for drinking water, according to the Mexican standards. PFA showed high adsorption capacities (Qe), even in the presence of multiple metals and low cation concentration. Mass transport phenomena were characterized as a function of the crosslinking degree and pH. To simulate real-life operation conditions, water fluxes across PFA membranes were characterized as a function of their crosslinking degrees and controlled external pressures. PFA membranes allowed fluxes at pressures of up to 2 kg/cm2 with no deformation or breaking. Tensile strength, strain stress, elastic deformation, and Young's modulus were assessed. In contrast with previous reports, no further PFA modifications were required to obtain an excellent adsorption performance, which results in lower production costs. The ease of PFA synthesis and handling, and low production cost make it an ideal material to be applied for remediating the polluted urban water.

Highlights

Heavy metal poisoning remains a significant problem for all life forms, especially in developing countries with deficient sanitation control
Our results show that the efficiency for heavy metal removal is inversely proportional to the hydrochloric acid (HCl) concentration used as crosslinker
We found that poly(vinyl formal) (PFA) membranes are synthesized, have a low cost of materials, and resist a wide range of pH and showed adequate mechanical resistance, which makes them excellent materials for resisting extreme environmental conditions

Summary

Introduction

Heavy metal poisoning remains a significant problem for all life forms, especially in developing countries with deficient sanitation control. Heavy metals are incorporated into the food chain from leaching through the soil to the aquifers used to irrigate crops and as drinking water (Hejna et al 2018; Jiang et al 2021; Peng et al 2021). Several studies have shown that Mexican aquifers and adjacent soils contain high concentrations of heavy metals (Armienta & Segovia 2008; Maldonado et al 2008; Pastrana-Corral et al 2017; Navarrete-Rodríguez et al 2020). The primary human sources of heavy metals and other dangerous elements are mining, smelters, oil refineries, brickwork and cement plants, coal combustion, paints, among many others (Romieu et al 1994; Rodríguez-Mercado & Altamirano-Lozano 2013; Diaz-Ruiz et al 2017)

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