Dual crosslinking of low-methoxyl pectin by calcium and europium for the simultaneous removal of pharmaceuticals and divalent heavy metals

Javier Martínez-Sabando, Francesco Coin, Juan Carlos Raposo, Aitor Larrañaga, Jorge H. Melillo, and Silvina Cerveny.
Chemical Engineering Journal 475, 146162 (2023)

Water is fundamental to our society’s progress and economic development and essential for human survival, agriculture, healthcare, industry, and safety. Furthermore, water is intrinsically linked to the financial well-being of our communities, and currently, there is no alternative to water on the surface of our planet. However, emerging contaminants, a group of unregulated pollutants such as pharmaceuticals, heavy metals, pesticides, and personal care products, are being detected in water sources more frequently than ever, and it is necessary to take action urgently. These contaminants pose severe environmental and human health risks and are difficult and expensive to remove.

In this study (collaboration between CFM, DIPC, MPC, and UPV/EHU) has developed an adsorbent based on pectin (a recyclable, biodegradable, and cost-effective material), which is highly effective for the simultaneous removal of both heavy metals and pharmaceutical products from water. The novel approach includes the gelation of pectin by crosslinking it with different agents: calcium, europium, and their combination. The reticulated pectin structures exhibited significant structural differences depending on the type of crosslinking agent used, affecting adsorption capacity. Specifically, calcium cations partially formed a crystalline “egg-box” structure, whereas europium cations produced an amorphous network without crystalline regions. The dual-crosslinking system resulted in an intermediate network with crystalline and amorphous regions.

The findings show that dual-cross-linked pectin is a highly effective adsorbent for the simultaneous removal of heavy metals and pharmaceutical products. The material can capture over 99% of metals and more than 70% of drugs. This novel approach of crosslinking pectin with multiple agents has the potential to significantly enhance its remediation capacity, offering a promising solution for the simultaneous removal of numerous pollutants from water.

Schematic representation of water remediation
using pectin-based adsorbents.