Although a small number of metals and metalloids are necessary as “micronutrients” for plants and animals, which include some heavy metals such as cobalt, copper, chromium, zinc, lead, cadmium, etc. in trace amounts, their increased concentrations are highly toxic to almost all organisms. A primary cause of heavy metal pollution is anthropogenic activities and impact on human health and toxicity limits are well established. Herein we report a proof of concept of environmentally benign chemadsorbents and chelators synthesized via chemical modification of natural biopolymers such as alginates for selective recovery and recycling of industrially relevant heavy metals. Reductive amination chemistry was utilized for the addition of amino acids to alginate polymer (LVG). Preliminary data with small molecule modifiers including phenylalanine, tyrosine, serine and aspartic acid were conducted with metal salts of coper and cadmium. Chelation tests under acidic, neutral, and basic conditions were conducted and basic environment gave promising trends of better chelation even after prolonged hours of dialysis. Elemental analysis of metal chelated polymer solutions was conducted using FAAS for quantification one predetermined intervals while dialyzing the samples under given pH conditions. Ongoing tests using additional relevant monomers and dimers of amino acids, metal coordination reversibility under different pH environments, and trend studies are ongoing to get a better grasp of chelation capacity of these modified biopolymers.

Sustainable approaches for heavy metals recovery and recycling with natural biopolymers

ACS Spring 2022

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