<span lang="EN-CA">Biopolymer Ionosorbents for Heavy-Metal Removal: Mechanisms, Validation, and Scale-Up

Heavy-metal contamination of water remains a persistent environmental and public health challenge because many metal ions are non-biodegradable, mobile under changing solution chemistry, and prone to bioaccumulation. This structured narrative critical review evaluates carbohydrate-polymer ionosorbents based on chitosan, alginate, cellulose, and hybrid derivatives for the removal of Pb(II), Cd(II), Cu(II), Cr(VI), Hg(II), Ni(II), Zn(II), and related species. Functionalization routes, including cross-linking, grafting, thiolation, amination, carboxylation, phosphorylation, and composite formation, are interpreted through a two-tier evidence framework that separates primary metal-removal studies from contextual sources (e.g., dye adsorption, polymer chemistry, and modeling theory). Particular attention is given to common weaknesses in adsorption research: overreliance on maximum adsorption capacity (qmax), inadequate separation of adsorption from precipitation, unsupported mechanistic assignments, limited uncertainty reporting, and excessive dependence on idealized single-metal systems. These issues are addressed by requiring pH and precipitation controls, metal-speciation evidence where relevant, cautious interpretation of model fitting, and comparison of materials using matrix composition, regeneration stability, and flow-through relevance rather than qmax alone. The review identifies real-water validation, extended adsorption-desorption cycling, fixed-bed operation, techno-economic assessment, life-cycle assessment, and end-of-life management as the main barriers to scale-up. Credible implementation will require reproducible synthesis, transparent characterization, realistic water matrices, cycle-by-cycle performance reporting, and process-oriented design.

کلیدواژه ها:

Chitosan ، alginate ، Cellulose ، ionosorbents ، heavy metals ، real-water matrices