Adsorption Mechanisms of Alginate-Based Materials in Water Treatment

Alginate, a naturally derived polysaccharide, has emerged as a versatile platform for water treatment due to its abundance of carboxyl and hydroxyl groups. When formulated into beads, gels or composite matrices, alginate offers tunable porosity and surface chemistry that facilitate multiple adsorption pathways. Primary mechanisms include ion exchange, where divalent cations such as Pb²⁺ or Cr³⁺ displace Ca²⁺ in the alginate network; electrostatic attraction between negatively charged carboxylate sites and positively charged pollutants; and complexation arising from coordination of metal ions with oxygen donors. In composite materials, functional modifiers (for example polyethyleneimine or biochar) introduce additional binding sites, enhance surface area and promote synergistic capture through hydrogen bonding or π–π interactions. Kinetic studies often reveal pseudo-second-order behaviour, indicating chemisorption as a rate‐limiting step, while equilibrium analyses with Langmuir or Freundlich isotherms describe monolayer coverage and heterogeneous surface energies. Beyond heavy‐metal removal, alginate‐based aerogels and photocatalytic hybrids extend application to organic micropollutants and microbial contaminants by combining adsorption with redox or photochemical transformations. Overall, the structural versatility of alginate and its capacity for functionalisation underpin a diverse array of removal strategies, offering scalable, low‐cost routes to potable water and industrial effluent treatment worldwide.

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Adsorption Mechanisms of Alginate-Based Materials in Water Treatment publication trend

The graph below shows the total number of articles in adsorption mechanisms of alginate-based materials in water treatment across all publications each year (not limited to Nature Index journals).

Technical terms

Alginate: A polysaccharide composed of mannuronate and guluronate units, widely used to form gels through ionic crosslinking with divalent cations.

Ion exchange: A reversible process in which cations in solution replace counter‐ions bound within a solid matrix, enabling selective removal of target species.

Chemisorption: Adsorption that involves the formation of chemical bonds between adsorbate and surface sites, often leading to pseudo-second-order kinetics.

Langmuir isotherm: A model describing monolayer adsorption on a homogeneous surface with finite binding sites, used to determine maximum adsorption capacity.

Electrostatic interaction: Attraction or repulsion between charged species, key for binding metal cations to negatively charged functional groups on the adsorbent.

References

1. Facile synthesis of sodium lignosulfonate/polyethyleneimine/sodium alginate beads with ultra-high adsorption capacity for Cr(VI) removal from water. Journal of Hazardous Materials (2022).
2. Biopolymeric Ni3S4/Ag2S/TiO2/Calcium Alginate Aerogel for the Decontamination of Pharmaceutical Drug and Microbial Pollutants from Wastewater. Nanomaterials (2022).
3. Photocatalytic Removal of Cr(VI) by Thiourea Modified Sodium Alginate/Biochar Composite Gel. Gels (2022).