Industrial pollution is placing unprecedented pressure on freshwater resources, but a new generation of biodegradable materials could offer a more sustainable way to remove toxic contaminants from wastewater. Researchers at Hasanuddin University in Indonesia, led by physicist Dr. Heryanto Heryanto, have reviewed rapid advances in composite beads made from chitosan and alginate—two naturally derived polymers that can be engineered to capture heavy metals, synthetic dyes, pharmaceutical residues, and other emerging pollutants. Their analysis presents these materials as more than simple alternatives to activated carbon: with the right structural modifications, they could become recoverable, reusable, and highly adaptable treatment platforms for a circular water economy.
The review, published in Bioresource Technology Reports, examines how the chemistry and architecture of chitosan–alginate beads determine their performance. Chitosan is derived primarily from chitin, a structural material found in crustacean shells and other biological sources, while alginate is obtained from brown algae. Both polymers contain functional groups capable of interacting with dissolved pollutants. Chitosan is rich in amino and hydroxyl groups, whereas alginate contains carboxyl groups. These chemical sites can attract and bind contaminants through electrostatic interactions, ion exchange, hydrogen bonding, complex formation, and, in some cases, surface precipitation. When the polymers are combined into three-dimensional beads, their complementary chemistry creates a porous, water-compatible network that can act as a microscopic pollutant trap.
The need for such materials is urgent because industrial, agricultural, and urban wastewater can carry complex mixtures of contaminants that are difficult to remove with a single conventional process. Heavy metals such as lead, copper, cadmium, and chromium can persist in ecosystems and accumulate in living organisms. Synthetic dyes may block light penetration in waterways and contain chemically stable structures that resist degradation. Pharmaceutical compounds, meanwhile, can remain biologically active at very low concentrations, potentially contributing to ecological disruption and antimicrobial resistance. Adsorption is widely used to address these challenges because it is relatively simple to operate, can function across different pollutant classes, and often requires less energy than advanced oxidation or membrane-based systems. Yet commercial activated carbon and synthetic ion-exchange resins can be expensive, difficult to regenerate, and poorly biodegradable after disposal.
The Hasanuddin University review highlights why chitosan and alginate have become leading candidates for next-generation adsorbents. Their raw materials are renewable, and in some cases can be sourced from biological waste streams, including seafood-processing residues and algal biomass. This opens the possibility of producing treatment materials while simultaneously reducing waste. The polymers can also be shaped into beads, membranes, films, hydrogels, and other configurations, but bead systems are particularly attractive because they can be added to contaminated water, separated after treatment, and potentially regenerated for repeated use. Their visible, millimeter-scale form is also more practical than fine powders, which may be difficult to recover and could create secondary contamination if released into treated water.
However, pure chitosan and alginate networks have important weaknesses. They can swell excessively in water, lose structural integrity under acidic or alkaline conditions, and lack the mechanical strength required for long-term operation in industrial treatment systems. Their adsorption performance may also decline after repeated regeneration cycles. To overcome these problems, researchers have developed hybrid beads by incorporating additives such as activated carbon, graphene oxide, and magnetite, or iron oxide nanoparticles. These components can increase the available surface area and introduce additional binding sites, while also reinforcing the polymer matrix. Graphene oxide, for example, provides oxygen-containing groups and a large reactive surface that can interact with metals, dyes, and organic molecules. Activated carbon contributes a network of micropores and mesopores, enabling pollutants to penetrate deeper into the bead.
Magnetite offers a particularly compelling advantage: magnetic recovery. When Fe₃O₄ particles are embedded in chitosan–alginate beads, the spent adsorbent can potentially be collected from treated water using an external magnetic field rather than filtration or sedimentation. This can simplify separation, reduce material loss, and improve the feasibility of repeated use. The additives may also influence adsorption kinetics—the speed at which pollutants move from the water onto the bead surface—and adsorption capacity, which describes how much contaminant a given mass of material can capture. In a carefully designed composite, the polymers provide flexibility and chemical functionality, the reinforcing phase improves stability, and the active filler creates additional pathways for pollutant capture.
The review also considers the thermodynamic and physicochemical factors that govern these interactions. Adsorption behavior depends on pH, temperature, initial pollutant concentration, contact time, competing ions, and the chemical composition of the wastewater. Changes in pH can alter both the charge of the pollutant and the protonation state of functional groups within the polymers, strengthening or weakening attraction between them. Temperature can affect diffusion through the bead and determine whether adsorption is favorable, while ionic strength may cause common salts to compete with target contaminants for available binding sites. Understanding these variables is essential for moving beyond laboratory demonstrations. A bead that performs exceptionally well in purified water may behave very differently in a real industrial effluent containing dozens of competing substances.
To map the development of the field, the researchers conducted a systematic analysis of Scopus-indexed studies published between 2018 and 2026. The publication trend revealed rapidly growing interest in chitosan-based composite materials, with chitosan–alginate systems repeatedly appearing among the most studied platforms. This growth reflects a broader shift in materials science: rather than relying on a single high-performance substance, researchers are combining natural polymers with carbon materials, nanostructures, minerals, and responsive components to produce multifunctional adsorbents. Such combinations can improve pollutant selectivity, accelerate removal, strengthen the beads, and create recovery mechanisms that are unavailable in unmodified biopolymers.
The authors emphasize that impressive adsorption capacity alone will not determine whether these materials reach wastewater treatment plants. Industrial adoption will depend on whether the beads can be manufactured consistently at large scale, withstand prolonged exposure to complex wastewater, and maintain performance through many regeneration cycles. Researchers will also need to evaluate the environmental safety of additives, particularly nanoparticles, and confirm that they do not leach from the polymer matrix during use. Life-cycle assessments and techno-economic studies will be equally important. A material made from renewable feedstocks is not automatically sustainable if its production requires excessive energy, hazardous chemicals, or costly purification. The most promising systems will be those that balance adsorption performance with low manufacturing costs, minimal environmental impact, easy recovery, and reliable regeneration.
According to Dr. Heryanto, the significance of these composite beads extends beyond wastewater remediation. Their tunable chemistry and responsive behavior could make them useful in precision medicine, smart agriculture, and other technologies that require selective capture or controlled release of molecules. In the near term, however, their greatest opportunity may lie in helping communities and industries treat contaminated water with materials that are biodegradable, reusable, and potentially derived from waste. By connecting renewable resources, advanced composite design, and pollutant recovery, chitosan–alginate beads align with global goals for clean water, responsible production, and sustainable infrastructure. The review suggests that the next breakthrough may not come from a single new adsorbent, but from designing natural materials intelligently enough to work repeatedly in the messy, chemically diverse conditions of the real world.
Subject of Research: Chitosan- and alginate-based composite beads for wastewater remediation
Article Title: Trends in recent advances of chitosan and alginate-based composite beads for wastewater remediation
News Publication Date: 10 July 2026
Web References: Bioresource Technology Reports; DOI: https://doi.org/10.1016/j.biteb.2026.102914
References: “Trends in recent advances of chitosan and alginate-based composite beads for wastewater remediation,” Bioresource Technology Reports, DOI: 10.1016/j.biteb.2026.102914
Image Credits: “Worker at waste water treatment facility” by World Bank Photo Collection via Flickr
Keywords: wastewater remediation, chitosan, alginate, composite beads, adsorption, biopolymer composites, heavy metals, synthetic dyes, pharmaceutical pollutants, activated carbon, graphene oxide, magnetite, sustainable materials, circular bioeconomy, water treatment
