Adsorption Mechanisms for Pesticide Removal from Aqueous Solutions

Adsorption has emerged as a pivotal method for the removal of pesticide residues from water, combining high efficiency with operational simplicity. At its core, adsorption relies on the transfer of pesticide molecules from the bulk solution onto the surface of a solid phase, or adsorbent. Mechanistically, this process may be governed by physisorption—where weak van der Waals forces or electrostatic attractions predominate—or by chemisorption, which involves specific chemical bonding. The efficiency of adsorption is strongly influenced by the physicochemical characteristics of both the adsorbent (surface area, pore structure, functional groups) and the pesticide (molecular size, polarity, aromaticity). Common adsorbent classes include activated carbons, biochars, clays, polymer hydrogels and magnetic nanocomposites. Equilibrium isotherms, notably Langmuir and Freundlich models, are used to describe how pesticides populate the adsorbent surface at varying concentrations, while kinetic models (pseudo-first-order or pseudo-second-order) reveal the rate-limiting steps of uptake. Thermodynamic parameters, such as changes in enthalpy and entropy, further elucidate the nature of adsorption interactions. In practice, adsorption offers flexibility across scales—from decentralised treatment units in rural settings to large-scale industrial effluent plants—and can be tailored to target a broad spectrum of pesticide chemistries, thereby supporting global efforts to safeguard water quality and public health.

Research from Nature Portfolio

Recent studies have demonstrated advances in smart process optimisation and novel composite adsorbents. One investigation applied response surface methodology and hybrid neural-network genetic-algorithm models to optimise the batch removal of an organophosphate pesticide using porous pumice. By systematically varying pH, adsorbent dosage, initial concentration and contact time, the study identified conditions yielding maximal uptake, while fitting equilibrium data to Langmuir and Temkin isotherms and kinetics to pseudo-first- and pseudo-second-order models. Thermodynamic analysis confirmed a spontaneous, endothermic adsorption process. Another work introduced a magnetic mesoporous hydrogel nanocomposite, synthesised by embedding Fe₃O₄ nanoparticles and bentonite clay within a crosslinked pectin matrix. The resulting material exhibited high porosity, abundant reactive sites and a strong negative zeta potential, leading to exceptional adsorption capacities for chlorpyrifos and concurrent removal of an organic dye. Adsorption followed the Freundlich isotherm and pseudo-second-order kinetics, and the magnetic composite could be recovered and reused over multiple cycles with minimal loss of performance.

Adsorption Mechanisms for Pesticide Removal from Aqueous Solutions publication trend

The graph below shows the total number of articles in adsorption mechanisms for pesticide removal from aqueous solutions across all publications each year (not limited to Nature Index journals).

Technical terms

Adsorption: The accumulation of molecules from a fluid onto a solid surface through physical or chemical interactions.

Isotherm: A mathematical model describing how adsorbate concentration on the adsorbent surface relates to its equilibrium concentration in solution at constant temperature.

Kinetics: The study of the rate at which adsorption proceeds and the identification of rate-controlling steps.

Biochar: A carbon-rich material produced by pyrolysis of biomass, valued for its porous structure and surface reactivity in pollutant adsorption.

Hydrogel: A three-dimensional, crosslinked polymer network capable of absorbing large volumes of water and hosting active adsorption sites.

Zeta potential: A measure of the surface charge of particles in suspension, influencing colloidal stability and electrostatic interactions with charged pollutants.

References

1. Removal of pesticides from water and wastewater: Chemical, physical and biological treatment approaches. Environmental Technology & Innovation (2020).
2. Process optimization and enhancement of pesticide adsorption by porous adsorbents by regression analysis and parametric modelling. Scientific Reports (2021).
3. Enhancement of adsorption efficiency of crystal violet and chlorpyrifos onto pectin hydrogel@Fe3O4-bentonite as a versatile nanoadsorbent. Scientific Reports (2023).
4. Adsorption Kinetics of Imidacloprid, Acetamiprid and Methomyl Pesticides in Aqueous Solution onto Eucalyptus Woodchip Derived Biochar. Minerals (2022).
5. Removal of Pesticides from Waters by Adsorption: Comparison between Synthetic Zeolites and Mesoporous Silica Materials. A Review. Materials (2021).
6. Porous Activated Carbon from Lignocellulosic Agricultural Waste for the Removal of Acetampirid Pesticide from Aqueous Solutions. Molecules (2020).