Researchers have developed a magnetized composite adsorbent from locally available raw kaolin and waste sheep wool that removed up to 99.97% of hexavalent chromium from water in batch experiments. The study, published in Discover Chemical Engineering, reports the development and systematic characterization of the material along with batch adsorption tests designed to evaluate how contact time, adsorbent dosage, temperature, pH, initial chromium(VI) concentration and particle size affect removal efficiency.
Characterization of the composite using FTIR, SEM and XRD analyses indicated successful integration of functional groups, a heterogeneous surface morphology, and a stable structural matrix that the authors describe as highly favorable for metal binding.
The batch experiments identified a set of optimized conditions under which performance peaked: an adsorbent dosage of 2.5 grams per liter, a temperature of 20 degrees Celsius, a pH of 2, a contact time of 210 minutes, and a particle size of 63 micrometers. Under those conditions the composite achieved its maximum reported removal efficiency of 99.97% for Cr(VI).
Equilibrium studies revealed a maximum adsorption capacity of 2.48 milligrams per gram, reached at an initial Cr(VI) concentration of 10 milligrams per liter.
The equilibrium data were best described by the Freundlich isotherm model, with a coefficient of determination of 0.961. The Freundlich model assumes multilayer adsorption on a heterogeneous surface, so the fit suggests that binding occurred on varied surface sites rather than a uniform single layer. Kinetic analysis showed the data adhered to the pseudo-second-order model, with an R² of 0.999, which the authors interpret as signifying chemisorption as the rate-limiting mechanism.
Thermodynamic parameters confirmed that the adsorption process was spontaneous and exothermic, with a standard enthalpy change of −37.82 kilojoules per mole.
The authors conclude that the composite serves as an outstanding and environmentally sustainable adsorbent.
As with any newly characterized adsorbent, the reported figures describe performance under the specific optimized conditions tested in the study.
Subject of Research: Development of a locally sourced kaolin–sheep wool composite adsorbent for removing hexavalent chromium from water
Article Title: Hexavalent chromium removal performance of a locally sourced kaolin sheep wool composite adsorbent
Article References: Birhanu, M., Worku, Z., & Habtu, N. G. (2026). Hexavalent chromium removal performance of a locally sourced kaolin sheep wool composite adsorbent. Discover Chemical Engineering. https://doi.org/10.1007/s43938-026-00153-9
Image Credits: AI Generated
DOI: 10.1007/s43938-026-00153-9
Keywords: hexavalent chromium, adsorption, kaolin, sheep wool, composite adsorbent, water treatment, Freundlich isotherm, pseudo-second-order kinetics, thermodynamics, magnetized adsorbent, Hexavalent, chromium
News Source: Bethany Barker. (November 5, 2026). Kaolin and sheep wool composite removes nearly all hexavalent chromium from water. Scienmag.
