📄 chemistry

Efficiency of fly ash geopolymer–MXene nanocomposite for ibuprofen removal from water

This study demonstrates that fly ash-based geopolymer and its MXene nanocomposite serve as effective, low-cost adsorbents for removing ibuprofen from water, achieving significant removal efficiencies under optimized conditions through surface interactions governed by second-order kinetics.

Original authors: Nurul Atikah Heshammuddin, Nor Hidayah Abu Bakar, Saidatul Nadhirah Ruzaidi, Radin Maya Saphira Radin Mohamed, Ahmer Ali Siyal, Nurina Fitriani, Hereyra Sudan Tedong

Published 2026-07-03

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Nurul Atikah Heshammuddin, Nor Hidayah Abu Bakar, Saidatul Nadhirah Ruzaidi, Radin Maya Saphira Radin Mohamed, Ahmer Ali Siyal, Nurina Fitriani, Hereyra Sudan Tedong

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your local river is like a giant, clear swimming pool. Over time, tiny amounts of medicine—specifically ibuprofen, the stuff you take for headaches and pain—have been leaking into this pool from our homes and hospitals. Even though the amounts are small, these "invisible guests" don't belong there and can hurt the fish and the ecosystem.

This research paper is like a team of scientists trying to build a better "net" to catch these invisible guests before they cause trouble. They wanted to see if they could make a super-efficient sponge out of two specific ingredients: Fly Ash (a waste product from coal power plants) and MXene (a high-tech, ultra-thin material made of titanium and carbon).

Here is the story of what they found, explained simply:

1. Building the "Super Sponge"

The scientists took waste fly ash and turned it into a hard, porous material called a geopolymer. Think of this as a rough, rocky sponge. On its own, it's okay at catching ibuprofen, but it has some limitations.

Then, they tried to upgrade this sponge by mixing in the high-tech MXene material. Imagine sprinkling ultra-fine, sticky glitter into the rocky sponge. They hoped this "glitter" would make the sponge stickier and better at grabbing the medicine. They baked this mixture together to create their new nanocomposite.

2. What the Microscope Showed

When they looked at their creations under a powerful microscope (like a super-magnifying glass), they saw:

The Rocky Sponge (Fly Ash Geopolymer): It had lots of tiny holes and nooks, perfect for trapping things.
The Upgraded Sponge (With MXene): It looked a bit more chaotic. The "glitter" (MXene) had started to rust or oxidize a little bit, turning into a mix of aluminum and titanium oxide. It was still there, but it wasn't as perfectly layered as the scientists hoped.

3. The "Tug-of-War" Experiment

To test how well these sponges worked, the scientists set up a series of "tug-of-war" games in a lab. They mixed the sponges with water containing ibuprofen and changed the rules to see what worked best:

The pH Factor (Acidity): Just like how some people prefer sweet tea and others prefer lemonade, the sponges had different favorite flavors.
- The plain Rocky Sponge worked best in slightly neutral water (like a calm lake).
- The Upgraded Sponge actually preferred slightly sour (acidic) water.
Time: They let the sponges sit in the water for different amounts of time. They found that 2 hours was the sweet spot. If they waited too long, the sponges got tired and stopped catching more medicine.
Amount of Sponge: They tried using different amounts of the material. They found that using exactly 1 gram was the Goldilocks zone. Too little, and the sponge couldn't catch everything; too much, and the sponge particles clumped together like wet sand, blocking their own holes.

4. The Results: Who Won?

Here is the surprising twist in the story. The scientists expected the "Upgraded Sponge" (with the high-tech MXene) to be the clear winner. However, the results showed:

The Plain Rocky Sponge actually removed 48.75% of the ibuprofen.
The Upgraded Sponge only removed 42.5%.

Why did the fancy upgrade fail?
It turns out that the "glitter" (MXene) got a bit damaged during the mixing process. It oxidized (like rust forming on iron) and clumped together. Instead of helping, these clumps actually blocked some of the tiny holes in the sponge, making it harder for the ibuprofen to get inside.

5. How the Catching Happened

The scientists also studied how the sponge caught the medicine:

The "Handshake" (Chemistry): They found that the sponge didn't just physically trap the medicine; it actually formed weak chemical "handshakes" (hydrogen bonds) with the ibuprofen molecules.
The Speed: The process followed a specific pattern where the speed of catching depended on how many "handshakes" were available, rather than just how fast the molecules were moving around.

The Bottom Line

This research tells us that while high-tech materials like MXene sound amazing, simply mixing them with waste materials doesn't always guarantee a better result. In this specific case, the plain, low-cost fly ash sponge actually did a better job of cleaning the water than the fancy upgraded version.

The study concludes that these fly ash sponges are a promising, cheap way to clean up water, but if we want to use the high-tech MXene version, we need to figure out how to keep the "glitter" from rusting and clumping up so it can do its job properly.

Technical Summary: Efficiency of Fly Ash Geopolymer–MXene Nanocomposite for Ibuprofen Removal from Water

Problem Statement
Pharmaceutical residues, specifically non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (IBU), persist in wastewater and surface waters, posing ecological risks such as endocrine disruption and toxicity to aquatic life. Traditional wastewater treatment facilities often fail to effectively remove these contaminants, while advanced methods like membrane filtration and advanced oxidation face challenges regarding cost, scalability, and by-product generation. Consequently, adsorption has emerged as a viable, cost-efficient alternative. However, existing fly ash geopolymer (FG) adsorbents are limited by restricted surface areas and partially inaccessible active sites. While MXenes (Ti₃C₂Tₓ) possess high surface areas and functional groups that could enhance adsorption, there is a scarcity of research assessing the efficacy of MXene-modified geopolymers for pharmaceutical removal.

Methodology
This study synthesized and evaluated two adsorbents: a standard fly ash geopolymer (FG) and a fly ash geopolymer–MXene nanocomposite (FG-MX).

Synthesis: MXene (Ti₃C₂Tₓ) was produced by etching Ti₃AlC₂ (MAX phase) with hydrofluoric acid (HF), followed by delamination in dimethyl sulfoxide (DMSO) and freeze-drying. The FG-MX composite was created by mixing the MXene into a fly ash geopolymer slurry (activated by NaOH and Na₂SiO₃), curing at 60°C, and drying.
Characterization: The materials were analyzed using FTIR (functional groups), XRD (phase identification), and FESEM (microstructural morphology).
Adsorption Experiments: Batch adsorption tests were conducted to remove IBU from aqueous solutions. Parameters optimized via Response Surface Methodology (RSM) included solution pH (2–10), contact time, adsorbent dosage (0.5–1.5 g), and initial IBU concentration (100–500 mg/L).
Modeling: Adsorption kinetics were evaluated using pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion models. Equilibrium data were fitted to Langmuir, Freundlich, and Temkin isotherms. Thermodynamic parameters (ΔG°, ΔH°, ΔS°, Ea) were calculated to assess spontaneity and energy changes.

Key Results

Material Characterization: FTIR confirmed the presence of hydroxyl (–OH) and fluoride (–F) groups in both materials, facilitating hydrogen bonding. XRD revealed an amorphous geopolymer matrix with quartz and hematite phases; the FG-MX composite additionally showed peaks corresponding to aluminium–titanium oxide (Al–Ti–O), indicating partial oxidation of the MXene. FESEM showed heterogeneous nanoscale morphologies (80–200 nm) with accessible pores, though some flaky structures were observed in FG-MX.
Optimization: The optimal conditions differed slightly between materials:
- FG: pH 6, 1 g dosage, 120 min contact time, 100 mg/L initial concentration.
- FG-MX: pH 4, 1 g dosage, 120 min contact time, 100 mg/L initial concentration.
Removal Efficiency: Under optimal conditions, the standard FG achieved a removal efficiency of 48.75%, while the FG-MX composite achieved 42.5%. The authors attribute the lower performance of FG-MX to the partial oxidation of MXene and particle agglomeration, which reduced active site availability.
Kinetics and Isotherms:
- Kinetics: Adsorption followed pseudo-second-order (PSO) kinetics, suggesting chemisorption and surface interaction govern the process. The FG-MX composite showed a high correlation coefficient (R² = 0.9993) for the PSO model at higher concentrations.
- Isotherms: The Langmuir model provided the best fit, indicating monolayer adsorption. The maximum monolayer adsorption capacity ( $q_{max}$ ) was calculated as 905.10 mg/g for FG and 873.26 mg/g for FG-MX.
Thermodynamics: The process was found to be spontaneous (negative ΔG°) and endothermic (positive ΔH°), primarily driven by physisorption mechanisms.

Significance and Claims
The paper claims that fly ash-based geopolymer materials are promising, low-cost adsorbents for removing pharmaceutical contaminants from water. While the addition of MXene did not result in a higher removal percentage under the specific optimal conditions tested—likely due to synthesis-induced oxidation and agglomeration—the FG-MX composite demonstrated significant adsorption capacity and robust chemisorptive properties. The study concludes that optimizing the dispersion of MXene and controlling oxidation during synthesis are critical for future improvements. The research contributes to the development of sustainable adsorbents by clarifying the kinetic, equilibrium, and thermodynamic mechanisms involved in IBU removal using these composite materials.