Kazakhstan’s native plant offers a greener route to cleaning dye-contaminated wastewater

Key findings

• Cellulose was successfully extracted from Phlomis tuberosa L., an indigenous plant of Kazakhstan.
• The cellulose was combined with PVDF to improve membrane strength, stability and operational durability.
• The optimised membrane removed methylene blue dye with an adsorption capacity of 94 mg/g within 100 minutes.
• Experimental adsorption data followed pseudo-second-order kinetics and the Langmuir isotherm model.
• Molecular modelling showed that electrostatic attraction, hydrogen bonding and van der Waals forces are responsible for dye adsorption.
• The study demonstrates a promising route for transforming plant biomass into sustainable water purification materials.

Synthetic dyes are widely used in the textile, cosmetic, paper, leather and pharmaceutical industries, but their release into wastewater remains a major environmental challenge. Among them, methylene blue is one of the most common cationic dyes. It is highly soluble in water, chemically stable, resistant to biodegradation and can pose risks to aquatic ecosystems and human health even at low concentrations.

A new study presents a sustainable membrane material made from cellulose extracted from the stems of Phlomis tuberosa L., a plant indigenous to Kazakhstan. The researchers show that this underutilised plant biomass can be transformed into a high-performance cellulose-based membrane capable of removing methylene blue from wastewater.

The study addresses two important questions in water treatment: how to develop efficient adsorbent materials from renewable resources, and how to understand the molecular interactions that make pollutant removal possible.

To produce the membrane, cellulose was first extracted from P. tuberosa stems through chemical pretreatment and bleaching. The cellulose was then combined with polyvinylidene fluoride, or PVDF, a polymer known for its mechanical strength and thermal stability. This hybrid approach helped improve the membrane’s structural integrity, durability and reusability, while preserving the adsorption properties of cellulose.

The resulting cellulose/PVDF membranes were examined using several advanced analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. These analyses confirmed successful cellulose isolation, improved crystallinity, and the presence of functional groups such as hydroxyl, carbonyl, C–H and N–H groups, which are important for dye binding.

Among the tested membranes, the optimised cellulose/PVDF membrane with a 90:10 composition showed the best performance. It achieved a methylene blue adsorption capacity of 94 mg/g at neutral pH within 100 minutes, demonstrating rapid and efficient dye uptake under mild conditions. The adsorption process followed pseudo-second-order kinetics and was best described by the Langmuir isotherm model, indicating that the dye molecules mainly formed a uniform monolayer on the membrane surface.

Beyond experimental testing, the study also used density functional theory calculations and molecular dynamics simulations to investigate how methylene blue interacts with the cellulose membrane at the molecular level. These computational results showed that adsorption is driven by a combination of electrostatic interactions, hydrogen bonding and van der Waals forces. The simulations further confirmed that the cellulose surface can immobilise methylene blue molecules in water through stable non-covalent interactions.

The findings highlight the potential of P. tuberosa-derived cellulose membranes as renewable and efficient materials for wastewater treatment. By converting local plant biomass into a functional environmental material, the study supports the principles of green chemistry, circular economy and sustainable water purification.

The research also opens a pathway for further development of bio-based adsorptive membranes from underutilised plant resources. With additional optimisation of regeneration performance, long-term durability and scalability, such membranes could contribute to more sustainable solutions for industrial wastewater remediation.