A significant environmental concern is posed by wastewater containing dyes. When dealing with a polluted medium, adsorption is a beneficial method for the removal of contaminants. This study used argan nutshell as a precursor to synthesize activated carbon via chemical activation with Na₂CO₃ at 600 °C. The prepared activated carbon (Na@Ac) was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and zeta potential measurements. The results showed that the prepared activated carbon has a high surface area (1543 m²/g) and microporous structure. Furthermore, many parameters for Rhodamine B (RhB) dye removal efficiency, including pH, initial pollutant concentration, and temperature, were optimized by response surface methodology (RSM) with a central composite design. Based on the RSM, the best efficiency was 96.84% for the removal of RhB at pH 5, temperature 20 °C, and initial concentration 33.2 mg/L. The kinetic of RhB dye adsorption onto Na@Ac was effectively explained by a pseudo-second-order model, with a maximum uptake capacity of 35.9 mg/g. Moreover, Density functional theory (DFT) calculations were used to understand the adsorption mechanism of the RhB dye onto the Na@Ac. Based on the DFT calculations, hydrogen bonding and π-π interactions may be preferred mechanisms of RhB dye adsorption onto Na@Ac. The Na@Ac could be a promising adsorbent for the removal of Rhodamine B from polluted wastewater.

This study focuses on the synthesis of new materials based on hydroxyethyl cellulose (HEC) and (3-aminopropyl)triethoxysilane (APTES) in a single-step process, adopting an efficient and innovative approach. The structural and physical properties of the synthesized polymers were meticulously characterized using analytical techniques, including FTIR/ATR, ¹H, ¹³C, 135-DEPT, ²⁹Si NMR, elemental analysis, and TGA/DTA. The morphology and amorphous profile of HEC-APTES were examined through SEM-EDX and XRD, respectively. In this study, a comprehensive analysis was conducted to gain a deeper understanding of the underlying mechanism and critical reaction conditions governing the interaction between HEC and the organosilane reagent. Various reaction parameters, such as reaction time, silane molar ratio (0.5:1, 1:1, 2:1, and 3:1 relative to HEC), and the autocatalysis of HEC alkoxides, were systematically investigated. Particularly, the combined influence of the reaction medium and the amount of added APTES on the grafting mechanism and mode was carefully examined. Lastly, an assessment of the solubility, dispersion, contact angle and bioactivity against various types of bacteria and fungi in the HEC-APTES samples was conducted to conclude this study. HEC-APTES demonstrates notable antifungal activity against Rhodotorula glutinis, Geotrichum candidum, and Aspergillus niger, with minimum fungicidal concentrations (MFC) of >20 mg/L, 2.5 mg/L, and 2.5 mg/L, respectively.

This study focuses on the development of eco-friendly biobased adsorbents through a sustainable hydrothermal and freeze-drying synthesis process, utilizing cost-effective bio-sourced materials to minimize energy consumption and waste. The biobased adsorbents were elaborated using hydroxyethyl cellulose-ionic liquids and bentonite clay. The elaborated biocomposites were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy/attenuated total reflection (FTIR/ATR), thermogravimetric analysis (TGA), and electron microscopy-energy dispersive X-ray (SEM–EDX), Brunauer–Emmett–Teller (BET) and zeta potential (ZP). Structural analysis confirms the intercalation and incorporation of HEC-ILs polymeric chains into Be-Na matrix and the formation of biocomposites. The [HEC-ILs/Be-Na] composite was subsequently employed for solid-phase extraction of Co(II) by investigating the effect of pH, initial Co(II) concentrations, time, temperature, and the presence of co-existing ions (Na(I), Li(I), Mn(II), Ni(II), and Al(III)). The adsorption kinetics of Co(II) metal ions were suitably characterized using the pseudo-second-order model (with R² > 0.99). Furthermore, the adsorption isotherms conformed to the Langmuir model (with R² > 0.97), suggesting a chemisorption process with an adsorption capacity of 69.8 mg/g. The thermodynamic study reveals that the adsorption process exhibits characteristics of spontaneity and endothermicity (ΔH° = 74.197 kJ mol⁻¹, ΔG° < 0 kJ mol⁻¹). The proposed mechanism for Co(II) adsorption on the developed biocomposite involves electrostatic interactions, ion exchange, and anion-π interactions. The biobased composite exhibited remarkable selectivity for Co(II) and demonstrated great potential as an adsorbent for industrial applications. Graphical abstract

This study presents a simple and ecofriendly pathway for synthesizing of cellulose acid half-esters, utilizing a toxic organic solvent-free synthesis strategy and ensuring a green approach. The esterification of hydroxyethyl cellulose (HEC), derived from Stipa tenacissima, with maleic, succinic, and phthalic anhydrides was investigated, revealing significant structural and physicochemical modifications. Increasing the anhydride/HEC molar ratio enhanced the degree of substitution (DS), reaching values of 1.4, 1.28, and 0.51 for HEC-AS, HEC-AM, and HEC-AP, respectively. High reaction temperatures (>100 °C) promoted cross-linking, affecting the solubility of the modified polymers. Structural analysis showed that the organization of acid half-esters strongly influenced wetting properties and thermal behavior. HEC-AM and HEC-AP exhibited lower T_g values (40 °C and 91.82 °C) due to hydrogen bonding reorganization and the resulted configuration of the acid half-ester groups, while HEC-AS remained stable at 117.76 °C. These structural differences resulted in distinct contact angles of 55°, 90°, and 102°, respectively. Solubility and surface charge studies further confirmed the impact of modification on polymer charge behavior, resulting in an anionic character. These findings demonstrate the effectiveness of this green synthesis strategy in tailoring biopolymer properties for functional applications.

In this study, novel biocomposites based on sodium-bentonite (Be-Na) and hydroxyethyl cellulose (HEC) acid half-esters were developed through an environmentally friendly, aqueous-phase synthesis. A strategy combining solution blending, hydrothermal treatment, and freeze-drying was employed to promote the intercalation of anionic HEC derivatives into the interlayer galleries of Be-Na. The selected acid half-esters were chosen for their anionic and amphiphilic nature, enabling improved compatibility between hydrophilic clay and organic polymer matrices while enhancing dispersion and structural uniformity. A comprehensive morphological characterization was conducted on the synthesized materials, revealing an intercalated structure in the synthesized biocomposites, facilitated by the hydrothermal process. The incorporation of Be-Na nanofillers led to an enhancement in the thermal properties of the polymer chains, and a synthesis mechanism for the biocomposites was anticipated. Subsequently, these biocomposites were evaluated for their effectiveness in the separation of Ni(II) ions from complex mixtures. The Be-Na/HEC-AP biocomposite proved to be particularly promising, demonstrating increased adsorption efficiency compared to other biocomposites, even at acidic pH levels. Kinetic studies revealed an adsorption process consistent with PFO kinetics, while the Langmuir model with a chemisorption process better described the adsorption behavior of Ni(II) ions. Furthermore, the adsorption capacity of the Be-Na/HEC-AP biocomposite was determined to be 3.27 mmol/g. Significant selectivity towards Ni(II) ions was observed, and the material remained stable even after 5 cycles of adsorption–desorption. The Be-Na/HEC-AP biocomposite, with its high Ni(II) adsorption capacity, stability over multiple cycles, and green scalable synthesis, shows strong potential for industrial wastewater treatment applications. Graphical abstract