Assessment of various treatment methods and reagents for cleanup and conditioning of sphagnum peat moss as sorbents in removal of malachite green as a cationic organic dye probe from water

Sustainable hydrophobic bio-based adsorbent from modified sphagnum moss for efficient oil-water separation

Oil spills pose a major environmental challenge, highlighting the urgent need for effective materials capable of achieving efficient oil-water separation to mitigate their detrimental impacts. While various bio-based and synthetic adsorbents have been explored for this purpose, existing materials often suffer from low adsorption capacity, poor reusability, limited hydrophobicity, or environmental concerns. In particular, natural bio-based materials frequently exhibit inherent hydrophilicity, limiting their effectiveness in selective oil adsorption. To address this gap, we developed a novel bio-based oil adsorbent derived from sphagnum moss, modified via sequential pretreatment with hydrogen peroxide and sodium hydroxide, followed by chemical functionalization with silane. This modification enhanced hydrophobicity and structural stability, overcoming the limitations of unmodified bio-based adsorbents. Characterization using SEM, XPS, FTIR, and TGA confirmed the successful grafting of hydrophobic functional groups and the formation of a uniformly rough surface, leading to a water contact angle of 157°. Comparative analysis demonstrated that the modified sphagnum moss exhibited a significantly enhanced adsorption capacity of 22.756 g/g for motor oil, outperforming conventional bio-based adsorbents, including currently prevalent biological adsorbents (1.69-12.8 g/g) and biochar (8.1-18.2 g/g). Furthermore, the adsorption kinetics conformed to a pseudo-second-order model, indicating chemisorption as the dominant mechanism. This suggests strong interactions between oil molecules and the functionalized surface, contributing to enhanced efficiency and selectivity. These findings highlight the novelty, superior performance, and environmental compatibility of modified sphagnum moss as an effective and sustainable solution for oil spill remediation. Its high adsorption capacity, selective oil affinity, and reusability make it a promising alternative to existing bio-based adsorbents, providing an eco-friendly approach to oil spill management and environmental restoration.

Alkali assisted hydrophobic reinforcement of coconut fiber for enhanced removal of cationic dyes: equilibrium, kinetics, and thermodynamic insight

The present study illustrates enhanced removal of methylene blue (MB) and malachite green (MG) from water using alkali-activated coconut fiber (ACF) as adsorbent. Alkali activation effectively reduces the lignocellulosic components present within coco-fiber which in turn reinforces the coco-fiber to become more water-stable. The material was characterized by FTIR, SEM-EDS, BET, XRD, and pH_ZPC. BET surface area was found to be 10.901 m² g^-1, whereas pH_ZPC of the material is 6.05. FESEM images reveal rod-like morphology. Batch experiments were optimized with respect to contact time (0-120 min), temperature (288-308 K), pH (3-10), dose (1-5 g) and input dye concentration (10-50 mg L^-1). The maximum adsorption coefficient was found to be 133.11 and 110.74 mg g^-1 for MB and MG respectively. Adsorptions are best described by pseudo-second-order kinetics (k_MB = 1.712, R² = 0.999; k_MG = 1.399, R² = 0.999) and Langmuir isotherm model (R² = 0.999). Thermodynamic data suggests a spontaneous (ΔG, -14 kJ mol^-1) and feasible process. Spent material could be regenerated by using 0.5 M HCl. Up to 50% retention of activities was seen after five cycles. It can be concluded that alkali-activated coconut fiber is an economic and sustainable choice for dye removal. Novelty statement: Spent coconut was converted into an effective biosorbent by simple alkali activation under ambient conditions to increase the hydrophobicity of the fibers by reducing the lignocellulosic components. Two cationic dyes; methylene blue and malachite green have been efficiently removed with adsorption capacities of 133.11 and 110.74 mg g^-1. The operation is simple, economically viable, and partially fulfills the principles of green engineering. Comparing with contemporary adsorbents, this material offers higher adsorption capacities with multi-cycle reusability and enhanced water stability.