Dewaxed Honeycomb as an Economic and Sustainable Scavenger for Malachite Green from Water

Sequestration of a food dye (sunset yellow) from wastewater using natural adsorbent: a kinetic, isotherm and interference study

Cocos nucifera, commonly known as coconut is rich in coir dust (CCD) at its outer surface, which is a very significant agri waste used as biosorbent for wastewater treatment. The current work addresses use of CCD for removal of hazardous Sunset Yellow dye (SY) FCF widely used as coloring agent in food industry, from wastewater. The uptake capacity in batch and column mode is 82 mg/g and 160 mg/g respectively. Characterization study including SEM, FTIR and BET results also supported the adsorption process. The comparative analysis with other natural biosorbents showed best results of biosorption with CCD. The output was better at high pH (10) and lower concentration of dye (5 mg/L). The kinetic study suggested pseudo second order rate revealing both adsorbate-adsorbent interdependency. The presence of covalent bonding or valence forces between the interfaces, suggested chemisorption as the rate limiting mechanism with valence forces, hydrogen bonding and pi-pi stacking being the chief forces responsible in binding of the dye molecules to the surface. The isotherm supported Langmuir model with monolayer and uniform adsorption at the interfaces. The interference test confirmed slight decrease in percent adsorption with interference from chloride and sulfate as dominating ions. The techno-economic feasibility highly recommended in field application of the substitute (net profit value, 1.256 Rs/m3, input cost, 0.052 Rs/m3). The industrial sample analysis with lab to land approach justified sustainability and commercial viability of the present work.

Wodyetia bifurcata (foxtail palm tree) leaves as a super-augmented instantaneous methylene blue remover from simulated water and wastewater

Wodyetia bifurcata, also known as foxtail palm tree leaves, was tested for highly effective methylene blue (MB) removal from commercial and artificial effluent. BET surface area measurement, FESEM, FTIR, and pHzpc were used to get information on the shape and structure of the particles. Several important factors were used to determine its adsorption activity, including intake concentration, contact duration, and pH level. Accelerated adsorption is seen in the experimental results, with more than 94% adsorption occurring successfully in the initial 12 min and reaching equilibrium within 15 min (% removal = 97.45%) at neutral pH. It was discovered that the maximum adsorption capacity was 58.74 mg g-1 at 308 K. The adsorption procedure confirms an active adsorption process of linear and non-linear kinetics of pseudo-second order, and the adsorption path is well addressed by the Freundlich model both in linear and non-linear form, having an R2 value close to unity. Thermodynamic characteristics point to an exothermic, viable, spontaneous reaction with higher entropy. Utilizing a 1:1 MeOH/H2O ratio, spent adsorbent may be readily regenerated by as much as 75% with a possible three-cycle usage. The practical application of biosorbents was confirmed by real-time effectiveness testing using MB-carrying industrial wastewater, and up to 45.75% adsorption was shown. A relative standard deviation confirmed statistical dependability. All things considered, the current material provides a clean and environmentally friendly way to remove MB dye from various wastewater types.

Exploring Ficus religiosa inflorescence powder as an eco-friendly and sustainable solution for the removal of crystal violet with a disposal solution

This study investigates the potential of using Ficus religiosa inflorescence (peepal tree) as an efficient solution for removing crystal violet from simulated and industrial wastewater. Various analyses were conducted to understand the adsorbent's structure, including particle morphology, BET surface area, FTIR, and pHZPC. The adsorption process was studied under different physicochemical factors such as temperature, concentration, contact time, and pH. Results revealed rapid adsorption, with 94.15% removal efficiency within the first 15 min at neutral pH. The highest observed adsorption capacity was 198.03 mg g-1, following pseudo-second-order kinetics (R2 = 0.99), indicating chemisorption. The Langmuir model accurately described the adsorption pathway (R2 = 0.99), showing monolayer adsorption. Thermodynamic analysis indicated an exothermic, feasible, and spontaneous process with increased entropy. The adsorbent could be easily regenerated using a 1:1 MeOH/H2O mixture for up to three cycles, yielding up to 73.86%. Real-time application with industrial effluent containing crystal violet showed up to 44.70% adsorption. The experiments demonstrated reliability with evaluated standard deviations (0.017935-0.000577) and relative standard deviations (0.439-0.673%), confirming statistical reliability. In conclusion, it presents a sustainable and eco-friendly approach for removing crystal violet dye from diverse wastewater sources.

Think before throw: waste chili stalk powder for facile scavenging of cationic dyes from water

Chili stalk powder (CS), a non-conventional adsorbent, has been exercised for facile removal of cationic dyes from simulated and wastewater by batch technique. The prepared material has been characterized by Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller analysis (BET), powder X-ray diffraction (powder XRD), and pHZPC and tested best with methylene blue and crystal violet under ambient conditions. FTIR denotes the presence of carbonyl and polyphenolic groups, responsible for dye adsorption. BET surface area analysis evaluates the porous nature and specific surface area of the material, and powder XRD confirms its amorphous nature. The porous structure could be ascertained from the FESEM image, and energy dispersive X-ray analysis (EDX) confirms the elemental composition. The pH above pHzpc shows an increase in removal efficiency. The maximum adsorption capacities are 49.53 and 36.88 mg/g for methylene blue (MB) and crystal violet (CV) respectively. Linear as well as non-linear plots for kinetic and isotherm models were studied. Both dye uptake fits the linear plot of Langmuir adsorption isotherm (R2 = 0.999 and 0.995) and pseudo-second-order kinetics (R2 = 0.998 and 0.999). In the non-linear plot, the adsorption process for both dyes fit Langmuir (R2 = 0.999 for MB and R2 = 0.983 for CV) as well as Freundlich adsorption (R2 = 0.999 for MB and R2 = 0.994 for CV). 75.48% crystal violet (CV) and 73.35% methylene blue (MB) regeneration were successful in 1:1 methanol medium and reused for up to three cycles. The uptake mechanism is suggested to be a union of π-π stacking, electrostatic interaction, and weak hydrogen bonding. The material was tested with industrial effluent to prove its application in real wastewater treatment. Moreover, the material shows superior adsorption capacity than contemporary phytosorbents. To conclude, a zero-cost adsorbent using green chili stalk has been demonstrated for wastewater treatment.

From Hive to Highway: Waste Honeycombs as a Sustainable Modifier for Asphalt Binder Formulations in South Korea

Navigating the crossroads of sustainable infrastructure and innovative waste management, this research unveils the potential of waste honeycombs (WHCs)-an overlooked byproduct of apiculture-as a potent modifier for asphalt binder formulations. This endeavor addresses the dual challenge of enhancing road pavement sustainability and mitigating environmental degradation. A meticulous methodology evaluated the impact of varying WHC concentrations (5, 10, and 15 wt.%) on the asphalt binder, examining its attributes pre- and post-aging. Employing an array of analytical tools-thin-layer chromatography-flame ionization detection (TLC-FID); Fourier transform-infrared spectroscopy (FT-IR); scanning electron microscopy (SEM); thermogravimetric analysis (TGA); and a suite of conventional tests such as penetration, softening point, viscosity, ductility, dynamic shear rheometer (DSR), and multiple stress-creep recovery (MSCR)-provided a comprehensive insight into the binder's behavior. TLC-FID analyses revealed that WHC, with its 92 wt.% resin content, altered the SARA profile across distinct aging conditions, notably reducing asphaltene content, a factor linked to binder stiffness. The colloidal instability index (IC) further attested to this, pointing to a more thermodynamically stable system with WHC's inclusion. Meanwhile, FT-IR confirmed a physical interaction between WHC and asphalt without introducing new chemical entities. SEM observations highlighted the superior miscibility of WHC with asphalt, evidenced by a unique microtexture. With marked precision, TGA assessments unveiled a bolstering of asphalt's inherent thermal resilience consequent to a minor WHC integration. From the conventional tests, shifts in penetration, softening point, and viscosity were observed, with reduced viscosity, indicating improved workability. Lastly, while rutting potential was sensitive to WHC concentrations, fatigue resistance notably heightened with minor to moderate WHC inclusions. In essence, this pioneering study advocates for WHC's integration into asphalt formulations, offering enhanced road performance coupled with sustainable waste utilization. The findings underscore the synergy between environmental stewardship and infrastructural advancement.

Pristine wild sugarcane (Saccharum spontaneum) as a biosorbent for removal of methylene blue from wastewater: isotherm, kinetics and regeneration studies

Saccharum spontaneum, popularly known as Kashful (KF) is a seasonal perennial grass with thin culms, mostly an abundantly growing shrub during the autumn season in southern Asia. It is used as no-cost scavenger to convincingly arrest methylene blue, a recalcitrant dye from colored effluent. FTIR, FESEM-EDX, and BET surface area characterize the material well whereas the surface activity was evaluated from zero-point charge (pHZPC = 6.720). FTIR highlights the presence of polyphenolic and carboxylate moieties. The surface texture is rod-like with intermittent non-homogeneous pores with occasional fractures. The equilibrium reaches within 60 min with the maximum adsorption capacity of 20.917 mg/g. The fibrous powder of kashful stalk (KFS) follows pseudo-second-order (R2 = 0.999 for linear and R2 = 0.985 for non-linear) kinetics and both Langmuir and Freundlich isotherm model (for linear, Langmuir R2=0.995; for non-linear, R2 = 0.994 for both Langmuir and Freundlich model). The uptake process was spontaneous (ΔG= -3.077 kJ/mol) and endothermic (ΔH = 17.815 kJ/mol). 1:1 methanol could regenerate the dye-loaded material in up to 55% and onward efficiency was conducive for three consecutive cycles. Industrial effluent analysis suggests a real-time removal of ∼55% in the first cycle. Saccharum spontaneum could be exercised to solve environmental problems related to colored water.

Degradation of malachite green by g-C3N4-modified magnetic attapulgite composites under visible-light conditions

Water resources are seriously threatened by dye wastewater, and the removal of the dye molecules from the wastewater has garnered considerable interest. People have favored photocatalytic technology in recent years for the treatment of dye wastewater. In this work, attapulgite (ATP) was used as a carrier, Fe3O4 and g-C3N4 were grafted onto ATP, and the surface was then modified with polyethyleneimine (PEI) to produce photocatalyst ATP-Fe3O4-g-C3N4-PEI, which was used in Malachite green (MG) dye wastewater. The structure and surface properties of the composites were analyzed and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray spectrum (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Uv-vis spectrum analysis, zeta potential measurement, and vibrating-sample magnetometry (VSM) analysis. The removal performance of ATP-Fe3O4-gC3N4-PEI for MG was studied, and the removal mechanism was explored and revealed. It has been shown that the heterojunction formed by Fe3O4 and g-C3N4 can inhibit the compounding of photogenerated electrons and holes, effectively improving the performance of the ATP-Fe3O4-g-C3N4-PEI. Electron paramagnetic resonance (EPR) analysis confirmed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) and superoxide radicals (·O2-) to degrade the MG. It was believed that ATP-Fe3O4-g-C3N4-PEI could generate hydroxyl radicals (·OH) through the photocatalysis and the Fenton reaction of the composite materials. Under the action of H+, ·O2-, and ·OH, the removal rate of MG by ATP-Fe3O4-g-C3N4-PEI exceeded 98 % at an optimal condition. The intermediate products and degradation pathways of MG degradation were also inferred by LC-MS analysis. These results showed that the prepared photocatalyst has excellent degradation performance for MG and could be used in dye wastewater treatment.

Augmented dye eradication from wastewater using alkali-aided, reinforced waste acacia (Acacia auriculiformis) leaves

The present investigation demonstrates the augmented dye scavenging from wastewater using alkali-mutated acacia (Acacia auriculiformis) leaves powder. The material was synthesized by mild chemical activation by using 0.1 M sodium hydroxide as an activator under room temperature stirring for 3h and isolated as a dark brown powder. The material was characterized using FTIR, FESEM, XRD, and pHzpc; and tested successfully with crystal violet and methylene blue. While FTIR confirms the presence of polyphenolic and polysaccharide moieties, FESEM reveals unprecedented circular hollow pipe-like channels decorated in a highly ordered fashion, facing pores for optimum dye uptake. The adsorption is tunable with working pH, and the maximum adsorption capacities are 67.25 and 78.55 mg g-1 for CV and MB. Both adsorption process follows Langmuir isotherm (R2 = 0.994) and pseudo-2nd-order kinetics (R2 = 0.999). Thermodynamic analysis verifies a spontaneous process with an endothermic interaction beside an elevated degree of randomness. About 80% of the spent material could be regenerated using 1:1 methanol/water. Analysis of industrial effluent suggests 37% removal per cycle, with an operating ceiling of 95%. To wind up, due to huge availability, porous nature, and superior adsorption capacity over other phytosorbents, NaOH-activated acacia leaves could be considered as techno-economic and potential scavengers for sustainable water treatment.

Thiosulfate impregnated spent tea leaves for the remarkable uptake of malachite green

Herein we demonstrate an enhanced performance of acid-assisted thiosulfate-impregnated spent/waste tea leaves (TWTL) for the removal of malachite green (MG) from water by batch mode. The material was characterized by pHZPC, FTIR, powder XRD, SEM, and proximate analysis. FTIR suggests the presence of polyphenolic moieties whereas a lignocellulosic peak was observed in powder XRD. SEM image shows a grafted surface texture with intermittent blocks, which upon dye uptake becomes somewhat condensed. Under optimized conditions, the highest removal efficiency of 126.8 mg/g was achieved at pH 7. A fast adsorption process was noticed with >97% removal within the first 10 min. Adsorption follows pseudo-second-order kinetics (R2 = 0.999) and the Langmuir model (R2 = 0.999). The material can be regenerated by dilute hydrochloric acid and can be reused for up to four cycles. Treatment of industrial effluent was successful in up to 47.56%. Our results highlight the potential of thiosulfate-treated spent tea leaves as a choice for the efficient removal of malachite green from water.

Brinjal (Solanum melongena) stalk waste as an effective scavenger for Eriochrome Black-T from water and wastewater: an approach towards waste to best

Stalks of brinjal (Solanum melongena), hereinafter SM, have been exercised as an efficient and sustainable adsorbent material for the elimination of Eriochrome Black-T (EBT) from an aqueous solution. The material was characterized by FTIR, FESEM, BET surface area, pH_pzc, and proximate analysis. FTIR spectrum suggests the presence of polyphenolic moieties, responsible for successful dye binding. FESEM images show an unprecedented octopus-like texture containing micropores. The central head transforms the architecture of a flower. The evaluated BET surface area of 10.042 m²/g and pore volume 1.055 × 10^-2cm³/g suggest a porous material. The pH_pzc of the material was evaluated to be 7.05, and under optimized conditions, the maximum adsorption capacity was found 52.631 mg/g at pH 7. The operational parameters were studied concerning contact time (0-90 min), pH (5-11), initial concentration (10-40 mg/L), and interfering ions (PO₄^-3, AsO₄^-3, Hg⁺², Pb⁺²). Adsorption follows Langmuir isotherm best (R² = 0.996), and pseudo-second-order kinetics (R² = 0.991) indicate a monolayer and homogeneous adsorption. 83% regeneration was successful with 0.1(M) sodium hydroxide solution. The material can be reused for up to three cycles with 90% efficiency retention. Analysis of EBT containing industrial effluent indicates that 52.62% of EBT can be removed.

Alkali treated water chestnut (Trapa natans L.) shells as a promising phytosorbent for malachite green removal from water

Search for eco-friendly adsorbents for sustainable dye treatment is on the rise. The present study demonstrated the enhanced removal of malachite green (MG) with alkali-modified shells of water chestnut (AWCN) under optimized physio-chemical parameters. Alkali treatment significantly reduces the lignocellulosic components which in turn increased the water stability. The material was been characterized by pHzpc, FTIR, FESEM-EDAX, and BET surface area analysis. pH-dependent adsorption was noticed and the maximum adsorption capacity was determined as 136.46 mg/g. Adsorption followed pseudo-second-order kinetics (R²=0.99) and Langmuir isotherm model (R²=0.99). Thermodynamic parameters suggested that the adsorption process is spontaneous (ΔG°= -2.99 kJ/mol), favorable and endothermic (ΔH°=34.72 kJ/mol). Simple regeneration allows multi-cycle use with minimal loss of activity. The mechanism has been proposed to be a combination of electrostatic interaction, H-bonding, and π-π stacking between AWCN and MG. In conclusion, alkali modification of Trapa natans L. shells provides excellent removal of MG from water.

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.