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.

Neolamarckia cadamba (cadamba) waste pulp as a natural and techno-economic scavenger for methylene blue from aqueous solutions.

In this work, Neolamarckia cadamba (cadamba), also known as bur flower tree has been exercised to demonstrate as an excellent methylene blue scavenger from simulated as well as industrial wastewater. The particle morphology and structural insights were gained from FESEM, BET surface area, FTIR, and pHZPC. The adsorption behavior was mapped by different physico-chemical parameters such as contact time, pH, input concentration, and temperature. Experimental data reveal rapid adsorption, and >90% uptake was successful within the first 15 min and reaches equilibrium by 45 min (removal efficiency = 94.15%) at neutral pH. The maximum adsorption capacity was found to be 115.60 mg/g. The uptake process follows pseudo-second-order kinetics (R2 = 0.99), confirming a chemisorption process while the Langmuir model (R2 = 0.99) satisfactorily addresses the adsorption path. Thermodynamic parameters suggest a spontaneous, feasible, and exothermic process with increased entropy. Spent adsorbent could easily be regenerated in up to 74% using 1:1 MeOH/H2O with a potential of three-cycle use. Real-time efficacy has been established with an MB containing industrial effluent and up to 44.70% adsorption, which confirms the material's practical applicability. Statistical reliability was confirmed by the relative standard deviation. Altogether, the present material offers clean and green removal of methylene blue dye from versatile wastewater.

The search for cleaner and greener protocols for water treatment is on the rise. With this line, we have chosen non-edible fruit pulps of Neolamarckia cadamba for extraordinary methylene blue uptake from diverse contaminated water bodies. Compared to contemporary materials, the excellent adsorption capacity (115.60 mg/g) with methylene blue dye offers an edge. The material could be regenerated easily and reused for three cycles. The method doesn't involve any chemical treatment, is greener, and could be applied on a large scale. Due to huge availability, excellent adsorption capacity, reusability, and simple preparation provide advantages to the material for sustainable water treatment.

Green synthesis of MnO2-embedded Rauvolfia tetraphylla leaves (MnO2@RTL) for crystal violet dye removal and as an antibacterial agent.

The application of green synthesized nanocomposites for the prevention of environmental pollution is increasing nowadays. Here, a green composite has been synthesized by embedding MnO2 on Rauvolfia tetraphylla leaves using its leaf extract hereinafter termed as MnO2@RTL, and demonstrated for crystal violet (CV) dye removal from simulated and real wastewater. The surface properties of the material were determined by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) surface area, pHZPC, and zeta potential. The material exhibits a remarkable adsorption capacity of 61.162 mg/g at 328 K and pH 7. The adsorption was best fitted with Pseudo-second-order kinetic (R2 = 0.998) and a combination of Langmuir and Freundlich isotherm model (R2 = 0.994-0.999). The thermodynamic study revealed spontaneous (ΔG values = - 2.988 to - 4.978 kJ/mol) and endothermic (ΔH values = 6.830 to 11.018 kJ/mol) adsorption. After adsorption, 80% regeneration occurred with 50% methanol, and recycled up to five times. Advantageously, the material was able to remove CV dye in the presence of coexistent ions and from industrial wastewater, confirming field applicability. The adsorption capacity of the material is superior to previously reported materials. The standard deviation and relative standard deviations have been evaluated to be 0.000422-0.000667 and 0.473-0.749%, which suggests the reliability of the experiments. The exhausted material, after recycling, was pyrolyzed to overcome the disposal problem. It was established as a secondary adsorbent with 73% efficiency which makes the material win-win. The material showed antibacterial properties with Staphylococcus aureus bacteria with a zone of inhibition 5 mm.

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.

Lignocellulosic waste plant litters have enormous potential for biosorption of heavy metals and dyes for their economic viability and environment-friendly nature. The present investigation highlights the promising cationic dye scavenging ability of alkali-treated waste acacia (A. auriculiformis) leaves from simulated and industrial wastewater. With adsorption capacities of 67.25 and 78.55 mg g⁻¹ for crystal violet and methylene blue respectively, the protocol shows promise in colored water treatment. Easy preparation, classy removal efficiency, and recyclability offer the key advantage with a techno-economic impact.

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.

Saccharum spontaneum, also known as wild sugarcane is an abundantly available long grass with relatively slender culms; usually 100­150 cm tall, grows in the autumn season (August-October) in the south-east part of Asia, and displays steady tillering. Being a non-preferred meal for local herbivores, the material lies abandoned as bio-waste. At the same time, the search for a newer and cleaner alternative for wastewater treatment is on the rise. In line with the waste-to-wealth protocol for a sustainable environment, we have demonstrated the facile uptake of a recalcitrant dye methylene blue (20.917 mg/g) using its stalks powder. The present method is free from any hazardous chemical activation, acid-base treatment, or pyrolysis. With the ability to treat industrial effluent, the material highlights an impactful application in a lab-to-land fashion.

Non-conventional, burnt Shorea robusta leaf extract mediated green synthesis of zinc oxide nanoparticles and facile removal of eriochrome black T dye from water.

The present study evaluates the synthesis of zinc oxide nanoparticles (ZnO NPs) using water extract of Sal leaves (Shorea Robusta) for efficient removal of Eriochrome black-T from the water and wastewater. The material is characterized using FESEM, FTIR, EDX, pHzpc, XRD, BET, and TGA analysis. XRD confirmed the synthesis of ZnO with an average crystallite size of 35.24 nm a surface area of 95.939 m2/g and a pore volume of 0.280 cm3/g. The pHzpc of the material is 7.45. The study evaluates the effects of contact time (0-100 min), pH (3-10), concentration (10-50 mg/L), and temperature (298-328K). The Langmuir isotherm model (R2 = 0.993) and pseudo-second-order kinetic model (R2 = 0.998) were found to be the best-fit models. The maximum uptake capacity is 265.554 mg/g. The interaction is spontaneous (ΔG° -12.889 to-14.898 kJ/mol), endothermic ΔH° (4.290-14.216 kJ/mol) with an increase in spontaneity at the solid-liquid junction. The dye-loaded ZnO NPs were successfully regenerated in dilute NaOH solution and 1:1 methanol water, achieving regeneration efficiencies of 78% and 60%, respectively. The reusability of the ZnO NPs was ascertained for up to three consecutive cycles.

A promising method for synthesizing zinc oxide nanoparticles using water extract from burnt Shorea robusta leaves as a precipitating and capping agent has been demonstrated with a high yield. The method is economical and convenient without the use of any chemical precipitating agents. The prepared material efficiently removes Eriochrome black T dye, commonly used in various industries for dyeing silk and nylon, from the solution.We report the first-ever synthesis of ZnO NP using the water extract of burnt leaves, and its application is tested for dye removal. A high surface area of 95.939 m²/g was determined, which is also higher in comparison to many works published. The maximum adsorption capacity recorded for EBT removal is 265.55 mg/g, which is relatively higher than other commercially synthesized zinc oxide.

Towards a win-win chemistry: extraction of C.I. orange from Kamala fruit (Mallotus philippensis), and simultaneous exercise of its peels for the removal of Methylene Blue from water.

Kamala fruit (Mallotus philippensis), hereinafter MP, has been simultaneously exercised for the extraction of a natural dye, C.I. orange and its peels were converted into an efficient adsorbent for the rapid removal of methylene blue (MB) dye from aqueous solutions. The material has been characterized by Fourier Transform Infra-red (FTIR),Field Emission Scanning Electron Microscopy- Electron dispersive spectroscopy (FESEM-EDS), Brunauer-Emmett-Teller (BET) surface area, and pHZPC. FTIR suggests the presence of polyphenolic moieties responsible for adsorption, whereas FESEM confirms the porous texture. Optimization of process variables such as contact time, pH, adsorbent dose, and temperature of operation indicates that the adsorption gets modulated by the pH, with a best at 11. The Freundlich model (R2 = 0.994), and pseudo-second-order kinetics (R2 = 0.999) best describe the adsorption pathway. Dilute hydrochloric acid is sufficient to induce >66% regeneration, which ensures reusability. With the maximal uptake for MB is 30.2 mg/g at ambient conditions, the superiority over the existing materials has been confirmed. Treatment of dye containing industrial effluent suggests about a 50% reduction in one cycle. It can be concluded that both-way benefits, namely natural dye extraction and preparation of a peel-based adsorbent for methylene blue removal from aqueous solution, can be achieved using the kamala fruit peels.

Mallotus philippensis, a seasonal fruit, commonly known as Kamala, was employed to serve a dual advantage of extracting a natural dye called C.I. orange from the peels; thereinafter, the peels were converted as an adsorbent to remove Methylene blue from water and industrial wastewater with high efficacy. From 100 g of raw material, 1.7 g of C.I. orange dye was extracted, along with 44 g of peel-based adsorbent. The maximum adsorption capacity for MB is 30.2 mg/g at ambient conditions, better and more impactful than contemporary adsorbents. The approach is firmly established in the circular economy as a dual benefit agent, generating clean and green revenue through natural dye extraction.

Exploring the promising potential of fallen bamboo leaves (Bambusa bambos) for efficient removal of crystal violet from wastewater.

Fallen bamboo leaves (Bambusa bambos), hereinafter BL have been designed to be transformed into an efficient and sustainable adsorbent for the removal of crystal violet (CV) dye from wastewater with up to 95% scavenging ability. BL have been characterized by Fourier transform infrared (FTIR) spectra, field emission scanning electron microscopy (FESEM), and zero point charge (pHzpc). The maximum adsorption capacity is 30 mg/g at pH 10. Physico-chemical parameters have been investigated concerning pH, contact time, initial concentration, and coexistent ions. Pseudo-second-order kinetics is followed best (R2 =0.999) signifying a chemisorption pathway. Besides, intra-particle diffusion plays a governing role in the film diffusion of crystal violet into the core of the adsorbent. Langmuir isotherm model fits best (R2=0.972) suggesting a uniform, monolayer, and homogeneous adsorption. Regeneration was successful with methanol (65%) and reusability was tested for three cycles and was found to retain activity up to 80%. Analysis of CV containing industrial effluent suggests that a 36.8% reduction is possible with BL. The effect of co-existent ions suggests little influence on the adsorption. Compared to other contemporary and relevant adsorbents, it can be concluded that BL can be exercised for the sustainable decontamination of CV-containing wastewater.

Bambusa bambos, the giant thorny bamboo is an abundantly available plant throughout the year, has been successfully exercised using its fallen leaves to scavenge crystal violet, a cationic dye from water and wastewater. Up to 95% adsorption was noticed at ambient conditions, which when further extrapolated for industrial effluent analysis, shows a remarkable 36.8% decontamination/cycle. With an adsorption capacity of 30 mg/g, it enjoys an edge over contemporary phytosorbents. The process is free from any chemical treatment, green in nature, and sustainable. Abundant availability and economic viability allow an impactful application of fallen bamboo leaves for water and wastewater treatment in a lab-to-land sequence.

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.

Tea, being one of the most popular beverages produces huge waste which requires proper management. With this aim; the thiosulfate-impregnated spent tea leaves have been exercised for effective separation of malachite green from contaminated water. Thiosulfate impregnation under mildly acidic conditions activates the tea leaves and makes the material robust with enhanced water stability than its untreated variety. With a remarkable maximum adsorption capacity of 126.8 mg/g under ambient conditions, the present methodology enjoys the edge over related phytosorbents. The protocol is techno-economic, environment friendly, and could be extended to possible field applications.

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, pHpzc, 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 × 10-2 cm3/g suggest a porous material. The pHpzc 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.

Brinjal (Solanum melongena), being one of the most cultivated vegetables around the globe, generates voluminous waste as stalks which warrant proper management. With this aim, such stalks were converted to a phytosorbent and selected for removal of Eriochrome black-T (EBT), a dye that is used by industry persons and science students in their laboratory experiments. The prepared material is highly porous, water-stable, regenerable, and reusable. The protocol is economically viable, easy, and efficient for industrial effluent treatment as well. With a notable maximum adsorption capacity of 52.631 mg/g, the material could offer an ideal choice for dye decontamination.

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.

Waste shells of water chestnut (Trapa natans L.), a waterborne fruit have been modified using sodium hydroxide solution and tested for removal of malachite green by batch method. Excellent adsorption capacity (136.46 mg/g) was obtained under ambient conditions. As of now, very little work has been reported on water chestnut shells for the removal of dyes from wastewater. The present work shows an excellent adsorption capacity among all the previous work on water chestnut for dye remediation. Alkali activation significantly reduces hydrophilic/lignocellulosic components within the shells, which in turn makes the material more water stable and sustainable.

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 pHZPC. BET surface area was found to be 10.901 m2 g-1, whereas pHZPC 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 (kMB = 1.712, R2 = 0.999; kMG = 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.

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

Dewaxed honeycomb powder (HCP) was used as a promising adsorbent for removal of malachite green (MG) from aqueous solution. Raw honeycomb was strategically dewaxed by petroleum ether, and the purified product was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), pHzpc, and proximate analysis. A high uptake capacity (123 mg/g) was found at neutral pH. Experimental data follow pseudo-second-order kinetics (k 2 as 0.45 × 10-2 g/min/mg, R 2 = 0.986) and Langmuir isotherm with R 2 0.999. Thermodynamic parameters suggested a spontaneous (ΔG = -26.28 kJ/mol) and exothermic (ΔH = -11.61 kJ/mol) process, which suggests increased randomness (ΔS = 0.0486 kJ/mol) at the solid-liquid interface during the adsorption process. The material can be regenerated by ordinary salt solution (1 M NaCl) and efficiently reused for three cycles with a minimal loss in efficiency. Adsorption mechanism is proposed to be a combination of electrostatic interaction and π-π stacking between aromatic units of HCP and MG. Abundant availability, possibility of wax commercialization, economic sustainability, and comprehensive waste management make HCP an ideal choice for dye decolorization.