Adsorptive removal of eriochrome black T from aqueous solution by using polypyrrole Carica papaya peel nanobiocomposite

This study investigates, for the first time, the potential of Thuja plicata (TP) cone-derived activated carbon for the removal of the azo dye Reactive Red 2 (RR2) from aqueous solutions. Activated carbon was produced via microwave irradiation to enhance the adsorption capacity of the raw material. The prepared activated carbon (TPAC), synthesised using a chemical activating agent, was characterised by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis demonstrated that TPAC exhibited increased surface porosity and an irregular morphology after adsorption at the optimal pH. EDX results confirmed that carbon and oxygen were the dominant elements, with elevated contents post-activation. BET analysis indicated a decrease in the specific surface area from 66.64 to 20.35 m2 g−1 after RR2 adsorption, likely due to pore blockage. Batch adsorption experiments were conducted to evaluate the influence of several parameters, including solution pH, adsorbent dosage, initial dye concentration, and temperature. The maximum removal efficiency (54%) was achieved at pH 3 with an adsorbent dosage of 0.01 g. The adsorption capacity increased with rising dye concentration, reaching a maximum of 309.56 mg g−1 at 60 mg L−1. Adsorption isotherms, kinetics, and thermodynamic properties were also evaluated. The Freundlich isotherm model exhibited the best fit to the equilibrium data, indicating multilayer adsorption on a heterogeneous surface. Kinetic data were best described by the pseudo-second-order model, suggesting that chemisorption was the rate-limiting step. Thermodynamic analysis confirmed that the adsorption of RR2 onto TPAC was a spontaneous and exothermic process.

Kinetic and thermodynamic investigations of sewage sludge biochar in removal of Remazol Brilliant Blue R dye from aqueous solution and evaluation of residual dyes cytotoxicity

Adsorption is widely recognized as one of the most effective methods for treating wastewater contaminated with synthetic dyes. Its advantages include high efficiency, selectivity, environmental safety, and process simplicity. Research focused on optimizing the adsorption removal of commonly used anionic dyes, particularly through the utilization of novel adsorbents derived from agro-industrial wastes, holds significant importance. This study aimed to optimize the removal of anionic dyes (Acid Red 14 and Acid Orange 20) from aqueous solutions using corn stalks modified with cetylpyridinium bromide. Optimization was conducted using response surface methodology (RSM) coupled with a central composite design (CCD). We have examined the effects of pH, adsorbent dose, initial dye concentration, and temperature on the removal efficiency of both Acid Red 14 and Acid Orange 20. The developed mathematical models were validated using analysis of variance (ANOVA). The quadratic regression equations showed high coefficients of determination (R? = 0.9835 for Acid Red 14 and R? = 0.9964 for Acid Orange 20), which were statistically significant (P < 0.05). It was found that the linear effects of pH, adsorbent dose, initial dye concentration, and temperature were statistically significant for the effective removal of both dyes. Among these factors, the adsorbent dose exhibited a strong synergistic effect, while pH, initial dye concentration, and temperature showed antagonistic effects. Furthermore, the interaction between initial dye concentration and pH had a pronounced antagonistic effect on the adsorption process. Optimal conditions for maximum dye removal were determined to be a pH of 2, an adsorbent dose of 10.5 g?L–1, an initial dye concentration of 50 mg?L–1, and a temperature of 20 °C. Under these conditions, removal efficiencies of 98 % for Acid Red 14 and 99 % for Acid Orange 20 were achieved. The results obtained can contribute to the development of effective wastewater treatment technologies targeting anionic azo dyes. The use of modified agro-industrial wastes as adsorbents for anionic azo dyes offers dual benefits by reducing both treatment costs and biomass disposal issues.

This study investigates the potential applicability of hen feather (HF) to remove methyl red (MR) dye from aqueous solution with the variation of experimental conditions: contact time (1–180 min), pH (4–8), initial dye concentration (5–50 mg/L) and adsorbent dose (3–25 g/L). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) evaluate the surface morphology and chemistry of HF, respectively. The maximum removal of MR by HF was 92% when the optimum conditions were initial MR dye concentration 5 mg/L, pH 4, adsorbent dose 7 g/L and 90 min equilibrium contact time. Langmuir isotherm (R2 = 0.98) was more suited than Freundlich isotherm (R2 = 0.96) for experimental data, and the highest monolayer adsorption capacity was 6.02 mg/g. The kinetics adsorption data fitted well to pseudo-second-order model (R2 = 0.999) and more than one process was involved during the adsorption mechanism but film diffusion was the potential rate-controlling step. The findings of the study show that HF is a very effective and low-cost adsorbent for removing MR dye from aqueous solutions.

The adsorption of Congo red dye from aqueous solution using Sodium thiosulphate-pretreated Pumpkin pod, was studied. The adsorbent was characterized by determining some physicochemical properties as well as the SEM and FTIR spectra. A two-level and four-factor factorial experimental design, with adsorbent dosage (0.1 to 0.3 g), pH (6.5 to 9), initial dye concentration (10 to 50 mg) and contact time (10 to 90 min) as process variables was used. Two common adsorption isotherms were fitted to the adsorption data, while the pseudo-first order and pseudo-second order kinetic models were also tested on the adsorption process. The determined properties, surface morphology and functional groups in the adsorbent, suggest that the pretreated Pumpkin pod could serve as an efficient adsorbent. Percentage dye removal increased, while adsorption capacity decreased with increase in adsorbent dosage. The pH had no effect on both the percentage removal and adsorption capacity. Increasing the initial dye concentration led to a decrease in percentage removal and an increase in adsorption capacity, while both the percentage removal and adsorption capacity increased with increase in contact time. These trends are in agreement with many reported works. The developed model could navigate the design space. A maximum percentage removal of 81.05% was obtained at optimum values of 0.3 g adsorbent dosage, initial dye concentration of 50 mg/l and a contact time of 90 minutes. The mechanism of the dye adsorption followed a heterogeneous poly layer coverage of the dye on the adsorbent surface, while the pseudo-second order kinetic model was observed to describe the kinetics of the process. Pumpkin pod pretreated with Sodium thiosulphate, can be used as a cheap and efficient adsorbent for the removal Congo red dye from aqueous solutions such as Textile industry wastewaters.

Computation of adsorption parameters for the removal of dye from wastewater by microwave assisted sawdust: Theoretical and experimental analysis.

The adsorptive removal of Telon Blue AGLF (TB AGLF) from aqueous solution using sunflower pulp was studied. The effects of pH, adsorbent dose, temperature, and initial dye concentration on the adsorption capacity and the removal % of TB AGLF were investigated. Experimental results showed that sunflower pulp was excellent agroindustrial adsorbent with maximum dye removal efficiency of 97.22% for a very short time (under conditions of 100 mg L−1initial dye concentration, pH = 3,T=50°C, and 1 g L−1of adsorbent dose). The binary effects of initial dye concentration and temperature on the adsorption properties of sunflower pulp were analysed by RSM and two model equations for predicting adsorption capacity and dye removal % of pulp because arbitrarily chosen initial dye concentration and temperature were developed by using response surface methodology (RSM). Experimental values of the adsorption capacity and dye removal % were in good agreement with the predicted values by the improved models. Adsorption experiments and kinetic regression results indicated that the experimental data were well defined with pseudo-second-order kinetic model.

A zeolite-montmorillonite (zeolite-Mt) nano-adsorbent was prepared by calcination at 600°C. The synthesized nano-adsorbent was tested for removal of a toxic and cationic dye (crystal violet) from water, and it was characterized by various techniques. The effects of variables such as pH, temperature, adsorbent dosage and initial dye concentration on the removal efficiency of the dye were investigated by response surface methodology (RSM). Experimental conditions were optimized by RSM to achieve the maximum dye removal efficiency. Optimum conditions for maximum removal of dye were obtained at pH 9, temperature of 25°C, adsorbent dosage of 2 g L−1 and initial dye concentration of 40 mg L−1. Under these conditions, the maximum removal efficiency obtained was 99.9%. Various isotherms were applied to study adsorption equilibrium, and of these, the Freundlich isotherm provided the best fit. In addition, the fractal-like integrated kinetic Langmuir model was the most appropriate among several kinetic models. The thermodynamic parameters were also determined. The zeolite-Mt prepared under optimum conditions displayed a greater adsorption capacity than activated carbon (manufactured by Merck) and than various other adsorbents.

This study is investigated the potential of sugarcane bagasse, an agriculture waste as adsorbent for the removal of methyl orange dye from aqueous solution. Numerous research had been done in preparing low cost adsorbent from agricultural by-products. Activated carbon undoubtedly is the most prevailing adsorbent because of its high surface area adsorption capacity, and degree of surface reactivity. The activation process during preparation of activated carbon is normally been performed at high temperature (i.e. higher than 500 °C) and involved with a harsh chemical. This study investigated the potential of modified sugarcane bagasse with polyethylenimine (PEI) for removal of methyl orange (MO) dyes. The effect of PEI modified sugarcane bagasse adsorbent parameter on the efficiency of dyes removal including contact time, initial dye concentration, adsorbent dosage, temperature and pH have been investigated. The optimum result for MO dye removal achieve up to 82.0 % for parameters, contact time (240 min), initial dye concentration (0.01 g/L), adsorbent dosage (0.15 g/50 mL), temperature (30 oC) and pH (7). The maximum percentage dye removal of MO dye was reached at contact time 240 min with percentage 82.78 % for 240 min and initial dye concentration 0.05 g/L at percentage 82.78 %. Based on the optimum result, the adsorbent was efficient in decolorised diluted solution. PEI modified sugarcane has high potential as low cost adsorbent for wastewater treatment containing dyes.

For environmental applications, the production of inexpensive but superior adsorbents is essential. The Taguchi method was applied as an experimental design in this paper to determine the optimum conditions for the removal of crystal violet dye using pistachio shell powder in batch experiments. The effects of pH (3–9), initial dye concentration (2–10 mg•L-1), contact time (30–360 mins) and adsorbent dose (0.25–4 g•L-1) were studied using an L16 orthogonal array in order to achieve the maximum dye removal. For a "the-larger-the-better" response, the percent dye removal was transformed into an accurate S/N ratio. In the studied range for various parameters, the optimal condition was found to be pH = 6, initial dye concentration=10 mg•L-1, contact time=360 mins and adsorbent dose = 4 g•L-1. Under the optimum conditions, dye removal percentage was obtained to be 93.6±0.1%. The analysis of variance results indicate that percentage contribution of control factor in descending order is adsorbent dose (33.17%) > initial dye concentration (27.43%) > pH (22.89%) > contact time (16.52%).

Dye-containing wastewater has been known as a serious environmental treat. There are many treatment methods, but they are not practical in many developing countries. In this study, batch adsorption of acid yellow 17 dye from aqueous solution has been carried out on a laboratory scale using activated water hyacinth root powder. The dye removal efficiency was measured using a UV-Vis spectrometer. Adsorption experiments were carried out in a batch process at different operating parameters including initial dye concentration, adsorbent dose, contact time, and solution pH. From the experimental data, the maximum dye removal efficiency achieved was 92.26% at pH 2, initial dye concentration 50 mg/L, contact time 120 min, and adsorbent dose 20 g/L. Experimental studies indicated pseudo-second-order kinetic (R2 = 1) and Langmuir isotherm (R2 = 0.953) models could better describe acid yellow 17 dye adsorption on the activated water hyacinth. Adsorption experiments revealed that activated water hyacinth prepared from locally available infesting water bodies had a high potential for removing acid yellow 17 dye from aqueous solution.

Biosorption of malachite green dye from aqueous solution by calcium alginate nanoparticles: Equilibrium study

The adsorption of crystal violet (CV) from aqueous solution by sugarcane bagasse (SCB), an agro-industrial residue, was investigated in a batch experimental setup. A two level four factor (24) full factorial central composite design (CCD) with the help of Design Expert Version 7.1.6 (Stat-Ease, USA) was used for adsorption process optimization and evaluation of interaction effects of different operating parameters: agitation speed (80–180 rpm), initial solution pH (4.0–8.0), initial dye concentration (100–200 mg L–1), and adsorbent dose (2–5 g L–1). A multiple coefficient of determination (R2) value of 0.98, model F value of 266.36 and its low P-value (<0.0001) along with lower value of coefficient of variation (2.70%) indicated the fitness of the response surface quadratic model developed during the present study. Numerical optimization applying desirability function was used to identify the optimum conditions for maximum removal of CV. The optimum conditions were found to be agitation speed = 165 rpm, initial solution pH = 8.0, initial dye concentration = 200 mg L–1 and adsorbent dose = 2.0 g L–1. A confirmatory experiment was performed to evaluate the accuracy of the optimization procedure and maximum CV removal of 93.21% was achieved under the optimized conditions.

Dyes are known as one of the most dangerous industrial pollutants which can cause skin diseases, allergy, and provoke cancer and mutation in humans. Therefore, one of the important environmental issues is the effective removal of dyes from industrial wastewater. In the current work, BaFe12O19/CoFe2O4@polyethylene glycol (abbreviated as BFO/CFO@PEG) nanocomposite was synthesized and evaluated regarding its capacity for adsorptive removal of a model dye Acid Blue 92 (denoted as AB92) from aqueous solutions. The characteristics of the prepared nanocomposite was determined by tests such as X-ray diffraction (XRD), scanning electron microscope (SEM), vibration sample magnetization (VSM), and Fourier transform infrared spectroscopy (FTIR). The effects of conditional parameters including pH (2–12), initial concentration of dye (20–100 mg/L), adsorbent dosage (0.02–0.1 g/L) and contact time (0-180 min) on the adsorption of dye were investigated and then optimized. The results indicated that with the increase of the adsorbent dosage from 0.02 to 0.1 g/L, the removal efficiency increased from 74.1% to 78.6%, and the adsorbed amount decreased from 148.25 to 31.44 mg/g. The maximum removal efficiency (77.54%) and adsorption capacity (31.02 mg/g) were observed at pH 2. Therefore, the general optimization conditions revealed that the maximum adsorption efficiency of dye was obtained in condition of initial concentration of 20 mg/L, contact time of 1 h and pH of solution equal 2. The adsorption isotherm and kinetic data were evaluated using a series of models. The pseudo-second order kinetic model and Freundlich isotherm model show the best fitting with experimental data with R2∼0.999.

ABSTRACTDirect Red 81 (DR-81) dye with a very high water solubility is widely used in many industries particularly textile industries. This study aimed to evaluate the practicability of using iron filings for the adsorption of DR-81 dye from the aqueous solutions. The effects of pH, adsorbent dose, initial DR-81 dye concentration, and adsorption time on adsorption process were also evaluated. The maximum of adsorption efficiency of DR-81 dye achieved in the optimum pH: 3, adsorbent dose: 2.5 g/L, contact time: 30 min, and initial dye concentration: 50 mg/L. The dye adsorption efficiency is increased by increasing the adsorbent dose and adsorption time. The kinetic and isotherm studies indicated that the adsorption process obeys a pseudo–first–order and Langmuir isotherm models. The experimental studies indicated that iron filings had the potential to act as an alternative adsorbent to remove the DR-81 dye from an aqueous solution.