Water footprint management in textile industry through Acid Blue 113 remediation using halloysite nanoclay as a sustainable adsorbent

Experimental studies were carried out to adsorb Acid Blue 113 (AB113), an azo dye that is probably a mutagen, from aqueous environments using commercially available, inexpensive halloysite nanoclay (HNC). Water footprint management in the remediation of dye from aqueous medium and textile industrial effluent (TIE) was the focus of a laboratory-scale experiment planned and carried out to align with the guidelines of sustainability and valorization. One interesting feature of this study is that the adsorption process is almost independent of the temperature (27-50 °C) and pH (2-12) range studied, which aligns with sustainability and valorization necessities. We conducted a laboratory-scale experiment to assess the water footprint of textile industrial effluent (TIE). To determine how operational factors affected the effectiveness of dye removal, we looked into initial dye concentration (25-200 mg L-1), contact time (15-180 min), adsorbent dosage (0.500-6.000 g L-1), initial pH (2-12), and temperature (30-50 °C). The findings showed that higher initial dye concentration, a 60-min contact time, and a pH range of 2-12 provide dye removal efficiency (qe = 95.00 mg g-1). A two-level fractional factorial experimental design (FFED) was employed to determine the factors influencing HNC's adsorption capacity and evaluate the feasibility and effectiveness of the approach. The optimal values of the variables were determined using interaction factors derived from multiple regression studies based on FFED to maximize the second-order polynomial equation. Under optimal conditions of pH 1, the adsorbent dosage of 0.500 g L-1, beginning dye concentration of 623 mg L-1, adsorption time of 139 min with orbital shaking of 165 rpm at 49 °C, the maximum adsorption value achieved by statistical optimization was 329 mg g-1. Four two-parameter and six three-parameter isotherm models were used to analyze equilibrium data. The pseudo-first-order and pseudo-second-order models were applied in our adsorption kinetic investigations. Webber-Morris, Dumwald-Wagner, and film diffusion models were used to examine the diffusion effects. The adsorption system's thermodynamic parameters, Gibbs free energy (ΔG0), entropy (ΔS0), and change in enthalpy (ΔH0) were also measured and assessed. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the dye, the adsorbent, and the dye-adsorbed HNC. The experiments showed that HNC is an economical and efficient adsorbent for eliminating AB113 dye from aqueous solutions and effluent from the textile industry. It is possible to use the dye-adsorbed HNC, known as "sludge", as a strengthening material for creating composites from waste plastic. Preliminary research examined and contrasted the physico-mechanical and chemical characteristics of dye-adsorbed HNC thermoplastic and thermoset composites with those of HNC composites.

2,4-Dichlorophenoxyacetic acid (2,4-D) adsorptive removal by algal magnetic activated carbon nanocomposite

In the present study, ferric oxide nanoparticles impregnated with activated carbon from Ulva prolifera biomass (UPAC-Fe₂O₃) were prepared and employed to remove 2,4-Dichlorophenoxyacetic acid (2,4-D) by adsorption. The UPAC-Fe₂O₃ nanocomposite was characterized for its structural and functional properties by a variety of techniques. The nanocomposite had a jagged, irregular surface with pores due to uneven scattering of Fe₂O₃ nanoparticles, whereas elemental analysis portrayed the incidence of carbon, oxygen, and iron. XRD analysis established the crystalline and amorphous planes corresponding to the iron oxide and carbon phase respectively. FT-IR analyzed the functional groups that confirmed the integration of Fe₂O₃ nanoparticles onto nanocomposite surfaces. VSM and XPS studies uncovered the superparamagnetic nature and presence of carbon and Fe₂O_3, respectively, in the UPAC-Fe₂O₃ nanocomposite. While the surface area was 292.51 m²/g, the size and volume of the pores were at 2.61 nm and 0.1906 cm³/g, respectively, indicating the mesoporous nature and suitability of the nanocomposites that could be used as adsorbents. Adsorptive removal of 2,4-D by nanocomposite for variations in process parameters like pH, dosage, agitation speed, adsorption time, and 2,4-D concentration was studied. The adsorption of 2,4-D by UPAC-Fe₂O₃ nanocomposite was monolayer chemisorption owing to Langmuir isotherm behavior along with a pseudo-second-order kinetic model. The maximum adsorption capacity and second order rate constant values were 60.61 mg/g and 0.0405 g/mg min respectively. Thermodynamic analysis revealed the spontaneous and feasible endothermic adsorption process. These findings confirm the suitability of the synthesized UPAC-Fe₂O₃ nanocomposite to be used as an adsorbent for toxic herbicide waste streams.

Adsorptive removal of hazardous dye (crystal violet) using bay leaves (Laurus nobilis L.): surface characterization, batch adsorption studies, and statistical analysis

In this study, the surface properties of Laurus nobilis L. were determined by inverse gas chromatography. From this, the surface of Laurus nobilis L. was found to be an acidic ([Formula: see text]). Then, the adsorption of hazardous crystal violet dye on Laurus nobilis L. was examined. For the adsorption process, the optimum conditions were determined as contact time (60 min), adsorbent dosage (1.0 g/L), agitation rate (200 rpm), and initial pH (≅ 7). The efficiencies of initial concentration, contact time, temperature, and their binary combinations on the improvement of adsorption percentage were statistically investigated via three different two-way ANOVA analyses. Adsorption data were applied to different isotherms, and it was determined that the Langmuir isotherm (r² = 0.9998) was the most suitable isotherm for the adsorption process. The [Formula: see text] value was calculated as 400.0 mg/g at 25 °C from the Langmuir isotherm. According to kinetic models, it was observed that the adsorption occurred in three steps. According to enthalpy (+ 7.52 kJ/mol), activation energy (+ 8.91 kJ/mol), and Gibbs free energy (- 30.0 kJ/mol) values, it was determined that the adsorption occurred endothermically and spontaneously. As a result of reusability studies, it was determined that the adsorbent could be used repeatedly.

Efficient removal of 2,4-D from solution using a novel antibacterial adsorbent based on tiger nut residues: adsorption and antibacterial study

We engineered a tiger nut residue (TNR, a low-cost agricultural waste material) through a facile and simple process to take advantage of the introduced functional groups (cetylpyridinium chloride, CPC) in the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in batch mode and further investigated its impingement on bacterial growth in a yeast-dextrose broth. The surface characterizations of the adsorbent were achieved through Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller method (BET), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The batch adsorption studies revealed that solution pH, adsorbent dose, temperature, and salt affected the adsorptive capacity of TNR-CPC. The equilibrium data were best fitted by Langmuir isotherm model with a maximum monolayer adsorption capacity of 90.2 mg g^-1 at 318 K and pH 3. Pseudo-second-order model best fitted the kinetics data for the adsorption process. Physisorption largely mediated the adsorption system with spontaneity and a shift in entropy of the aqueous solid-solute interface reflecting decreased randomness with an exothermic character. TNR-CPC demonstrated a good reusability potential making it highly economical and compares well with other adsorbents for decontamination of 2,4-D. The adsorption of 2,4-D proceeded through a probable trio-mechanism; electrostatic attraction between the carboxylate anion of 2,4-D and the pyridinium cation of TNR-CPC, hydrogen bonding between the hydroxyl (-OH) group inherent in the TNR and the carboxyl groups in 2,4-D and a triggered π-π stacking between the benzene structures in the adsorbate and the adsorbent. TNR-CPC reported about 99% inhibition rate against both gram-positive S. aureus and gram-negative E. coli. It would be appropriate to investigate the potential of TNR-CPC as a potential replacement to the metal oxides used in wastewater treatment for antibacterial capabilities, and its effects against airborne bacteria could also be of interest.

Adsorption of atrazine and 2,4-D pesticides on alternative biochars from cedar bark sawdust (Cedrella fissilis)

Bark residues of the forest species Cedrela fissilis were physically and chemically modified with zinc chloride (ZnCl₂) as an activating agent. The two modified materials were analyzed as adsorbents in removing atrazine and 2,4-D herbicides from effluents. Firstly, the precursor material and the modified ones were characterized by different techniques to identify the structural changes that occurred in the surfaces. Through TGA, it was observed that both modified materials have thermal stability close to each other and are highly superior to the precursor. X-ray diffractions proved that the amorphous structure was not altered, the three materials being highly heterogeneous and irregular. The micrographs showed that the treatments brought new spaces and cavities on the surface, especially for the material carbonized with ZnCl₂. The pH_PZC of the modified materials was close to 7.5. The physically modified material had a surface area of 47.31 m² g^-1 and pore volume of 0.0095 cm³ g^-1, whereas the carbonized material had a surface area of 98.12 m² g^-1 and pore volume of 0.0099 cm³ g^-1. Initial tests indicated that none of the adsorbents were efficient in removing 2,4-D. However, they showed good potential for removing atrazine. The Koble-Corrigan isothermal model best fits the experimental data, with a maximum capacity of 3.44 mg g^-1 and 2.70 mg g^-1 for physically modified and with ZnCl₂, respectively. The kinetic studies showed that the system tends to enter into equilibrium after 120 min, presenting good statistical indicators to the linear driving force model (LDF). The surface diffusion coefficients were 2.18×10^-9 and 2.37×10^-9 cm² s^-1 for atrazine adsorption on the physically and chemically modified materials. These results showed that the application of residues from the processing of cedar bark is promising. However, new future studies must be carried out to improve the porous development of the material and obtain greater adsorption capacities.