Comparative Studies of Removal of Methyl Green and Basic Fuchsin from Wastewater by a Novel Magnetic Nanoparticles Mg-Ferrites

Multiple cobalt active sites evenly embedded in mesoporous carbon nanospheres derived from a polymer-metal-organic framework: efficient removal and photodegradation of malachite green

A series of robust photocatalysts of mesoporous carbon nanospheres embedded with multiple cobalt active sites (Co/Co x O y @mC) have been constructed for efficient removal and photodegradation of malachite green (MG). Here, a cobalt-based polymeric-metal-organic framework (polyMOF(Co)) was constructed by using a polyether ligand containing 1,4-benzenedicarboxylic acid units. Afterward, polyMOF(Co) was calcined into a series of Co/Co x O y @mC hybrids at diverse high temperatures (400, 600, and 800 °C) under a N2 atmosphere. Therefore, Co coordination centers were transformed into various active sites such as Co, CoO, and Co3O4, which were embedded within the mesoporous carbon network derived from the polymeric skeleton. Considering the even distribution of Co-related active species and high porosity inherited from polyMOF(Co), the constructed Co/Co x O y @mC hybrid obtained at 600 °C illustrated higher removal ability (79%) with a maximum adsorption capacity of 314 mg g-1 within 120 min and better photodegradation performance (degradation rate of 95%) toward MG than those of the other photocatalysts obtained at 400 and 800 °C. Moreover, the possible photocatalytic reaction mechanisms, including the transfer behavior of charge carriers, generation of reactive species, and intermediate degradation of products, were provided. The present work showed an alternative strategy for the feasible and efficient preparation of photocatalysts based on MOFs.

Polyethylene glycol functionalized reduced graphene oxide coupled with zinc oxide composite adsorbent for removal of phenolic wastewater

The development of agricultural activities and industrialization recently has various adverse impacts on living organisms. The ever-increasing problem of organic pollution has been an environmental concern to the community. Among these, phenolic pollutants like 2,4-dichlorophenol (2,4-DCP), phenol, 2-chlorophenol (2-CP), and bisphenol-A (BPA) are priority toxic pollutants that are continuously released into environment from many industries. In this work, a biocompatible zinc oxide incorporated polyethylene glycol functionalized reduced graphene oxide composite (RGO-PEG-ZnO) was synthesized and explored for the adsorptive removal of toxic phenolic pollutants from water. The optimized adsorption parameters were solution pH 7, adsorption time 60 min, temperature 25 °C, and dosage 0.25 g/L. The isotherms were well fitted by the Langmuir model for BPA and phenol, whereas for 2-CP, and 2,4-DCP, Freundlich was the best-fitted model, and the maximum uptake of BPA, phenol, 2-CP, and 2,4-DCP were 485.756, 511.248, 531.804, 570.641 mg/g, respectively. The kinetic data for all the phenolic pollutants follow the pseudo-second-order model. The thermodynamic analysis shows that Gibb's free energy (ΔG^o) values for all the pollutants were negative, confirming that the process was spontaneous. The positive values of change in enthalpy (ΔH^o) 28.261, 37.205, 46.182, and 61.682 kJ/mol for BPA, phenol, 2-CP, and 2,4-DCP, respectively, confirm that the above adsorption process was endothermic. The composite can be used for up to five cycles with a small reduction in the removal percentage. Adsorption performance of the synthesized composite for synthetic industrial effluents shows that up to 86.54% removal occurred in 45 min adsorption time. Based on the remarkably rapid adsorption and high adsorption capacity, RGO-PEG-ZnO composite can be considered an efficient adsorbent for treating phenolic pollutants from wastewater.

Synthesis of novel epichlorohydrin cross-linked β-cyclodextrin functionalized with reduced graphene oxide composite adsorbent for treatment of phenolic wastewater

A novel composite consisting reduced graphene oxide-functionalized beta-cyclodextrin epichlorohydrin polymer (RGO-βCD-ECH) was synthesized for the treatment of phenolic wastewater. Batch study of phenolic pollutants (2,4-dichlorophenol, 2-chlorophenol, and phenol) was analyzed using the synthesized composite as an adsorbent from an aqueous solution. The optimized parameters were temperature 25 °C, adsorption time 60 min, solution pH 7, and dosage 0.25 g/L. The isotherm data were more suitably fitted by the Langmuir isotherm model. The maximum uptake for 2,4-dichlorophenol, phenol, and 2-chlorophenol was 702.853, 659.475, and 674.155 mg/g, respectively, at 25 ± 1 °C. The kinetic data for all the phenolic pollutants follow the pseudo-second-order model, and the rate was controlled by film diffusion. Thermodynamic data revealed that the process of removing phenolic pollutants is spontaneous and endothermic. The composite can be used up to five cycles with a small reduction in the removal. Adsorption performance of the synthesized composite for synthetic industrial effluents shows that up to 78% removal occurred in 60 min adsorption time. Based on the remarkably rapid adsorption and high adsorption capacity, the synthesized composite can be considered an efficient adsorbent for treating phenolic pollutants from wastewater.

Investigation of thermal, antibacterial and heavy metal ion removal behavior of polyamide/polyimide iron oxide nanocomposites

In this study, a newly-designed diamine (DA) containing pyridine and carbazole groups was synthesized and the relevant polyamides (PAs) and polyimides (PIs) were prepared by polymerization reaction between the DA monomer and terephthalic acid, adipic acid, and pyromellitic dianhydride. In addition, polymer nanocomposites were prepared through a combination of the synthesized polymers with modified magnetite iron oxide nanoparticles. The synthesized compounds were fully characterized by hydrogen nuclear magnetic resonance (1HNMR), fourier-transform infrared (FTIR), field emitting scanning electron microscopy (FESEM), energy dispersive X-Ray (EDX), Transmission electron microscopy (TEM), Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) analyses. All of the synthesized properties of compounds such as thermal stability, viscosity, elimination capability of heavy metals ions adsorption, and antibacterial activity were investigated. Polyamides and PI showed good solubility in aprotic solvents and the viscosity was in the range of 0.72–0.89 dL/g. Also, the glass-transition temperature (Tg) of synthetic polymers was in the range of 214–273°C and 10% weight loss temperatures (T10%) for the synthesized compounds were in the temperature range of 280–492°C in N2, and the percentage of residual ash between 61 and 74%. The adsorption rate of Hg2+, Co2+, Pb2+, Cr2+, and Cd2+ metal ions by PA containing terephthalic acid (PAT) and its nanocomposite (NCPAT) showed that nanocomposite has a better performance compared to PAT. The highest and lowest removal efficiency was related to Hg2+ and Pb2+ ion, respectively. Finally, antibacterial test results against Gram-positive and Gram-negative bacteria showed favorable inhibitory effects of all the synthesized polymers.

Hollow Polyaniline Microsphere/MnO2/Fe3O4 Nanocomposites in Adsorptive Removal of Toxic Dyes from Contaminated Water

Dyes are considered as recalcitrant compounds and are not easily removed through conventional water treatment processes. The present study demonstrated the fabrication of polyaniline hollow microsphere (PNHM)/MnO₂/Fe₃O₄ composites by in situ deposition of MnO₂ and Fe₃O₄ nanoparticles on the surface of PNHM. The physicochemical characteristics and adsorption behavior of the prepared PNHM/MnO₂/Fe₃O₄ composites towards the removal of toxic methyl green (MG) and Congo red (CR) dyes have been investigated. The characterization study revealed the successful synthesis of the prepared PNHM/MnO₂/Fe₃O₄ adsorbent with a high Brunauer-Emmett-Teller (BET) surface area of 191.79 m²/g. The batch adsorption study showed about 88 and 98% adsorption efficiencies for MG and CR dyes, respectively, at an optimum dose of 1 g/L of PNHM/MnO₂/Fe₃O₄ at pH ∼6.75 at room temperature (303 ± 3 K). The adsorption phenomena of MG and CR dyes were well described by the Elovich and pseudo-second-order kinetics, respectively, and Freundlich isotherm model. The thermodynamics study shows that the adsorption reactions were endothermic and spontaneous in nature. The maximum adsorption capacity (Q_max) for MG and CR dyes was observed as 1142.13 and 599.49 mg/g, respectively. The responsible adsorption mechanisms involved in dye removal were electrostatic interaction, ion exchange, and the formation of the covalent bonds. The coexisting ion study revealed that the presence of phosphate co-ion considerably reduced the CR dye removal efficiency. However, the desorption-regeneration study demonstrated the successful reuse of the spent PNHM/MnO₂/Fe₃O₄ material for the adsorption of MG and CR dyes for several cycles. Given the aforementioned findings, the PNHM/MnO₂/Fe₃O₄ nanocomposites could be considered as a promising adsorbent for the remediation of dye-contaminated water.

Removal of Basic Fuchsin from water by using mussel powdered eggshell membrane as novel bioadsorbent: Equilibrium, kinetics, and thermodynamic studies

This study aims to remove organic cationic dye Basic Fuchsin (BF) by adsorption onto a low cost eggshell membrane (ESM) in batch mode at 293 K. XRD analysis confirms the amorphous nature of ESM meanwhile FTIR spectroscopy reveals the presence of several functional groups such as hydroxyl (-OH), sulfhydryl (-SH), carboxyl (-COOH), and amino (-NH₂). Morphological observations by SEM indicate its fibrous microstructure. BET analysis shows a surface area of 11.56 m² g^-1 and the presence of mesopores with a volume of 6.173 10^-3 cm³ g^-1. The value of pH_PZC of ESM is 7.05. The influence of adsorbent dose, contact time, pH, temperature and dye concentration is examined. The highest adsorption capacity around 48 mg.g^-1is achieved for a dye concentration 250 ppm, pH 6 and 25 °C. In addition, adsorption has been found to follow pseudo-second order kinetics. The analysis of the experimental data using linear forms based on Langmuir, Freundlich and Temkin isotherm models indicate that the best fit is obtained with Freundlich model. Thermodynamic parameters (Gibbs free energy, enthalpy, and entropy) reveal that the adsorption of BF onto ESM is an exothermic and spontaneous process. A comprehensive mechanism for BF adsorption by ESM has been proposed.

Effective removal of lead(ii) from wastewater by amine-functionalized magnesium ferrite nanoparticles

Magnetic nanoadsorbent in the form of amine-functionalized MgFe₂O₄nanoparticles was successfully synthesized and adopted for Pb²⁺removal from scenario simulated wastewater.