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Molybdenum trioxide/polypyrrole (MoO3/Ppy) nanocomposite was prepared via oxidative polymerization of pyrrole monomer with MoO3 nanoparticles. The adsorption of Cd+2 and nile blue (NB) onto the nanocomposite was investigated in terms of various process parameters. The characterization of MoO3/Ppy nanocomposite was carried out by Fourier transform‐infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive X‐ray spectroscopy. Higher R2 (0.992–0.997 for Cd+2 and 0.997–0.998 for NB) and lower standard error of estimation values (1.04–1.82 for Cd+2 and 0.87–1.07 for NB) for Freundlich isotherm highlighted the multilayer adsorption onto heterogeneous nanocomposite surface. The higher Qm values at 323 K for Cd+2 (181 mg/g) and NB (189 mg/g) compared to many reported adsorbents proved the adsorptive superiority of MoO3/Ppy. The energy of adsorption (E) values from Dubinin–Radushkevich model was 1.26–1.38 and 1.36–1.44 kJ/mol for Cd+2 and NB, respectively, suggesting physical adsorption. Pseudo‐second order kinetic model governed the adsorption of Cd+2 and NB with intraparticle and liquid film diffusion controlling the mechanism. The negative ΔG values (8.4–9.4 kJ/mol) and positive ΔH values (2.5–6.1 kJ/mol) implied spontaneous and endothermic adsorption process. The positive ΔS values (0.036–0.048 kJ/mol/K) indicated increased randomness at MoO3/Ppy‐Cd+2 or NB interface. The MoO3/Ppy nanocomposite proved to be suitable and efficient adsorbent for sequestering of Cd+2 and NB from aqueous solution.

Herein, a simplistic redox polymerization strategy was utilized for the fabrication of a poly­(methacrylic acid)/montmorillonite hydrogel nanocomposite (PMA/nMMT) and probed as a sorbent for sequestration of two pharmaceutical contaminants, viz., amoxicillin (AMX) and diclofenac (DF), from wastewater. The synthesized hydrogel nanocomposite was characterized by the Fourier transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques to analyze structural characteristics and sorption interactions. The efficacy of PMA/nMMT was thoroughly investigated for the sequestration of AMX and DF from the aquatic phase with a variation in operative variables like agitation time, sorbent dosage, pH, and initial sorbate concentration. The reaction kinetics was essentially consistent with the pseudo-second-order model with rate dominated by the intraparticle diffusion model as well as the film diffusion mechanism. The Freundlich isotherm appropriated the equilibrium data over the entire range of concentration. Thermodynamic investigation explored the spontaneous and endothermic nature of the process. The most possible mechanism has been explained, which includes electrostatic interaction, hydrogen bonding, cationic exchange, and partition mechanism. Economic feasibility, better sorption capacity (152.65 for AMX and 152.86 mg/g for DF), and efficient regeneration and reusability even after four consecutive sorption–desorption cycles ascertained PMA/nMMT as a potential sorbent for AMX and DF uptake from the aqueous phase.

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NiFe 2 O 4 /polythiophene nanocomposite was synthesized by in situ chemical oxidative polymerization of thiophene in NiFe 2 O 4 nanoparticles presence, whereas NiFe 2 O 4 nanoparticles were prepared via coprecipitation method. Fourier transform infrared (FTIR), X-ray diffraction (XRD), UV-Visible, and SEM, EDX techniques were used for characterization of the nanocomposite. The effect of various parameters such as adsorbent dose, contact time, initial dye concentration, and initial pH of solution on the adsorption of Janus green B (JG) and Fuchsin basic (FB) onto the nanocomposite was optimized by batch studies. The equilibrium uptake data ascribed well to the Langmuir model with maximum adsorption capacity of 143 and 498 mg/g at 303 K for JG and FB, respectively. The exceptional high adsorption capacity of NiFe 2 O 4 /polythiophene nanocomposite for JG and FB was ascribed to π-π and electrostatic interactions. Kinetics studies pointed out that JG and FB removal followed pseudo-second order model. The negative values of ΔH (JG: -47.28; FB: −38.00 kJ/ mol) and ΔG (JG: −9.347 to −6.442; FB: −14.16 to -12.85 kJ/mol) pointed out the feasibility, spontaneity, and exothermic nature of removal process. Negative value of ΔS (JG: -0.125; FB: -0.078 kJ/mol) suggested decrease in randomness at the solid/ liquid interface. The results showed that NiFe 2 O 4 /polythiophene is an appealing adsorbent for the uptake of JG and FB dyes from aquatic environment. K E Y W O R D S adsorption, Fuchsin basic, Janus green B, NiFe 2 O 4 /polythiophene nanocomposite, non-linear regression analyses, thermodynamics

The FeWO4/polypyrrole nanocomposite (FeWO4/PPy NC), prepared by oxidative polymerization of pyrrole monomer with FeWO4 NPs, is used for adsorption and photocatalytic degradation of rose bengal and alizarin red S. The characterization of the nanocomposite (NC) is performed by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy, and transmission electron microscopy. The performance of FeWO4/PPy NC is appraised under varying conditions of agitation time/solar irradiation time, initial dyes concentration, adsorbent/photocatalyst dose, and initial solution pH. The Langmuir isotherm and pseudo‐second‐order kinetic models best express the equilibrium data. The FeWO4/PPy NC exhibits a maximum saturation capacity of 202.63 mg/g for rose bengal (RB) and 142.80 mg/g for alizarin red S (ARS). The adsorption of both dyes follows liquid film and intraparticle diffusion. Thermodynamic studies demonstrate feasibility, spontaneity, and exothermic essence of the removal process. The NC shows remarkable visible‐light photocatalytic activity at 100–120 min irradiation time, 40 mg/L dyes solution concentration, 0.5 g/L of photocatalyst, and pH 6. Photodegradation reaction obeys first‐order kinetics. The mechanism of adsorption of RB and ARS is governed by electrostatic attraction, hydrogen bonding, van der Waals, and π–π interactions. A good regeneration capacity up to four sorption–desorption cycles, high saturation capacity, and remarkable photodegradation efficiency depicts that FeWO4/PPy NC can be used efficiently for decolorization of RB and ARS in aqueous medium.

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