This work focuses on the preparation and application of silver nanoparticles/organophilic clay/polyethylene glycol for the catalytic reduction of the contaminants methylene blue (MB) and 4-nitrophenol (4-NP) in a simple and binary system. Algerian clay was subjected to a series of treatments including acid treatment, ion exchange with the surfactant hexadecyltrimethylammonium bromide (HTABr), immobilization of polyethylene glycol polymer, and finally dispersion of AgNPs. The molecular weight of polyethylene glycol was varied (100, 200, and 4000) to study its effect on the stabilization of silver nanoparticles (AgNPs) and the catalytic activity of the resulting samples. The results showed that the catalyst with the highest molecular weight of polyethylene glycol had the highest AgNP content. Catalyst mass, NaBH₄ concentration, and type of catalyst were shown to have a significant influence on the conversion and rate constant. The material with the highest silver nanoparticle content was identified as the optimal catalyst for the reduction of both pollutants. The measured rate constants for the reduction of methylene blue (MB) and 4-nitrophenol (4-NP) were 164 × 10⁻⁴ s⁻¹ and 25 × 10⁻⁴ s⁻¹, respectively. The reduction of MB and 4-NP in the binary system showed high selectivity for MB dye, with rate constants of 64 × 10⁻⁴ s⁻¹ and 9 × 10⁻⁴ s⁻¹ for MB and 4-NP, respectively. The reuse of the best catalyst via MB dye reduction for four cycles showed good results without loss of performance.

Water pollution by organic dyes poses serious environmental and health challenges, demanding efficient and selective remediation methods. In this study, we engineered tailored organo-clay nanocomposites by modifying montmorillonite with hexadecyltrimethylammonium bromide (HTAB) and intercalating polyethylene glycol (PEG) chains of two distinct molecular weights (PEG200 and PEG4000). Comprehensive characterization techniques (XRD, FTIR, SEM, zeta potential, and TGA) confirmed the successful modification of the composites. Notably, PEG4000 promoted significant interlayer expansion, as evidenced by the shift of the (00l) reflection corresponding to the basal spacing d, indicating an increase in basal spacing. This expansion contributed to the formation of a well-ordered porous framework with uniformly distributed pores. In contrast, PEG200 produced smaller pores with a more uniform distribution but induced less pronounced interlayer expansion. Adsorption tests demonstrated rapid kinetics, achieving equilibrium in under 15 min, and impressive capacities: 420 mg/g of methylene blue (MB) adsorbed on PEG200/MMT@HTAB, and 385 mg/g of Congo red (CR) on PEG4000/MMT@HTAB. The crucial role of PEG chain length in adsorption selectivity was assessed, showing that shorter PEG chains favored methylene blue adsorption by producing narrower pores and faster kinetics, while longer PEG chains enhanced CR uptake via a stable, interconnected pore network that facilitates diffusion of larger dye molecules. Thermodynamic and Dubinin–Radushkevich analyses confirmed that the adsorption was spontaneous, exothermic, and predominantly driven by physical adsorption mechanisms involving weak van der Waals and dipole interactions. These findings highlight the potential of PEG-modified montmorillonite nanocomposites as cost-effective, efficient, and tunable adsorbents for rapid and selective removal of organic dyes in wastewater treatment.

In this work, zeolite LTA (Linde Type A) was synthesised from natural clay as a novel adsorbent for copper and lead ions removal from water effluents. The applied process allowed the reuse of kaolin, as natural clay, for the production of zeolite LTA through a stepwise process, which involved the formation of metakaolin. The results of characterisation showed the formation of crystalline cubic crystals of zeolite with a mean dimension of 2–3 microns, indicating the successful nucleation and development of the LTA zeolite phase. Batch adsorption studies were carried out to study the removal ability of zeolite LTA by testing Cu²⁺ and Pb²⁺ ions. Effects of contact time, pH, and adsorbent dosage were investigated. At pH > 5, the removal efficiency for both metals exceeded 95%. As the zeolite dosage increases from 2 to 10 g/L, the removal effectiveness for both metals markedly enhances (>95% at 10 g/L for lead ions and >90% at 10 g/L for copper ions). The adsorbent showed a higher adsorption capacity in removing lead compared to copper (Q_m = 81.5 mg/g for Pb²⁺ and 67.5 mg/g for Cu²⁺). The adsorption process was well described by the pseudo-second-order kinetic model, while the Langmuir isotherm adequately depicted the equilibrium behavior. Notably, the kinetics revealed distinct contributions from chemisorption and physisorption, with the AOAS model effectively quantifying their respective roles in metal ion removal. The findings revealed that prepared zeolite LTA acts as an efficient adsorbent to remove heavy metals.