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• ZSM-5 zeolite synthesized using chitin as a molding agent has the potential to recover rare earth elements; • Increasing the temperature decreased the adsorption amount of rare earth elements; • The Ce, La, and Nd removal process forms a monolayer in zeolite; • Si-functional groups predominate in the rare earth element removal; • Electrostatic interactions and the formation of complexes were involved in Ce, La, and Nd adsorption onto zeolite. The recovery of rare earth elements (REE) is essential to meet the growing demand for these resources and promote the reuse of available resources. This study investigated the potential of ZSM-5 zeolite in the recovery of trivalent ions of cerium, lanthanum and neodymium under conditions of pH 6 and temperatures between 298 and 328 K. REE equilibrium isotherms were analyzed using five statistical physics models. The results indicate that removing all REE occurs predominantly in monolayers, as these models showed better prediction performance (coefficient of determination > 0.97 and mean squared error < 18.0). The best model determined that lanthanum and neodymium have one adsorption energy, while cerium has two adsorption energies involved in the process. The predominant functional groups are those containing silicon. Increasing temperature causes an increase in the number of REE ions captured per functional group, which reduces the adsorption space available on the surface. The model parameters indicate that the adsorption of these ions implies a multi-ionic mechanism (number of ions adsorbed per site greater than 1) and is an exothermic process. Based on the calculated adsorption capacities at saturation, the order of preference in adsorption can be established: neodymium > cerium > lanthanum. The adsorption energies indicate that the process occurred mainly due to physical forces since all energy values are below 40 kJ mol−1. The study's results led to the proposal of a mechanism for the adsorption of REE on ZSM-5 zeolite, which highlights the predominance of electrostatic interactions and complex formation, which result in the formation of a monolayer on the adsorbent's surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ciprofloxacin (CIP) adsorption from fresh synthetic urine was studied; • A double layer with one energy model described well the equilibrium data; • GO showed high adsorption capacity in different media (≥291.39 mg g−1); • Experiments using CIP concentrations commonly found in urine were performed. This work uses conventional and statistical physics modeling approaches to address ciprofloxacin (CIP) adsorption by graphene oxide (GO) from aqueous solution and fresh synthetic urine. Instrumental techniques such as FTIR, XRD, SEM, TGA, BET, and EDS were employed to characterize the adsorbent material. The adsorption experiments were performed in a typical batch using different initial concentrations of CIP, adsorbent dosage, pH, and temperatures. Besides, the statistical physics approach was employed to investigate the CIP adsorption onto GO. Five models based on mono, double, and multilayers were used to describe the equilibrium isotherms. Steric and energetic parameters such as the number of adsorbed molecules per site, receptor site density, and half-saturation were considered. The kinetic data were adjusted using three conventional models (pseudo 1st order, pseudo 2nd order, and general order). The pH effect and influence of adsorbent dosage on adsorption performance were also investigated and discussed. In addition, adsorption mechanisms hypotheses were proposed based on experimental data and adsorption modeling using a statistical physics approach. Furthermore, the current work reports the removal of CIP at concentrations commonly found in urine considering factors such as fraction excreted in unmetabolized form, daily defined dose, and average daily urine volume excreted. The adsorption capacity values in aqueous medium and fresh synthetic urine were were 354.24 and 291.39 mg g−1, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biogenic silica wastes modified for TOC removal and treatment of oilfield-produced water; • The adsorbent showed a large surface area of over 1000 m2/g; • The adsorbent was highly recyclable, being reused in up to 15 cycles; • CAM adsorbent removed 73 % of TOC from real produced water in 150 min. The escalating fuel demand generates significant volumes of oilfield-produced water containing complex environmental pollutants such as phenol. This study proposes a purification method for converting activated carbon (CAM), obtained at zero cost as a by-product of biogenic silica production, into an effective adsorbent. The activated carbon was characterized extensively for its morphological, structural, and chemical properties, revealing a substantial surface area exceeding 1000 m2/g. The adsorption process for phenol removal was investigated through kinetics, isotherms, and thermodynamic analyses. Kinetic data analysis favored the PSO models within 150 min, while equilibrium studies showed the best fit for the Sips and Liu models. CAM achieved an adsorption capacity of 23.9 mg g−1 for phenol removal at pH 6, the typical pH of produced water. The adsorption process was found to be exothermic and spontaneous. The produced adsorbent demonstrated high recyclability, with up to 15 reuse cycles achievable through regeneration via thermal desorption at 180 °C. Furthermore, CAM removed 73 % of total organic carbon from real produced water within 150 min. Thus, using activated carbon intrinsically carbonized during silica production is an economically viable and attractive solution for treating phenol-contaminated oilfield-produced water. [ABSTRACT FROM AUTHOR]