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This study introduces calcined water hyacinth (CWH), processed at 650°C, as a novel and environmentally friendly adsorbent for phosphorus (P) removal from wastewater. Building on previous findings that identified CWH as a rich source of metal oxides and hydroxides (e.g., Ca(OH)₂, Al₂O₃, MgO, Fe₃O₄), this research explores its application in fixed-bed column systems for continuous adsorption processes. The study demonstrates that CWH effectively removes phosphorus through apatite formation, showcasing its potential for real-world water treatment. The phosphorus adsorption capacity increased from 23.64 to 26.55 mg/g when the flow rate was reduced from 1.5 to 0.5 mL/min. Breakthrough curves fitted to the Thomas, Adams-Bohart, and Yoon-Nelson models provided critical insights into column performance, while the Bed Depth Service Time (BDST) model confirmed the feasibility of employing CWH in continuous-flow systems. The practical tests on synthetic municipal wastewater, which revealed a maximum adsorption capacity of 5.20 mg/g, further demonstrated CWH's effectiveness for treating wastewater with low phosphorus concentrations, providing reassurance about its real-world applicability. Furthermore, the study found that increasing the adsorbent height improved column performance by extending breakthrough and exhaustion times, whereas higher flow rates led to faster saturation and reduced capacity. The exhausted CWH material can be repurposed as a soil amendment or fertilizer feedstock, supporting nutrient recycling. [ABSTRACT FROM AUTHOR]

Introduction: the treatment of leachates containing heavy metals, such as copper (Cu) and lead (Pb), is crucial as their levels often exceed permissible limits established by regulations. This study focuses on evaluating the efficiency of treating these metals using adsorption with processed coffee pulp. Objective: the objective of this study is to determine the removal rates and adsorption capacity of copper and lead in landfill leachates. Methods: adsorption isotherms were conducted in individual solutions using the Langmuir and Freundlich models. A 2^3 experimental design and response surface analysis were applied to evaluate the variables. Additionally, thermodynamic parameters were determined to understand the type of adsorption. Results: the results indicate that the Langmuir model best fits the adsorption of copper and lead. The maximum adsorption capacities for copper at doses of 1.3 and 5 g of adsorbent material were 0.29, 0.12, and 0.59 mg/g, while for lead, they were 0.05, 0.02, and 0.02 mg/g. The adsorption rates for copper were 65.3%, 71.0%, and 69.4%, and for lead, they were 30.30%, 13.80%, and 25.40% at the respective doses. Conclusion: the thermodynamic parameters suggest that the adsorption mechanism is chemical in nature, supporting the effectiveness of processed coffee pulp as an adsorbent material for the removal of heavy metals in leachates. [ABSTRACT FROM AUTHOR]

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Metformin, widely prescribed to treat type 2 diabetes for its effectiveness and low cost, has raised concerns about its presence in aqueous effluents and its potential environmental and public health impacts. To address this issue, xerogels were synthesized from resorcinol and formaldehyde, with molar ratios ranging from 0.05 to 0.40. These xerogels were thoroughly characterized using FT-IR, SEM, TGA, and TEM analyses. Batch adsorption experiments were performed with standard metformin solutions at concentrations of 50 and 500 mg/L, varying pH, and temperature to determine the adsorption isotherms of the synthesized xerogels. The adsorption data revealed a maximum adsorption capacity of 325 mg/g at pH 11 and 25 °C. Quantum chemical calculations revealed that electrostatic interactions govern metformin adsorption onto xerogels. The xerogels' adsorption capacity was evaluated in competitive systems with CaCl2, NaCl, MgCl2, and synthetic urines. Reuse cycles demonstrated that xerogels could be reused for up to three cycles without any loss in adsorptive efficiency. The adsorption mechanisms of metformin in the adsorption process highlight the strong electrostatic interactions and hydrogen bonds between the adsorbate and the adsorbent material. Xerogels synthesized show promise as efficient adsorbents to remove metformin from aqueous solutions, helping to mitigate its environmental impact. [ABSTRACT FROM AUTHOR]

This study focuses on the encapsulation of the entire series of halides by the 512 cage of twenty water molecules and on the characterization of water to water and water to anion interactions. State-of-the-art computations are used to determine equilibrium geometries, energy related quantities, and thermal stability towards dissociation and to dissect the nature and strength of intermolecular interactions holding the clusters as stable units. Two types of structures are revealed: heavily deformed cages for F− indicating a preference for microsolvation, and slightly deformed cages for the remaining anions indicating a preference for encapsulation. The primary variable dictating the properties of the clusters is the charge density of the central halide, with the most severe effects observed for the F− case. For the remaining halides, the anion may be safely viewed as a sort of "big electron" with little local disruptive power, enough to affect the network of non-covalent hydrogen bonds in the cage, but not enough to break it. Gibbs energies for dissociation either into cavity and halide or into water molecules and halide suggest that, in a similar way as to methane clathrate, a more weakly bonded complex that has been detected in the gas phase, all halide containing clathrate-like structures should be amenable to experimental detection in the gas phase at moderate temperature and pressure conditions. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC) displays a Pt‐like behavior in catalysis, applied in hydrogenation processes. Numerous theoretical studies have modeled the behavior and use of adsorbed hydrogen without obtaining a general picture, missing basic links between H2 dissociation and generation of high surface coverage (ΘH>0.5 ML). Here, the capability of C‐ and W‐terminations of the α‐WC(0001) surface is analyzed to dissociate several H2 molecules to produce coverages, ΘH, ranging from low to very high values (0.13<ΘH<2.00 ML). Density functional theory and an ab initio atomistic thermodynamic were used to achieve the conditions for H2 dissociation. The WC−C surface has higher capacity to dissociate H2 molecules than WC−W. However, both surfaces can reach full surface coverage, ΘH=1 ML, at mild ambient conditions, T=300 K and P=1 atm, and even up to 500 K at low and high pressures. The H‐adatoms on WC−W are more labile than on WC−C. The binding of adsorbates is hindered at high ΘH, implying a need to modulate ΘH according to the application. The results give the basis to understand the capabilities of WC‐based catalysts in hydrogenation‐related reactions, with the advantage of WC being a hydrogen reservoir at mild practical catalytic conditions. [ABSTRACT FROM AUTHOR]