Effects of electrolytes and fractionated dissolved organic matter on selective adsorption of pharmaceuticals on terephthalic acid-based metal-organic frameworks

Simultaneous immobilization of ammonia and phosphorous by thermally treated sediment co-modified with hydrophilic organic matter and zeolite

The use of calcined sediments (CS) for thin-layer capping is an environment-friendly technology for controlling nitrogen (N) or phosphorus (P) release. However, the effects of CS derived materials and efficiency in controlling the sedimentary N/P ratio have not been thoroughly investigated. While zeolite-based materials have been proven efficient to remove ammonia, it is limited by the low adsorption capacity of PO₄^3-. Herein, CS co-modified with zeolite and hydrophilic organic matter (HIM) was synthesized to simultaneously immobilize ammonium-N (NH₄⁺-N) and remove P, due to the superior ecological security of natural HIM. Studies on the influences of calcination temperature and composition ratio indicated that 600 °C and 40% zeolite were the optimal parameters leading to the highest adsorption capacity and lowest equilibrium concentration. Compared with doping with polyaluminum chloride, doping with HIM not only enhanced P removal but also achieved higher NH₄⁺-N immobilization efficacy. The efficiency of zeolite/CS/HIM capping and amendment in prohibiting the discharge of N/P from sediments was assessed via simulation experiments, and the relevant control mechanism was studied at the molecular level. The results indicated that zeolite/CS/HIM can reduce 49.98% and 72.27% of the N flux and 32.10% and 76.47% of the P flux in slightly and highly polluted sediments, respectively. Capping and incubation with zeolite/CS/HIM simultaneously resulted in substantial reductions in NH₄⁺-N and dissolved total P in overlying water and pore water. Chemical state analysis indicated that HIM enhanced the NH₄⁺-N adsorption ability of CS owing to its abundant carbonyl groups and indirectly increased P adsorption by protonating mineral surface groups. This research provides a novel strategy to control sedimentary nutrient release by adopting an efficient and ecologically secure remediation method to rehabilitate eutrophic lake systems.

Comprehensive evaluation of cobalt incorporated cryptomelane-type manganese oxide molecular sieve as an efficient adsorbent for enhanced removal of europium from wastewater systems

Extraction of radionuclide contaminants from wastewater systems has recently drawn widespread attention, and then developing a novel and green extracting technology has also become an enormous challenge. Herein, a facile hydrothermal method was employed to fabricate cobalt-incorporated cryptomelane-type manganese oxide molecular sieve (Co-OMS-2) for extraction Eu(III) from wastewater under diverse experimental conditions. All kinds of characterized techniques, such as SEM, TEM, XRD, FTIR, BET, EDS and XPS had verified the qualified synthesis process and splendid structural features of the Co-OMS-2. The maximum adsorption capacity of Co-OMS-2 was 7.62 × 10^-4 mol/g for Eu(III) at 298 K, which was superior than primarily traditional materials reported previous literatures. The high adsorption capacity of Eu(III) onto Co-OMS-2 was primarily attributed to high specific surface area and abundant surface functional groups, and the interactions were mainly contributed to strong surface complexation and electrostatic attraction. Under the condition of low pH, the outer-sphere surface complexation and cation exchange were primary mechanisms to Eu(III) adsorption onto Co-OMS-2 composites, while inner-sphere surface complexation was mainly assigned to Eu(III) adsorption onto Co-OMS-2 under the high pH sections. The Co-OMS-2 composite achieved equilibrium in a relatively short time, and this excellent performance was conducive to the treatment of Eu(III) under the extreme emergency conditions. In view of the extraordinary adsorption capacity and recycled reusability, the Co-OMS-2 composites can be as prospective adsorbents adopted for the extraction of Eu(III) in real wastewater management.

Transport of Carbamazepine, Ciprofloxacin and Sulfamethoxazole in Activated Carbon: Solubility and Relationships between Structure and Diffusional Parameters

The transport of carbamazepine, ciprofloxacin and sulfamethoxazole in the different pores of activated carbon in an aqueous solution is a dynamic process that is entirely dependent on the intrinsic parameters of these molecules and of the adsorbent. The macroscopic processes that take place are analyzed by interfacial diffusion and reaction models. Modeling of the experimental kinetic curves obtained following batch treatment of each solute at 2 µg/L in tap water showed (i) that the transport and sorption rates were controlled by external diffusion and intraparticle diffusion and (ii) that the effective diffusion coefficient for each solute, with the surface and pore diffusion coefficients, were linked by a linear relationship. A statistical analysis of the experimental data established correlations between the diffusional parameters and some geometrical parameters of these three molecules. Given the major discontinuities observed in the adsorption kinetics, the modeling of the experimental data required the use of traditional kinetic models, as well as a new kinetic model composed of the pseudo first or second order model and a sigmoidal expression. The predictions of this model were excellent. The solubility of each molecule below 60 °C was formulated by an empirical expression.