Comprehensive insight into adsorption of chlortetracycline hydrochloride by room-temperature synthesized water-stable Zr-based metal-organic gel/sodium alginate beads

Chlortetracycline hydrochloride (CTC) is one of the prevailing antibiotic pollutants that harm both environmental ecosystem and human health. Herein, Zr-based metal-organic gels (Zr-MOGs) with lower-coordinated active sites and hierarchically porous structures are fabricated via a facile straightforward room-temperature strategy for CTC treatment. More importantly, we incorporated the powder Zr-MOGs into low-cost sodium alginate (SA) matrix to achieve shaped Zr-based metal-organic gel/SA beads for enhancing the adsorption ability and ameliorating the recyclability. The Langmuir maximum adsorption capacities of Zr-MOGs and Zr-MOG/SA beads could reach 143.9 mg/g and 246.9 mg/g, respectively. What's more, in the manual syringe unit and continuous bead column experiments, Zr-MOG/SA beads could achieve an eluted CTC removal ratio as high as 93.6% and 95.5% in the real water sample, respectively. On top of that, the adsorption mechanisms were put forward as a combination of pore filling, electrostatic interaction, hydrophilic-lipophilic balance, coordination, π-π interaction as well as hydrogen bonding interaction. This study outlines a workable strategy for the facile preparation of candidate adsorbents for wastewater treatment.

Shaddock peels derived multilayer biochar with embedded CoO@Co nanoparticles for peroxymonosulfate based wastewater treatment

The utilization of bio-wastes, such as shaddock peels, is of great significance for sustainable development. Combined with the potential of peroxymonosulfate (PMS) based advanced oxidation process (AOP) in wastewater treatment, a highly efficient functional catalyst, derived from shaddock peels biochar (SPC) and embedded with CoO@Co nanoparticles, i.e. Co-SPC-x(y), was prepared using a facile impregnation-calcination method and used for refractory organics degradation with PMS. The decoration amount of Co and annealing temperature were optimized, and the effects of various reaction factors were investigated. The results indicated that the optimized sample of Co-SPC-10 (900) consisted of multilayer biochar with curly edges and highly dispersed CoO@Co nanoparticles in the range of 20-200 nm, which is in cubic metallic Co and CoO. Moreover, it also possessed a specific surface area of 248.6 m²/g, and exhibited excellent PMS activation ability with ∼100% chlortetracycline hydrochloride (CTC) removal ratio within only 12 min of operation. The Co-SPC-10 (900)/PMS system showed relatively high tolerance for HPO₄^2-, NO₃^- and SO₄^2-, while the Cl^- and HA had considerable effects on it. Mechanism exploration results revealed that both radical and non-radical pathways existed in the Co-SPC-10 (900)/PMS system, in which the multilayered biochar functioned as an electron transfer carrier to facilitate the continuous cycle of Co²⁺/Co³⁺ in the CoO@Co nanoparticles by reacting with the absorbed CTC and PMS, resulting in the production of •OH, SO₄^•-, O₂^•- and ¹O₂. Additionally, the Co-SPC-10 (900) also showed good stability and catalytic oxidation performance for various refractory organics.

Degradation of chlortetracycline hydrochloride by peroxymonosulfate activation on natural manganese sand through response surface methodology

This work studies the degradation of chlortetracycline hydrochloride (CTC) by activated peroxymonosulfate (PMS) with natural manganese sand (NMS). Meanwhile, the NMS was characterized and analyzed by isothermal nitrogen adsorption (BET), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM). It can be induced that NMS material may contain C, O, Al, Si, Fe, Mn, and K, and the proportion of each is 6%, 9%, 13%, 34%, 27%, 5%, and 6%. Critical parameters, including initial pH value, catalyst dosage, and PMS amount, were optimized through response surface methodology. One of the essential significances of response surface methodology (RSM) is the establishment and optimization of the mathematical model to reduce the complexity of the experimental process. It can provide the degree of mutual influence between various factors and optimize the response based on the investigated factors. Results indicated that 81.65% of CTC could be degraded under the optimized conditions of PMS amount 2.02 g/L, the NMS dosage 0.29 g/L and pH 3.87. Also, it shows that NMS is the most powerful of each factor on the degradation efficiency. We proposed the degradation pathways of CTC from the liquid chromatograph-mass spectrometer (LC-MS) results. Therefore, NMS could be applied as an efficient activator of peroxymonosulfate to purify the water and wastewater.

Cotransport of micro- and nano-plastics with chlortetracycline hydrochloride in saturated porous media: Effects of physicochemical heterogeneities and ionic strength

Global production and use of plastics have resulted in the wide dissemination of micro- and nano-plastics (MNPs) to the natural environment. Potentially acting as a vector, the role of MNPs on the fate and transport of environmental pollutants (e.g., antibiotics such as chlortetracycline hydrochloride; CTC) has garnered global concern recently. Herein, the cotransport of MNPs and CTC in columns packed with uncoated sand or soil colloid-coated sand (SCCS) under different degrees of physicochemical heterogeneity and ionic strength was systematically explored. Our results show that MNPs and CTC inhibit the transport of each other when they coexist. The adsorption of CTC onto sand grains, soil colloids, and MNPs, as well as the aggregation of MNPs in the presence of CTC could be the major contributors to the enhanced retention of CTC and MNPs. In SCCS with different degrees of soil colloid coating, the adsorption of CTC on soil colloids is critical to influence the transport of CTC, and the nonlinear retention of MNPs to soil colloids is mainly attributed to the alteration of collector surface roughness by soil colloids. High ionic strength slightly facilitates CTC transport due to the competition for adsorption sites and the formation of CTC macromolecules, but significantly inhibits MNPs transport by suppressing the electrostatic double layers based on colloid stability theory. Consequently, the cotransport of MNPs and CTC is governed by the coupled interplay of collector surface roughness and chemical heterogeneity, due to the soil colloid coatings and the adsorbed CTC on the surfaces associated with solution chemistries such as ionic strength. Increased cotransport of MNPs and CTC occurred under a higher concentration of MNPs due to a larger number of adsorption sites for CTC. Our findings advance the current understanding of the complex cotransport of MNPs and antibiotics in the environment. This information is valuable for understanding contaminant fate and formulating strategies for environmental remediation due to the contamination of MNPs and co-occurring contaminants.

Alliance between doping Ag and dual ligands-enhanced fluorescent gold nanoclusters for the assays of vitamin B12 and chlortetracycline hydrochloride

A stable, water-soluble, heightened quantum yields (QYs) Au nanoclusters by the alliance between doping Ag and dual ligands (thiosalicylic acid and bovine serum albumin) (TSA/BSA-Au/AgNCs) was prepared using one-step wet chemical synthesis. The effect of different types of aromatic thiols and the molar ratio of Au-Ag on the photo-luminescence performance of AuNCs was discussed in detail. The alloy NCs is shown to be viable fluorescent method for vitamin B12 (VB12) and chlortetracycline hydrochloride (CCH) assays, and become an excellent temperature sensor in the range of 10-50 °C. The fluorescence (FL) of TSA/BSA-Au/AgNCs was quenched with the addition of VB12 or CCH coming from Förster resonance energy transfer (FRET) combined with inner filter effect (IFE). The method can detect VB12/CCH by fluorometry with a linear response in the range of 0.33-60.0/0.33-60.0 μmol·L^-1 and a 71.0/64.0 nmol·L^-1 detection limit (at 3σ/slope). Furthermore, the proposed method was extended to the assays of VB12 in mineral water or tablets and CCH in veterinary drug or ointment with satisfactory results.

Chlortetracycline hydrochloride removal by different biochar/Fe composites: A comparative study

In the last years, the synthesis and applications of biochar/Fe composites have been extensively studied, but only few papers have systematically evaluated their removal performances. Herein, we successfully synthesized and structurally characterized Fe⁰, Fe₃C, and Fe₃O₄-coated biochars (BCs) for the removal of chlortetracycline hydrochloride (CH). Evaluation of their removal rate and affinity revealed that Fe⁰@BC could achieve better and faster CH removal and degradation than Fe₃C@BC and Fe₃O₄@BC. The removal rate was controlled by the O-Fe content and solution pH after the reaction. The CH adsorption occurred on the O C groups of Fe⁰@BC and the OC and OFe groups of Fe₃C@BC and Fe₃O₄@BC. Electron paramagnetic resonance analysis and radical quenching experiments indicated that HO and ¹O₂/ O₂^- were mainly responsible for CH degradation by biochar/Fe composites. Additional parameters, such as effects of initial concentrations and coexisting anions, regeneration capacity, cost and actual wastewater treatment were also explored. Principal component analysis was applied for a comprehensive and quantitative assessment of the three materials, indicating Fe⁰@BC is the most beneficial functional material for CH removal.

Multi-walled carbon nanotube/amino-functionalized MIL-53(Fe) composites: Remarkable adsorptive removal of antibiotics from aqueous solutions

A novel adsorbent composite was synthesized by combining amino-functionalized MIL-53(Fe) with multi-walled carbon nanotubes (MWCNT), and used to adsorb tetracycline hydrochloride (TCN) and chlortetracycline hydrochloride (CTC). The maximum adsorption capacities of TCN and CTC over MWCNT/NH₂-MIL-53(Fe) at 25 °C were 368.49 and 254.04 mg g^-1, which are, respectively, 1.79 and 8.37 times higher than that of chaff biochar. Interestingly, the mesoporosity of MWCNT/NH₂-MIL-53(Fe) significantly increased through introduction of MWCNT into NH₂-MIL-53(Fe), which proved to be favorable for the production of active adsorption sites. Besides, the remarkably increased adsorption capacity can be ascribed to the hydrogen bonding between amino functional groups on MWCNT/NH₂-MIL-53(Fe) and hydroxyl functional groups on TCN or CTC. Moreover, the π-π interaction between adsorbate and adsorbent was considered the main reason for the adsorption of TCN and CTC. The great adsorption capacity, as well as excellent reusability, demonstrated the potential application of MWCNT/NH₂-MIL-53(Fe) in the removal of TCN and CTC from aqueous solutions.