Removal of pharmaceutical and personal care products (PPCPs) by MOF-derived carbons: A review

Occurrence and risks of pharmaceuticals, personal care products, and endocrine-disrupting compounds in Chinese surface waters

The continuous and rapid increase of chemical pollution in surface waters has become a pressing and widely recognized global concern. As emerging contaminants (ECs) in surface waters, pharmaceutical and personal care products (PPCPs), and endocrine-disrupting compounds (EDCs) have attracted considerable attention due to their wide occurrence and potential threat to human health. Therefore, a comprehensive understanding of the occurrence and risks of ECs in Chinese surface waters is urgently required. This study summarizes and assesses the environmental occurrence concentrations and ecological risks of 42 pharmaceuticals, 15 personal care products (PCPs), and 20 EDCs frequently detected in Chinese surface waters. The ECs were primarily detected in China's densely populated and highly industrialized regions. Most detected PPCPs and EDCs had concentrations between ng/L to µg/L, whereas norfloxacin, caffeine, and erythromycin had relatively high contamination levels, even exceeding 2000 ng/L. Risk evaluation based on the risk quotient method revealed that 34 PPCPs and EDCs in Chinese surface waters did not pose a significant risk, whereas 4-nonylphenol, 4-tert-octylphenol, 17α-ethinyl estradiol, 17β-estradiol, and triclocarban did. This review provides a comprehensive summary of the occurrence and associated hazards of typical PPCPs and EDCs in Chinese surface waters over the past decade, and will aid in the regulation and control of these ECs in Chinese surface waters.

Nitrogen-doped mesoporous activated carbon from Lentinus edodes residue: an optimized adsorbent for pharmaceuticals in aqueous solutions

In this study, phosphoric acid activation was employed to synthesize nitrogen-doped mesoporous activated carbon (designated as MR1) from Lentinus edodes (shiitake mushroom) residue, while aiming to efficiently remove acetaminophen (APAP), carbamazepine (CBZ), and metronidazole (MNZ) from aqueous solutions. We characterized the physicochemical properties of the produced adsorbents using scanning electron microscopy (SEM), nitrogen adsorption isotherms, and X-ray photoelectron spectroscopy (XPS). MR1, MR2, and MR3 were prepared using phosphoric acid impregnation ratios of 1, 2, and 3 mL/g, respectively. Notably, MR1 exhibited a significant mesoporous structure with a volume of 0.825 cm3/g and a quaternary nitrogen content of 2.6%. This endowed MR1 with a high adsorption capacity for APAP, CBZ, and MNZ, positioning it as a promising candidate for water purification applications. The adsorption behavior of the contaminants followed the Freundlich isotherm model, suggesting a multilayer adsorption process. Notably, MR1 showed excellent durability and recyclability, maintaining 95% of its initial adsorption efficiency after five regeneration cycles and indicating its potential for sustainable use in water treatment processes.

Microfluidic sensors for the detection of emerging contaminants in water: A review

In recent years, numerous emerging contaminants have been identified in surface water, groundwater, and drinking water. Developing novel sensing methods for detecting diverse emerging pollutants in water is urgently needed, as even at low concentrations, these pollutants can pose a serious threat to human health and environmental safety. Traditional testing methods are based on laboratory equipment, which is highly sensitive but complex to operate, costly, and not suitable for on-site monitoring. Microfluidic sensors offer several benefits, including rapid evaluation, minimal sample usage, accurate liquid manipulation, compact size, automation, and in-situ detection capabilities. They provide promising and efficient analytical tools for high-performance sensing platforms in monitoring emerging contaminants in water. In this paper, recent research advances in microfluidic sensors for the detection of emerging contaminants in water are reviewed. Initially, a concise overview is provided about the various substrate materials, corresponding microfabrication techniques, different driving forces, and commonly used detection techniques for microfluidic devices. Subsequently, a comprehensive analysis is conducted on microfluidic detection methods for endocrine-disrupting chemicals, pharmaceuticals and personal care products, microplastics, and perfluorinated compounds. Finally, the prospects and future challenges of microfluidic sensors in this field are discussed.

On-site extraction using a 3D printed device coated with Zn/Co-ZIF-derived carbon followed by an on-line SIA-HPLC-FL system for fluoroquinolones determination in wastewater

A 3D printed device covered with Zn/Co-ZIF-derived carbon allows the on-site extraction of fluoroquinolones (FQs) from wastewater, avoiding the sample transportation to the laboratory, and the subsequent elution, separation and determination using an on-line flow system based on sequential injection analysis (SIA) coupled to HPLC-FL. Several parameters that affect the extraction efficiency and desorption were optimized including the sorption phase immobilization technique on the 3D device, extraction time, pH effect, sample volume as well as the type of eluent, eluent volume, and flow rate. Under optimum conditions, detection limits of 3-9 ng L-1 were achieved for norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin and difloxacin. The precision expressed as relative standard deviation (%RSD, n = 3), showed intraday and interday ranges of 1.5-5.3% and 2.8-5.7%, respectively, demonstrating a good precision of the proposed methodology. To assess matrix effects and accuracy of the proposed method in real samples, recovery studies were performed without and with FQs spiked at different concentrations (0.5-10 μg L-1) to wastewater samples, showing good recoveries in the range of 91-104%. The results allow to confirm the applicability of MOF-derived carbons as adsorbents for on-site extraction, and the satisfactory separation and quantification of FQs by a SIA-HPLC-FL on-line system after their desorption with small eluent volumes.

Role of the hydrolytic-acidogenic phase on the removal of bisphenol A and sildenafil during anaerobic treatment

This paper presents the main results of the removal of two pharmaceutical and personal care products (PPCPs), bisphenol A (BPA) and sildenafil (SDF), by applying anaerobic biological batch tests. The biomass used was previously acclimatized and the experiment lasted 28 days. The effect of factors such as compound (BPA and SDF), concentration and type of inoculum was assessed, considering the factorial experimental design. The results indicated that evaluated factors did not significantly affect the PPCPs elimination in the evaluated range with a confidence level of 95%. On the other hand, the removal percentages obtained with BPA were mainly related to mechanisms, such as sorption and abiotic reactions. Regarding SDF, biodegradation was the predominant mechanism of removal under the experimental conditions of this study; however, the degradation of SDF was partial, with percentages lower than 43% in the tests with hydrolytic/acidogenic inoculum (H/A) and lower than 41% in the tests with methanogenic inoculum (MET). Finally, these findings indicated that hydrolysis/acidogenesis phase is a main contributor to SDF biodegradation in anaerobic digestion. The study provides a starting point for future research that seeks to improve treatment systems to optimize the removal of pollutants from different water sources.

Construction of type-II scheme SnO@HfC photocatalyst for bisphenol A degradation via peroxymonosulfate activation; DFT and self-cleaning analysis

In this study, novel stannous oxide@hafnium carbide (SnO@HfC) nanocomposite was successfully manufactured by an appropriate hydrothermal scheme which was utilized for the photocatalytic degradation of BPA by stimulation of peroxymonosulfate (PMS) and self-cleaning application. Numerous methods were applied for the characterization of photocatalyst and demonstrated the successful preparation of SnO@HfC nanocomposite. The crystal structures, band structures and density of states for SnO and HfC were explored by DFT analysis. The amazing PMS stimulation performance of SnO@HfC nanocomposite originated from the establishment of a heterojunction, which led to the enhancement of the light response aptitude and the electron conduction competence of the composite. BPA was degraded by 0.75 g/L PMS and SnO@HfC at neutral pH during the period of 60 min. In order to identify active groups in the reaction procedure, quenching experiments and electron paramagnetic resonance (EPR) approaches were also used. In the subsequent active species scavenging assays, where sulfate radicals, hydroxyl radicals, holes, and superoxide radicals were engaged in the degradation of BPA. While, liquid phase mass spectrometry (LC-MS) was used to pinpoint the intermediate metabolites in the course of degradation. SnO@HfC/PMS/light system delivered excellent TOC removal efficiency and less ions leaching. The SnO@HfC nanocomposite proved good durability and reusability in continuous cycle tests along with excellent self-cleaning function on the glass substrate. The SnO@HfC nanocomposite performs admirably in terms of self-cleaning application. The SnO@HfC nanocomposite is expected to be used in the future for the treatment of wastewater that contains pharmaceuticals due to its superior stability and reusability after five consecutive cycles.

Nitrogen-doped carbon materials prepared using different organic precursors as catalysts of peroxymonosulfate to degrade sulfamethoxazole: First-time performance leading to the incorrect selection of the best catalyst

Nitrogen-doped carbon materials are effective catalysts for peroxymonosulfate (PMS) activation to eliminate organic contaminants. In this research, the activity of nitrogen-doped carbon materials was significantly improved by optimizing the carbon source, and the reusability of the catalyst is used to select the best catalyst instead of depending on the performance in the first use, for avoiding the "short-life" catalyst with great initial activity. Fixing ferric nitrate nonahydrate and melamine as the metal and nitrogen sources, four catalysts were prepared using glucose, glucosamine hydrochloride, dopamine, and trimesic acid as the carbon sources, respectively. Based on the performance in PMS activation for sulfamethoxazole (SMX) removal, in the first use, the activity was Fe-DA-CN (carbon source: dopamine) > Fe-BTC-CN (carbon source: trimesic acid) > Fe-GLU-CN (carbon source: glucosamine) > Fe-DGLU-CN (carbon source: glucose). With no washing for the second time use, the activity was Fe-BTC-CN (0.135 min^-1) ≫ Fe-DA-CN (0.037 min^-1) > Fe-GLU-CN (0.032 min^-1) > Fe-DGLU-CN (0.017 min^-1). The large specific surface area, superior graphitization, and high CO/C-N group content endow Fe-BTC-CN with high ability in PMS activity. Surface-bound radicals are responsible for SMX elimination, and most of the SMX degradation intermediates have lower ecotoxicity than SMX.

Accelerated electron transfer process via MOF-derived FeCo/C for enhanced degradation of antibiotic contaminants towards heterogeneous electro-Fenton system

The Fe(III) to Fe(II) process limits the rate of the electro-Fenton system. In this study, MIL-101(Fe) derived porous carbon skeleton-coated FeCo bimetallic catalyst Fe₄/Co@PC-700 was prepared as a heterogeneous electro-Fenton (EF) catalytic process. The experimental results showed its good performance in catalytic removal of antibiotic contaminants, the rate constant of tetracycline (TC) degradation catalyzed by Fe₄/Co@PC-700 was 8.93 times higher than that of Fe@PC-700 under the pH conditions of raw water (pH = 5.86), exhibited good removal of TC, oxytetracycline (OTC), hygromycin (CTC), chloramphenicol (CAP) and ciprofloxacin (CIP). It was shown that the introduction of Co promoted more Fe⁰ production, allowing the material to exhibit faster Fe(III)/Fe(II) cycling rates. ¹O₂ and high-priced metal oxygen species were identified as the main active species of the system, in addition to the analysis of possible degradation pathways and toxicity of intermediates of TC. Finally, the stability and adaptability of Fe₄/Co@PC-700 and EF systems to different water matrices were evaluated, showing that Fe₄/Co@PC-700 was easy to recover and could be applied to different water matrices. This study provides a reference for the design and system application of heterogeneous EF catalysts.

Radially aligned hierarchical N-doped porous carbon beads derived from oil-sand asphaltene for long-life water filtration and wastewater treatment

The application of waste-derived highly efficient adsorbent for organic pollutants removal from water and wastewater is presented. Highly porous carbon beads with radially aligned macrochannels were prepared from asphaltene. Well-ordered inwardly aligned macrovoids favored solute diffusion and maximized the liquid accommodation capacity. A further N-doping could modulate the sorbent hydrophilicity leading to an outstanding absorption performance for a range of organic solvents and oily chemicals. N-doped carbon beads were effective sorbents of lopinavir (LNV) and ritonavir (RNV) from water and wastewater. The process of sorption was fast, and the highest removal was noted for RNV than LPV. N-doping favored LNV and RNV adsorption due to the increased porous structure of N-doped asphaltene beads. The chemisorption of both LPV and RTV was a rate-limiting step. The presence of co-pollutants in treated wastewater enhanced LPV and RNV removal and an up to 470 % increase was noted. The presence of LPV or RTV in distilled water was not toxic to Aliivibrio fischeri or even can stimulate their growth. However, after the adsorption process, the solution of RTV reduced its toxicity significantly and the final solution was not toxic. The opposite effect was noted for LPV. Given the repeatability, high removal performance, and cost-effectiveness of the asphaltene-based carbon microtubes when compared to other well-known sorbents such as carbon nanotubes, they demonstrated great potential as a low-cost and effective agent for long-life water filtration and wastewater treatment.

La2CoO4+δ perovskite-mediated peroxymonosulfate activation for the efficient degradation of bisphenol A

Sulfate radical-based technology has been considered as an efficient technology to remove pharmaceuticals and personal care products (PPCPs) with heterogeneous metal-mediated catalysts for the activation of peroxymonosulfate (PMS). In this study, La₂CoO_4+δ perovskite with Ruddlesden-Popper type structure was synthesised by the sol-gel method, which was employed in PMS activation. Different characteriazation technologies were applied for the characterization of La₂CoO_4+δ , such as SEM-EDX, XRD, and XPS technologies. A common organic compound, bisphenol A (BPA), is used as a target contaminant, and the effect impactors were fully investigated and explained. The results showed that when the dosage of La₂CoO_4+δ was 0.5 g L^-1 and the concentration of PMS was 1.0 mM in neutral pH solution, about 91.1% degradation efficiency was achieved within 25 minutes. Quenching experiments were introduced in the system to verify the catalytic mechanism of PMS for the BPA degradation, proving the existence of superoxide, hydroxyl radicals and sulfate radicals, which are responsible for the catalytic degradation of BPA. Moreover, the reusability and stability of the catalyst were also conducted which showed good stability during the reaction. This work would improve the applications of A₂BO₄-type perovskites for activating PMS to degrade BPA.

Synthesis and characterization of ZnBTC-based MOFs: effect of solvents and salt

In this work, we studied the optimization of synthetic approaches to creating structurally modified metal-organic frameworks under various synthesis conditions. We investigated the influence of the various solvents and zinc salts on the structural characteristics of the metal-organic framework based on benzene-1,3,5-tricarboxylic acid (H3BTC). The results indicate that the variation of the types of both solvent and salt is a parameter affecting the crystallinity, phase purity, and morphology of the metal-organic framework. This was confirmed by comprehensive structural characterization (SEM, EDX, PXRD).

Amine-functionalized MOF-derived carbon materials for efficient removal of Congo red dye from aqueous solutions: simulation and adsorption studies

In this study, a novel polyethyleneimine (PEI) modified MOF-derived carbon adsorbent (PEI@MDC) was proposed, which exhibited significant adsorption capacity for Congo Red (CR) in aqueous solutions. FT-IR and XPS results showed that PEI was successfully grafted onto MDC, increasing the content of amine groups on the surface of MDC. The adsorption process conformed to the Langmuir isotherm adsorption model and pseudo-second-order kinetic equation, indicating that the adsorption of CR on PEI@MDC was covered by a single layer, and the adsorption process was controlled by chemical processes. According to the Langmuir model, the maximum adsorption capacity at 30 °C was 1723.86 mg g^-1. Hydrogen bonding and electrostatic interactions between CR and PEI@MDC surface functional groups were the main mechanisms controlling the adsorption process. After five adsorption-desorption cycles, PEI@MDC still showed a high adsorption capacity for CR, indicating that the adsorbent had an excellent regeneration ability.