Removal of the environmental pollutant carbamazepine using molecular imprinted adsorbents: Molecular simulation, adsorption properties, and mechanisms

Synthesis of Zero valent Copper/iron nanoparticles using Piper betle leaves for the removal of pharmaceutical contaminant Atorvastatin

In this study, bimetallic Cu-Fe nanoparticles were synthesized using the green approach with Piper betle leaves, and the removal efficiency of one of the pharmaceutical compounds, Atorvastatin, was investigated. UV, SEM, FTIR, EDAX, particle size, and zeta potential measurements were used to confirm nanoparticle fabrication. The removal efficiency of Atorvastatin (10 mg/L) by bimetallic Cu-Fe nanoparticles was 67% with a contact time of 30 minutes at pH 4, the adsorbent dosage of 0.2 g/L, and stirring at 100 rpm. Piper betle bimetallic Cu-Fe nanoparticles have demonstrated excellent stability, reusability, and durability, even after being reused five times. Furthermore, the synthesized bimetallic Cu-Fe nanoparticles demonstrated remarkable antimicrobial properties against gram-negative strains such as Escherichia coli and Klebsiella pneumoniae, gram-positive strains such as Staphylococcus aureus and Bacillus subtilis, and fungi such as Aspergillus niger. In addition, the antioxidant properties of the synthesized bimetallic Cu-Fe nanoparticles were assessed using the DPPH radical scavenging assay. The results indicated that the nanoparticles had good antioxidant activity. Thus, using Piper betle extract to make Cu-Fe nanoparticles made the procedure less expensive, chemical-free, and environmentally friendly, and the synthesized bimetallic Cu-Fe nanoparticles helped remove the pharmaceutical compound Atorvastatin from wastewater.

Preparation of novel gallic acid-based dummy-template molecularly imprinted polymer adsorbents for rapid adsorption of dibutyl phthalate from water

Phthalate esters (PAEs) are plasticizers widely used in the industry and easily released into the environment, posing a serious threat to human health. Molecularly imprinted polymers (MIPs) are important as selective adsorbents for the removal of PAEs. In this study, three kinds of mussel-inspired MIPs for the removal of PAEs were first prepared with gallic acid (GA), hexanediamine (HD), tannic acid (TA), and dopamine (DA) under mild conditions. The adsorption results showed that the MIP with low cost derived from GA and HD (GAHD-MIP) obtained the highest adsorption capacity among these materials. Furthermore, 97.43% of equilibrium capacity could be reached within the first 5 min of adsorption. Especially, the dummy template of diallyl phthalate (DAP) with low toxicity was observed to be more suitable to prepare MIPs than dibutyl phthalate (DBP), although DBP was the target of adsorption. The adsorption process was in accordance with the pseudo-second-order kinetics model. In the isotherm analysis, the adsorption behavior agreed with the Freundlich model. Additionally, the material maintained high adsorption performance after 7 cycles of regeneration tests. The GAHD-MIP adsorbents in this study, with low cost, rapid adsorption equilibrium, green raw materials, and low toxicity dummy template, provide a valuable reference for the design and development of new MIPs.

Innovative approaches to suppress non-specific adsorption in molecularly imprinted polymers for sensing applications

Molecularly imprinted polymers (MIPs) are synthetic antibodies developed to bind selectively with specific molecules. They function through a particular recognition process involving their cavities and functional groups. Nevertheless, functional groups located outside these cavities are the main cause of non-specific molecule binding, thus reducing the effectiveness of MIPs in sensing applications. This work focused on enhancing the selectivity and performance of MIPs through electrostatic modification with surfactants. The study investigates the use of two surfactants, namely sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB), to eliminate non-specific adsorption in MIPs. The binding isotherms of the target molecule sulfamethoxazole (SMX) on MIPs and non-imprinted polymers (NIPs) were analyzed, showing higher adsorption capacity of MIPs due to the specific cavities. The modification with SDS or CTAB effectively eliminated non-specific adsorption in MIPs. The kinetic adsorption behavior further demonstrated the efficacy of MIP+--SDS/CTAB in the selective adsorption of SMX. Calibration curves showcase the methodology's analytical capabilities, achieving low limit of detection for SMX 6 ng mL-1 using MIP +-SDS. The stability study confirmed that the developed MIP +/--SDS/CTAB remains stable even at high temperatures, demonstrating its suitability for on-site applications. The methodology was successfully applied to detect SMX in milk and water samples, achieving promising recoveries. Overall, the electrostatic modification of MIPs with surfactants emerges as a valuable strategy for enhancing selectivity and performance in target molecule recognition and detection.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.

A novel carbonized polymer dots-based molecularly imprinted polymer with superior affinity and selectivity for oxytetracycline removal

Molecularly imprinted polymers (MIPs) synthesized from chain functional monomers are restricted by spatial extension and exhibit relatively poor affinity and selectivity; this results in unsatisfactory applications in complex media. In this study, we prepared unique spherical carbonized polymer dots (CPDs-OH) via the incomplete carbonization of 1-allyl-3-vinylimidazolium bromide and ethylene glycol, and used it as a functional monomer to prepare a newly imprinted polymer (CPDs-OH@MIP) in aqueous media. As a result, the CPDs-OH@MIP exhibited effective recognition of oxytetracycline with an impressive imprinting factor of 6.17, surpassing MIPs prepared with chain functional monomers (1-3). Furthermore, CPDs-OH@MIP exhibited excellent adsorption for oxytetracycline (278.52 mg g-1) and achieved equilibrium in 30 min, with stronger resistance to coexisting cations, anions, and humic acid. Compared to other MIPs and adsorbents, the recognition performance of CPDs-OH@MIP improved 2-4 times; this polymer could remove >92.1% of oxytetracycline in real water samples with at least 10 cycle times. CPDs-OH@MIP prepared using the special spherical monomer forms a denser structure with fewer nonimprinted regions and precisely imprinted sites, remarkably improving the affinity and selectivity of MIPs combined via hydrogen bonds and electrostatic and π-π interactions. Our proposed strategy provides an effective basis for breakthroughs in the practical application of MIPs.

The erythromycin sorption removal at environmentally relevant concentration based on molecular imprinted polymer: Performance and mechanism

The antibiotic pollution emerged in different environments has raised a great concern. Adsorption is an effective method to solve the problem. However, conventional adsorbents are not always efficient for antibiotic removal with interferences. Therefore, in this study, molecularly imprinted polymer (EMIP) with selective adsorption ability was prepared to remove a typical antibiotic-erythromycin (ERY) at environmentally relevant concentration. The specific surface area of EMIP was 265.62 m2/g with large pore volume, small pore size and hydrophobic surface. The adsorption capacity of EMIP was increased from 211.08 to 4015.51 μg/g when the concentration of ERY was increased from 5.00 to 100.00 μg/L. The isothermal adsorption process was fitted well with the Langmuir model. The adsorption kinetic could be well described by the pseudo-second-order model. With co-existing of interferences, the imprinting factor for ERY was 2.57, which demonstrated EMIP had good adsorption selectivity. After five consecutive adsorption-desorption experiments, the adsorption capacity of EMIP was still over 80%. The results of molecular dynamic simulation showed the adsorption energy between ERY and EMIP was high, which was favorable for ERY adsorption removal. Hopefully, the results of this study could provide new insights for trace antibiotic removal by molecular imprinting polymers in different aqueous environments.

Occurrences of typical PPCPs during wastewater treatment and the composting of sewage sludge with micron-sized and nano-sized Fe3O4

New pollutants, pharmaceuticals and personal care products (PPCPs), accumulate in sewage sludge (SS) in wastewater treatment plants (WWTPs), posing risks to the environment and to human health. In the present study, the fates of typical PPCPs, carbamazepine (CBZ), triclosan (TCS), ibuprofen (IBU) and galaxolide (HHCB), were examined during WW treatment. Additionally, SS collected from a WWTP was used for aerobic composting to investigate the influences of micron-sized Fe3O4 (M-Fe) and nano-sized Fe3O4 (N-Fe) on the degradation of these PPCPs and the succession of microbial communities during the composting process. The results showed that the mean concentrations of CBZ, TCS, IBU and HHCB in the influent of the WWTP were 926.5, 174.4, 8869, and 967.3 ng/g, respectively, and in the effluent were 107.6, 47.0, 283.4, and 88.4 ng/g, respectively. The removal rate averaged ∼80%, while the enrichment rates of the PPCPs in SS ranged from 37.2% to 60.5%. M-Fe and N-Fe reduced NH3 emissions by 32.9% and 54.1% and N2O emissions by 26.2% and 50.8%, respectively. Moreover, the addition of M-Fe and N-Fe effectively increased PPCP degradation rates 1.12-1.66-fold. During the whole process, the additions of M-Fe and N-Fe significantly shifted microbial community structure, and the abundances of Proteobacteria, Chloroflexi, and Actinobacteria were increased during the thermophilic stage, marking them as key PPCP-degrading phyla. Taken together, our results indicated that the addition of M-Fe and N-Fe is an effective method for improving the quality of end compost and accelerating the degradation of PPCPs.

Recent Developments in the Detection of Organic Contaminants Using Molecularly Imprinted Polymers Combined with Various Analytical Techniques

Molecularly imprinted polymers (MIPs) encompass a diverse array of polymeric matrices that exhibit the unique capacity to selectively identify a designated template molecule through specific chemical moieties. Thanks to their pivotal attributes, including exceptional selectivity, extended shelf stability, and other distinct characteristics, this class of compounds has garnered interest in the development of highly responsive sensor systems. As a result, the incorporation of MIPs in crafting distinctive sensors and analytical procedures tailored for specific analytes across various domains has increasingly become a common practice within contemporary analytical chemistry. Furthermore, the range of polymers amenable to MIP formulation significantly influences the potential utilization of both conventional and innovative analytical methodologies. This versatility expands the array of possibilities in which MIP-based sensing can be employed in recognition systems. The following review summarizes the notable progress achieved within the preceding seven-year period in employing MIP-based sensing techniques for analyte determination.

Efficient removal of polybrominated diphenyl ethers from soil washing effluent by dummy molecular imprinted adsorbents: Selectivity and mechanisms

Surfactant enhanced elution is an effective method for removing hydrophobic organic pollutants from soils. The key to the development of leaching technology is selective removal of targeted pollutants in soil washing effluent and recycling of surfactant solutions. In this study, a molecular imprinting technique was applied to selectively sorb polybrominated diphenyl ethers (PBDEs) in soil washing effluent. The novel molecular imprinted polymers (MIPs) using different template molecules were synthesized by precipitation polymerization. Adsorption behaviors and mechanisms of MIPs were studied through experiments and theoretical calculations. The results show that 4-bromo-4'-hydroxybiphenyl and toluene can be effective imprinting molecule for MIPs synthesis. The maximal adsorption capacity of selected dummy molecular imprinted polymer (D₁-MIP) was 1032.36 µmol/g, and that of part molecular imprinted polymer (P-MIP) was 981.13 µmol/g. Their imprinting factors in 5 PBDEs adsorption ranged from 2.13 to 5.88, the recovery percentage of Triton X-100 can reach 99.09%, confirming the feasibility of reusing surfactant. Various PBDEs could be removed by MIPs, and Quantitative Structure Property Relationship analysis revealed that PBDEs' molecular volume, planarity, polarity, and hydrophobicity have major influences on their adsorption performance. DFT calculation revealed that Van der Waals force and hydrogen bonding played important roles during selective adsorption. These results can provide effective theoretical guidance for surfactant enhanced soil elution in practical engineering applications.

Glyphosate Separating and Sensing for Precision Agriculture and Environmental Protection in the Era of Smart Materials

The present article critically and comprehensively reviews the most recent reports on smart sensors for determining glyphosate (GLP), an active agent of GLP-based herbicides (GBHs) traditionally used in agriculture over the past decades. Commercialized in 1974, GBHs have now reached 350 million hectares of crops in over 140 countries with an annual turnover of 11 billion USD worldwide. However, rolling exploitation of GLP and GBHs in the last decades has led to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide of farm and companies' workers. Intoxication with these herbicides dysregulates the microbiome-gut-brain axis, cholinergic neurotransmission, and endocrine system, causing paralytic ileus, hyperkalemia, oliguria, pulmonary edema, and cardiogenic shock. Precision agriculture, i.e., an (information technology)-enhanced approach to crop management, including a site-specific determination of agrochemicals, derives from the benefits of smart materials (SMs), data science, and nanosensors. Those typically feature fluorescent molecularly imprinted polymers or immunochemical aptamer artificial receptors integrated with electrochemical transducers. Fabricated as portable or wearable lab-on-chips, smartphones, and soft robotics and connected with SM-based devices that provide machine learning algorithms and online databases, they integrate, process, analyze, and interpret massive amounts of spatiotemporal data in a user-friendly and decision-making manner. Exploited for the ultrasensitive determination of toxins, including GLP, they will become practical tools in farmlands and point-of-care testing. Expectedly, smart sensors can be used for personalized diagnostics, real-time water, food, soil, and air quality monitoring, site-specific herbicide management, and crop control.

Novel strategy for copper precipitation from cupric complexes wastewater: Catalytic oxidation or reduction self-decomplexation?

Cupric (Cu(II)) complexes in industrial wastewater are responsible for the failure of conventional alkaline precipitation, but the properties of cuprous (Cu(I)) complexes at alkaline circumstance have not been focused. This report proposed a novel strategy for the remediation of Cu(II)-complexed wastewater by coupling alkaline precipitation with green benign reductant, namely, hydroxylamine hydrochloride (HA). This remediation process (HA-OH) exhibits superior Cu removal efficiency that cannot be achieved with the same dosage of oxidants (3 mM). The possibility of Cu(I) activated O₂ catalysis and self-decomplexation precipitation were investigated, and the results identified that ¹O₂ was generated from Cu(II)/Cu(I) cycle, but it was insufficient to annihilate organic ligands. Cu(I) self-decomplexation was the dominate mechanism of Cu removal. For real industrial wastewater, HA-OH process can realize the efficient Cu₂O precipitation and Cu recovery. This novel strategy utilized intrinsic pollutant in wastewater without introducing other metals, complicated materials, and expensive equipment, broadening the insight for the remediation of Cu(II)-complexed wastewater.

Recent advances in the removal of emerging contaminants from water by novel molecularly imprinted materials in advanced oxidation processes-A review

Recently, there has been a global focus on effectively treating emerging contaminants (ECs) in water bodies. Advanced oxidation processes (AOPs) are the primary technology used for ECs removal. However, the low concentrations of ECs make it difficult to overcome the interference of background substances in complex water quality, which limits the practical application of AOPs. To address this limitation, many researchers are developing new catalysts with preferential adsorption. Molecular imprinting technology (MIT) combined with conventional catalysts has been found to effectively enhance the selectivity of catalysts for the targeted catalytic degradation of pollutants. This review presents a comprehensive summary of the progress made in research on molecularly imprinted polymers (MIPs) in the selective oxidation of ECs in water. The preparation methods, principles, and control points of novel MIP catalysts are discussed. Furthermore, the performance and mechanism of the catalysts in photocatalytic oxidation, electrocatalytic oxidation, and persulfate activation are analyzed with examples. The possible ecotoxicological risks of MIP catalysts are also discussed. Finally, the challenges and prospects of applying MIP catalysts in AOP are presented along with proposed solutions. This review provides a better understanding of using MIP catalysts in AOPs to target the degradation of ECs.

Alkyl chain length of quaternized SBA-15 and solution conditions determine hydrophobic and electrostatic interactions for carbamazepine adsorption

Santa Barbara Amorphous-15 (SBA) is a stable and mesoporous silica material. Quaternized SBA-15 with alkyl chains (Q_SBA) exhibits electrostatic attraction for anionic molecules via the N⁺ moiety of the ammonium group, whereas its alkyl chain length determines its hydrophobic interactions. In this study, Q_SBA with different alkyl chain lengths were synthesized using the trimethyl, dimethyloctyl, and dimethyoctadecyl groups (C1Q_SBA, C8Q_SBA, and C18Q_SBA, respectively). Carbamazepine (CBZ) is a widely prescribed pharmaceutical compound, but is difficult to remove using conventional water treatments. The CBZ adsorption characteristics of Q_SBA were examined to determine its adsorption mechanism by changing the alkyl chain length and solution conditions (pH and ionic strength). A longer alkyl chain resulted in slower adsorption (up to 120 min), while the amount of CBZ adsorbed was higher for longer alkyl chains per unit mass of Q_SBA at equilibrium. The maximum adsorption capacities of C1Q_SBA, C8Q_SBA, and C18Q_SBA, were 3.14, 6.56, and 24.5 mg/g, respectively, as obtained using the Langmuir model. For the tested initial CBZ concentrations (2-100 mg/L), the adsorption capacity increased with increasing alkyl chain length. Because CBZ does not dissociate readily (pK_a = 13.9), stable hydrophobic adsorption was observed despite the changes in pH (0.41-0.92, 1.70-2.24, and 7.56-9.10 mg/g for C1Q_SBA, C8Q_SBA, and C18Q_SBA, respectively); the exception was pH 2. Increasing the ionic strength from 0.1 to 100 mM enhanced the adsorption capacity of C18Q_SBA from 9.27 ± 0.42 to 14.94 ± 0.17 mg/g because the hydrophobic interactions were increased while the electrostatic attraction of the N⁺ was reduced. Thus, the ionic strength was a stronger control factor determining hydrophobic adsorption of CBZ than the solution pH. Based on the changes in hydrophobicity, which depends on the alkyl chain length, it was possible to enhance CBZ adsorption and investigate the adsorption mechanism in detail. Thus, this study aids the development of adsorbents suitable for pharmaceuticals with controlling molecular structure of QSBA and solution conditions.

Strategic preparation of porous magnetic molecularly imprinted polymers via a simple and green method for high-performance adsorption and removal of meropenem

In this study, a facile method has been developed to synthesize a novel type of porous magnetic molecularly imprinted polymers (Fe₃O₄-MER-MMIPs) for the selective adsorption and removal of meropenem. The Fe₃O₄-MER-MMIPs, with abundant functional groups and sufficient magnetism for easy separation, are prepared in aqueous solutions. The porous carriers reduce the overall mass of the MMIPs, greatly improving their adsorption capacity per unit mass and optimizing the overall value of the adsorbents. The green preparation conditions, adsorption performance, and physical and chemical properties of Fe₃O₄-MER-MMIPs have been carefully studied. The developed submicron materials exhibit a homogeneous morphology, satisfactory superparamagnetism (60 emu g^-1), large adsorption capacity (11.49 mg g^-1), quick adsorption kinetics (40 min), and good practical implementation in human serum and environmental water. Finally, the protocol developed in this work delivers a green and feasible method for synthesizing highly efficient adsorbents for the specific adsorption and removal of other antibiotics as well.

Facile preparation of uniform-sized covalent organic framework nanoflowers as versatile sample-pretreatment platforms for sensitive and specific determination of hazardous substances

Covalent-organic frameworks (COFs) have lately received extensive interest for their outstanding performance, especially to adsorption of hazards, while easy-preparation of uniform-sized COFs hold a great challenge. This research presented a simple synthesis method of flower-shaped COF (nanoflower) with strong hydrophobic surface at room temperature. Taking advantage of its easy-prepared and uniform-sized features, we proposed a versatile and efficient sample-pretreatment platform by employing the nanoflower COF for affinity adsorption of various hydrophobic biotoxins and further surface imprinting for selective enrichment of specific biotoxin (COF@MIP), respectively. The COF@MIP was integrating COF with molecular imprinting technique to achieve selective identification of sterigmatocystin (ST) with high specificity and sensitivity. They both exhibited well reusability, preserving 81% of initial activity after being used for six cycles. The as-prepared materials coupled with offline solid phase extraction (SPE) and high performance liquid chromatography (HPLC) were successfully applied to five common cereals with good recoveries in the range of 70.3-100.7%. Moreover, the principle of versatile sample pretreatment and detection platform based on the facile-prepared and uniform-sized COF nanoflower would be easily extended to other hazards. It provided a prospective approach for the pretreatment and determination of hazardous substances with low level in complex sample matrix.

Treatment of PBDEs from Soil-Washing Effluent by Granular-Activated Carbon: Adsorption Behavior, Influencing Factors and Density Functional Theory Calculation

Soil-washing is a potential technology for the disposal of soil contaminated by e-waste; however, the produced soil-washing effluent will contain polybrominated diphenyl ethers (PBDEs) and a large number of surfactants, which are harmful to the environment, so the treatment of PBDEs and the recycling of surfactants are the key to the application of soil-washing technology. In this study, coconut shell granular-activated carbon (GAC) was applied to remove PBDEs from Triton X-100 (TX-100) surfactant which simulates soil-washing effluent. The adsorption results show that, GAC can simultaneously achieve effective removal of 4,4′-dibromodiphenyl ether (BDE-15) and efficient recovery of TX-100. Under optimal conditions, the maximum adsorption capacity of BDE-15 could reach 623.19 μmol/g, and the recovery rate of TX-100 was always higher than 83%. The adsorption process of 4,4′-dibromodiphenyl ether (BDE-15) by GAC could best be described using the pseudo-second-order kinetic model and Freundlich isothermal adsorption model. The coexistence ions had almost no effect on the removal of BDE-15 and the recovery rate of TX-100, and the solution pH had little effect on the recovery rate of TX-100; BDE-15 had the best removal effect under the condition of weak acid to weak base, indicating that GAC has good environmental adaptability. After adsorption, GAC could be regenerated with methanol and the adsorption effect of BDE-15 could still reach more than 81%. Density functional theory (DFT) calculation and characterization results showed that, Van der Waals interaction and π–π interaction are dominant between BDE-15 and GAC, and hydrogen bond interactions also exist. The existence of oxygen-containing functional groups is conducive to the adsorption of BDE-15, and the carboxyl group (-COOH) has the strongest promoting effect. The study proved the feasibility of GAC to effectively remove PBDEs and recover surfactants from the soil-washing effluent, and revealed the interaction mechanism between PBDEs and GAC, which can provide reference for the application of soil-washing technology.

Facile synthesis of core–shell structured magnetic Fe3O4@SiO2@Au molecularly imprinted polymers for high effective extraction and determination of 4-methylmethcathinone in human urine samples

In this study, a novel material of core–shell structured magnetic molecularly imprinted polymers (Fe3O4@SiO2@Au (FSA)-MIPs) was successfully prepared for the rapid and selective determination of 4-methylmethcathinone (mephedrone, 4-MMC). The adsorption capacity of FSA-MIPs is 34.7 mg·g−1 at 308 K, which is significantly higher than magnetic non-imprinted polymers profiting from the imprinting effect. The FSA-MIPs have a short equilibrium (20 min) and could be reused more than six times. Moreover, the selectivity coefficients of FSA-MIPs for 4-MMC, 3,4-dimethylmethcathinone, butylone, 4-ethylmethcathinone, acetylfentanyl, and methylene blue are 4.01, 5.65, 7.62, 12.30, and 20.87 respectively, further indicating the markedly enhanced binding selectivity of FSA-MIPs. As an adsorbent, the FSA-MIPs were successfully applied for effective extraction of 4-MMC in three human urine samples with the recovery rates ranging from 85.5–92.6%. The results confirmed that the FSA-MIPs have good prospects in the extraction and separation of synthetic cathinones, which is suitable for further application in the criminal sciences field.

Accurate Removal of Toxic Organic Pollutants from Complex Water Matrices

Characteristic emerging pollutants at low concentration have raised much attention for causing a bottleneck in water remediation, especially in complex water matrices where high concentration of interferents coexist. In the future, tailored treatment methods are therefore of increasing significance for accurate removal of target pollutants in different water matrices. This critical review focuses on the overall strategies for accurately removing highly toxic emerging pollutants in the presence of typical interferents. The main difficulties hindering the improvement of selectivity in complex matrices are analyzed, implying that it is difficult to adopt a universal approach for multiple targets and water substrates. Selective methods based on assorted principles are proposed aiming to improve the anti-interference ability. Thus, typical approaches and fundamentals to achieve selectivity are subsequently summarized including their mechanism, superiority and inferior position, application scope, improvement method and the bottlenecks. The results show that different methods may be applicable to certain conditions and target pollutants. To better understand the mechanism of each selective method and further select the appropriate method, advanced methods for qualitative and quantitative characterization of selectivity are presented. The processes of adsorption, interaction, electron transfer, and bond breaking are discussed. Some comparable selective quantitative methods are helpful for promoting the development of related fields. The research framework of selectivity removal and its fundamentals are established. Presently, although continuous advances and remarkable achievements have been attained in the selective removal of characteristic organic pollutants, there are still various substantial challenges and opportunities. It is hopeful to inspire the researches on the new generation of water and wastewater treatment technology, which can selectively and preferentially treat characteristic pollutants, and establish a reliable research framework to lead the direction of environmental science.

Adsorption properties and recognition mechanisms of a novel surface imprinted polymer for selective removal of Cu(II)-citrate complexes

Cu(II)-citrate (Cu(II)-CA) complex, as one of the components in plating solutions, increases the difficulty of Cu(II) treatment due to its stable structure and high mobility. In this work, a novel surface imprinted polymer (Cu-CA-SIP) for selective removal of Cu(II)-CA complex from aqueous solution is synthesized by using polyethyleneimine (PEI) grafted onto chloromethylated polystyrene (CMP) microspheres. Cu(II)-CA anions are successfully imprinted with the molar ration of 1:1 by Cu-CA-SIP at initial pH 4.0. Nearly 100% removal rate can be achieved even at low Cu(II)-CA concentration (0.5 mmol/L), and the maximum Cu(II) uptake of Cu-CA-SIP reaches 1.38 mmol/g at 303 K. In Cu(II)/Fe(III)-CA, Cu(II)/Ni(II)-CA, Cu(II)/Zn(II)-CA and Cu(II)/Cd(II)-CA systems, the relative selectivity coefficients of Cu-CA-SIP for Cu(II)-CA are 9.66, 2.32, 1.40 and 44.55, respectively. Moreover, Cu-CA-SIP can be retrieved with negligible loss of adsorption capacity after six times of reuse. The Cu-CA-SIP column can effectively treat the actual electroplating wastewater within 114 BV, and can still reach 104 BV after three dynamic cycles. Therefore, an innovative imprinted material is designed for the first time on the basis of coordination-configuration recognition mechanism for the treatment of electroplating wastewater, providing a new insight in developing surface imprinted polymer in environmental remediation.

Remediation of pharmaceuticals from contaminated water by molecularly imprinted polymers: a review

The release of pharmaceuticals into the environment induces adverse effects on the metabolism of humans and other living species, calling for advanced remediation methods. Conventional removal methods are often non-selective and cause secondary contamination. These issues may be partly solved by the use of recently-developped adsorbents such as molecularly imprinted polymers. Here we review the synthesis and application of molecularly imprinted polymers for removing pharmaceuticals in water. Molecularly imprinted polymers are synthesized via several multiple-step polymerization methods. Molecularly imprinted polymers are potent adsorbents at the laboratory scale, yet their efficiency is limited by template leakage and polymer quality. Adsorption performance of multi-templated molecularly imprinted polymers depends on the design of wastewater treatment plants, pharmaceutical consumption patterns and the population serviced by these wastewater treatment plants.

A descriptive and comparative analysis on the adsorption of PPCPs by molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) have aroused great attention as a new material for the removal or detection of pharmaceuticals and personal care products (PPCPs). However, it is not clear about the superiority and deficiency of MIPs in the process of removing or detecting PPCPs. Herein, we evaluated the performance of MIPs in the aspects of adsorption capacity, binding affinity, adsorption rate, and compatibility to other techniques, and proposed ways to improve its performance. Without regard to the selectivity of MIPs, for the PPCPs adsorption, MIPs surprisingly did not always perform better than the conventional adsorbents (non-imprinted polymers, biochar, activated carbon and resin), indicating that MIPs should be used where selectivity is crucial, for example recovery of specific PPCPs in an environmental sample extraction process. Compared to the traditional solid-phase extraction for PPCPs detection pretreatment, the usage of MIPs as substitute extraction agents could obtain high selectivity of specific substance, due to the uniformity and effectiveness of the specific sites. A promising development in the future would be to combine other simple and rapid quantitative technologies, such as electro/photochemical sensor and catalytic degradation, to realize rapid and sensitive detection of trace PPCPs.

Understanding the factors affecting adsorption of pharmaceuticals on different adsorbents - A critical literature update

Remediation of emerging pharmaceutically active compounds (PhACs) as micropollutants in wastewater is of foremost importance as they can cause extremely detrimental effects on life upon bioaccumulation and generation of drug-resistance microorganisms. Presently used physicochemical treatments, such as electrochemical oxidation, nanofiltration and reverse osmosis, are not feasible owing to high operating costs, incomplete removal of contaminants along with toxic by-products formation. Adsorption with the utilization of facile and efficient nanoparticulate adsorbents having distinctive properties of high surface area, excellent adsorption capacity, ability to undergo surface engineering and good regeneration displays great potential in this aspect along with the incorporation of nanotechnology for effective treatment. The application of such nanosorbents provides optimal performance under a wide range of physicochemical conditions, decreased secondary pollution with reduced mechanical stress along with excellent organic compound sequestration capacity, which in turn improves the quality of potable water in a sustainable way compared to current treatments. The present review intends to consolidate the range of factors that affect the process of adsorption of different PhACs on to various nanosorbents and also highlights the adsorption mechanism aiding in the retrieval.

Designed new magnetic functional three-dimensional hierarchical flowerlike micro-nano structure of N-Co@C/NiCo-layered double oxides for highly efficient co-adsorption of multiple environmental pollutants

In order to eliminate multiple coexisting pollutants in environmental wastewater, a magnetic three-dimensional hierarchical porous flower-like N, Co-doped graphitic carbon nano-polyhedra decorated NiCo-layered double oxides (N-Co@C/NiCo-LDOs) adsorption material was synthesized, which consisted of two-dimensional LDOs nanosheets with functionalized surfaces (N, Co-doped graphitic carbon loaded on both sides of NiCo-LDOs nanosheets). The adsorption properties of N-Co@C/NiCo-LDOs for five types of typical pollutants (cationic dyes: rhodamine b, methylene blue; pesticides: ethofenprox, bifenthrin; anionic dyes: methyl orange, congo red; inorganic cations: Cr²⁺, Cd²⁺, Pb²⁺, Zn²⁺, inorganic anions: Cr₂O₇^2-, AsO₃^3-) were investigated systematically in single and coexisting systems. Combined with the results of FTIR and zeta potential, the adsorption mechanism was discussed. By virtue of its hierarchical porous architecture and the combined effect of functionalized surfaces and LODs supporter, the as-prepared N-Co@C/NiCo-LDOs demonstrates excellent adsorption performance towards five types of typical pollutants with fast adsorption rate, high adsorption capacity and good co-adsorption performance. More importantly, the N-Co@C/NiCo-LDOs showed satisfactory removal efficiency, stability and reusability in model wastewater. The broad-spectrum, rapid, easily separable, and reusable adsorption properties make N-Co@C/NiCo-LDOs promising for highly efficient wastewater treatments. This work also provides a feasible way for the preparation of adsorption materials for the treatment of complex wastewater systems.

A Review on the Removal of Carbamazepine from Aqueous Solution by Using Activated Carbon and Biochar

Carbamazepine (CBZ), one of the most used pharmaceuticals worldwide and a Contaminant of Emerging Concern, represents a potential risk for the environment and human health. Wastewater treatment plants (WWTPs) are a significant source of CBZ to the environment, polluting the whole water cycle. In this review, the CBZ presence and fate in the urban water cycle are addressed, with a focus on adsorption as a possible solution for its removal. Specifically, the scientific literature on CBZ removal by activated carbon and its possible substitute Biochar, is comprehensively scanned and summed up, in view of increasing the circularity in water treatments. CBZ adsorption onto activated carbon and biochar is analyzed considering several aspects, such as physicochemical characteristics of the adsorbents, operational conditions of the adsorption processes and adsorption kinetics and isotherms models. WWTPs usually show almost no removal of CBZ (even negative), whereas removal is witnessed in drinking water treatment plants through advanced treatments (even >90%). Among these, adsorption is considered one of the preferable methods, being economical and easier to operate. Adsorption capacity of CBZ is influenced by the characteristics of the adsorbent precursors, pyrolysis temperature and modification or activation processes. Among operational conditions, pH shows low influence on the process, as CBZ has no charge in most pH ranges. Differently, increasing temperature and rotational speed favor the adsorption of CBZ. The presence of other micro-contaminants and organic matter decreases the CBZ adsorption due to competition effects. These results, however, concern mainly laboratory-scale studies, hence, full-scale investigations are recommended to take into account the complexity of the real conditions.

Targeted degradation of refractory organic compounds in wastewaters based on molecular imprinting catalysts

Efficient removal of low-concentration refractory pollutants is a crucial problem to ensuring water safety. The use of heterogeneous catalysis of molecular imprinting technology combined with traditional catalysts is a promising method to improve removal efficiency. Presently, the research into molecular imprinting targeting catalysts focuses mainly on material preparation and performance optimization. However, more researchers are investigating other applications of imprinting materials. This review provides recent progress in photocatalyst preparation, electrocatalyst, and Fenton-like catalysts synthesized by molecular imprinting. The principle and control points of target catalysts prepared by precipitation polymerization (PP) and surface molecular imprinting (S-MIP) are introduced. Also, the application of imprinted catalysts in targeted degradation of drugs, pesticides, environmental hormones, and other refractory pollutants is summarized. In addition, the reusability and stability of imprinted catalyst in water treatment are discussed, and the possible ecotoxicity risk is analyzed. Finally, we appraised the prospects, challenges, and opportunities of imprinted catalysts in the advanced oxidation process. This paper provides a reference for the targeted degradation of refractory pollutants and the preparation of targeted catalysts.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.

A Review on Molecularly Imprinted Polymers Preparation by Computational Simulation-Aided Methods

Molecularly imprinted polymers (MIPs) are obtained by initiating the polymerization of functional monomers surrounding a template molecule in the presence of crosslinkers and porogens. The best adsorption performance can be achieved by optimizing the polymerization conditions, but this process is time consuming and labor-intensive. Theoretical calculation based on calculation simulations and intermolecular forces is an effective method to solve this problem because it is convenient, versatile, environmentally friendly, and inexpensive. In this article, computational simulation modeling methods are introduced, and the theoretical optimization methods of various molecular simulation calculation software for preparing molecularly imprinted polymers are proposed. The progress in research on and application of molecularly imprinted polymers prepared by computational simulations and computational software in the past two decades are reviewed. Computer molecular simulation methods, including molecular mechanics, molecular dynamics and quantum mechanics, are universally applicable for the MIP-based materials. Furthermore, the new role of computational simulation in the future development of molecular imprinting technology is explored.

Adsorption behavior of a tri-functionalized imprinted resin with high selectivity for 5-sulfosalicylic acid: Batch experiments and DFT calculation

The presence of aromatic compounds with multiple functional groups such as 5-sulfosalicylic acid (SSA) in water bodies is a threat to aquatic organisms and human health. Phenol (PH) with the -OH group, benzoic acid with -COOH and benzenesulfonic acid (BSA) with -SO₃H can be considered as SSA structural unit. In this study, three functional monomers, namely, N-methylallylamine, diallylamine, and triallylamine, with strong affinity for PH, BA, and BSA, respectively, were selected from 16 monomers by using density functional theory (DFT). Molecularly imprinted resin (MIP-4) with tri-functional groups and excellent selectivity for SSA was synthesized using a macroporous polystyrene resin (NDA-1800) as the carrier. In binary systems, MIP-4 exhibited excellent imprinting effect and adsorption selectivity for SSA. X-ray spectroscopy data and DFT calculations illustrated that the adsorption of SSA on MIP-4 was mainly dependent on the strong electrostatic interaction between the protonated amine group on the resin and -SO₃^- of SSA, as well as, the hydrogen bond between the neutral amine group and -OH and -COOH of SSA; the order of the three functional groups in identification was -OH > -COOH > -SO₃H. In addition, the adsorption performance of MIP-4 was retained after five adsorption-desorption cycles.

Selective adsorption of ofloxacin and ciprofloxacin from a binary system using lignin-based adsorbents: Quantitative analysis, adsorption mechanisms, and structure-activity relationship

A series of actinia-shaped lignin-based adsorbents (LNAEs) featuring lignin (LN) as the core and grafted poly(acrylic acid) (PAA) as the tentacle were designed and fabricated. Two fluoroquinolones (FQs) with similar molecular structures, ofloxacin (OFL) and ciprofloxacin (CIP), were used as targets to study the selective adsorption performance of LNAEs associated with the structural effects of the LN-based adsorbents in FQs binary aqueous system. The adsorption of the two FQs by LNAEs complied with the competitive Langmuir isothermal model, and showed selective removal of CIP over OFL due to the additional negative charge-assisted hydrogen bond (CAHB) formed between the carboxyl group of LNAEs and the secondary amino group of CIP, in addition to the effects of electrostatic attraction and normal hydrogen bonds, according to quantitative studies and density functional theory analysis. A binary nonlinear model based on phenomenological theory was applied to study the effects of PAA branched-chain length and distribution on the selective adsorption performance of the LN-based adsorbents. Accordingly, the branched-chain distribution played a more important role and higher distribution density of branched PAA could expose more adsorption sites on LNAEs' surface and improve the adsorptive selectivity. This study offers a well understanding of the structure-activity relationship of the surface grafting-modified adsorbents in binary pollutant systems and fundamental guidance for the exploitation and design of novel and efficient adsorbents.

Removal of fluoroquinolone antibiotics using actinia-shaped lignin-based adsorbents: Role of the length and distribution of branched-chains

A series of actinia-shaped lignin-based adsorbents (LNAEs) featuring lignin(LN) as the core and grafted poly(acrylic acid) (PAA) as the tentacle were designed and fabricated. LNAEs were applied to remove ofloxacin and ciprofloxacin from water, and their maximum adsorption capacities were 0.835 and 0.965 mmol/g at pH 6.0, respectively. However, their adsorption capacities were up to about 20 % and 31 % reductions in the present of NaCl and humic acid, respectively. Electrostatic attraction (EA) and hydrogen bonding (HB), including ordinary HB and negative charged auxiliary HB, were mainly involved in adsorption. Experimental and calculation results indicated HB contributes more than EA. The effects of two structural factors of LNAEs, namely, PAA branched-chain length(L) and distribution density(D), on the adsorption performance associated with HB and EA, were quantitatively discussed using a binary nonlinear model based on phenomenological theory. The fitting results were completely consistent with the experimental findings. D was more efficient than L in promoting HB and EA in adsorption due to the cooperative effects of adjacent branched-chains and enhanced activity of terminal groups. This study provides a better understanding of the structure-activity relationship of surface grafting-modified adsorbents and fundamental guidance for the exploitation and design of novel and efficient adsorbents.

Construction of natural polymeric imprinted materials and their applications in water treatment: A review

Molecularly imprinted materials (MIMs) have been widely used in various fields, including water treatment, chemical sensing, and biotechnology, because of their specific recognition and high selectivity. MIMs are usually obtained via two successive steps, namely, (1) copolymerization and crosslinking reactions of the preassembled complex of comonomers and a specific target compound (2) and thorough removal of template molecules. Some functional polymers are directly used as supporting materials and functional groups assembled with target compound are provided to simplify the preparation of MIMs. Natural polymers, such as chitosan, cyclodextrin, sodium alginate, starch, cellulose, lignin and their derivatives, are good candidates because of their environmentally friendly properties, low costs, and abundant active functional groups. In this study, different methods for the preparation of natural polymeric MIMs were reviewed in terms of the construction of microscopic binding cavities and macroscopic visible condensed structures with different shapes. Natural polymeric MIMs in water treatment applications, such as adsorption and detection of various pollutants from aqueous solutions, were summarized. Prospects on the development of novel and high-performance natural polymeric MIMs were discussed to overcome the difficulties in their preparation and applications.

Innovative utilization of molecular imprinting technology for selective adsorption and (photo)catalytic eradication of organic pollutants

The rapid development of industrialization and urbanization results in a numerous production of various organic chemicals to meet the increasing demand in high-quality life. During the synthesis and utilization of these chemical products, their residues unavoidably emerged in environments to severely threaten human's health. It is thus urgent to exploit effective technology for readily removing the organic pollutants with high selectivity and good reusability. As one of the most promising approaches, molecular imprinting technology (MIT) employs a chemically synthetic route to construct artificial recognition sites in highly-crosslinked matrix with complementary cavity and functional groups to target species, which have been attracting more and more interest for environmental remediation, such as the selective adsorption/separation and improved catalytic degradation of pollutants. In this review, MIT is first introduced briefly to understand their preparing process, recognition mechanism and common imprinted systems. Then, their specific binding affinities are demonstrated for selectively adsorbing and removing target molecules with a large capacity. Furthermore, the innovative utilization of MIT in catalytic eradication of pollutants is comprehensively overviewed to emphasize their enhanced efficiency and improved performances, which are classified by the used catalytically-active nanocrystals and imprinted systems. After summarizing recent advances in these fields, some limitations are discussed and possible suggestions are given to guide the future exploitation on MIT for environmental protection.

Silica-clay nanocomposites for the removal of antibiotics in the water usage cycle

The increasingly frequent detection of resistant organic micropollutants in waters calls for better treatment of these molecules that are recognized to be dangerous for human health and the environment. As an alternative to conventional adsorbent material such as activated carbon, silica-clay nanocomposites were synthesized for the removal of pharmaceuticals in contaminated water. Their efficiency with respect to carbamazepine, ciprofloxacin, danofloxacin, doxycycline, and sulfamethoxazole was assessed in model water and real groundwater spiked with the five contaminants. Results showed that the efficacy of contaminant removal depends on the chemical properties of the micropollutants. Among the adsorbents tested, the nanocomposite made of 95% clay and 5% SiO₂ NPs was the most efficient and was easily recovered from solution after treatment compared with pure clay, for example. The composite is thus a good candidate in terms of operating costs and environmental sustainability for the removal of organic contaminants.

Flocculation Efficiency and Mechanism of Carbamazepine by Microbial Flocculant Extracted from Klebsiella pneumoniae J1

The microbial flocculant (MFX) extracted from Klebsiella pneumoniae J1 was used to remove carbamazepine in prepared wastewater and domestic sewage. The influence factors and flocculation mechanism were studied. The optimal carbamazepine removal conditions for MFX were pH of 7-8, 7 mL of flocculant, 0.1 mL of coagulant, and 35°C, and the removal rate reached 81.75%. MFX was efficient in the removal of carbamazepine in both domestic sewage (75.03%) and secondary sedimentation tank effluent (69.76%). The pseudo-first-order kinetic equation fitted the adsorption process better than the pseudo-second-order kinetic equation, which suggested that the adsorption was not pure chemical adsorption. The analysis of floc size suggested that the repulsive force between carbamazepine and MFX was weakened under alkalescent conditions, which can help the growth and coherence of flocs and increase the carbamazepine removal efficiency. Enough dosage of MFX can generate larger flocs, but excessive dosage of MFX will decrease the carbamazepine removal rate because of increase in electrostatic repulsion. The analysis of 3D-EEM and FTIR suggested that hydroxyl, amino, and carboxyl in MFX played an important role in the removal of carbamazepine. As an eco-friendly and highly efficient microbial flocculant, MFX has potential for practical applications in carbamazepine removal.

Remediation of 1-Nitropyrene in Soil: A Comparative Study with Pyrene

Nitrated polycyclic aromatic hydrocarbons (nPAHs) are ubiquitous environmental pollutants, which exhibits higher toxicity than their corresponding parent PAHs (pPAHs). Recent studies demonstrated that the nPAHs could represent major soil pollution, however the remediation of nPAHs has been rarely reported. In this study, biological, physical, and chemical methods have been applied to remove 1-nitropyrene, the model nPAH, in contaminated soil. A comparative study with pyrene has also been investigated and evaluated. The results suggest that the physical method with activated carbon is an efficient and economical approach, removing 88.1% and 78.0% of 1-nitropyrene and pyrene respectively, within one day. The zero-valent ion has a similar removal performance on 1-nitropyrene (83.1%), converting 1-nitropyrene to 1-aminopyrene in soil via chemical reduction and decreasing the mutagenicity and carcinogenicity of 1-nitropyrene. Biological remediation that employs scallion as a plant model can reduce 55.0% of 1-nitropyrene in soil (from 39.6 to 17.8 μg/kg), while 77.9% of pyrene can be removed by plant. This indicates that nPAHs might be more persistent than corresponding pPAHs in soil. It is anticipated that this study could draw public awareness of nitro-derivatives of pPAHs and provide remediation technologies of carcinogenic nPAHs in soil.