Benzotriazole Removal Research Articles

Nitrogen-reliant degradation behaviors of characteristic NHCs by UV-based advanced oxidation processes: Kinetics, pathways and toxicity assessment

In recent decades, nitrogen-containing heterocyclic compounds (NHCs) have been widely synthesized and applied due to their excellent coordination capability of heterocyclic N atoms. However, their high toxicity and poor biodegradability pose significant hazards to aquatic ecosystems. Three characteristic NHCs (cNHCs) with similar molecular structures but minor differences in the number and position of N atoms, namely benzotriazole (BTA), benzimidazole (BMZ), and indazole (IDZ), were selected to evaluate impacts of these differences on their degradation behaviors during UV/H2O2 treatments. It was found that the key mechanism for the removal of BTA, BMZ, and IDZ in the UV/H2O2 processes was the generation of ∙OH through UV-excited H2O2 decomposition. Density functional theory (DFT) calculations revealed that the variation in the number and position of heterocyclic ring N atoms significantly affected the electron cloud distribution of the cNHCs, thereby resulting in different reactivities. Mineralization results and N evolution experiments indicated that N elements were initially released in the form of ammonia nitrogen during UV/H2O2 treatments, which then underwent oxidation to form nitrite and nitrate. The two ortho-N atoms were most easily mineralized and release inorganic nitrogen, followed by the two meta-N atoms. However, the BTA compound containing three N atoms, exhibited inertness towards radicals after hydroxylation, thereby hindering mineralization. A dual-directional transformation products (TPs) identification protocol was employed to identify 30 TPs of the cNHCs and propose recommended degradation pathways. Furthermore, Vibrio fischeri bioluminescence inhibition bioassay and QSAR prediction models were used to preliminarily screen and identify 13 toxic TPs with potential ecological risks.

Synergistic Effect of Composite Complex Agent on BTA Removal in Post-Cu-CMP: Experimental and Theoretical Analysis

Nowadays the development of nanoscale-interconnected integrated circuit chips makes the chemical mechanical polishing (CMP) and post-CMP cleaning more challenging. In general, organic residues such as benzotriazole (BTA) can adsorb on the wafer surface after CMP process and form thin films to prevent the contact between cleaning solution and the wafer surface, which thus can seriously affect the post-CMP cleaning process. And the efficient removal of BTA remains problematic due to the potential introduction of additional impurities. Therefore, a new alkaline cleaning solution based on citric acid (CA) was proposed to improve the removal efficiency of BTA. Results exhibit that the cleaning efficiency of BTA residues can reach 98.86% with 400 ppm tetraethyl ammonium hydroxide (TEAH) and 0.6 wt% CA (pH = 10.5). X-ray photoelectron spectroscopy (XPS) measurements show that the cleaning solution can coordinate with copper ions to break the ionization balance of Cu-BTA. In addition, the electronic properties and reaction sites on copper surface were determined by quantum chemical calculation and density functional theory (DFT). The theoretical analysis indicates that CA has hydroxyl and carboxyl functional groups, and its presence with TEAH can promote the complexation of Cu ions, which accelerates the breakage of Cu-BTA and the desorption of BTA from the copper surface.

Peroxymonosulfate Activation by Cu-OMS-2 Nanofibers for Efficient Degradation of N-Containing Heterocycles in Aquatic Solution.

In this research, the degradation of different types of N-containing heterocycle (NHC) contaminants by Cu-OMS-2 via peroxymonosulfate (PMS) activation in an aqueous environment was investigated. First, the effects of different reaction parameters were optimized using benzotriazole (BTR) as the model contaminant, and the optimal reaction conditions were 8 mM PMS, 0.35 g/L Cu-OMS-2, and 30 °C. Nine different types of NHC contaminants were effectively degraded under these reaction conditions, and the degradation efficiencies and the mineralization rates of those NHCs were more than 68 and 46%, respectively. Moreover, the Cu-OMS-2/PMS process presented excellent performance at a wide pH ranging from 3.0 to 11.0 and in the presence of some representative anions (NO3- and SO42-) and dissolved organic matter (fumaric acid). The inhibition sequence of anions on BTR removal during the Cu-OMS-2/PMS process was H2PO4- > HCO3- > Cl- > CO32- > NO3- > SO42-. It was also found that 74.5 and 71.3% BTR degradation rates were achieved in actual water bodies, such as tap water and Yellow River water, respectively. Besides, the Cu-OMS-2 heterogeneous catalyst had excellent stability and reusability, and the degradation rate of BTR was still at 77.0% after 5 cycles. Finally, electron paramagnetic resonance analysis and scavenging tests showed that 1O2 and SO4- • were the primary reactive oxygen species. Accordingly, Cu-OMS-2 nanomaterial was an efficient and sustainable heterogeneous catalyst to activate PMS for the decontamination of BTR in water remediation.

Photoelectrocatalytic based simultaneous removal of multiple organic micro-pollutants by using a visible light driven BiVO4 photoanode

In this research, photoelectrocatalytic (PEC) based advanced oxidation process (AOP) was studied for the removal of multiple OMPs through an oxidative mechanism. This study investigated the application of a BiVO4 photoanode in simultaneous removal of three selected OMPs: acetaminophen (ACT), benzotriazole (BTA) and propranolol (PRO). This study was carried out in demineralized water with a starting concentration of each organic micro-pollutant (OMP) at 45 μg L−1. In order to fabricate BiVO4 photoanodes, a facile and effective dip-coating method was used to deposit BiVO4 photocatalytic layers on fluorine doped tin oxide (FTO) substrate. UV–vis diffusive reflectance spectroscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) confirmed the successful fabrication of porous BiVO4 photoanode having an absorbance edge at around 526 nm. The fabricated photoanode showed incident photon to current conversion efficiency (IPCE) of 9.23% (λmax=445 nm) under 1 Sun standard illumination. Application of the fabricated photoanodes for the simultaneous removal of ACT, PRO and BTA at an applied voltage of 1 V (vs Ag/AgCl) under solar simulated light resulted in 99% removal of both ACT and PRO, and 70% removal of BTA. The first order rate coefficients and half-life times of ACT and PRO were about three times higher than those of BTA.

Synergistic Effect of Complexing Agent TAD and Corrosion Inhibitor PZ on BTA Removal in Copper Post-CMP Cleaning

Benzotriazole (BTA) as a common corrosion inhibitor in the chemical mechanical polishing (CMP) process, can effectively protect the copper (Cu) surface, but its organic residues will form a passivation film on the wafer surface to prevent the contact between the cleaning solution and the wafer surface, so the removal of BTA is a major problem in the post-CMP cleaning. In this paper, N,N’-Bis(3-aminopropyl)−1,2-ethanediamine (TAD) and pyrazole (PZ) were used as the main components in the alkaline cleaning solution and fatty alcohol polyoxy ethylene ether (JFCE) was added as an auxiliary surfactant to investigate the removal of BTA. The complexation ability of TAD and the corrosion inhibition ability of PZ were verified by electrochemical experiments, and the reaction sites of the interaction between TAD and Cu surface were analyzed by quantum chemical calculations. Meanwhile, the mechanism of the synergistic removal of BTA by TAD and PZ was investigated by electrochemical methods. The final optimized cleaning solution consisted of 1 mmol L−1 TAD, 0.1 mmol L−1 PZ and 1 wt% JFCE and its good cleaning performance was verified by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), which provided guidance for the development of the cleaning solution.

The abiotic removal of organic micropollutants with iron and manganese oxides in rapid sand filters for groundwater treatment.

Rapid sand filters (RSFs) have shown potential for removing organic micropollutants (OMPs) from groundwater. However, the abiotic removal mechanisms are not well understood. In this study, we collect sand from two field RSFs that are operated in series. The sand from the primary filter abiotically removes 87.5% of salicylic acid, 81.4% of paracetamol, and 80.2% of benzotriazole, while the sand from the secondary filter only removes paracetamol (84.6%). The field collected sand is coated by a blend of iron oxides (FeOx) and manganese oxides (MnOx) combined with organic matter, phosphate, and calcium. FeOx adsorbs salicylic acid via bonding of carboxyl group with FeOx. The desorption of salicylic acid from field sand indicates that salicylic acid is not oxidized by FeOx. MnOx adsorbs paracetamol through electrostatic interactions, and further transforms it into p-benzoquinone imine through hydrolysis-oxidation. FeOx significantly adsorbs organic matter, calcium, and phosphate, which in turn influences OMP removal. Organic matter on field sand surfaces limits OMP removal by blocking sorption sites on the oxides. However, calcium and phosphate on field sand support benzotriazole removal via surface complexation and hydrogen bonding. This paper provides further insight into the abiotic removal mechanisms of OMPs in field RSFs.

Performance and Mechanism of Functionalized Water Hyacinth Biochar for Adsorption and Removal of Benzotriazole and Lead in Water.

In this paper, water hyacinth is used to prepare biochar (WBC). A biochar-aluminum-zinc-layered double hydroxide composite functional material (WL) is synthesized via a simple co-precipitation method which is used to adsorb and remove benzotriazole (BTA) and lead (Pb2+) in an aqueous solution. In particular, this research paper uses various characterization methods to analyze WL and to explore the adsorption performance and adsorption mechanism of WL on BTA and Pb2+ in an aqueous solution through batch adsorption experiments combined with model fitting and spectroscopy techniques. The results indicate that the surface of WL contains a thick sheet-like structure with many wrinkles which would provide many adsorption sites for pollutants. At room temperature (25 °C), the maximum adsorption capacities of WL on BTA and Pb2+ are 248.44 mg·g-1 and 227.13 mg·g-1, respectively. In a binary system, during the process of using WL to adsorb BTA and Pb2+, compared with that in the absorption on Pb2+, WL shows a stronger affinity in the adsorption on BTA, and BTA would thus be preferred in the absorption process. The adsorption process of WL on BTA and Pb2+ is spontaneous and is endothermic monolayer chemisorption. In addition, the adsorption of WL on BTA and Pb2+ involves many mechanisms, but the main adsorption mechanisms are different. Among them, hydrogen bonding dominates the adsorption on BTA, while functional groups (C-O and C=O) complexation dominates the adsorption on Pb2+. When WL adsorbs BTA and Pb2+, the coexistence of cations (K+, Na+, and Ca2+) has a strong anti-interference ability, and WL can use a lower concentration of fulvic acid (FA) (<20 mg·L-1) to improve its adsorption performance. Last but not least, WL has a stable regenerative performance in a one-component system and a binary system, which indicates that WL has excellent potential for the remediation of BTA and Pb2+ in water.

Experimental characterization and dynamical modeling evaluation for enhanced BTA removal by three amino acids in post-Cu-CMP cleaning

Post-chemical mechanical polishing (CMP) cleaning is an indispensable process to remove organic residues and particles on the wafer surface after CMP. Benzotriazole (BTA), a dominant corrosion inhibitor in Cu-CMP slurry, can easily remain on the copper surface after CMP, affecting the performance and yield of devices, and its removal has attracted more attention. This paper revealed the effect and mechanism of three amino acids, lysine, serine, and proline, on BTA removal in tetraethyl ammonium hydroxide-based alkaline solutions during post-Cu-CMP cleaning. Experimental results showed a diminishing enhancement in the cleaning efficiency of BTA after adding lysine (97.1%), serine (96.7%), and proline (94.1%) with almost the same concentration. Ultraviolet–visible absorption spectrum proved the lysine’s complexing ability was slightly better than the other. Besides, quantum chemical parameters of amino acid molecules calculated by density functional theory further suggested that lysine has more reactive sites and mainly bonds with copper through N2 and N8. The adsorption structures of three amino acids were simulated through the molecular dynamics method, and lysine turned out to be parallel absorbed on the Cu (111) surface with the lowest adsorption energy of −30.24 eV. Finally, the cleaning process simulation revealed the dynamic behaviors of BTA and lysine.

Heat-activated peroxydisulfate and peroxymonosulfate-mediated degradation of benzotriazole: Effects of chloride on kinetics, pathways and transformation product toxicity

The impact of chloride (Cl⁻) in heat-activated peroxydisulfate (PDS) and peroxymonosulfate (PMS) processes for benzotriazole (BTA) degradation was investigated. Results showed that 0.42 mM BTA could be degraded by PDS and PMS under 70 °C in presence and absence of Cl⁻. The PMS-mediated BTA degradation rate increased with increasing Cl⁻ concentration up to 1000 mg/L, while a further increase of Cl⁻ concentration decreased the BTA degradation rate. In contrast, Cl⁻ inhibited PDS-mediated BTA degradation at concentrations tested between 100 and 10,000 mg/L. Radical scavenging experiments indicated that BTA degradation was mainly driven by hydroxyl and sulfate radicals in PDS and PMS systems without Cl⁻. However, reactive chlorine species (RCS) significantly boosted the PMS system for BTA degradation in presence of Cl⁻. Variation in pH substantially influenced the PMS system, but not the PDS system, whether in presence and absence of Cl⁻. By LC-MS/MS analysis, forty-two transformation products (TPs) were identified resulting from BTA degradation. Based on the TPs, polymerization, hydroxylation, benzene ring-opening, and carboxylic acid formation were hypothesized to be the main degradation mechanisms in absence of Cl⁻, whereas chlorination, triazole ring-opening, and nitration were the additional degradation steps in presence of Cl⁻. These findings help understand the influence of Cl⁻ on BTA removal rate and degradation pathway in saline wastewater. Moreover, more chlorinated TPs were found in PMS/Cl⁻ system than in PDS/Cl⁻ system, which was also reflected in absorbable organic halides (AOX) and end-product toxicity analyses. The PMS/Cl⁻ process also produced other undesirable by-products, such as chlorates which were not detected in the PDS/Cl⁻ process. This shows that PDS and PMS-based advanced oxidation processes can notably differ in terms of toxic by-product formation. Thus, they need to be critically evaluated before applying for organic pollutant degradation under saline conditions.

Application of an optimized alkaline cleaning solution for inhibitor removal during the post-CMP process: Performance evaluation and mechanism analysis

With the continuous miniaturization of the feature size of semiconductor integrated circuits, the development of chemical mechanical polishing (CMP) technology for copper interconnection has been promoted, and at the same time, more stringent requirements and challenges have been put forward for post-CMP cleaning technology. Benzotriazole (BTA), which has been used as an inhibitor to decrease metal corrosion especially in copper CMP process, is the main object to be removed after the CMP process due to its highly hydrophobic nature. However, the current post-CMP cleaning method cannot achieve an effective balance between high removal efficiency of BTA and excellent surface quality after CMP cleaning. Therefore, a novel and efficient alkaline cleaning solution for post-CMP cleaning of copper is proposed, which is based on tetraethylammonium hydroxide (TEAOH), l-glutamate (Glu) and polyvinylpyrrolidone (PVP). The cleaning effect of copper surface was characterized by contact angle measurement, electrochemical system, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The ion exchange of TEAOH and Glu promotes desorption of BTA molecules from the copper surface. The presence of PVP plays a key role in improving the surface quality after cleaning. This cleaning solution was proved to be effective for BTA removal and achieving a nearly defect-free clean surface.

Occurrence and removal of benzotriazole and benzothiazole in drinking water treatment plants

The occurrence and removal of four benzotriazoles (BTRs) and five benzothiazoles (BTHs) in drinking water treatment plants (DWTPs) and bottled water were investigated. The mean total BTR and BTH concentrations were 390 and 117 ng/L in raw water, 51.2 and 66.5 ng/L in treated water, and 0.758 and 48.4 ng/L in bottled water, respectively. Different distribution patterns were observed according to the water type, with the dominant BTR being 1H-BTR (mean: 57.8%) in raw water and a predominance of BTH in bottled water (mean: 84.6%). In the DWTPs, the mean removal of BTRs (90.9%) was better than that of BTHs (29.3%). The BTRs were efficiently removed in DWTPs, and in particular during adsorption processes. 5Cl-BTR had a high removal efficiency (75.7%) in the adsorption processes, followed by 5M-BTR (70.0%), 5,6-di-MeBTR (58.4%), and 1H-BTR (50.1%). By contrast, BTHs were not efficiently removed in DWTPs, although relatively high removal efficiencies were achieved with an ozonation process (43.1%) compared to other treatment processes. In treated drinking and bottled water, the hazard quotients (HQs) of the representative BTRs and BTHs were acceptable (defined as HQ < 1), with a safety margin of 2–5 orders of magnitude.

Reactive chlorine species in the enhanced degradation of UV stabilizers during the sunlight/free chlorine process

Benzotriazole (BT) and 5-methyl-1H-benzotriazole (5-MeBT) are the most commonly used UV stabilizers and recalcitrant contaminants that are widely distributed in aquatic environments. The novelty of this study was to investigate the role of RCSs in the enhanced degradation of BT and 5-MeBT during the sunlight/free chlorine process. The results showed that sunlight/free chlorine could enhance the degradation of BT and 5-MeBT compared with that obtained with sunlight irradiation and chlorination alone, and this process was well described by pseudo-first-order kinetics. The degradation rate constants of BT and 5-MeBT during sunlight/free chlorine treatment at pH 7 were 0.094 ± 0.001 min−1 and 0.134 ± 0.002 min−1, respectively. The degradation rates further increased with increases in the chlorine dosage and under alkaline conditions (3.818 ± 0.243 min−1 for BT and 7.754 ± 0.716 min−1 for 5-MeBT at pH 9). The enhanced removal obtained during the sunlight/free chlorine process could be attributed to the generation of HO• and reactive chlorine species (RCSs), such as Cl• and ClO•. Under alkaline conditions, RCSs were the dominant reactive species, and their contribution increased from 21.2% to 98.7% with increases in the pH from 7 to 9; this phenomenon was due to changes in free chlorine and BT speciation. Radical scavenging tests further verified that BT was mainly decomposed by ClO•, and ClO• showed high reactivity toward deprotonated BT through second-order rate constant estimation. A byproduct analysis demonstrated that BT underwent hydroxylation and chlorine substitution, and a high yield of 1-chlorobenzotriazole (1-ClBT) formation was observed. Even though the sunlight/free chlorine process resulted in a low level of mineralization, no Microtox® toxicity was detected in the treated solutions. Briefly, the significant contribution of ClO• to BT removal under alkaline conditions implies that sunlight/free chlorine could be utilized in a broader range of treatment conditions.

Harnessing plant-microbiome interactions for bioremediation across a freshwater urbanization gradient

Urbanization impacts land, air, and water, creating environmental gradients between cities and rural areas. Urban stormwater delivers myriad co-occurring, understudied, and mostly unregulated contaminants to aquatic ecosystems, causing a pollution gradient. Recipient ecosystems host interacting species that can affect each others’ growth and responses to these contaminants. For example, plants and their microbiomes often reciprocally increase growth and contaminant tolerance. Here, we identified ecological variables affecting contaminant fate across an urban-rural gradient using 50 sources of the aquatic plant Lemna minor (duckweed) and associated microbes, and two co-occurring winter contaminants of temperate cities, benzotriazole and salt. We conducted experiments totalling >2,500 independent host-microbe-contaminant microcosms. Benzotriazole and salt negatively affected duckweed growth, but not microbial growth, and duckweeds maintained faster growth with their local, rather than disrupted, microbiota. Benzotriazole transformation products of plant, microbial, and phototransformation pathways were linked to duckweed and microbial growth, and were affected by salt co-contamination, microbiome disruption, and source sites of duckweeds and microbes. Duckweeds from urban sites grew faster and enhanced phytotransformation, but supported less total transformation of benzotriazole. Increasing microbial community diversity correlated with greater removal of benzotriazole, but taxonomic groups may explain shifts across transformation pathways: the genus Aeromonas was linked to increasing phototransformation. Because benzotriazole toxicity could depend on amount and type of in situ transformation, this variation across duckweeds and microbes could be harnessed for better management of urban stormwater. Broadly, our results demonstrate that plant-microbiome interactions harbour manipulable variation for bioremediation applications.

Mechanisms, toxicity and optimal conditions - research on the removal of benzotriazoles from water using Wolffia arrhiza

In the presented work, phytoremediation with the use of floating plant Wolffia arrhiza (L.) Horkel ex Wimm. was proposed as a method of removing the selected benzotriazoles (BTRs): 1H–benzotriazole (1H-BTR), 4-methyl-1H-benzotriazole (4M-BTR), 5-methyl-1H-benzotriazole (5M-BTR) and 5-chlorobenzotriazole (5Cl-BTR) from water. The efficiency of phytoremediation depends on three factors: daily time of exposure to light, pH of the model solution, and the amount of plans. Using a design of experiment (DoE) methods the following optimal values were selected: plant amount 1.8 g, light exposure 13 h and pH 7 per 100 mL of the model solution. It was found that the loss of BTRs in optimal conditions ranged from 92 to 100 % except for 4M-BTR, for which only 23 % of removal was achieved after 14 days of cultivation of W. arrhiza. The half-life values for studied compounds ranged from 0.98 days for 5Cl-BTR to 36.19 for 4M-BTR. The observed rapid vanishing of 5M-BTR is supposed by the simultaneous transformation of 5M-BTR into 4M-BTR. The detailed study of BTRs degradation pointed that the plant uptake is mainly responsible for the benzotriazoles concentration decrease. Toxicity tests showed that the tested organic compounds induce oxidative stress in W. arrhiza, which manifested among others, in reduced levels of chlorophyll in cultures with benzotriazoles compared to control.

Exploring organic micropollutant biodegradation under dynamic substrate loading in rapid sand filters

Microbial removal of trace organic micropollutants (OMPs) from drinking water sources remains challenging. Nitrifying and heterotrophic bacteria in rapid sand filters (RSFs) are capable of biodegrading OMPs while growing on ammonia and dissolved organic matter (DOM). The loading patterns of ammonia and DOM may therefore affect microbial activities as well as OMP biodegradation. So far, there is very limited information on the effect of substrate loading on OMP biodegradation at environmentally relevant concentrations (∼ 1 µg/L) in RSFs. We investigated the biodegradation rates of 16 OMPs at various substrate loading rates and/or empty bed contact times (EBCT). The presence of DOM improved the biodegradation of paracetamol (41.8%) by functioning as supplementary carbon source for the heterotrophic degrader, while hindering the biodegradation of 2,4-D, mecoprop and benzotriazole due to substrate competition. Lower loading ratios of DOM/benzotriazole benefited benzotriazole biodegradation by reducing substrate competition. Higher ammonia loading rates enhanced benzotriazole removal by stimulating nitrification-based co-metabolism. However, stimulating nitrification inhibited heterotrophic activity, which in turn inhibited the biodegradation of paracetamol, 2,4-D and mecoprop. A longer EBCT promoted metformin biodegradation as it is a slowly biodegradable compound, but suppressed the biodegradation of paracetamol and benzotriazole due to limited substrate supply. Therefore, the optimal substrate loading pattern is contingent on the type of OMP, which can be chosen based on the priority compounds in practice. The overall results contribute to understanding OMP biodegradation mechanisms at trace concentrations and offer a step towards enhancing microbial removal of OMPs from drinking water by optimally using RSFs.

PH-Triggered Removal of Nitrogenous Organic Micropollutants from Water by Using Metal-Organic Polyhedra.

Water pollution threatens human and environmental health worldwide. Thus, there is a pressing need for new approaches to water purification. Herein, we report a novel supramolecular strategy based on the use of a metal‐organic polyhedron (MOP) as a capture agent to remove nitrogenous organic micropollutants from water, even at very low concentrations (ppm), based exclusively on coordination chemistry at the external surface of the MOP. Specifically, we exploit the exohedral coordination positions of RhII‐MOP to coordinatively sequester pollutants bearing N‐donor atoms in aqueous solution, and then harness their exposed surface carboxyl groups to control their aqueous solubility through acid/base reactions. We validated this approach for removal of benzotriazole, benzothiazole, isoquinoline, and 1‐napthylamine from water.

Flow-through electrochemical removal of benzotriazole by electroactive ceramic membrane

Benzotriazole (BTA) is a widely used anticorrosive additive that is of endurance, bioaccumulation and toxicity, and BTA industrial wastewater treatment remains a challenge. This study reports efficient electrochemical removal of BTA by titanium oxide (TiSO) electroactive ceramic membrane (ECM), indicated by 98.1% removal at current density of 20 mA∙cm−2 and permeate flux of 692 LHM under cathode-to-anode flow pattern (1 h). Electrochemical analysis demonstrated the pH-dependent formation of anti-corrosive BTA film on the TiSO anode, which was responsible for improved BTA removal for cathode-to-anode (CA) flow pattern compared with that for anode-to-cathode (AC). The modelling results showed the CA flow pattern to be more favourable for BTA oxidation mediated by electro-generated •OH by preventing the formation of deactivation film via creating an alkaline boundary layer at the anode/electrolyte interface. Intermediates and essential active sites were identified by using experimental analysis and theoretical density functional theory (DFT) calculations, thereby the most likely degradation pathways were underlined. Toxicity analysis revealed remarkable decrease in oral rat LD50 values and bioaccumulation factor during electrochemical degradation of BTA. This study provides a proof-in-concept demonstration of effective removal for anti-corrosive emerging pollutants by TiSO-ECM under flow-through pattern.

Composite complex agent based on organic amine alkali for BTA removal in post CMP cleaning of copper interconnection

The combination of FA/OII chelating agent and double complexing agent ammonium citrate can shift the ionization to the right (the dissolution of Cu-BTA), effectively break the Cu-N bond, and accelerate BTA removal on the copper surface. • Ammonium citrate's nucleophilic attack may occur near C2 and O4 atoms. • The electrophilic attack may occur near N22 and N26 atoms. • The pH value of the cleaning solution is stable at 10.24 for optimal removal of BTA. • Effect and mechanism of composite complex agent were studied by electrochemical, contact angle, SEM, FTIR and XPS. • Composite complex agent can complex copper ions, form copper amine complex and break the ionization balance of Cu-BTA. Benzotriazole (BTA) is a common corrosion inhibitor in chemical mechanical polishing (CMP). It is also the main pollutant to be removed in post CMP cleaning. In this paper, a new type of alkaline cleaning solution based on composite complexing agent was proposed for BTA removal. The optimal concentration and pH value of the cleaning solution were explored using electrochemical measurement and contact angle measurement. When the components were 200 ppm FA/OII chelating agent and 0.1 vol% ammonium citrate (pH = 10.24), BTA residue on copper surface can be effectively removed. Density Functional Theory (DFT) proved that ammonium citrate's nucleophilic attack may occur around C2 and O4 atoms, respectively. The electrophilic attack of ammonium citrate may occur around N22 and N26 atoms, respectively. The results of scanning electron microscopy (SEM) showed that a lower surface roughness was obtained after cleaning. Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the cleaning solution could complex copper ions, break the ionization balance of Cu-BTA and accelerate its dissolution, so as to remove BTA effectively.

Preparation, characterization, and application of modified magnetic biochar for the removal of benzotriazole: process optimization, isotherm and kinetic studies, and adsorbent regeneration.

The adsorption of benzotriazole (BTA) by chemically modified magnetic biochar (MMBC) as a cheap and abundant biosorbent was investigated and optimized using response surface methodology (RSM). Initially, the MMBC composite was synthesized and characterized by scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) techniques. The characterization results confirmed the existence of Fe3O4 in the composite structure, which had uniformly dispersed over biochar (BC) with porous texture. Moreover, the presence of Zn and Cl elements in EDX analysis indicated that the magnetic biochar (MBC) had been modified successfully. The effects of chemical modification methods on the adsorption capacity of magnetic biochar were investigated. Maximum BTA removal efficiency was demonstrated by MMBC, modifying using ZnCl2 (>99%). Optimization was carried out based on reaction time, BTA concentration and the concentration of adsorbent. Optimum experimental conditions for the removal of BTA from aqueous solutions were found to be 35 min of reaction time, 0.55 g/L of adsorbent, and 50 mg/L of initial BTA concentration. At these optimal conditions, the predicted BTA adsorption efficiency was 92.6%. The adsorption process followed the Avrami fractional-order reaction kinetic and the Langmuir adsorption isotherm with the maximum adsorption capacity of 563.1 mg/g. The values of thermodynamic parameters demonstrated that the adsorption of BTA on ZnCl2-MBC is endothermic and spontaneous. Under optimum usage of MMBC, the adsorptive removal efficiency of BTA non-significantly decreased from 99.2 to 93.9% after the 5th cycle. Thus, MMBC can be recommended as an environmentally friendly and cost-effective adsorbent to remove micropollutants from water.

Simultaneous adsorption of organic and inorganic micropollutants from rainwater by bentonite and bentonite‑carbon nanotubes composites

Recently, there are numerous organic and inorganic micropollutants exist in the water environment, thus it is necessary to develop a new versatile adsorbent for simultaneous removal of different water pollutants. The aim of this study was to evaluate natural, thermally-treated bentonites (0–700 °C) and bentonite‑carbon nanotubes composites (Ben100 + SWCNT and Ben100 + SWCNT-OH) in terms of their capabilities for simultaneous adsorption of organic micropollutants and heavy metals from rainwater. Ben-CNT composites consisted of 60 wt% of bentonite (Ben100) and 40 wt% of single-walled carbon nanotubes (SWCNT) or single walled carbon nanotubes with hydroxyl groups (SWCNT-OH). The composition of the rainwater has been modified by adding lead nitrate, zinc nitrate and other organic micropollutants, including benzotriazole (BZT) and anthracene (ANT). Overall, removal of BZT and ANT varied from 4.5% to 93% and from 50% to 95.5%, respectively. Ben100 + SWCNT and Ben100 + SWCNT-OH exhibited increased removal percentage to 93% (BZT) and 95.5% (ANT), respectively. The fitting degree showed that Freundlich model was the most suitable for BZT and ANT adsorption on Ben100 and Ben100 + SWCNT, while Langmuir provided the best fit for Ben100 + SWCNT-OH. From bentonites (0–700 °C), the highest removal of both zinc and lead was observed for Ben100 and Ben300, while the lowest for Ben500 and Ben700. Ben100 + SWCNT and Ben100 + SWCNT-OH composites demonstrated over 90% removal percentage of zinc and lead. During adsorption of these compounds, the time required to reach equilibrium was very short (30 min) for both composites. The study showed that Ben-CNT composites are the effective adsorbents for removing micropollutants and heavy metals from aqueous solutions.