Micropollutants are ubiquitous in water sources, posing threats to both human health and ecosystems. Conventional water and wastewater treatment processes are inefficient in micropollutant removal. In this study, the energy-effective and environmentally friendly solar light–driven periodate (PI) and peroxydisulfate (PDS) synergistic activation process (PI/PDS/solar light) is developed for efficient micropollutant decontamination. The PI/PDS/solar light process (0.5 mM PI and 0.25 mM PDS) achieves 100

The frequent occurrence of antibiotics in wastewater poses a serious threat to human health and ecosystem safety. High-valent cobalt-oxo (Co(IV)=O) is a promising reactive species for antibiotic degradation, however, the selective and highly efficient generation of Co(IV)=O in advanced oxidation processes (AOPs) remains challenging. Herein, we develop a photoelectrochemical peroxymonosulfate activation (PEC/PMS) system using a cobalt-doping MoS2@CC (Co-MoS2@CC) photoanode to generate Co(IV)=O for efficient antibiotic degradation. The Co doping significantly improves the PEC properties of Co-MoS2@CC and increases its active sites, achieving a high sulfamethoxazole (SMX) degradation rate constant (0.497 min(-1)) in the PEC/PMS system. Mechanistic investigations reveal that the PEC system activates PMS through a non-radical pathway to selectively form Co(IV)=O (with a high steady-state concentration of 1.95 x 10(-9) M) in-situ on Co-MoS2@CC as the dominant reactive species for SMX degradation (93.4% contribution). The photogenerated holes are a critical driving force for Co(IV)=O formation, while the photogenerated electrons accelerate the valence cycling of Co species to facilitate Co(IV)=O generation. Additionally, the PEC/PMS treatment significantly reduces SMX toxicity by efficiently disrupting its molecular structure. Furthermore, the PEC/PMS system demonstrates excellent practicality, evidenced by stably producing Co(IV)=O under pH 5 similar to 9 and effectively degrading five frequently detected antibiotics in real wastewater over five cycles. The study provides in-depth insight into the rational design of the PEC/PMS system for the selective formation of Co(IV)=O.

Conventional water treatment plants are found to be incapable of degrading pharmaceuticals and personal care products (PPCPs), thereby imposing high risks to human health. As a solution to the deficiency of conventional water treatment plants, although the photocatalysis (PC)/chlorine process has been demonstrated to be feasible for incorporating PPCP degradation and disinfection, its development has been limited by the rapid recombination of charge carriers, secondary pollution, and intense formation of disinfection byproducts (DBPs). To overcome these limitations of the PC/chlorine process, we have developed a novel photoelectrochemical (PEC)/chlorine system with enhanced charge separation forced by external bias in this study. A dual-vacancy-engineered BiVO4 (V-Bi,V-O-BiVO4) photoanode with improved PEC properties was synthesized for the PEC/chlorine system, which can prevent secondary disinfection by immobilizing the photocatalyst. The effectiveness of the PEC/chlorine system is shown by achieving an enhanced carbamazepine (CBZ, a PPCP) degradation rate constant of 0.065 min(-1) (compared with 0.041 min(-1) for the PC/chlorine system) and complete inactivation of 3-log/mL E. coli within 1 min in a batch reactor. The mechanistic study reveals that both photogenerated electrons and holes engage in chlorine activation, producing (OH)-O-center dot and (OCl)-O-center dot as the predominant reactive species for PPCP degradation. Notably, compared to the PC/chlorine process, the PEC/chlorine system reduces DBP formation by 44.6 %, ensuring the safety of the treated water. Furthermore, the scalability of the PEC/chlorine system from a batch to continuous flow reactor is proven by achieving excellent performance in PPCP degradation and E. coli disinfection with a low power-intensive UV light source. This study provides detailed insights into the potential applications of the PEC/chlorine process for PPCP degradation and disinfection in future water treatment processes.

The solar/chlorine process provides an energy-efficient technique for the abatement of some pharmaceuticals and personal care products (PPCPs) but it is inefficient in degrading PPCPs lacking electron-donating group and suffers high formation of disinfection byproducts (DBPs). In this study, a photothermal approach is developed to promote chlorine activation (photothermal/chlorine) under solar radiation to effectively remove a wide range of structurally diverse PPCPs and to control DBPs formation. To this end, a carbon black (CB) coated 3D porous melamine sponge (MS), namely CB@MS, is developed for the photothermal/chlorine application, achieving significantly enhanced PPCPs degradation with an ibuprofen (IBU) removal rate constant (0.22 min-1) 3.76 times that of the solar/chlorine process (0.058 min-1). Mechanistic investigations revealed that CB@MS confines the thermal energy within the 3D porous structure to achieve high localized heating for boosting PPCPs degradation in the confined space, which is equivalent to the thermal effect achieved by the solar/chlorine process at constant solution temperature of around 70 degrees C. Moreover, the photothermal/chlorine process reduces TOCl and DBPs formation by 77.6 % and 67.5 %, ascribed to adsorption by CB@MS, less chlorine exposure, and altered PPCPs degradation pathways. The broad applicability in various water matrices, and good reusability and stability of the photothermal/chlorine system also ensure its excellent practicality. This study offers in-depth mechanisms and practical insights into the development of a novel photothermal/chlorine process for PPCPs abatement and DBPs control.

Phosphate removal and recovery from contaminated water are crucial in addressing eutrophication and global phosphorus (P) scarcity. Conventional adsorption reactors and adsorbent regeneration techniques fall short of meeting the demands for efficient phosphorus removal and recovery. This study, for the first time, presents a semi -fluidized reactor using La2(CO3)3-loaded anion -exchange resin (LC@AER) for enhanced phosphorus removal and in -situ adsorbent regeneration. The response surface methodology (RSM) analysis identifies the ideal conditions for optimizing adsorption efficiency and highlights the substantial influence of pH and sulfate concentration on the phosphate adsorption capacity. The Thomas and Yoon-Nelson models exhibit excellent fits with breakthrough curves (R2>0.99), facilitating the determination of the adsorbent dosage for practical applications. In the semi -fluidized reactor, LC@AER performs efficiently in five adsorption-desorption cycles with an average adsorption capacity of 44.67 mg/g and a regeneration efficiency of 92.22%, achieving enhancements of 86.8% for phosphate adsorption and 61.22% for adsorbent regeneration (compared with fixed -bed columns using LC@AER). These results demonstrate that the semi -fluidized reactor enables LC@AER to achieve excellent reusability, ensuring its promising industrialization prospects. The enhanced performance is attributed to the semi -fluidized reactor offering better interaction between the adsorbent and liquid and overcoming issues of the dead zone and channeling. This study has substantial significance for sustainable phosphorus pollution management and provides key parameters for potential industrial -scale applications of this process.

Conventional wastewater treatment plants (WWTPs) face challenges due to high carbon emissions and energy consumption. Herein, a low-carbon-emission photoelectrochemical (PEC) system using an oxygen-vacancy-rich Fe2O3@BiVO4 (Ov-Fe2O3@BiVO4) photoanode that is aimed at replacing biological treatment and disinfection, is developed to simultaneously remove organic compounds, ammonia (NH4+-N), and bacteria from real saline sewage (after primary treatment) while generating green H2. The PEC system demonstrates remarkable performance in the treatment of real saline sewage, as evidenced by the fact that the treated sewage is able to meet local discharge standards of chemical oxygen demand (COD), ammonia-N, and Escherichia coli (E. coli) after two hours of operation under simulated solar light at 2.0 V (vs. Ag/AgCl). Most importantly, it generates 11.51 mol/m3 of green H2 (equal to 0.458 kWh/m3 of electricity) and results in notable reductions of 76.7 % in scope 1 emissions (direct GHG emissions) and 62.5 % in total carbon emissions compared to conventional WWTPs. The scavenging tests and estimated steady-state concentrations of reactive species indicate that Cl•, ClO•, and Cl2•− are the primary contributors to the degradation of organic pollutants, while ClO• is dominant in converting ammonia to N2. Additionally, the excellent reusability, stability and easy regeneration of the Ov-Fe2O3@BiVO4 photoanode and its good performance in treating different batches of real sewage guarantee the high practicability of the PEC system. This study has successfully validated the PEC system as a low-carbon-emission technology approach for saline sewage treatment coupled with green H2 generation, demonstrating its enormous practical potential.

The selective transformation of organics from wastewater to value-added chemicals is considered an upcycling process beneficial for carbon neutrality. Herein, we present an innovative electrocatalytic oxidation (ECO) system aimed at achieving the selective conversion of phenols in wastewater to para-benzoquinone (p-BQ), a valuable chemical widely utilized in the manufacturing and chemical industries. Notably, 96.4% of phenol abatement and 78.9% of p-BQ yield are synchronously obtained over a preferred carbon cloth-supported ruthenium nanoparticles (Ru/C) anode. Such unprecedented results stem from the weak Ru-O bond between the Ru active sites and generated p-BQ, which facilitates the desorption of p-BQ from the anode surface. This property not only prevents the excessive oxidation of the generated p-BQ but also reinstates the Ru active sites essential for the rapid ECO of phenol. Furthermore, this ECO system operates at ambient conditions and obviates the need for potent chemical oxidants, establishing a sustainable avenue for p-BQ production. Importantly, the system efficacy can be adaptable in actual phenol-containing coking wastewater, highlighting its potential practical application prospect. As a proof of concept, we construct an electrified Ru/C membrane for ECO of phenol, attaining phenol removal of 95.8% coupled with p-BQ selectivity of 73.1%, which demonstrates the feasibility of the ECO system in a scalable flow-through operation mode. This work provides a promising ECO strategy for realizing both phenols removal and valuable organics recovery from phenolic wastewater.

Micropollutants and bacteria are prevalent pollutants in wastewater, posing significant risks to ecosystems and human health. As peracetic acid (PAA) is being increasingly used as a disinfectant, activation of PAA by low-cost and high-performance activators is a promising strategy for wastewater treatment. In this study, the sulfur-doped magnetic CoFe2O4 (SCFO) is successfully developed for efficient PAA activation to simultaneously decontaminate and disinfect wastewater. PAA/SCFO-0.3 exhibits exceptional performance, degrading 100% of 8 μM sulfamethoxazole (SMX) with a first-pseudo reaction rate of 1.275 min−1, and achieving 5.3-log inactivation of Escherichia coli (E. coli) within 3 min at a PAA dosage of 0.2 mM and catalyst dosage of 0.025 g/L (initial pH 6.5). Scavenging experiments and electron paramagnetic resonance (EPR) analysis identify CH3C(O)O• and CH3C(O)OO• as the dominant reactive species for SMX degradation. The sulfur species in SCFO-0.3 facilitate Co2+ regeneration and regulate charge transfer, promoting PAA activation for SMX degradation. Moreover, the PAA/SCFO-0.3 system demonstrates operational feasibility over a broad range of water matrices and has excellent stability and reusability (maintaining 93% removal of SMX after 5 cycles), demonstrating its potential for industrial applications. This study provides insights into enhancing PAA activation through sulfur doping in transition metal catalysts and highlights the practical applicability of the PAA/SCFO-0.3 system as an advanced alternative to conventional disinfection for simultaneous decontamination and disinfection in wastewater.

Photocatalysis offers a promising avenue for completely eliminating harmful algal blooms (HABs), a significant threat to global freshwater reserves. In this study, a series of BiOBrxI1-x photocatalysts were synthesized and the most optimal catalyst was integrated with pristine g-C3N4 and pre-synthesized CoFe2O4/g-C3N4 and NiFe2O4/g-C3N4 to form binary and ternary composite heterojunction photocatalysts (BiOBr0.95I0.05/g-C3N4 - BG, CoFe2O4/BiOBr0.95I0.05/g-C3N4 - CBG, and NiFe2O4/BiOBr0.95I0.05/g-C3N4 - NBG). The synthesized photocatalysts were thoroughly characterized and their performance was evaluated through the visible light driven photocatalytic degradation of both Microcystis aeruginosa (prokaryotic) and Scenedesmus acuminatus (eukaryotic) algal cells sourced directly from ponds. The exceptional photocatalytic efficiency of CBG evidenced through the variation in chlorophyll-a content, malondialdehyde, and electrolytic leakage confirmed the complete rupture of the algal cells after 3 h of light exposure. This was further reconfirmed through fluorescence microscopy analysis and interestingly, both HABs failed to re-grow even after 10 days. The enhanced performance of CBG was attributed to the boosted generation of charge carriers facilitated by its extended visible light absorption, which in turn produced reactive oxygen species ((center dot)O2- and (OH)-O-center dot radicals) that caused irreparable oxidative damage to algal cells, while effectively suppressing the exciton pair recombination supported by its double Z-scheme heterojunction. Furthermore, the magnetic recyclability feature of CBG facilitated its easy removal from treated water for avoiding secondary pollution. The design of magnetically recyclable photocatalysts for degrading both prokaryotic and eukaryotic HABs demonstrated here is anticipated to inspire the development of efficient photocatalysts and design of cost-effective solutions required for treating ponds and lakes infected with HABs.

Lanthanum carbonate @ anion exchange resin (LC@AER) has shown promise in adsorption processes due to its high maximum adsorption capacity and excellent stability in comparison with other lanthanum-based adsorbents. Nevertheless, there is a lack of significant investigation in evaluating the collective effect of the most influential parameters and determining the molecular complexes between the adsorbent and phosphate. This work aims to comprehensively evaluate and optimize the phosphate adsorption performance in fixed-bed columns and to determine the most favourable molecular configurations. Firstly, a response surface model (RSM) was developed to describe the phosphate adsorption performance in fixed-bed columns under the collective effect of selected independent variables, including influent pH, co-existing sulfate concentration, and empty bed contact time (EBCT). The RSM analysis reveals the significant effects of influent pH and co-existing sulfate concentration on phosphate adsorption. Moreover, the model achieves a correlation coefficient of >0.9, demonstrating its suitability for describing the experimental data. Secondly, various phosphate-lanthanum carbonate configurations were formulated, and the respective adsorption energies were compared using density functional theory (DFT) calculations. Subsequently, bidentate mononuclear complexes are determined as the most favourable configurations. The successful matching of the simulated peak locations with the experimental deconvoluted spectra further confirms the presence of such complexes in the system. Overall, this work provides an improved foundation and underlayer theory for potential future scale-up work on phosphate adsorption over LC@AER.

The critical review covers the applications, associated mechanisms, challenges, and prospects of magnetically recyclable nanophotocatalysts in photocatalysis-related processes.

Due to the specific affinity of lanthanum (La) toward phosphate over a wide pH range, La compounds such as lanthanum oxide (LO), lanthanum hydroxide (LH), and lanthanum carbonate (LC) have been integrated into various La-based adsorbents in recent years. In order to evaluate the differences among LO, LH, and LC in terms of phosphate removal performance (adsorption capacity, pH-dependent behavior, and selectivity), stability (La leaching), and reusability, data from the literature are consolidated. Furthermore, key properties of the respective compounds such as solubility and speciation are examined to identify possible underlying reasons. LC exhibits superior adsorption capacity and a wider optimum pH range for phosphate binding and lower La leaching, but reusability data of the various compounds remain inconclusive. Based on their superior performance and stability in laboratory studies, LC may have greater lifespan and can serve as a viable alternative to LO and LH for future studies on phosphate removal in order to maximize phosphate removal efficiency while simultaneously reducing secondary pollution. To further develop La-based adsorbents for phosphate removal and recovery, direct comparisons are needed among La compounds using more complex matrices such as wastewater and river water. Furthermore, the role of crystal structure in the phosphate removal performance of different compounds must be carefully assessed. Finally, to evaluate the feasibility of practical application and understand the effects of continuous flow operation on phosphate removal and recovery efficiency, more pilot-scale studies involving La-based adsorbents should be conducted. Performance, stability, and reusability of different La compounds are crucial to the practicability of La-based adsorbents for phosphate removal along with addressing key challenges associated with real-world usage. The simultaneous incorporation of other metals presents a possible way to improve on the inherent properties of La-based adsorbents to enable them to better address these challenges.

Automated algae classification using machine learning is a more efficient and effective solution compared to manual classification, which can be tedious and time-consuming. However, the practical application of such a classification approach is restricted by the scarcity of labeled freshwater algae datasets, especially for rarer algae. To overcome these challenges, this study proposes to generate artificial algal images with StyleGAN2-ADA and use both the generated and real images to train machine-learning-driven algae classification models. This approach significantly enhances the performance of classification models, particularly in their ability to identify rare algae. Overall, the proposed approach improves the F1-score of lightweight MobileNetV3 classification models covering all 20 freshwater algae covered in this research from 88.4% to 96.2%, while for the models that cover only the rarer algae, the experiments show an improvement from 80% to 96.5% in terms of F1-score. The results show that the approach enables the trained algae classification systems to effectively cover algae with limited image data.

The inefficiency of conventional water treatment technologies for the treatment of antibiotics has become a global concern. Herein, a promising photoelectrocatalytic (PEC) system enhanced by PMS was developed to treat antibiotics in drinking water in which a modified molybdenum disulfide embedded carbon cloth photoanode (namely 1T/2H-MoS2@C/CC, 1T and 2H for hexagonal and trigonal structures) served as a photoanode. The 1T/2H-MoS2@C/CC photoanode exhibited enhanced PEC performance due to the construction of the 1T rich structure. Under the synergetic effect of PEC and PMS, 2 ppm norfloxacin was completely removed in 30 min by the 1T/2H-MoS2@C/CC photoanode at a 1.5 V applied potential with 40 ppm PMS addition. Mechanistic investigations demonstrated that O-1(2), HO center dot, SO4 center dot- and O-2(center dot-) contributed to norfloxacin degradation, and the PMS activation pathways for the generation of these reactive species were also revealed. The intermediates of NOR degradation by the PEC/PMS system were analyzed, suggesting that the C-N bond, piperazine ring, and fluoride group on NOR molecular framework were attacked. The resistance of the PEC/PMS system to different water matrices and good reusability (87.6% at the fifth cycle) and stability (0.05 mg/L Mo4+ leaching) of the 1T/2H-MoS2@C/CC photoanode ensured the excellent practical potential of the developed PEC/PMS system. Overall, the PEC/PMS system with 1T/2H-MoS2@C/CC as the photoanode is proven to be feasible for practical antibiotics removal from drinking water.

Conventional wastewater treatment plants (WWTPs) suffer from high carbon emissions and are inefficient in removing emerging organic pollutants (EOPs). Consequently, we have developed a low operational carbon emissions multifunctional photoelectrochemical (PEC) system for saline sewage treatment to simultaneously remove organic pollutants, ammonia, and bacteria, coupled with H2 evolution. A reduced BiVO4 (r-BiVO4) photoanode with enhanced PEC properties, ascribed to constructing sufficient oxygen vacancies and V4+ species, was synthesized for the aforementioned technique. The PEC/r-BiVO4 process could treat saline sewage to meet local WWTPs' discharge standard in 40 min at 2.0 V vs Ag/AgCl and completely degrade carbamazepine (one of EOPs), coupled with 633 μmol of H2 production; 93.29% reduction in operational carbon emissions and 77.82% decrease in direct emissions were achieved by the PEC/r-BiVO4 process compared with large-scale WWTPs, attributed to the restrained generation of CH4 and N2O. The PEC system activated chloride ions in sewage to generate numerous reactive chlorine species and facilitate •OH production, promoting contaminants removal. The PEC system exhibited operational feasibility at varying pH and total suspended solids concentrations and has outstanding reusability and stability, confirming its promising practical potential. This study proposed a novel PEC reaction for reducing operational carbon emissions from saline sewage treatment.

Metals produced as by-products of the electroplating process pose threats to both human and environmental health, so it is important that they are removed from electroplating effluents. In this study, a dual-function hydrogel composite, prepared from a pair of cationic and anionic hydrogel composites via a facile method, was tested in batch and in a fluidized-bed column to treat a simulated electroplating effluent. For the batch treatment, both adsorption and desorption reached equilibrium within 30 min, showing the dual-function composite's fast adsorption capacity. Additionally, the removal efficiency was found to be pH-independent, and insignificant effect was found in the co-presence of monovalent ions (up to 10 meq L-1). Reusability of the dual-function composite was tested for six cycles, where the treated effluent consistently met discharge standards, and the reused adsorbent was confirmed by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy to be highly stable. The fast settling by gravity of the dual-function composite in batch motivated further studies of the material in a fluidized-bed column. Process variables such as feed flow, airflow, and adsorbent's bed depth were optimized using response surface methodology (RSM). Using an optimal solution, the model predicted a treatable cationic volume of 1045 mL and an anionic volume of 1695 mL; their corresponding experimental values were 1028 and 1680 mL. Therefore, in terms of practicality (fast removal, pH-independence, high stability, and gravity-driven settling), the application of the dual-function composite in a fluidized-bed reactor has shown much promise for the simultaneous removal of post-electroplating cationic and anionic metals.

Conventional colloid filtration theory (CFT) uses the single collector contact efficiency (eta) to describe the mass transfer of colloids to a collector surface. However, this approach neglects the full complexity of the pore structure and flow field of real porous media. In this study, the porous medium geometry, flow field, and colloid mass transfer are quantified using a pore-network model (PNM). A database of pore scale eta is established by finite-element method to train a Neural-network model (NNM). The reasonable prediction of eta indicates the potential of using the developed NNMs as an alternative to correlation equations, which can free the users from repeated numerical simulation. In contrast to the prediction by conventional CFT, the value of eta in the PNM occurs as a distribution, which is dependent upon the geometry parameters of the PNM. The mean value of eta increases with the standard deviation of pore radius and decreases with the curvature number, but the dependency on coordination number is more complex. Upscaled values of the deposition rate coefficient (kd) corresponding to the distribution of eta are calculated by the breakthrough curves by PNMs. The prediction of kd by PNM is then compared with that by CFT. Results show that kd predicted by PNM shows more significant response to velocity change, and less remarkable response to colloid density change than kd predicted by CFT. The comparison between the flow velocity distribution between PNM and CFT shows that the high-velocity region of the flow field in the porous media has been neglected in CFT, which can lead to insufficient consideration of convection. The results of this work imply that it is necessary to consider the influence of the complex pore structure of porous media on the collection of colloids.

The inefficiency of conventional water treatment technologies for the treatment of antibiotics has become a global concern. Herein, a promising photoelectrocatalytic (PEC) system enhanced by peroxymonosulfate (PMS) was developed to treat antibiotics in drinking water in which a modified molybdenum disulfide embedded carbon cloth photoanode (namely 1T/2H-MoS2@C/CC) served as a photoanode. The 1T/2H-MoS2@C/CC photoanode exhibited enhanced PEC performance due to the construction of the 1T rich structure. Under the synergetic effect of PEC and PMS, norfloxacin was completely removed in 30 minutes by the 1T/2H-MoS2@C/CC photoanode at a 1.5 V applied potential with 40 ppm PMS addition. Mechanistic investigations demonstrated that 1O2 was the dominant reactive species for norfloxacin (NOR) degradation, and the PMS activation pathways for 1O2 generation were also revealed. The intermediates of NOR degradation by the PEC/PMS system were analyzed, suggesting that the C-N bond, piperazine ring, and fluoride group on NOR molecular framework were attacked. The resistance of the PEC/PMS system to different water matrices and good reusability and stability of the 1T/2H-MoS2@C/CC photoanode ensured the excellent practical potential of the developed PEC/PMS system. Overall, the PEC/PMS system with 1T/2H-MoS2@C/CC as the photoanode is proven to be feasible for practical antibiotics removal from drinking water.

The use of lanthanum for phosphate removal has gained increasing attention due to its relative abundance, non-toxicity, and strong affinity toward phosphate. In this regard, although lanthanum hydroxide exhibits promising phosphate removal ability, its practical application remains limited due to certain technical issues including its structural instability and leaching. To circumvent these issues, a lanthanum carbonatebased adsorbent was developed in this study. Lanthanum carbonate@anion exchange resin (LC@AER) and lanthanum hydroxide@anion exchange resin (LH@AER) beads were first prepared through in-situ precipitation using identical bead-to-precursor mass ratios. LC@AER beads were chosen for further study as they displayed better adsorption capacity and stability, and the bead-to-precursor mass ratio was further optimized to improve performance and stability. LC@AER (1:2) beads exhibited a maximum adsorption capacity of 77.43 mg-P/g and excellent selectivity toward phosphate in the presence of various co-existing anions. Experiments using river water indicated high phosphate removal efficiency, demonstrating potential for treating river water. Investigations revealed key differences in phosphate binding mechanisms for batch and column experiments. In batch setting, phosphate is primarily captured through ligand exchange and inner-sphere complexation. However, over prolonged column operation, surface precipitation and electrostatic attraction (between phosphate and quaternary ammonium) become increasingly important for binding phosphate, which may affect phosphate recovery efficiency and must be accounted for in process design. Overall, the findings indicate that lanthanum carbonate serves as a good alternative to lanthanum hydroxide and that LC@AER (1:2) beads are promising for phosphate removal. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

The mobility of nano zero-valent iron (nZVI) will greatly affect its practical application as a remediation material for contaminated groundwater. One-dimensional (1D) column tests are commonly used in previous work to study its migration behavior, but the two-dimensional (2D) test is still very limited. This study reports a novel research system to study the 2D transport and retention behavior of colloids and solutes, which includes a 2D model test setup and the corresponding image analysis method. The transport behaviors of methyl orange (MO), nZVI, and phosphate-loaded nZVI (PnZVI) are studied using this system. The results show that the research system can reasonably describe the tempo-spatial concentration distribution of colloids and solutes. After phosphate adsorption, the mobility of nZVI is enhanced due to the increase in negative surface charge, which implies a potential environmental risk of nZVI to facilitate contaminant transport. The migration of PnZVI is not significantly influenced by its density, which is faster than MO in the longitudinal direction. The range of the plume of PnZVI in the longitudinal direction is larger than that of MO, which implies that PnZVI has a stronger longitudinal dispersion than MO.