Poor Separation Research Articles

BiVO4 As a Sustainable and Emerging Photocatalyst: Synthesis Methodologies, Engineering Properties, and Its Volatile Organic Compounds Degradation Efficiency.

Bismuth vanadate (BiVO4) is one of the best bismuth-based semiconducting materials because of its narrow band gap energy, good visible light absorption, unique physical and chemical characteristics, and non-toxic nature. In addition, BiVO4 with different morphologies has been synthesized and exhibited excellent visible light photocatalytic efficiency in the degradation of various organic pollutants, including volatile organic compounds (VOCs). Nevertheless, the commercial scale utilization of BiVO4 is significantly limited because of the poor separation (faster recombination rate) and transport ability of photogenerated electron-hole pairs. So, engineering/modifications of BiVO4 materials are performed to enhance their structural, electronic, and morphological properties. Thus, this review article aims to provide a critical overview of advanced oxidation processes (AOPs), various semiconducting nanomaterials, BiVO4 synthesis methodologies, engineering of BiVO4 properties through making binary and ternary nanocomposites, and coupling with metals/non-metals and metal nanoparticles and the development of Z-scheme type nanocomposites, etc., and their visible light photocatalytic efficiency in VOCs degradation. In addition, future challenges and the way forward for improving the commercial-scale application of BiVO4-based semiconducting nanomaterials are also discussed. Thus, we hope that this review is a valuable resource for designing BiVO4-based nanocomposites with superior visible-light-driven photocatalytic efficiency in VOCs degradation.

Facile synthesis of ZIF‐67@PVA/CA nanofibrous aerogel as efficient and recyclable catalyst for the degradation of organic pollutants through peroxymonosulfate activation

AbstractMetal–organic frameworks (MOFs) are one of the most promising advanced heterogeneous catalysts for the activation of peroxymonosulfate (PMS) to degrade organic contaminants in water, and have been extensively studied. However, MOFs in powder form usually have the disadvantage of poor separation and regeneration, making it significantly challenging for practical applications. In this study, ultralight zeolitic imidazolate framework‐67@poly(vinyl alcohol)/citric acid nanofibrous aerogel (ZIF‐67@PVA/CA NFA) was prepared by a convenient and facile in‐situ growth method and it had excellent catalytic efficiency and recyclability. The factors affecting the activation of PMS by ZIF‐67@PVA/CA NFA, such as PMS concentration, reaction temperature, solution pH, and organic pollutant concentration, were investigated. Taking advantage of the distinctive structural characteristics of MOF and nanofibrous aerogels, the obtained ZIF‐67@PVA/CA NFA exhibited ultralow density, hierarchical porosity, remarkably high catalytic activity for activation of PMS for the degradation of organic pollutants. Furthermore, ZIF‐67@PVA/CA NFA also displayed excellent recyclability along with retention of high catalytic stability. The present study provides a new strategy for the efficient fabrication of three‐dimensional heterogeneous catalyst for the activation of PMS, with great potential in wastewater treatment.

Optimization of fluid flow in membrane chromatography devices using computational fluid dynamic simulations

Flow uniformity within the device is critically important in membrane chromatography. Recent studies have shown that the design of the device has a significant impact on flow uniformity, and thereby on separation efficiency. The main premise of this work is that computational fluid dynamics (CFD) could serve as a fast and inexpensive tool for preliminary optimization of the design of a membrane chromatography device. CFD also helps in identifying factors that affect flow uniformity. In this paper, CFD is used to compare the fluidic attributes of conventional membrane chromatography devices such as the stacked disc and radial flow devices with those of more recently developed ones such as the different versions of the laterally-fed membrane chromatography (LFMC) device. These are compared based on pulse tracer solute dispersion, which is a useful metric for measuring flow uniformity, and is thereby a good predictor of chromatographic separation performance. The poor separation performance typically observed with conventional membrane chromatography devices could be attributed to the high degree of solute dispersion within these devices. CFD is then used to analyze the impact of factors such as membrane aspect ratio, and channel dimensions on the performance of z2-laterally-fed membrane chromatography (z2LFMC) devices. The results discussed in the paper demonstrate that CFD could indeed serve as a powerful optimization and performance prediction tool for membrane chromatography.

Combing Hollow Shell Structure and Z-Scheme Heterojunction Construction for Promoting CO2 Photoreduction

CO2 photoreduction is considered one of the potential ways to achieve carbon neutralization since it uses green solar energy without introducing additional carbon sources during the process of converting CO2 to fuels. However, limited light utilization and poor charge separation often give rise to undesirable CO2 photoreduction performance. Herein, a generic approach using carbon spheres as templates to construct transition metal oxides with multishelled hollow structures is reported. The multishelled hollow structure has been proven to be efficient for improving CO2 photoreduction. Furthermore, we constructed a Z-scheme heterojunction photocatalyst (CdS/Au/ZnCrO4) through introducing CdS into a multishelled hollow ZnCrO4 sphere with Au nanoparticles as a charge transfer medium. Benefiting from the multishelled hollow structure’s induced light utilization and large surface area and Z-scheme heterojuncion promoted charge separation, a high CO production of 2.95 μmol g–1 h–1 was achieved on CdS/Au/ZnCrO4 without using any sacrificial agents, which was 18.4 times and 24.6 times higher than that of CdS and ZnCrO4. This work provides a generic method for constructing controllable multishelled hollow spheres and is expected to offer guidance for promoting CO2 photoreduction through structure regulation and heterojunction construction.

Facile Fabrication of Highly Active CeO2@ZnO Nanoheterojunction Photocatalysts.

Photocatalyst performance is often limited by the poor separation and rapid recombination of photoinduced charge carriers. A nanoheterojunction structure can facilitate the separation of charge carrier, increase their lifetime, and induce photocatalytic activity. In this study, CeO2@ZnO nanocomposites were produced by pyrolyzing Ce@Zn metal-organic frameworks prepared from cerium and zinc nitrate precursors. The effects of the Zn:Ce ratio on the microstructure, morphology, and optical properties of the nanocomposites were studied. In addition, the photocatalytic activity of the nanocomposites under light irradiation was assessed using rhodamine B as a model pollutant, and a mechanism for photodegradation was proposed. With the increase in the Zn:Ce ratio, the particle size decreased, and surface area increased. Furthermore, transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed the formation of a heterojunction interface, which enhanced photocarrier separation. The prepared photocatalysts show a higher photocatalytic activity than CeO2@ZnO nanocomposites previously reported in the literature. The proposed synthetic method is simple and may produce highly active photocatalysts for environmental remediation.

Nanostructured Tantalum Nitride for Enhanced Solar Water Splitting

High-performance solar-water-splitting technologies are of paramount interest for the cost-effective generation of hydrogen fuel; however, their realization is majorly limited by the poor solar light absorption and charge separation inside photoanode semiconductors. Herein, we develop photoanodes made from polycrystalline tantalum nitride nanorods (Ta3N5 NRs) to overcome the above-mentioned challenges. The morphology and crystalline properties of Ta3N5 NRs are optimized by tuning essential parameters of glancing angle deposition and nitridation techniques, respectively. Under a simulated AM1.5G solar spectrum, the photoanodes demonstrate a tremendous gain in photocurrent from 1.54 mA cm–2 to 10.96 mA cm–2 at 1.23 V versus reversible hydrogen electrode for water oxidation activity. Photoluminescence, transient diffuse reflectance spectroscopy, and theoretical analyses identify prominent factors (like charge carrier lifetime, diffusion length, etc.) responsible for the enhanced performance. Our work presents the significance of designing the narrow-energy band-gap photoanodes with broad implications toward efficient solar-water-splitting devices for green hydrogen production.

One-pot synthesis of porous graphitic carbon nitride with rich nitrogen vacancies and oxygen heteroatoms for boosting photocatalytic performance

Graphitic carbon nitride (g-C3N4), as an attractive photocatalyst, has been applied in environmental pollution control and energy conversion. However, its photocatalytic performance was plagued owing to the insufficient light absorption and poor photocarrier separation and transportation efficiencies. Herein, a porous g-C3N4 with rich nitrogen vacancies and oxygen heteroatoms was fabricated using a one-pot thermal polymerization method. Such method involves molecular homogenization of urea and ammonium bicarbonate, recrystallization of urea, and subsequent polycondensation and thermal stripping of g-C3N4 lamellas. The resultant g-C3N4 presents enriched exposed edges and interconnected open diffusion channels, and possesses abundant nitrogen vacancies and oxygen heteroatoms. This unique structure and composition of g-C3N4 contribute to exposure of active sites, migration of substrate and products, and visible light absorption in photocatalytic reactions. As expected, the design of nitrogen vacancies and oxygen heteroatoms in g-C3N4 modulated its electronic structure, thereby accelerating the photocarrier separation and further accelerating the output of •O2− radicals under light irradiation. The optimal g-C3N4 exhibited an extraordinary photodegradation performance for high concentration (C0 = 50 mg/L) of Rhodamine B. The photodegradation efficiencies are 97.5% and 99% in 90 min under visible light and sunlight irradiation, respectively. The work provides a porous g-C3N4 photocatalyst with intensified photocatalytic performance for environmental pollution control and emerging energy conversion.

Ni doped amorphous FeOOH layer as ultrafast hole transfer channel for enhanced PEC performance of BiVO4

Bismuth vanadate (BiVO4), as the potential and prospective photocatalyst, has been limited by the issue of poor separation and transfer of charge carrier for photoelectrocatalytic (PEC) water oxidation. Here, a significant increase of surface injection efficiency for BiVO4 is realized by the rationally designed Ni doped FeOOH (Ni:FeOOH) layer growing on BiVO4 photoanode (Ni:FeOOH/BiVO4), in which doped Ni2+ can induce partial-charge of FeOOH to serve as ultrafast transfer channel for hole transfer and transportation at the semiconductor/electrolyte interface. In addition, the Ni:FeOOH/BiVO4 shows the ηsurface value of 81.6 %, which is 3.28-fold and 1.47-fold of BiVO4 and FeOOH/BiVO4, respectively. The photocurrent density of Ni:FeOOH/BiVO4 is 4.21 mA cm−2 at 1.23 V vs. RHE, with the onset potential cathodically shifting 237 mV over BiVO4 and a long-term stability for suppressing surface charge recombination. The UPS and UV–Vis spectra have confirmed the type-II band alignment between Ni:FeOOH and BiVO4 for promoting carrier transfer. This facile and effective spin-coating method could deposit oxygen evolution catalysts (OECs) availably onto photoanodes with enhanced PEC water splitting.

Spatial Decoupling of Redox Chemistry for Efficient and Highly Selective Amine Photoconversion to Imines.

Light-driven primary amine oxidation to imines integrated with H2 production presents a promising means to simultaneous production of high-value-added fine chemicals and clean fuels. Yet, the effectiveness of this strategy is generally limited by the poor charge separation of photocatalysts and uncontrolled hydrogenation of imines to secondary amines. Herein, a spatial decoupling strategy is proposed to isolate redox chemistry at distinct sites of photocatalysts, and CoP core-ZnIn2S4 shell (CoP@ZnIn2S4) coaxial nanorods are assembled as the proof-of-concept photocatalyst. Directional and ultrafast carrier separation occurs between the CoP core and the ZnIn2S4 shell, as confirmed by in situ X-ray photoelectron spectroscopy, surface photovoltage spectroscopy, and transient absorption spectroscopy analyses. Toward the photoconversion of model substrate benzylamine to N-benzylbenzaldimine, CoP@ZnIn2S4 exhibits a 48-time higher production rate and >99% selectivity when compared to ZnIn2S4 (ca. 20% selectivity), and the detailed reaction mechanism has been verified by in situ diffuse reflectance infrared Fourier transform spectroscopy.

Determining Phase Separation Dynamics with an Automated Image Processing Algorithm.

The problems of extracting products efficiently from reaction workups are often overlooked. Issues such as emulsions and rag layer formation can cause long separation times and slow production, thus resulting in manufacturing inefficiencies. To better understand science within this area and to support process development, an image processing methodology has been developed that can automatically track the interface between liquid-liquid phases and provide a quantitative measure of the separation rate of two immiscible liquids. The algorithm is automated and has been successfully applied to 29 cases. Its robustness has been demonstrated with a variety of different liquid mixtures that exhibit a wide range of separation behavior-making such an algorithm suited to high-throughput experimentation. The information gathered from applying the algorithm shows how issues resulting from poor separations can be detected early in process development.

Improved charge transfer in polymeric carbon nitride synergistically induced by the aromatic rings modification and Schottky junctions for efficient photocatalytic CO2 reduction

Polymeric carbon nitride (CN) is one of the most prospective non-metallic catalysts at present, yet its photocatalytic activity is unsatisfactory mainly due to the poor intramolecular charge carrier separation efficiency originated form its special electronic structure. Herein, we demonstrate a synergistic strategy to improve the charge carriers transfer and separation efficiency of CN synchronously by extending the π-conjugated system via incorporation of O-containing aromatic ring in the CN skeleton (Ar-CN) and constructing a Schottky junction via decoration of Au nanoparticles (Au Nps). The introduced O-containing aromatic ring can create a local asymmetry, delocalize the π-conjugated system of CN, and thus promote the in-plane charge transport of CN, while the formed loading of Au Nps can further promote interlayer charge transfer efficiency of Ar-CN. The optimized 3 %Au/Ar-CN photocatalyst exhibits a high photocatalytic CO2 activity with a CO yield of 32.03 μmol·g−1·h−1, which is higher than those of CN (2.38 μmol·g−1·h−1) and Ar-CN (6.42 μmol·g−1·h−1). This study provides a feasible co-modification strategy to enhance the charge transfer and photocatalytic activity of CN by extending the π-conjugation system and constructing Schottky junctions.

Designing an energy-efficient multi-stage selective electrodialysis process based on high-performance materials for lithium extraction

Membrane technologies demonstrate great promise for treating salt lake brines with high Mg/Li mass ratios. However, current coupled membrane processes suffer from many obstacles, including poor membrane separation performance, high energy consumption, noncontinuous processes, large space occupation, and process complexity. Herein, we designed the multi-stage selective electrodialysis (S-ED) process with high-performance monovalent cation exchange membranes (MCEMs) to treat simulated penetration water from a one-stage nanofiltration (NF) process. The mussel-inspired gallic acid/polyethyleneimine assembled membrane (M-GA/PEI) with specific architecture and charge properties demonstrated better separation performance than CSO (a commercial MCEM) during the multi-stage S-ED process. The first-stage and second-stage S-ED processes with high-performance M-GA/PEI showed lower energy consumption (0.029–0.039 kWh·mol−1Li and 0.011–0.014 kWh·mol−1Li, respectively) than those with CSO and other processes with commercial MCEMs for lithium extraction (0.040–3.795 kWh·mol−1Li). This indicated that M-GA/PEI could be deployed as a substitute for commercial MCEMs to reduce the operation costs. This study provides new insights into the design of a multi-stage coupled membrane process (one-stage NF + first-stage S-ED + second-stage S-ED) based on high-performance materials for energy-efficient lithium extraction from salt lake brines towards a sustainable energy-water nexus.

Unconventional Substitution for BiVO4 to Enhance Photoelectrocatalytic Performance by Accelerating Polaron Hopping.

Bismuth vanadate (BiVO4) as a fascinating semiconductor for photoelectrocatalytic (PEC) water oxidation with suitable band gap (Eg) has been limited by the issue of poor separation and transportation of charge carriers. Herein, we propose an unconventional substitution of V5+ sites by Ti4+ in BiVO4 (Ti:BiVO4) for the similar ionic radii and accelerated polaron hopping. Ti:BiVO4 increased the photocurrent density 1.90 times up to 2.51 mA cm-2 at 1.23 V vs RHE and increased the charge carrier density 1.81 times to 5.86 × 1018 cm-3. Compared with bare BiVO4, Ti:BiVO4 improves the bulk separation efficiency to 88.3% at 1.23 V vs RHE. The DFT calculations have illustrated that Ti-doping modification could decrease the polaron hopping energy barrier, narrow the Eg, and decrease the overpotential of the oxygen evolution reaction (OER) concurrently. With further spin-coated FeOOH cocatalyst, the photoanode has a photocurrent density of 3.99 mA cm-2 at 1.23 V vs RHE. The excellent PEC performance of FeOOH/Ti:BiVO4 is attributed to the synergistic effect of the FeOOH layer and Ti doping, which could promote charge carrier separation and transfer by expediting polaron migration.

Single-Crystalline Bi2YO4Cl with Facet-Aided Photocarrier Separation for Robust Solar Water Splitting

Bi2YO4Cl is a robust mixed-anion compound suitable for solar water splitting but generally delivers a mediocre catalytic level due to poor separation of photocarriers (e– and h+). In this work, we have modified Bi2YO4Cl by facet-engineering techniques, which generate plate-like single crystals dominantly exposing {001} and {100} crystal facets. These two sets of crystal facets are of diverse energy states, thereby setting up an internal built-in electric field that can readily separate and guide the flow of photocarriers. Thanks to this facet-aided charge separation mechanism, the faceted Bi2YO4Cl single crystals deliver much higher activities for solar water splitting reactions than conventional counterparts. Notably, the faceted Bi2YO4Cl single crystals can achieve apparent quantum efficiency as high as 7.51 and 2.52% at 420 ± 20 nm for photocatalytic O2- and H2-evolution from water, respectively. Stable overall water splitting under visible light illumination (λ ≥ 420 nm) has also been attained by merging the faceted Bi2YO4Cl single crystals into a Z-scheme system. As a photoanode material, the faceted Bi2YO4Cl single crystals can reach a high photocurrent density of ∼1.57 mA·cm–2 at 1.23 V vs RHE under AM 1.5G with a Faradic efficiency of almost unity.

Exploring the Use of Raman Spectroscopy and Covariate-Adjusted Multivariate Analysis for the Detection of Irradiated Blood.

Biological dosimetry is a key technique for retrospective radiation dosimetry that provides individual estimates of absorbed dose of ionizing radiation, applicable for use in a large scale radiological/nuclear event. Current techniques for biodosimetry are labor intensive and time consuming and not high through-put. In this proof-of-concept study, we developed a new approach for detecting irradiated blood based on Raman spectroscopy of blood combined with multivariate analysis. Peripheral blood samples from 8 healthy male and female, anonymous donors, were exposed to either 5 Gy X ray radiation or unirradiated (0 Gy). At 3 h postirradiation, the blood was immediately frozen at -80°C. Raman spectra were measured from thawed blood using a portable spectrometer system. Data were preprocessed and analyzed using principal component analysis (PCA) to observe trends in the data, and by using partial least squares-discriminant analysis (PLS-DA) to build a model to discriminate between Raman spectra of control (0 Gy) and irradiated (5 Gy) blood. We found strong evidence of inter-donor variability in the form of donor-wise clustering of PCA scores corresponding to the control Raman spectra, in addition to the poor separation of PLS-DA scores associated with Raman intensities of 0 Gy vs. 5 Gy spectra. However, after adjustment for donor covariates using a linear mixed-effects model, we obtained a better separation between control and irradiated blood using PLS-DA. Evaluation of the coefficients of the PLS-DA loading vectors indicated radiation-induced changes in proteins, lipids and hemoglobin to be major contributors for this discrimination. This pilot study demonstrates the potential of application of Raman spectroscopy to support biodosimetry of blood and blood components.

Facile Approach for the Potential Large-Scale Production of Polylactide Nanofiber Membranes with Enhanced Hydrophilic Properties

Polylactide (PLA) nanofiber membranes with enhanced hydrophilic properties were prepared through electrospinning. As a result of their poor hydrophilic properties, common PLA nanofibers have poor hygroscopicity and separation efficiency when used as oil-water separation materials. In this research, cellulose diacetate (CDA) was used to improve the hydrophilic properties of PLA. The PLA/CDA blends were successfully electrospun to obtain nanofiber membranes with excellent hydrophilic properties and biodegradability. The effects of the additional amount of CDA on the surface morphology, crystalline structure, and hydrophilic properties of the PLA nanofiber membranes were investigated. The water flux of the PLA nanofiber membranes modified with different CDA amounts was also analyzed. The addition of CDA improved the hygroscopicity of the blended PLA membranes; the water contact angle of the PLA/CDA (6/4) fiber membrane was 97.8°, whereas that of the pure PLA fiber membrane was 134.9°. The addition of CDA enhanced hydrophilicity because it tended to decrease the diameter of PLA fibers and thus increased the specific surface area of the membranes. Blending PLA with CDA had no significant effect on the crystalline structure of the PLA fiber membranes. However, the tensile properties of the PLA/CDA nanofiber membranes worsened due to the poor compatibility between PLA and CDA. Interestingly, CDA endowed the nanofiber membranes with improved water flux. The water flux of the PLA/CDA (8/2) nanofiber membrane was 28,540.81 L/m2·h, which was considerably higher than that of the pure PLA fiber membrane (387.47 L/m2·h). The PLA/CDA nanofiber membranes can be feasibly applied as an environmentally friendly oil-water separation material because of their improved hydrophilic properties and excellent biodegradability.

Ni-Doped BiVO4 photoanode for efficient photoelectrochemical water splitting

BiVO4 (BVO) based photoanode is one of the most mega-potential materials for solar water splitting while suffers from poor charge transfer and separation efficiency limit its practical application. Herein, FeOOH/Ni-BiVO4 photoanode synthesized by the facile wet chemical method were investigated for improved charge transport and separation efficiency. The photoelectrochemical (PEC) measurements demonstrate that the water oxidation photocurrent density can reach as high as 3.02 mA cm−2 at 1.23 V vs RHE, and the surface separation efficiency can be boosted to 73.3 %, which increases around 4 times comparing with that of pure sample. Further depth studies showed that the Ni doping can effectively promote hole transport/trapping and introduce more active sites for the oxidation of water, while FeOOH co-catalyst could passivate the Ni-BiVO4 photoanode surface. This work provides a model for the design of BiVO4-based photoanodes with combined thermodynamic and kinetic advantages.

Hetero‐Janus Nanofibers as an Ideal Framework for Promoting Water‐pollutant Photoreforming Hydrogen Evolution

Photoreforming hydrogen evolution (Pr‐HE) of a water‐pollutant system could simultaneously achieve efficient hydrogen production and pollutant degradation. It provides a new way to solve energy and environmental issues, but the poor internal charge separation still limits its performance. This work designed hetero‐Janus nanofibers (HJNFs) with ordered electric field distribution and separated redox surfaces to promote Pr‐HE of the water‐pollutant system. Taking ZnO/NiO heterojunction as an example, the hetero‐Janus structures were prepared via “Dual‐channel” electrospinning and further confirmed by the element morphology analysis and asymmetric distribution of the XPS spectra. The theoretical simulation showed that Janus structures could effectively inhibit the electron trap and hole trap generation, then accelerate the directional carrier migration to the surface. Experimental investigations also confirmed that Janus structures could effectively suppress internal exciton luminescence and accelerate surface charge transfer. The Pr‐HE amount and the corresponding propranolol (PRO) degradation rate of HJNFs were 7.9 and 1.5 times higher than hetero‐mixed nanofibers (HMNFs). The enhancement factor of Pr‐HE in water‐PRO to pure water was about 3.1, but nearly zero for HMNFs. This prominent synergistic effect was due to the enhancement of charge separation and the inhibition of cascade side reaction from hetero‐Janus structures. Furthermore, the synchronous Pr‐HE and degradation reactions were significantly promoted by selective introducing Ag nanoparticles in one side of the HJNFs for enlarging the interfacial Fermi energy level difference. The hetero‐Janus strategy offers a new perspective on designing efficient photoreforming photocatalysts for energy and environment applications.

Euler Representation-Based Structural Balance Discriminant Projection for Machinery Fault Diagnosis

Fault diagnosis methods are usually sensitive to outliers and it is difficult to obtain and balance global and local discriminant information, which leads to poor separation between classes of low-dimensional discriminant features. For this problem, we propose an Euler representation-based structural balance discriminant projection (ESBDP) algorithm for rotating machine fault diagnosis. First, the method maps the high-dimensional fault features into the Euler representation space through the cosine metric to expand the differences between heterogeneous fault samples while reducing the impact on outliers. Then, four objective functions with different structure and class information are constructed in this space. On the basis of fully mining the geometric structure information of fault data, the local intra-class aggregation and global inter-class separability of the low-dimensional discriminative features are further improved. Finally, we provide an adaptive balance strategy for constructing a unified optimization model of ESBDP, which achieves the elastic balance between global and local features in the projection subspace. The diagnosis performance of the ESBDP algorithm is explored by two machinery fault cases of bearing and gearbox. Encouraging experimental results show that the algorithm can capture effective fault discriminative features and can improve the accuracy of fault diagnosis.

Two-dimensional gas chromatography coupled to isotope ratio mass spectrometry for determining high molecular weight polycyclic aromatic hydrocarbons in sediments

The accuracy of compound-specific isotope analysis (CSIA) of trace-level pollutants in complex environmental samples has always been limited by two main challenges: poor chromatographic separation and insufficient amounts of analytes. In this study, a two-dimensional gas chromatography-isotope ratio mass spectrometry (2DGC-IRMS) system was constructed for compound-specific δ13C analysis of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) in estuarine/marine sediments. This construction occurred through hyphenating an extra gas chromatography system (GC) to a conventional GC-IRMS using a commercially available multi-column switching-cryogenic trapping system (MCS-CTS). Compared with the previous 2DGC-IRMS strategy, which utilizes a Deans Switch device, the newly implemented 2DGC-IRMS scheme resulted in online purification of target analytes as well as enriched them online via duplicate injection and cryogenic trapping in CTS; this resultingly lowered the limits of detection (LOD) of CSIA. To improve the sample transfer efficiency to the IRMS, a broader-bore and longer fused-silica capillary was utilized to replace the original sample capillary running from the sample open split to the IRMS. A ẟ13C analysis of PAH standards showed accurate ẟ13C values, and high precisions (standard deviations 0.13–0.37%) were achieved, with the LOD of HMW-PAHs reduced to at least 1.0 mg/L (i.e., 0.07 to 0.09 nmol carbon per compound on-column). The successful application of this newly developed 2DGC-IRMS scheme provides a practical solution for the reliable CSIA of trace-level pollutants in complex environmental samples that cannot be measured using the conventional GC-IRMS system.