One-pot synthesis of isotype heterojunction g-C3N4-MU photocatalyst for effective tetracycline hydrochloride antibiotic and reactive orange 16 dye removal

The one-pot synthesis of g-C₃N₄-MU isotype heterojunction has been produced by the thermal polycondensation method by mixing different ratios of precursors between melamine and urea. The isotype heterojunction g-C₃N₄-MU samples were characterized by X-ray diffraction spectroscopy, scanning electron microscope and energy-dispersive X-ray-spectroscopy, UV–Visible diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The band-gap energy of these photocatalysts reveals that they can work well under visible light. The photocatalytic performance of the samples was investigated over the photodegradation of reactive orange-16 (RO-16) dye and tetracycline hydrochloride (TC-HCl) under visible light irradiation. The isotype heterojunction of g-C₃N₄-M6U10 showed the highest degradation of 95 and 85.6% for RO-16 and TC-HCl, respectively under irradiation time of 100 and 120 min. The major reactive species was identified as O₂^–. Moreover, the reusability of the photocatalyst was investigated up to 3 cycles with good efficiency. The present synthesized isotype heterojunction g-C₃N₄-MU could be applied as a facile pathway for synthesis and as an effective pathway to resolve various environmental problems.     

Construction of hybrid g-C3N4/CdO nanocomposite with improved photodegradation activity of RhB dye under visible light irradiation

The hybrid graphitic carbon nitride-cadmium oxide (g-C₃N₄/CdO) nanocomposite was fabricated using chemical precipitation and self-assembly method. The photocatalysts were characterised by XRD, XPS, FTIR, BET, TEM, FESEM, UV-Vis and PL spectroscopy. Based on the optical study, visible light harvesting was improved and the band gap of bulk g-C₃N₄ to hybrid g-C₃N₄/CdO nanocomposite was greatly reduced from 2.72 eV to 2.35 eV, signifying a better charge carrier mobility. The photocatalytic activity were further assessed by conducting rhodamine B (RhB) photodegradation reaction using visible light. An excellent dye removal efficiency of 96% was achieved when 1.5 g/L of hybrid g-C₃N₄/CdO nanocomposite was used with an initial concentration of 10 ppm for 120 min whereas only 66% of RhB was removed by bulk g-C₃N₄ within the same operating conditions. Besides, reusability tests were carried out and evidenced that hybrid g-C₃N₄/CdO nanocomposite can be recycled up to four times by retaining the degradation efficiency. The scavenging studies confirmed that the RhB photodegradation using hybrid g-C₃N₄/CdO nanocomposite was controlled by valance band h⁺ and O²⁻ oxidation reactions. Conclusively, the inclusion of CdO onto g-C₃N₄ resulted in remarkable photocatalytic activity for dye degradation applications.     

MIL-88A grown in-situ on graphitic carbon nitride (g-C3N4) as a novel sorbent: Synthesis,characterization, and high-performance of tetracycline removal and mechanism

The extensive and accumulative use of tetracycline (TC) in the environment has become a serious problem. In this study, MIL-88A/g-C₃N₄ micro-nano particles were successfully prepared through a simple, low-cost, one-step hydrothermal method for TC adsorption in water. At a pH of 7.0, the maximum adsorption capacity (154.51 mg·g⁻¹) of MIL-88A/g-C₃N₄ is reached at room temperature. Owing to its porous structure and large pore size (>2.06 nm) of MIL-88A/g-C₃N₄, TC can be adsorbed on both external and internal surfaces. Kinetic and thermodynamic studies have shown that the pseudo-second-order kinetic and the Langmuir-Freundlich model can be used to describe the adsorption process, which is a spontaneous endothermic process. The mechanism study reveals that the TC adsorption process by MIL-88A/g-C₃N₄ is mainly through electrostatic interaction and the ion exchange of COOH and NH₂ groups on MIL-88A/g-C₃N₄ to TC. After simple pickling and water washing, MIL-88A/g-C₃N₄ can still reach 83.1% of the original adsorption capacity after five cycles, which proves that MIL-88A/g-C₃N₄ can be a promising adsorbent.     

A novel Z-scheme Bi4O5I2/NiFe2O4 heterojunction photocatalyst with reliable recyclability for Rhodamine B degradation

Construction of heterojunction with reusability is one of the effective ways to avoid secondary pollution and strengthen photocatalysis. Herein, a magnetically recyclable Z-scheme Bi₄O₅I₂/NiFe₂O₄ heterojunction photocatalyst was successfully fabricated by a two-step hydrothermal method. Through adjusting the theoretical molar proportion of NiFe₂O₄ to Bi₄O₅I₂, it was verified that the optimal composite could decompose 98.5% Rhodamine B (RhB, 10 mg/L) within 60 min under simulative sunlight and 98.1% RhB within 80 min under visible light. According to the characterizations, the superior performance was mainly associated with the small band gap energy (2.44 eV) and efficient separation of photo-generated electrons and holes caused by the formation of heterojunction. Meanwhile, the enlarged specific area (27.6 m²/g) provided many adsorptive sites and active sites to improve the reaction further. Moreover, the trapping experiment indicated that the photodegradation involved O₂^–, OH and h⁺. After confirming the reliable activity, reusability and stability of the photocatalyst, an inferred mechanism was shown. In summary, the design of this magnetically recyclable Z-scheme Bi₄O₅I₂/NiFe₂O₄ heterojunction photocatalyst can become a new choice to purify wastewater.     

Construction of CoTiO3/BiOI p-n heterojunction with nanosheets-on microrods structure for enhanced photocatalytic degradation of organic pollutions

Herein, a novel CoTiO₃/BiOI (CTOB) p-n heterojunction with nanosheets-on microrods structure were prepared via a simple coprecipitation method for the first time. The catalysts were carefully characterized by various instruments. The CTOB heterostructures display improved photocatalytic performance towards RhB degradation. Among CTOB composites, CTOB-15 exhibits the optimal photocatalytic performance. Moreover, CTOB-15 also shows enhanced photocatalytic activity for MO and TC degradation compared to bare catalysts. The degradation rate constants for RhB and MO by CTOB-15 heterostructure are ca 1.6 and 1.4-fold higher than bare BiOI. The improved photocatalytic performance could be on account of the efficient separation of photoinduced carriers as well as enhanced light absorbance. Trapping experiments indicates that holes (h⁺) and superoxide anion radical (O₂^–) play a significant role in the removal of RhB by CTOB composites. The excellent photocatalytic activity and stability make it a promising photocatalyst in environmental remediation.     

Construction of hierarchical FeIn2S4/BiOBr S-scheme heterojunction with enhanced visible-light photocatalytic performance for antibiotics degradation

Constructing heterojunction provides a promising tactic to improve the photocatalytic efficiency of catalysts. In this paper, hierarchical FeIn₂S₄/BiOBr heterostructure photocatalysts were prepared by facile two step methods and applied to effectively remove ciprofloxacin (CIP) and tetracycline (TC) under visible light. Compared to single catalyst, FeIn₂S₄/BiOBr hybrids display significantly improved photocatalytic activity. Among the series, 6 wt% FeIn₂S₄/BiOBr shows the optimal photocatalytic performance, where the degradation efficiencies of TC and CIP are 3.15 and 2.88 times greater than pure BiOBr, respectively. Such an improvement could arise from the S-scheme heterojunctions and unique hierarchical structures, which brings stronger light absorption, higher photoexcited charge separation efficiency and superior redox ability. Furthermore, 6 wt% FeIn₂S₄/BiOBr composite exhibits excellent stability and reusability. Radical capture experiments and EPR analyses uncover that O₂^–, h⁺ and OH are primarily reactive substances during photocatalytic removal of TC. The products of TC were detected by LC-MS analyses and possible decomposition paths are proposed. Eventually, a possible photodegradation mechanism over FeIn₂S₄/BiOBr S-scheme heterojunction is proposed. These findings supply new perspective for the simple synthesis of S-scheme photocatalysts with promising applications in environment remediation.     

Novel porous perovskite composite CeO2@LaMnO3/3DOM SiO2 as an effective catalyst for activation of PMS toward oxidation of urotropine

Perovskites with stable crystal structure and excellent catalytic performance have attracted extensive attention in peroxomonosulfate (PMS) activation, however, severe agglomeration has always been the main obstacle limiting the catalytic activity of them, so novel perovskite catalysts are urgently needed. In this study, three-dimensional ordered macroporous silica (3DOM SiO₂) was prepared by colloidal crystal template method, then CeO₂@LaMnO₃/3DOM SiO₂ was prepared by sol-gel method combined with impregnation method and used to activate PMS for urotropine (URO) degradation. CeO₂@LaMnO₃/3DOM SiO₂ activated PMS system exhibited high URO removal efficiency and quick kinetic, as 99.98 % URO was degraded even within 30 min. The catalyst has a wide pH range and still has high catalytic activity in the presence of organic matter and inorganic ions. The three components in CeO₂@LaMnO₃/3DOM SiO₂ showed a synergetic effect. CeO₂ and LaMnO₃ were uniformly loaded on 3DOM SiO₂, which effectively avoided agglomeration. The specific surface area of CeO₂@LaMnO₃/3DOM SiO₂ was 11.88 times that of LaMnO₃ prepared by sol-gel method. There are two redox cycles of Ce³⁺/Ce⁴⁺ and Mn²⁺/Mn³⁺/Mn⁴⁺ in CeO₂ and LaMnO₃, respectively, which synergistically realize the activation of PMS. Both quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that that SO₄^?, OH and ¹O₂ jointly achieved the degradation of URO. In summary, CeO₂@LaMnO₃/3DOM SiO₂ would be a promising candidate for practical wastewater treatment.     

A novel and multifunctional flame retardant nucleating agent towards superior fire safety and crystallization properties for biodegradable poly (lactic acid)

In engineering application area, it has always been a challenge to simultaneously improve flame-retardant performance and crystallization rate of polylactic acid (PLA) biomaterials, thus restricting their extensive application. In this work, a multifunctional additive (4,4′-(phenylphosphoryl)bis(piperazine-4,1-diyl))bis(diphenylphosphine oxide) (PDPO) was successfully synthesized and used to fabricate flame retardant PLA biocomposites. The crystallization behavior, fire safety, mechanical properties and flame retardant mechanisms of PLA biocomposites were studied in detail. The results indicated that PDPO notably improved the crystallization rate and crystallinity of PLA biocomposites. When 4 wt% PDPO was incorporated, PLA/PDPO biocomposites successfully passed UL-94V-0 grade and their LOI values were improved from 19.0% of pure PLA to 29.4%. The introduction of PDPO promoted the premature degradation and carbonization of PLA substrate, and inhibited the transesterification of the PLA during thermal pyrolysis process. Besides, PDPO decomposed and produced the Ph and PO, which efficiently exerted the free radical trapping effect in vapor phase. Therefore, the spread of fire for PLA/PDPO was declined and even self-extinguished. Meanwhile, the low addition of PDPO presented little effect on the mechanical properties of PLA composites. This flame retardant PLA biocomposites showed broad application prospects in emerging fields such as electronic devices, automobiles, and 3D printing materials.     

Synergistic effect of visible-light-driven FeOOH@Bi2MoO6 for removal of ciprofloxacin over a wide pH range: Efficient separation of photogenerated carriers and fast Fe(III)/Fe(II) cycling

Fabrication of FeOOH@Bi₂MoO₆ composites was successfully carried out by the solvent thermal-impregnation method, and they were used as effective visible light-driven photo-Fenton catalysts. The catalyst can achieve effective degradation of CIP in the pH range of 3.5–10.5, which overcomes the problems of harsh pH application conditions and low H₂O₂ utilization in Fenton. Notably, FeOOH@Bi₂MoO₆ exhibited stronger photo-Fenton catalytic activity compared with pure FeOOH, pure Bi₂MoO₆ and their simple physical mixtures, indicating that the interfacial active sites of FeOOH and Bi₂MoO₆ are favorable for the rapid transfer of photogenerated electrons from Bi₂MoO₆ to FeOOH. Combined with the characterization analysis and performance experiments, the catalytic mechanism of the FeOOH@Bi₂MoO₆-H₂O₂ system is reasonably proposed. The photocatalytic-Fenton synergy facilitates the rapid separation of photogenerated carriers and the valence cycling of Fe(III)/Fe(II), which drives the reaction system to produce a large amount of OH, O₂^? and a small amount of h⁺ to participate in the degradation process of CIP. In this study, the preparation of composite catalysts and the coupled use of photocatalytic-Fenton provided a feasible idea to overcome the problems of narrow pH application and low H₂O₂ utilization in Fenton.     

Anchoring Bi4O5I2 and AgI nanoparticles over g-C3N4 nanosheets: Impressive visible-light-induced photocatalysts in elimination of hazardous contaminates by a cascade mechanism

In this research, Bi₄O₅I₂ and AgI nanoparticles were anchored over g-C₃N₄ nanosheets (denoted as NGCN/Bi₄O₅I₂/AgI) to preparation highly impressive visible-light-driven samples. The synthesized nanocomposites were investigated by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), UV–vis diffuse reflectance spectroscopy (DRS), energy dispersive analysis of X-rays (EDX), electrochemical impedance spectroscopy (EIS), photocurrent density, Brunauer-Emmett-Teller (BET), and photoluminescence (PL) analyses. Among the ternary photocatalysts, the NGCN/Bi₄O₅I₂/AgI (20%) photocatalyst illustrated the highest photoactivity in degradation of rhodamine B (RhB), which was approximately 58.4, 15.2, and 12.8 times higher than the GCN, NGCN, and NGCN/Bi₄O₅I₂ (20%) samples, respectively. Furthermore, the O₂⁻ was discovered as the main species in the respective system by the quenching tests. Also, by studying the electrochemical properties, a cascade photocatalytic mechanism was suggested based on the energy bands to describe the enhanced charge carriers migration and separation, which caused impressive photocatalytic performances in degradations of four hazardous contaminants. This study highlights the rational anchoring of Bi₄O₅I₂ and AgI nanoparticles over NGCN to prepare highly efficient photocatalysts for wastewater remediation.     

Microwave-assisted synthesis of high efficient α-Fe2O3/BiOI composites and its performance in photocatalytic degardation of organic pollutants

Herein, we prepare novel composites of α-Fe₂O₃/BiOI photocatalysts by one step microwave hydrothermal process. The SEM and TEM characterization results suggest microsphere shaped of BiOI with α-Fe₂O₃ nanoparticles decorated on the surface of BiOI nanosheets. According to the results of UV-vis DRS measurements, α-Fe₂O₃/BiOI exhibited more visible light adsorption. The composite exhibited the highest photoactivity for decomposition of methyl orange (MO) and antibiotics tetracycline (Tc) superior to that of the pure α-Fe₂O₃ and BiOI in the visible light. The degradation rate constant is 2.3 times and 2.0 times higher than that of pure BiOI and α-Fe₂O₃ under the same conditions for degradation MO and Tc respectively. The photodegradation performances of α-Fe₂O₃/BiOI composites were also investigated under different light sources irradiation. Based on the analysis results of radical capture experiment, the enhanced photocatalytic efficiency of α-Fe₂O₃/BiOI photocatalyst can be mainly indentified to be the dominant active species of hole (h⁺) and superoxide radical(O₂⁻).     

The carboxylate magnetic – Zinc based metal-organic framework heterojunction: Fe3O4-COOH@ZIF-8/Ag/Ag3PO4 for plasmon enhanced visible light Z-scheme photocatalysis

In this work, magnetic nanoparticles (MNPs) grafted with carboxylic acid (Fe₃O₄-COOH MNPs) were successfully prepared from incorporation of glutaric anhydride as a functional group on the surface of the ferrite NPs. The MNP was used as a template to induce the growth of ZIF-8 metal–organic framework (MOF) on its surface. The Fe₃O₄-COOH@ZIF-8 core-shell was incorporated with silver phosphate (Ag₃PO₄) and Ag nanoparticles (Ag NPs) to develop a visible light active Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst. The materials were characterized using a range of techniques. The photocatalytic activity was investigated systematically by degrading an organo-phosphorus pesticide, diazinon under visible light irradiation. Among synthesized samples, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ heterostructured system exhibited highest photocatalytic activity and improved stability compared to others for the degradation of diazinon under visible light. The superior activity and improved stability of this heterostructured photocatalyst was attributed to the synergistic effects from surface plasmon resonance (SPR) of Ag NPs and sequential energy transfer via Z-scheme mechanism, for effective separation of electron-hole pairs. Radical-trapping experiments demonstrate that holes (h⁺) and O₂⁻ are primary reactive species involved in photocatalytic oxidation process. Moreover, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst did not show any obvious loss of photocatalytic activity during five cycle tests, which indicate that the heterostructured photocatalyst was highly stable and can be used repeatedly. Therefore, the work provides new insights into the design and fabrication of metal-organic frameworks (MOFs) for use as a visible light photocatalyst for degrading organic contaminants.     

Photocatalytic performance of graphene quantum dot incorporated UiO-66-NH2 composite assembled on plasma-treated membrane

The UiO-66-NH₂ and graphene quantum dot suspension were synthesized through hydrothermal and electrochemical methods, respectively. The prepared species were assembled on a non-woven polypropylene substrate (NW-PP). The obtained microstructure and the efficiency of the assembling methods were compared to each other. The results showed that plasma treatmentof NW-PP, as the pre-treating procedure, was the most liable strategy concerning the homogenous distribuation of MOF (mass loading percentage of ~19.5 wt% of UiO-66-NH₂) and improved filtering performance. Next, the photocatalytic performance against methylene blue was increased through addition of graphene quantum dot (GQD) to the NW-PP. The photoluminescence results confirmed that the presence of GQDs effectively inhibited the recombination of photogenerated electron/hole pairs. In addition, the photocatalytic constant rate was increased up to ~three times in the presence of GQDs. Quenching tests proved that the photo-generated O₂^? played a major role in the photodegradation of the dye.     

Activating nano-bulk interplays for sustainable ammonia electrosynthesis

Small changes in a catalyst’s composition, modification, and/or integration into a reactor can have significant yet often poorly understood effects on (electro)catalysis. Here we demonstrate the careful tailoring of Ru/La_0.25Ce_0.75O_2−x catalysts through the post-synthesized hydrothermal treatment together with control over the Ru loadings to create hydroxyl groups and electronic restructuring for ammonia electrosynthesis. When integrated into a protonic ceramic electrolyzer, the in situ formed Ce³⁺−OH/Ru sites facilitate both the NN decoupling and NH formation at 400 °C and 1 bar of N₂, boosting the ammonia production rate (2.92 mol h⁻¹ m⁻²) up to 100-fold higher than the current state-of-the-art electrolyzers. Moreover, such catalysts and electrolyzer design concepts can be readily tuned to more complex applications such as coproducing ammonia and other chemicals with hydrocarbons as direct hydrogen sources. The creation of coordinated saturated support –OH/metal sites in the advanced electrolyzer offers an attractive approach for future clean-energy and green-chemical industries.     

Chlorine doped graphitic carbon nitride nanorings as an efficient photoresponsive catalyst for water oxidation and organic decomposition

Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride (Cl-doped g-C₃N₄) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction (OER). Remarkably, Cl-doped g-C₃N₄ nanorings display enhanced OER performance with a small overpotential of approximately 290 mV at current density of 10 mA cm⁻² and Tafel slope of 83 mV dec^-1, possessing comparable OER activity to precious metal oxides RuO₂ and IrO₂/C. The excellent catalytic performance of Cl-doped g-C₃N₄ nanorings originates from the strong oxidation capability, abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 mV and 28 mV dec^-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C₃N₄ nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the OH radicals arising spontaneously on CN-Cl₁₀₀ catalyst upon light irradiation. This work establishes Cl-doped g-C₃N₄ nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application.     

Effects of NO2 gas concentration on the degradation of polyphenylene sulfide non-woven bag filter at high temperature

The influence of NO₂ concentration and exposure time on the degradation of polyphenylene sulfide (PPS) fabric filter at high temperature was investigated in detail. PPS fiber damage in the filter became more severe with increasing NO₂ concentration and exposure time. The elastic modulus of the PPS filter increased rapidly during the initial stage of exposure, and then increased more slowly to reach an almost constant value, nearly independent of NO₂ concentration. The tensile strength also decreased significantly during the initial stage, gradually attaining a constant value with increasing exposure time. Higher NO₂ concentrations resulted in rapid reducing of the tensile strength. Short exposure time to lower NO₂ concentrations caused the oxidation of S atoms in PPS to SO and OSO, whereas oxidation of benzene rings in PPS were induced only with longer exposure times and higher NO₂ concentrations. The model proposed in our previous paper accurately expresses the change in PPS conversion and reaction rate for every NO₂ concentration. An improved model that successfully estimated the degradation of tensile strength in both the machine direction and transverse direction, regardless of NO₂ concentration, was also proposed.     

An ultra-high performance for reduction of 4-nitroaniline with optimized noble-metal-free Bi4NbO8Cl nanosheets under visible light irradiation

The reduction conversion of 4-nitroaniline (4-NA) to p-phenylenediamine (PPD) via semiconductor photocatalysis has been considered as one of the most promising technologies to satisfy the requirement of modern industrial development. In this work, Bi₄NbO₈Cl materials with different calcination temperatures were successfully obtained by a facile synthesis method. Attractively, Bi₄NbO₈Cl nanosheet was put forward to catalyze 4-nitroaniline into p-phenylenediamine (PPD), which presented an ultra-high performance for the reduction of 4-nitroaniline under visible light irradiation. The optimal Bi₄NbO₈Cl nanosheets without an additive of noble metal cocatalyst can achieve conversion of 4-nitroaniline into p-phenylenediamine in 5 min. Furthermore, the crystal structure, optical properties, microscopic morphology, element chemical states, and photoelectrochemical properties of these photocatalysts were systematically investigated by various physical and chemical characterizations. Thereinto, Bi₄NbO₈Cl material displays a uniform morphology of nanosheets, and the size of nanosheets becomes larger and larger with the increase of calcination temperature. Simultaneously, prominent durability and reproducibility were accomplished via the above-mentioned photocatalyst. In addition, the CO₂^? radicals acting as primary active species can be confirmed by some controlled experiments and active species trapping experiments. This work provides a high-efficiency photocatalyst for the hydrogenation of 4-nitroaniline into p-phenylenediamine (PPD), and a possible reaction mechanism was uncovered and proposed.     

Non-firing ceramics: Activation of silica powder surface by a planetary ball milling

“Non-firing” ceramics have recently attracted much attention in recent years because many functional materials can be achieved by this method without the aid of sintering process. Amorphous silica powder was mechanically treated by a planetary ball mill system, by which the surface of powders was activated and simultaneously particle size reduced extensively. Surface of powders with different milling conditions was investigated by scanning electron microscopy (SEM) and nitrogen adsorption isotherm. The surface activity of raw and treated silica powders was measured based on the water adsorbed volume on the powder surface. Results showed that the powder surface was activated, and the silica powders were pulverized as an effect of ball milling. At milling times as short as 15?min, the powder was rubbed against balls, and the friction between particle/ball breaks the bonds of functional groups like SiOSi on the surface of particles. For longer milling times, powders were pulverized and more new active surfaces were formed.     

A continuous-flow exposure method to determine degradation of polyphenylene sulfide non-woven bag-filter media by NO2 gas at high temperature

The degradation behavior of polyphenylene sulfide (PPS) fabric filter media by NO₂ gas at high temperatures was investigated in detail with a continuous-flow type exposure method, as specified in ISO16891:2016. An increase in the exposure time to NO₂ gas lessened the tensile strength and elongation of the PPS filter media in both machine and transverse directions. These reductions were observed in the transverse direction (TD) more markedly than in the machine direction (MD). Exposure to NO₂ gas enhanced the oxidation of sulfur, and introduced new oxygen-containing functional groups (e.g., SO and OSO) into the PPS molecular structure, which reduced the atomic ratio of carbon in the PPS filter media with increasing exposure time. These chemical degradations severely damaged the PPS fiber through cracking, splitting, and formation of protrusions on the surface.Furthermore, assuming that the chemical reaction between PPS and NO₂ gas is diffusion-controlled by NO₂, a model to estimate the change in the conversion of PPS and the NO₂ concentration in the exhaust gas was proposed, based on an unreacted core model. It could successfully reproduce the experimental data. A model to evaluate the change in the tensile strength of the filter media was also proposed, which could express experimental data only in the MD.