Degradation Of Gaseous Formaldehyde Research Articles

Enhanced photocatalytic gaseous formaldehyde degradation using N-CQDs/OVs-TiO2 composite under visible light: Unraveling the synergistic effects of N-CQDs and oxygen vacancies

Limited utilization of photogenerated charge carriers in titanium dioxide under visible light have hinder its application development. To address this challenge, a novel N-doped carbon quantum dots (N-CQDs) and oxygen vacancies (OVs) synergistically decorated on TiO2 (P25) was synthesized through a facile one-step hydrothermal method. Under visible light irradiation, the first order reaction rate constants of formaldehyde (HCHO) photocatalytic oxidation by OVs-TiO2 and N-CQDs/OVs-TiO2 was significantly higher than that of pristine P25, with 10.1 and 16.7 folds increase, respectively. Characterization results confirmed the generation of OVs on the surface of N-CQDs/TiO2 composite. The optical and electrochemical experiments suggested the electron capture center effect of OVs and the properties of N-CQDs in unique up-converted photoluminescence, efficient charge separation, as well as significant adsorption in visible light region. In addition, the work function also clarified that photoelectrons could transfer from N-CQDs to OVs-TiO2. Furthermore, different relative humidity and electron paramagnetic resonance (EPR) experiments demonstrated that the hydroxyl radical (•OH) was the dominant reactive radical in HCHO photodegradation. The •O2− could also enhance the photodegradation efficiency of HCHO. This work provides an in-depth understanding on the complementary roles of N-CQDs and OVs and is helpful for designing metallic oxide photocatalysts for volatile organic compounds removal.

Nanodisk–like activated carbon-branched polyamine for adsorption and degradation of gaseous formaldehyde

The adsorption potential of activated carbon (AC) is determined to a large extent by an interplay between its surface functional groups and target pollutants like volatile organic compounds (VOCs). Herein, we present a new approach to improve such property through the creation of nanodisk-like material by modifying the surface and morphology of AC with branched polyamine (BPA). The formulated AC-BPA possesses large number of surface functional moieties (e.g., amine, –COOH, –OH, and Cl−) to facilitate physical, chemical, and reactive adsorption to tackle a common air pollutant such as formaldehyde (FA). Despite its reduction in surface area (relative to AC), AC-BPA was demonstrated to have a significantly large potential for reactive adsorption and catalytic oxidation (RACO) against FA with high adsorption capacity (82.3 mg g−1) and partition coefficient (PC = of 0.64 mol kg−1 Pa−1) under dry condition. Interestingly, a noticeable enhancement in its performance is attained by the presence of moisture (e.g., 100 % RH) as evidenced by adsorption capacity of 144.3 mg g−1 (PC of 1.25 mol kg−1 Pa−1). This can be attributed to its rich heteroatom content (e.g., COO− and Cl−), possibly inducing partial ionization of water molecules and generating secondary active sites for FA adsorption. In-situ diffuse reflectance infrared Fourier-transform spectroscopy revealed that AC-BPA catalyzed the chemical transformation of FA into methylol adducts, H2O, and CO2. These findings indicate that FA adsorption is primarily influenced by surface functional groups rather than by surface area. This study is expected to pave the way for designing metal-free high-performance RACO materials against FA under ambient conditions.

Synthesis of CeO2–BiVO4 nano photocatalyst material and used for the degradation of gaseous formaldehyde

Formaldehyde is one of the common volatile organic compound (VOC) found in indoor environment. Reducing indoor formaldehyde exposure levels is an important issue because toxicological studies have demonstrated its carcinogenicity. In this study, hydrothermal method was used to prepare ceria-bismuth vanadate (CeO2–BiVO4) composite photocatalyst. CeO2–BiVO4 has the advantages of high-efficiency photocatalytic activity, and high stability making it a promising photocatalytic material in the fields of energy conversion and environmental protection. As-prepared samples were characterized by X-ray diffraction (XRD), reflection ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). XRD, TEM, and SEM verified that the material was successfully prepared. The energy level was measured by UV–Vis, and it was verified by PL that the CeO2–BiVO4 can reduce the recombination rate of electron holes. Here, BiVO4 is added to reduce the band gap of CeO2 to produce a visible light-driven catalyst. The photodegradation reaction of formaldehyde is carried out by mixing in different proportions of BiVO4 in to CeO2. The light source used in this experiment is a green light. In the experiment of formaldehyde degradation by irradiating CeO2/BiVO4 with a green light, the concentration of product carbon dioxide (CO2) and water (H2O) increases with the irradiation time. The experimental results show that CeO2-BiVO4 (4:1) catalyst has the highest formaldehyde degradation rate of 78%, and the total reaction time is 240 min. The importance of CeO2–BiVO4 as a photocatalytic material in formaldehyde degradation is to provide an environmentally friendly and efficient method to purify indoor air. It can help reduce the potential harm of formaldehyde to human health, improve indoor air quality, and contribute to creating a healthier and more comfortable indoor environment.

Multi-contact prismatic spiky block titanium dioxide–graphene covalent composites for formaldehyde degradation

In this study, in situ solvothermal growth was carried out to fabricate multi-contact prismatic spiky block TiO2–graphene covalent composites (PTG) with unique morphologies. Prismatic conical TiO2 projections were uniformly formed on graphene sheets, yielding block PTG with Ti–C and Ti–O–C covalent bonds. The crystal structure and morphological properties of PTG were characterized, and its photocatalytic performance was evaluated. The covalent doping of graphene sheets resulted in the superior gaseous formaldehyde degradation activity of PTG compared to that of prickly spherical TiO2, with a degradation rate of 80.1% under visible light after 120 min. Electron paramagnetic resonance spectroscopy revealed that PTG displayed a sustained radical response and maintained high catalytic activity after five cycles of formaldehyde degradation. The reliable cycling stability and visible-light-induced photocatalytic activity of PTG suggest its potential for application in the field of hazardous gas degradation.

Thermocatalytic Degradation of Gaseous Formaldehyde Using Transition Metal-Based Catalysts.

Formaldehyde (HCHO: FA) is one of the most abundant but hazardous gaseous pollutants. Transition metal oxide (TMO)-based thermocatalysts have gained much attention in its removal due to their excellent thermal stability and cost-effectiveness. Herein, a comprehensive review is offered to highlight the current progress in TMO-based thermocatalysts (e.g., manganese, cerium, cobalt, and their composites) in association with the strategies established for catalytic removal of FA. Efforts are hence made to describe the interactive role of key factors (e.g., exposed crystal facets, alkali metal/nitrogen modification, type of precursors, and alkali/acid treatment) governing the catalytic activity of TMO-based thermocatalysts against FA. Their performance has been evaluated further between two distinctive operation conditions (i.e., low versus high temperature) based on computational metrics such as reaction rate. Accordingly, the superiority of TMO-based composite catalysts over mono- and bi-metallic TMO catalysts is evident to reflect the abundant surface oxygen vacancies and enhanced FA adsorptivity of the former group. Finally, the present challenges and future prospects for TMO-based catalysts are discussed with respect to the catalytic oxidation of FA. This review is expected to offer valuable information to design and build high performance catalysts for the efficient degradation of volatile organic compounds.

Singlet-oxygen-driven photocatalytic degradation of gaseous formaldehyde and its mechanistic study

Conventional studies on photocatalytic oxidation reaction have focused primarily on hydroxyl radical (•OH) as a major reactive oxygen species (ROS). This perspective may not be suitable for gaseous HCHO photodegradation due to the short lifetime and diffusion length of •OH. Identification of divergent ROS and understanding their characteristics for the gas-phase photocatalytic oxidation are further required. Here, we report a BiOI/TiO2 p-n junction photocatalyst, which uses mobile singlet oxygen (1O2) as the main ROS for gaseous HCHO photooxidation. The introduction of p-n heterojunctions causes a charge transfer that prefers mobile 1O2 generation rather than •OH due to an energetically favorable desorption free energy, accelerating HCHO oxidation. Finally, we demonstrated the photocatalytic filter performance of HCHO-to-CO2 conversion for 150 h with a conversion efficiency of 87 ± 1.3 % in a single-pass reactor. Our systematic study reveals the potential of the overlooked 1O2-driven gaseous HCHO photocatalytic degradation process.

Constructing S-scheme CeO2/CN heterojunction for high efficiency light-induced photothermal synergistic catalytic degradation of gaseous formaldehyde under visible light irradiation

An efficient light-induced photothermal synergistic strategy was proposed to achieve efficient photocatalytic degradation of gaseous formaldehyde based on an innovative 0D/2D S-scheme CeO2/CN heterojunction. The S-scheme photocatalyst shows excellent photocatalytic formaldehyde degradation activity under visible light irradiation, which can be attributed to the synergistic effect of the following aspects: (I) the S-scheme heterojunction: photogenerated carriers with stronger redox ability; (II) the increased interface migration channel and reduced interface contact resistance facilitated the migration and separation of photogenerated carriers; (III) light-induced photothermal effect improved the temperature of photocatalyst. The optimal photocatalytic HCHO degradation rate of the S-scheme CeO2/CN-1:1 is 20.3, 4.7 and 1.8 times that of CN, CN-1:1 and traditional type-II CeO2@CN-1:1, respectively. Therefore, this work not only provides an efficient strategy for elimination of formaldehyde pollutants, but also provides new ideas for the design of efficient photocatalysts for other kinds of VOCs pollutants in the future.

Facial construction of Pd/BiPO4 toward efficient photocatalytic oxidation of formaldehyde under UV light irradiation

In this paper, the facile hydrothermal technique was used to create a high-performance serial of Pd/BiPO4 photocatalysts, which were then used to degrade gaseous formaldehyde into CO2 and H2O in a photoreactor chamber without secondary contaminations under UV radiation. X-ray diffraction (XRD), Ultraviolet–visible spectroscopy, Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscope (FESEM) and photoluminescence spectra (PL) were used to characterize all the as-prepared Pd/BiPO4 samples. The photocatalytic performances of the as-prepared Pd/BiPO4 for the degradation of gaseous formaldehyde were investigated under UV irradiation. The experimental results manifested that Pd/BiPO4 exhibited higher photocatalytic activities, as compared to the pure BiPO4. Especially, 1% Pd/BiPO4 presented the highest photocatalytic performance for the degradation of formaldehyde, which improved the degradation efficiency up to81%after 240 min under UV irradiation. Moreover, based on experimental results a possible photocatalytic mechanism was proposed. The predicted reaction mechanism was also verified with the density functional theory (DFT) calculations with very similar results. As a result, this work provides a useful model for designing efficient photocatalysts for the elimination of air pollution.

Enhanced photocatalytic performance of visible-light-driven CuOx/TiO2-x for degradation of gaseous formaldehyde: Roles of oxygen vacancies and nano copper oxides

Photocatalysis is an effective method for the removal of formaldehyde (HCHO), and high-efficiency visible-light-driven photocatalysts were urgently required. Herein, oxygen vacancies (OVs) and nano copper oxides (CuOx) synergistically modified TiO2 (CuOx/TiO2-x) photocatalysts were synthesized by one-step hydrothermal followed by impregnation method. The photocatalytic decomposition of HCHO reached 100% at initial concentration of 180 ppm under relative humidity (RH) = 60% by 0.1g CuOx/TiO2-x in 150 min visible light irradiation. Characterization results explored the complementary effect of OVs and CuOx systematically. The OVs increased the separation efficiency of photogenerated charge carriers and act as adsorption/active sites in HCHO photocatalytic oxidation. The moisture and O2 were adsorbed and actived by OVs to generate reactive oxygen species (ROS). After doped CuOx on the surface of TiO2-x, the photoexcited electrons in Cu2O could transfer to the conduction band (CB) of TiO2-x and the photoexcited electrons of TiO2-x could be captured by Cu nanoparticles. Therefore, more ROS were generated due to the synergistic effect of OVs and CuOx. The In-situ Fourier transform infrared (in-situ FTIR) measurements show the hydroxyl radical (•OH) was the dominant radical in HCHO photocatalytic oxidation, while •O2− could also upgrade the photodegradation efficiency of HCHO. Furthermore, the stability tests showed the degradation efficiency of HCHO still reached 90% after five recycles, indicating that CuOx/TiO2-x nanocomposites displayed a stable and high photoactivity in volatile organic compounds (VOCs) decomposition.

Exploring the photocatalytic conversion mechanism of gaseous formaldehyde degradation on TiO2–x-OV surface

To understand the conversion mechanism of photocatalytic gaseous formaldehyde (HCHO) degradation, strontium (Sr)-doped TiO2–x–OV catalysts was designed and synthesized in this study, with comparable HCHO removal performance. Our results proved that foreign-element doping reduced Ti4+ to the lower oxidation state Ti(4– x)+, and that the internal charge kinetics was largely facilitated by the unbalanced electron distribution. Oxygen vacancies (OVs) were developed spontaneously to realize an electron-localized phenomenon in TiO2–x–OV, thereby boosting O2 adsorption and activation for the enhanced generation of reactive oxygen species (ROS). At the chemisorption stage, in-situ DRIFTS spectra and density functional theory calculation results revealed that surface adsorbed O2 (Oads) and lattice O (Olat) engaged in the isomerisation of HCHO to dioxymethylene (DOM) on TiO2–x–OV and TiO2, respectively. Time-resolved DRIFTS spectra under light irradiation revealed that the DOM was then converted to formate and thoroughly oxidized to CO2 and H2O in TiO2–x–OV. While bicarbonate byproducts were detected from DOM hydroxylation or possible side conversion of CO2 in TiO2, owing to insufficient consumption of surface hydroxyl. Our study enhances the understanding on the photocatalytic oxidation of HCHO, thereby promoting the practical application in indoor air purification.

Immobilization of Silver Doped Titanium Dioxide onto Stainless Steel Wire Mesh for Photocatalytic Degradation of Gaseous Formaldehyde under Visible Light Irradiation

Titanium dioxide (TiO2) photocatalysis can degrade air pollutants into nontoxic substances but it can only be excited by UV light. To eliminate this limitation, silver (Ag) and/or graphene oxide (GO) doped TiO2 are applied to enhance visible light photocatalytic activity. In this study, Ag-TiO2 (0.5%, 1%, 2% w/w), GO/TiO2 and GO/Ag-TiO2 were synthesized and then coated on stainless steel mesh. Crystalline and molecule structures, chemical compositions and optical properties of the prepared photocatalyst samples were characterized with X-ray diffraction spectroscopy, X-ray fluorescence spectroscopy, Raman spectroscopy, UV-visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, and Scanning electron microscopy equipped with Energy dispersive X-ray spectroscopy techniques. The photocatalytic performances of the various doped catalysts were evaluated according to their abilities to degrade gaseous formaldehyde (HCHO) under visible light. The effect of operational parameters on the photocatalytic degradation of HCHO including layer numbers of photocatalyst, powers of fluorescent lamp and flow rates of HCHO were observed. The results indicated that the presence of Ti, O and Ag elements in Ag-TiO2 and Ti, O, Ag and C elements in GO/Ag-TiO2 was confirmed. Proper dispersion of the photocatalyst on the wire mesh was exhibited. Under visible light, the incorporation of Ag and GO in TiO2 photocatalysts produced higher degradation rates of HCHO than pure TiO2. The optimum operating conditions of HCHO degradation at initial concentration of 108.71.15 ppm over visible light irradiation for 30 min were 5 layers of 0.5% Ag-TiO2, 72 W fluorescent light and 300 ml/min of HCHO flow rate. Under these conditions, the removal efficiency of gaseous HCHO was 76.70±0.73%.

Hollow N-TiO2/MnO2 nanocomposite based yeast biomass for gaseous formaldehyde degradation under visible light

Synthesis of new hollow nano-composite photocatalysts based yeast biomass has been considered as a future innovation technology to control air pollution. This work demonstrates that a green, environmentally friendly, sustainable, and facile hydrothermal carbonization route of low-cost and renewable yeast biomass used to fabricate natural doping N-colloidal carbon spheres (NCSs) as a hard template for hollow N-TiO2/MnO2. The presence of natural doping nitrogen serves as a stabilizer and reductant. Hence, the yeast provided a solid frame with deposits nitrogen to form the hybrid N/yeast precursor. The resulting NCSs were obtained by hydrothermal method at 180°C for 6h. The characterization was performed using SEM, TEM, XRD, FTIR and N2 adsorption/desorption analysis. It was found that the findings fully retained the morphology of the yeast cells and the size of the hollow spheres was about 1.5–2μm. The results of catalytic test showed that the new hollow nanosphere N-TiO2/MnO2 possessed a higher photodegradation activity for gaseous formaldehyde under visible irradiation than the commercial TiO2, due to their higher surface area (160m2g−1), hollow structure and superior reducibility. Its catalytic efficiency was attained to be more than 90%, which is about 10 times higher than that of the conventional catalyst TiO2–P25.

Constructing S-Scheme CeO <sub>2</sub>/CN Heterojunction for High Efficiency Light-Induced Photothermal Synergistic Catalytic Degradation of Gaseous Formaldehyde Under Visible Light Irradiation

Constructing S-Scheme CeO <sub>2</sub>/CN Heterojunction for High Efficiency Light-Induced Photothermal Synergistic Catalytic Degradation of Gaseous Formaldehyde Under Visible Light Irradiation

K, Na and Cl co-doped TiO2nanorod arrays on carbon cloth for efficient photocatalytic degradation of formaldehyde under UV/visible LED irradiation

A photocatalytic reactor of TiO2nanorod arrays on carbon cloth for gaseous formaldehyde degradation.

A novel composite of triangular silver nanoplates on BiVO4 for gaseous formaldehyde degradation

In this work, a series of Ag/BiVO4 photocatalysts with various Ag nanostructures, namely spherical silver nanoparticles (SAgNPs) and triangular silver nanoplates (TAgNPts), were synthesized for degrading formaldehyde. The as-prepared photocatalysts were characterized through a variety of analytical techniques, such as X-ray diffraction, ultraviolet–visible spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and photoluminescence spectroscopy. From the experiment results, among the various types of photocatalysts, 0.003 wt% TAgNPts on BiVO4 induced the highest photocatalytic degradation rate (83.9%) for gaseous formaldehyde under visible light illumination for 5 h. The HCHO degradation rate on TAgNPt/BiVO4 was higher than those on BiVO4 (74.5%) and SAgNP/BiVO4 (81.0%). In addition, Ag/BiVO4 retained over 95% of its initial photocatalytic activity after five test cycles. Therefore, this work provides a promising approach for designing efficient photocatalysts for gaseous formaldehyde removal.

Reduced Graphene Oxide–Titanium Dioxide Nanocomposites: Structural Characterization and Photocatalytic Degradation of Gaseous Formaldehyde

TiO2/rGO nanocomposites are prepared by the solvothermal process using titanium sulfate and graphene oxide (GO) as raw materials utilized for the photodegradation of gaseous formaldehyde. Characterization by Fourier‐transform infrared (FTIR) spectroscopy, Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS) reveal that GO is partially reduced to reduced GO (rGO) and TiOC bond is formed between TiO2 and rGO. X‐ray diffraction (XRD) confirms that the presence of anatase TiO2. High‐resolution transmission electron microscopy (HRTEM) exhibits that TiO2 nanoparticles with a diameter of ≈20 nm are uniformly loaded on the wrinkled rGO sheets. UV‐vis spectroscopy reveals that the absorption intensity of TiO2/rGO increases with increasing GO content. Photoluminescence (PL) spectroscopy indicates that the ability of restraining electron–hole recombination initially increases with increasing GO content, followed by a gradual decrease. The TiO2/rGO nanocomposite (mTiO2:mGO = 40:1) demonstrates optimal photocatalytic performance with formaldehyde degradation rate of 96% in 2 h and stable activity, which can be ascribed to the larger reduction of GO (76.19%), higher TiOC bonds (17%), unfolded rGO sheets, and lower electron–hole recombination rate.

Synthesis of Pt-Loaded NiFe-LDH Nanosheets on Wood Veneer for Efficient Gaseous Formaldehyde Degradation.

Traditional methods of removing gaseous formaldehyde are often associated with high energy consumption and secondary pollution. In this study, a new wood veneer-based composite decorated with Pt-loaded NiFe-LDH nanosheets is successfully developed by a hydrothermal reaction and impregnation-chemical reduction. NiFe-LDH nanosheets as an adsorbent can capture formaldehyde molecules through their abundant hydroxyl groups. Pt nanoparticles as catalytic centers are evenly distributed on the surface of NiFe-LDH to excite the O atoms linked to NiFe-LDH and absorbed oxygen, which will further attack the absorbed formaldehyde molecules to generate CO2 and H2O. And the wood veneer not only increases the active area of the catalyst by endowing it with good dispersion but also provides convenient channels for reactants and products. In a simulated dark environment at room temperature, this synthetic wood veneer-based composite exhibits admirable catalytic activity, which can effectively degrade almost all gaseous formaldehyde with the initial concentration of 0.2 mg m-3 in 30 min and maintain a high catalytic activity of ≥97% after 10 cycles. This paper presents a feasible strategy for synthesizing an energy-efficient and ecofriendly wood veneer-based composite for efficient gaseous formaldehyde degradation at room temperature, which may play an important role in indoor air purification as a promising decorative material.

Kinetic and mechanistic analysis for the photodegradation of gaseous formaldehyde by core-shell CeO2@LDHs

While the removal of gaseous formaldehyde in breathing air via photocatalytic oxidation technology (POT) has shown great promise for pratical applications, the search of highly efficient and stable catalysts and mechanistic interpretations are highly desirable. We synthesized a core-shell structured composite of CeO2 and layered double hydroxides (CeO2@LDHs). The degradation of gaseous formaldehyde was realized with high efficiency under visible light irradiation using a home-built continuous flow reaction device at an industrial reaction scale. It was confirmed that the catalytic activity of LDHs after CeO2 complexation was significantly improved. Under optimum reaction conditions, a formaldehyde conversion of 86.9 % was achieved by CeO2@LDHs after 300 min equilibrium (3.73 μg g–1 h–1). Kinetic study showed that the flow rate of gaseous formaldehyde had the largest influence on the degradation rate of formaldehyde, followed by the relative humidity and the light intensity with a descending order. The rate equation and activation energy of photocatalytic degradation of formaldehyde were also obtained and discussed. The catalytically active radicals and the reaction intermediates were detected on CeO2@LDHs, shedding light on the intepretation of the reaction mechanism. Under the oxidation of hydroxyl and superoxide radicals and hot holes, gaseous formaldehyde was eventually degraded into carbon dioxide and water, as a result of the generation of formic acid, carbon hydrogen oxygen radicals (CHO) and CO2– radicals. The present study demonstrates a systematic logical flow from design, preparation and mechanistic understanding of efficient LDHs-based photocatalyst for the degradataion of gaseous formaldehyde under practical conditions.

Thermally treated zeolitic imidazolate framework-8 (ZIF-8) for visible light photocatalytic degradation of gaseous formaldehyde.

The development of wide-spectrum responsive photocatalysts for efficient formaldehyde (HCHO) removal is highly desired yet remains a great challenge. Here we successfully converted zeolitic imidazolate framework-8 (ZIF-8), one of the most well-studied metal–organic frameworks (MOFs), from routine ultraviolet-driven to novel broad-spectrum-driven photocatalyst via a facile thermal treatment. The isocyanate groups (–N Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CO) formed in the thermally treated ZIF-8 (ZIF-8-T) is crucial in enabling the superior photocatalytic performance in formaldehyde degradation. Specifically, the best-performing ZIF-8-T sample showed around 2.1 and 9.4 times the HCHO adsorption amount and the solar photocatalytic degradation rate, respectively, of pristine ZIF-8. In addition, ZIF-8-T exhibited visible light (λ ≥ 400 nm) photocatalytic HCHO degradation performance, photo-converting 72% and nearly 100% of 20 ppm and 10 ppm HCHO within 1 hour, respectively. This work affords new insights and knowledge that inspire and inform the design and development of MOF-based photocatalysts with broad-spectrum responses for efficient air purification operations.

Effect of calcination time of a quadruple-element doped titania nanoparticles in the photodegradation of gaseous formaldehyde under blue light irradiation.

The photocatalytic degradation of gaseous formaldehyde using Ag/F/N/W-doped titanium dioxide was examined. The photocatalytic reaction was conducted using photocatalysts immobilized on glass tubular reactors illuminated under blue LED lights. Factors affecting gaseous formaldehyde degradation such as photocatalyst's calcination time and dosage, initial formaldehyde concentration, light intensity and operating temperature were studied. Results show that the photocatalytic degradation rate increases with pollutant concentration indicating no mass transfer limitations within the formaldehyde concentration range used. The photodegradation of the formaldehyde using catalyst calcined for 5h reached ∼88%. The photocatalyst concentration giving the highest degradation rate is found to be 0.10 gL-1. Which means that upon increasing the concentration of the immobilized photocatalysts will increase its thickness and it may not increase the number of the photo-induced particles. On the other hand, increasing light intensity and operating temperature increased the photocatalytic degradation of gaseous formaldehyde. The maximum light intensity and operating temperature were measured at 25 Wm-2 and 40°C, respectively. Langmuir-Hinshelwood kinetic type model was used to describe the photocatalytic reaction. The photocatalytic degradation behavior of gaseous formaldehyde on the modified photocatalyst follows a pseudo-first order rate equation based on a Langmuir-Hinshelwood kinetic type model.