METHOD TO FABRICATE WOOD-DUST AND NANOMATERIALS COATED MEMBRANES FOR AIR PURIFIER

Abstract

Air pollution problems are originated from many sectors like electricity generation, industry, transport, construction, and agriculture and residential. This air pollution increases the global warming and climate change. The air quality related to the level of pollutants in the lowest part of the atmospheric air, which we breathe, whose quality reduced by excess concentration of specific pollutants, namely, Particulate matter (PM)10, PM2.5, PM1.0, total volatile organic compound (TVOC), formaldehyde (HCHO), etc. For well-being of society, human health, agriculture production, and ecosystem, government prescribed national air quality standards, which is failing to meet in urban cities. Therefore, technological development for purification of air to enhance air quality standards has to be considered and investigated. Our invention coats wood-dust and nanomaterial-on cellulose filter paper, which individually and in stacking together fabricate membrane filters for air purifier. The fabricated stacked 3L membrane of wood-dust and nanomaterial-coated on cellulose paper filters PM10, PM2.5, PM1.0, TVOC and HCHO effectively from 126 µg m-3, 110 µg m-3, 82 µg m-3, 9.999 mg m-3 and 1.999 mg m-3 to 22 µg m-3, 20 µg m-3, 14 µg m-3, 1.504 mg m-3 and 0.316 mg m-3. Whereas, stacked 6L membrane effectively purifies PM10, PM2.5, PM1.0, TVOC and HCHO from 104 μg m-3, 96 μg m-3, 72 μg m-3, 9.999 mg m-3, and 1.999 mg m-3 to 15 μg m-3, 18 μg m-3, 10 μg m-3, 1.016 mg m-3, and 0.229 mg m-3, respectively. Thus, our inventions provide inventive technological steps and scalable solution for the betterment of society. Our fabricated air purifier not limited to, but can be used at residential places, industries, dumping yards, grade separator of highways and city roads, laboratories, etc. to purifies various components of air pollutants.

Specification

Description:
DETAILED DESCRIPTION:
Example: 1
Preparation of WD powder and its coating on cellulose filter media:
The WD powder was prepared from Tectona grandis wood. Firstly, the wood was washed and then dried to remove water and moisture. The dried wood was grinded into a fine WD powder using a grinder. Finally, the resulting WD powder was coated onto cellulose filter paper using a spatula to form a uniform thin layer and sandwiched with other cellulose filter paper.

Example: 2
Preparation of LDH powder and its coating on cellulose filter media:
The synthesis of MgCu₂-LDH was conducted using a microwave-assisted process. magnesium sulfate (Mg(NO₃)₂), copper nitrate (Cu(NO₃)₂), and urea were added in a 1:2:6 molar ratio in a 80 mL of double distilled water (DDW). The mixture was continuously stirred with a magnetic stirrer to make uniform solution. Then, the solution was exposed to microwave irradiation at a power setting of 120 W for 15 minutes to form MgCu₂-LDH. The resulting MgCu₂-LDH was thoroughly washed several times with DDW and then dried at 80 °C for 12 hours. Finally, the dried MgCu₂-LDH powder was evenly coated onto cellulose filter paper using a spatula and sandwiched with other cellulose filter paper.

Example: 3
AC powder coating on cellulose filter media:
The AC powder was purchased from Merck and used without any filtering process. This AC powder was uniformly spread over cellulose filter paper using a spatula and sandwiched with other cellulose filter paper.








X-ray Diffraction (XRD)
X-ray Diffraction (XRD) is employed to analyze the crystal structure of MgCu₂LDH, a potential component in air filter media. XRD analysis provides insights into the phase structure of MgCu₂LDH, as shown in Fig. 3(a). Peaks at low 2θ values, such as 10° and 20°, correspond to the interlayer spacing, indicating the regularity and size of the LDH layers. The XRD patterns of AC display broad peaks between 20° to 30°, indicative of a noisy, disordered structure of typical amorphous carbon, as shown in Fig. 3(b).

Scanning Electron Microscopy (SEM)
The surface morphology of MgCu₂LDH and AC is shown in Figs. 4 (a, b) and (c, d), respectively. SEM micrograph analysis indicates that both samples are compact and porous. MgCu₂LDH and AC exhibit a well-developed network of interconnected sheets with enhanced porosity. These properties are expected to improve air filtration efficiency by effectively trapping pollutants. Porous and sheet structure is a vital feature for ensuring optimal filtration performance in air filter media.

Air Filter Testing Data
PM categorized as PM10, PM2.5, and PM1.0, represents airborne particles of varying diameters, with PM10.0 affecting the upper respiratory tract, PM2.5 penetrating deeper into the lungs, and PM1.0 posing the greatest health risks due to its ability to reach the bloodstream and impact vital organs. TVOCs, including HCHO, further exacerbate respiratory and neurological health concerns. Filter media like WD, LDH, and AC effectively mitigate these pollutants, as shown in Fig. 5, where PM levels especially PM2.5 and PM1.0 were significantly reduced within one minute, alongside reduces in TVOC and HCHO concentrations, demonstrating these materials' effectiveness in enhancing air quality and minimizing health risks associated with ultrafine particles and toxic gases.
The air filtration data by the membrane based on individual material coating like for WD, LDH, and AC filters over 7 minutes are presented in Fig. 5. Specifically, the results of PM filtration as a function of time are illustrated in Figs. 5(a, c, e), whereas for TVOC and HCHO are depicted in Figs. 5(b, d, f) for WD, LDH, and AC membrane, respectively. Initial membrane decreases the kinetic energy of PM during and block the same, as shown in Fig. 2. The concentrations of PM pollutants were PM10 110.4 µg m-3, PM2.5 96.6 µg m-3, and PM1.0 71.3 µg m-3, which was reduced to 34.5, 29.9, and 20.7 µg m-3, respectively, within just 1 minute and remain stable for further 6 minutes. Similarly, physical absorption of the PM pollutants passing through the LDH based membrane is shown in Fig. 5(c). The initial PM concentrations was 112 µg m-3 for PM10, 98 µg m-3 for PM2.5, and 73.5 µg m-3 for PM1.0, which were reduced to 31, 27, and 21 µg m-3, respectively, within the 1 minute and reduce very slowly for further 6 minutes. Also, the PM pollutant filtration while passing through the AC membrane is shown in Fig. 5(e), initial concentrations were PM10 101.5 µg m-3, 89.9 PM2.5 µg m-3, and PM1.0 66.7 µg m-3, which were reduced to 23.2, 20.3, and 14.5 µg m-3, respectively. Then, the TVOC and HCHO filtration results by the WD based membrane is illustrated in Fig. 5(b), where the initial concentration of 9.99 and 1.99 mg m-3 were reduced to 1.1 and 0.33 mg m-3, respectively. Similarly, the LDH and AC based membrane TVOC and HCHO filters are shown in Fig. 5(d, f). The TVOC concentration reduces from 9.99 to 3.44 mg m-3 and HCHO from 1.99 to 0.64 mg m-3 for LDH based membrane, and TVOC reduce from 9.99 to 1.62 mg m-3 and HCHO from 1.99 to 0.34 mg m-3 for AC based membrane filter. These results verify the efficient filtration of TVOC and HCHO by WD-based membrane filter. This higher filtration capacity of WD-based membrane may lie in its surface chemical functional group.
Furthermore, the stacked 3L membrane were tested to filter PM, TVOC and HCHO, as shown in Fig. 6 (a, b), for 7 minutes. The initial PM concentrations of PM10 126 µg m-3, PM2.5 110 µg m-3, and PM1.0 82 µg m-3 were reduced to 22, 20, and 14 µg m-3, respectively. Whereas, TVOC and HCHO concentrations were reduced from 9.99 and 1.99 mg m-3 to 1.50 and 0.31 mg m-3. Thus, the stacked 3L membrane-based filter effectively reduces the concentration PM, TVOC, and HCHO pollutants than individual material coated membrane. Also, the stacked 6L membrane-based filer testing for PM, TVOC, and HCHO is illustrated in Fig. 6(c, d). The PM concentrations PM10 104 µg m-3, PM2.5 96 µg m-3, and PM1.0 72 µg m-3 were reduced to 15, 18, and 10 µg m-3, respectively. TVOC and HCHO concentrations from 9.99 and 1.99 mg m-3 were reduced to 1.01 and 0.22 mg m-3, respectively. These results confirm the high efficiency of the 6L membrane filter over 3L for reducing particulate matter and gaseous pollutants. Overall, the economical WD filter demonstrated superior performance in reducing PM as well as gaseous pollutants, highlighting its effectiveness in improving air quality.
, Claims:1. The preparation method for air filter media involves cellulose filter paper which effectively filters air due to its unique structure and properties. Its dense, web-like structure creates a physical barrier that traps larger particles such as dust and pollen, as well as smaller particulate matter like PM10, PM2.5, and PM1.0. The natural electrostatic charge of the cellulose fibers enhances the capture of fine particles through electrostatic interactions. Additionally, the porous nature of the paper allows for the adsorption of gases and chemicals, such as TVOCs and HCHO, when coated with materials like WD, LDH, and AC. This customizability and high air permeability ensure efficient airflow while maintaining filtration performance.

The preparation method for air filter media, the layers of WD, LDH, and AC coated on cellulose filter paper comprises the following steps:

(i) Preparation of the membrane: cellulose filter paper is used as a membrane; this membrane was cut in a circular shape for properly fit inside the pipe.

(ii) Preparation of the coating materials: WD powder was prepared from Tectona grandis wood by washing, drying, and grinding. MgCu₂-LDH was synthesized via a microwave-assisted process. AC was purchased from Merck and use without any purification process.

(iii) Preparation of the filter media coating: The WD, LDH, and AC powder was coated uniformly onto cellulose filter paper using a spatula at room temperature and sandwiched with other cellulose filter paper.

In Step 2, the filter media layers of WD, LDH, and AC were prepared. Tectona grandis wood was dried to remove moisture, grind into a fine WD powder, and coated onto cellulose filter media. MgCu₂-LDH was synthesized using a microwave-assisted process by dissolving Mg(NO₃)₂, Cu(NO₃)₂, and urea in a 1:2:6 molar ratio in 80 mL of DDW, followed by microwave irradiation. The product was washed, dried at 80 °C for 12 hours, and coated onto cellulose filter media. Commercial-grade AC powder was directly coated onto the cellulose filter paper as the AC filter media.

In Step 3, the WD, LDH, and AC layers were uniformly coated onto cellulose filter paper, creating a sandwich structure between additional cellulose filter paper layers. This setup provides support for the WD, LDH, and AC filter media layers. This filter media also stacked with 3L and 6L.

2. The air filter system of claim 1, wherein:
The filter media was constructed by coating cellulose filter paper with individual layers of WD, LDH, and AC, which were then stacked together to form an integrated filtration system designed for optimal air purification. Each coated layer within the media is capable to capture specific pollutants, including particulate matter PM10, PM2.5, PM1.0, TVOCs, and HCHO. Configured to fit within a pipe, this multi-layered filter media enhances air filtration efficiency by addressing a wide range of airborne pollutants.

3. The air purification method using the air filter system of claim 1, comprising:
The filter system is fitted into the pipe, allowing controlled airflow and secure placement of the filtration media. Contaminated air is drawn into the system through an inlet pipe powered by an electric motor, directing it sequentially through the layered filter media. Each layer of the media is designed to progressively remove particulate PM, TVOC, and HCHO. The purified air is then passed out through an outlet at the opposite end of the system, ensuring efficient removal of pollutants.

4. The air filter system of claim 1, wherein:
The air quality of the filtered output is measured using an AQI meter to assess pollutant removal effectiveness. The economical WD layer demonstrates superior filtration performance, significantly reducing PM concentration levels. Additionally, it effectively lowers TVOCs and HCHO concentrations, achieving better overall results compared to the LDH and AC layers. Multi-layer configurations like 3L and 6L filters enhance pollutant reduction, with combined WD, LDH, and AC layers delivering superior air purification and health protection.

5. The air filter system of claim 1, wherein:
In this filtration process, we may utilize various materials as filter media, including biowaste to substitute WD, different types of LDH (Mg-Al, Cu-Al) to replace this MgCu2- LDH, and wood charcoal in place of AC.

6. The air filter system of claim 1, wherein:
The filter system is designed for diverse applications, including residential areas, industrial environments, highways, and laboratories, representing a promising technological advancement in air pollution mitigation with significant potential to enhance public health and environmental quality.

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