Sorbent Sheet Testing

Adsorbent pad testing mainly conducts scientific testing and analysis on oil absorption ratio testing, water absorption ratio testing, adsorption rate testing, liquid retention testing, pH value testing and ash content testing, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Oil absorption ratio testing: This item is used to evaluate the saturated adsorption capacity of the adsorbent pad for oil liquids. By determining the maximum mass of a specified oil product (such as No. 15 white oil, No. 46 machine oil or a standard test oil) that the pad of a unit mass can adsorb, it is expressed in the form of a multiple. This indicator is directly related to the use economy and leak treatment efficiency of the product, and is one of the core parameters for measuring its performance.

Water absorption ratio testing: This item measures the adsorption performance of the adsorbent pad for water. A pad of a certain mass is completely immersed in water, and after it is saturated, it is weighed, and the ratio of the mass of the adsorbed water to the original mass of the pad is calculated. The water absorption ratio is crucial for judging the applicability of the product in humid environments or oil-water mixture leakage scenarios, and the value is usually lower than its oil absorption ratio.

Adsorption rate testing: This test evaluates how quickly the adsorbent pad absorbs liquid. A test method simulating the leakage scenario is usually adopted, recording the time required for the pad to complete a specified proportion of adsorption from the moment of contact with the liquid. The adsorption rate directly affects the timeliness of emergency response, and has important reference value for handling rapidly spreading spills.

Liquid retention testing: Liquid retention, or liquid holding capacity, refers to the ability of the adsorbent pad to hold the adsorbed liquid without seepage or dripping when subjected to a certain pressure or external force after reaching adsorption saturation. The test method usually places the saturated pad under a specific pressure (such as 0.1 bar) and measures the amount of liquid seeping out, to evaluate the safety of the product in the subsequent recovery and treatment process.

pH value testing: Measures the acidity and alkalinity of the water extract of the adsorbent pad. This indicator is used to evaluate whether the product has corrosive or chemical reaction risks when in contact with sensitive equipment or chemicals. For some industrial applications, the adsorbent pad is required to remain neutral or weakly alkaline, to avoid secondary damage to metal surfaces or precision instruments.

Ash content testing: Determines the residual amount of inorganic matter of the adsorbent pad after complete combustion by the high-temperature burning method. The ash content reflects the purity of the product raw materials. An excessively high ash content may mean that too many fillers or impurities are used, which will not only affect the adsorption performance, but may also generate additional solid waste when the adsorbed waste liquid is treated.

Flammability testing: In accordance with the relevant safety standards (such as UL 94 and ASTM D4984), the combustion characteristics of the adsorbent pad under specific conditions are evaluated, including the ease of ignition, flame spread speed and self-extinguishing time. This test is crucial for judging the fire risk of the product in flammable and explosive environments (such as gas stations and chemical plants).

Testing Scope

Industrial oil adsorbent pads: This type of pad is mainly used to adsorb industrial oils such as machine tool cutting fluid, lubricating oil, hydraulic oil and transformer oil. The testing scope focuses on the high-multiple adsorption capacity for high-viscosity oils, chemical compatibility and the structural integrity evaluation under high-intensity mechanical environments.

General-purpose adsorbent pads: Suitable for adsorbing common oils, water and mild chemicals. Their testing scope covers the above basic performance indicators such as the oil absorption ratio, water absorption ratio, pH value and ash content. They are the most widely used category on the market with the most mature testing standards, and usually need to take into account the adsorption balance of multiple liquids.

Chemical adsorbent pads: Specially designed to adsorb corrosive or dangerous chemicals such as acids, alkalis, solvents and oxidants. In addition to the basic adsorption performance, the testing scope emphasizes their chemical inertness (such as acid and alkali resistance tests), dissolution resistance, and whether dangerous reactions such as heat generation and gas generation will occur after adsorbing specific chemicals.

Adsorbent pads for marine and waters: Used to handle offshore oil spills or oil pollution in inland water bodies. Their testing scope includes the adsorption performance in seawater or fresh water environments, anti-dispersal (to avoid secondary pollution), biodegradability evaluation, and whether they contain components toxic to aquatic organisms.

Adsorbent pads for laboratories and cleanrooms: Applied in environments with extremely high cleanliness requirements, such as biological laboratories and semiconductor workshops. The testing scope focuses on the low dust shedding rate of the pad, control of specific ion content such as silicon-free and halogen-free, sterility or low microbial limit, and no fibre residue after adsorption.

Raw materials of adsorbent pads: The polypropylene melt-blown fibres, natural cellulosic fibres and inorganic adsorbent materials constituting the pad are tested. The scope includes the particle size, fibre fineness, lipophilic and hydrophobic modification effect, and the environmental friendliness and stability of the hot-melt adhesive, controlling the performance of the final product from the source.

Testing Methods

Static adsorption method: This is the most classic test method. A dry adsorbent pad sample of a known mass is completely immersed in a container containing a standard test liquid and left to stand for a specified time (usually 10-20 minutes) to reach adsorption saturation. Then the free liquid is drained with a specific device (such as a draining rack) for a specified time, and the adsorption ratio is calculated by weighing. This method is simple to operate and has good result repeatability, and is the main method specified in the product standards.

Dynamic adsorption method (dripping method): Simulates the scenario of continuous liquid dripping. The test liquid is dripped onto the surface of the horizontally placed adsorbent pad at a constant rate, and the time from the start of dripping to the first penetration of the pad by the liquid and dripping out is recorded, or the total amount of liquid that the pad per unit area can adsorb before penetration is calculated. This method can better reflect the real-time performance of the product in the actual leak point control application.

Liquid retention pressure test method: The saturated adsorbent pad sample is placed in a dedicated fixture with a filter screen and receiver, and standard weights are applied on it to generate a constant pressure (such as 0.1 kg/cm²). After holding the pressure for a specified time, the mass of the squeezed-out liquid is measured and the liquid retention rate is calculated. This method intuitively evaluates the ability of the adsorbent pad to prevent secondary leakage during collection and transportation.

Ash content determination by the burning method: A precisely weighed adsorbent pad sample is placed in a constant-weight crucible, first carefully carbonized on an electric furnace until no smoke, then moved into a muffle furnace and burned at a specified temperature (such as 750±50 ℃) to constant weight. After cooling, the residual mass is weighed and the percentage of ash to the original sample mass is calculated. This method requires strict control of the heating program to prevent sample splashing.

Infrared spectroscopy analysis method: A Fourier transform infrared spectrometer (FTIR) is used to carry out qualitative analysis of the material of the adsorbent pad. By comparing the infrared absorption spectrum of the sample with the standard spectral library, its main chemical composition (such as polypropylene and cellulose) can be identified, and it can assist in judging whether a specific surface modification treatment has been carried out. It is an effective means of raw material quality control.

Scanning electron microscope observation method: A scanning electron microscope (SEM) is used to observe the micro morphology, diameter distribution, pore structure and interlayer bonding state of the adsorbent pad fibres. This method does not directly give performance values, but can explain the differences in macro indicators such as the adsorption performance and strength of the product from the micro level, providing direct evidence for product R&D and improvement.

Testing Standards

Domestic Standards:

1. GB/T 3920-2024, Textiles — Tests for colour fastness — Colour fastness to rubbing

2. GB 18401-2010, National general safety technical code for textile products

3. GB/T 3921-2008, Textiles — Tests for colour fastness — Colour fastness to washing with soap or soap and soda

4. GB/T 3922-2013, Textiles — Tests for colour fastness — Colour fastness to perspiration

5. GB/T 2910, Textiles — Quantitative chemical analysis

6. GB/T 7573-2009, Textiles — Determination of pH value of aqueous extract

International Standards:

1. ISO 105, Textiles — Tests for colour fastness

2. ISO 13934-1, Textiles — Tensile properties of fabrics — Part 1: Determination of maximum force and elongation at maximum force using the strip method

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Electronic balance: As the core weighing equipment, it is required that the accuracy reaches at least 0.001 g, for precisely weighing the mass of the sample and liquid before and after adsorption. It must be regularly calibrated to ensure the accuracy of the calculation of key data such as the adsorption ratio. When in use, it should be placed on a stable table without vibration and strong airflow.

Constant temperature and humidity chamber: Used for conditioning the adsorbent pad sample and test liquid before testing, so that they reach the temperature and humidity environment specified by the standard (usually 23±2 ℃ and 50±10% RH). This can eliminate the influence of environmental fluctuations on the test results, ensuring the comparability and repeatability of the test data between different batches and different laboratories.

Dedicated draining rack and receiver: A standardized device composed of a stainless steel wire mesh or grid, used to support the saturated adsorbent pad so that the unabsorbed free liquid drains out within the specified angle and time. The receiver is used to collect and weigh the drained liquid, and is an indispensable auxiliary tool for the static adsorption method.

Muffle furnace (high-temperature resistance furnace): Used for the ash content determination. It is required that the maximum temperature is not lower than 900 ℃, the temperature control is precise and the temperature in the furnace chamber is uniform. It should be equipped with a program temperature control system to execute the standard heating, burning and cooling procedures, ensuring complete ashing of the sample and experimental safety.

pH meter: Used to measure the acidity and alkalinity of the water extract of the adsorbent pad. A laboratory-grade pH meter with an accuracy of ±0.01 or higher should be selected, and it should be equipped with a temperature compensation function. Before use, a two-point calibration must be carried out with standard buffer solutions, and during measurement, it should be ensured that the electrode is fully immersed in the solution and the reading is stable.

Liquid viscometer: Since the adsorption performance is closely related to the viscosity of the test liquid, a rotational viscometer or capillary viscometer is needed to precisely determine the viscosity value of the standard test oil at different temperatures. Ensuring that the test liquid meets the viscosity range specified by the standard is one of the prerequisites for obtaining valid and comparable test results.