Environmental Assessment of Alkyl Polyglucoside
Alkyl polyglucoside is a kind of rapidly popular surfactant. Especially after the new production process has been optimized. Alkyl polyglucoside has a good synergistic effect with many anionic surfactants. It is used in industry to save surfactant consumption and improve performance. In addition, good foaming performance and high adaptability to the skin are the reasons why these surfactants are widely used in cosmetics and detergents.
All such products enter wastewater after use and finally reach the environment. Their impact on the environment is the key criterion for the ecological evaluation of these ingredients. In the case of alkyl polyglucoside, for example, whether the concentration in the surface water is safe and whether it poses a threat to the environment. The environmental assessment of alkyl polyglucoside mainly includes the following aspects.
1. Biodegradation of alkyl polyglucoside
The final degradation of alkyl polyglucoside, i.e. the determination of the conversion to CO2 and water, and enters the bacterial biomass. During the 4-week test period, both in the strict closed bottle test (OECD301D), the modified screening method (OECD301E), and the dissolved organic carbon (DOC) elimination test (OECD301A). In terms of degradation limit and time (reaching the degradation limit of the degradation process within 10 days), it also meets the standard without difficulty. Therefore, APG can be classified as “rapidly degradable”. It can be rapidly and ultimately degraded in the environment.
It is important to predict specific concentrations in surface water. Generally, the conditions of simulated wastewater treatment plants are used to study the degradation. Tracking the elimination of APG under the condition of a wastewater treatment plants is a prerequisite for the development of a sufficiently specific and sensitive analytical method. The elimination rate of APG reached 98% after only one week of the simulation experiment (OECD confirmed experiment). The evaluation period was also between 99.5% and 99.8% in the following 3 weeks. Combined with the above evaluation of APG’s “rapid degradation”, it can be concluded that APG also has high initial degradation and high final degradation in wastewater treatment plant conditions.
2. Ecological toxicity of alkyl polyglucoside
The ecotoxicity of alkyl polyglucoside, i.e. its effect on aquatic and terrestrial organisms.
Acute aquatic toxicity tests can characterize the ecotoxicity of chemical compounds. This test shows that APG is in the range of 1 to 10 mg/l effective concentration of typical surfactants. LC50 of fish, Daphnia and algae were 3 mg / L, 7 mg / L and 6 mg / L respectively. These clearly indicate that surfactants with such alkyl chain length have good ecotoxicity. It is related to the observation of the structure/performance relationship of many surfactants, The shorter chain, C8/10APG, proved to have lower acute toxicity. Therefore, the higher ecotoxicity of C12 / 14apg was used for further ecotoxicity study. In a 4-week zebrafish growth test, the maximum concentration of no indicative negative effect (NOEC) was 1.8mg/ L. The chronic toxicity test against Daphnia was measured in a 3-week proliferation test, showing a NOEC value of 1mg/ L. This value marks the most sensitive endpoint for all studies conducted with C12/14APG. In the chronic toxicity test of algae, the effect of the materials to be tested on cell proliferation was studied. The NOEC value was observed to be 2mg/ L, while the NOEC value of bacterial cell proliferation was more than 1000mg/ L, which was the lowest in connection with many other surfactants observed.
In order to directly evaluate the potential inhibitory effect of APG on bacteria, it is highly informative to use purification of the wasterwater treatment plant to determine the concentration of bacteria oxygen consumption without effect. The maximum concentration measured is 500 mg / L, which indicates that the acute effect of bacteria on APG is too high.
In principle, surfactants can also reach agricultural land through the use of agricultural sewage sludge. Experts have also studied acute and chronic toxicity tests of C12/14 APG on terrestrial (living) organisms. In the acute experiment with earthworms, even at the highest concentration of 654mg/l, there was no effect. The same concentration of APG had no effect on the growth of oat, radish, and tomato. Therefore, it can be assumed that APG has very low toxicity to terrestrial organisms.
According to this observation, the biotope has fully recovered the introduction point within 5 days after APG addition, while with other surfactants it would take a much longer time. From this, it can be concluded that even the direct introduction of very large amounts of APG into the river does not lead to any long-range biotope effects in the river water.
3.Evaluate the environmental risk of APG
According to European (EU) standards, the evaluation of ecological safety of products is based on the comparison. The ratio of the environmental concentration expected to be close to the actual condition (predicted environmental concentration PEC) to the concentration expected to have no negative effect in the environment (predicted non-effective concentration PNEC).
The determination of PEC was based on the assumption that APG containing 10% of the total nonionic surfactant as a heavy-duty detergent was placed on the exposure site. The maximum concentration of PEC in the river model study was 10 μg/l.
The second parameter for assessing environmental risk is called the predicted no-effect concentration for Ecology (PNEC). This is based on ecotoxicity data measured by C12/14 APG using conservative safety factors widely used in Europe. In the river model study, the PNEC is 100μg/kg. Therefore, the PEC / PNEC ratio of APG is 0.1. Since it has been indicated that the ratio of PEC/PNEC < 1 can eliminate any risk to the environment, APG can be considered as a very safe surfactant to the environment.
Alkyl polyglucoside has excellent biodegradability. These surfactants have good ecological toxicity in many applications under aerobic or anaerobic conditions. Even though the amount of APG greatly much higher than expected and does not cause harm to the environment. Therefore, the study shows that alkyl polyglucoside is a green surfactant with excellent environmental adaptability, which represents the comprehensive good ecological and important characteristics.