Agricultural Pollution Control using Electrospun Fibers

Agricultural activities may cause widespread pollution especially if its environment is not adequately monitored. Possible source of pollution includes fertilizers, pesticides and other compounds that may run off from the field and to the rivers. Electrospun nanofibers with its high surface area may be used either for detection or removal of contaminants.

Fertilizers added to enhance crop growth often causes serious pollution if too much of it leaks into the river. Phosphate is a common compound in fertilizer and it has been the target for removal from waste waters. Najib et al (2013) proposed the use of quaternized electrospun cellulose nanofibers for the removal of phosphates. The quaternized cellulose fiber were able to remove 55 mg/g mesh of phosphate.

Pesticides that are added to farm crops to control pests often harms life in the surrounding land. Niu et al (2013) investigated the effectiveness of using horse radish peroxidase (HRP) loaded into electrospun poly(d,l-lactide-co-glycolide) (PLGA) fibers for adsorption and degradation of pentachlorophenol (PCP) in water. PCP is a widely used pesticide in wood preservative and herbicide in many agricultural farms. Comparing the HRP in PLGA nanofibers with free HRP, free HRP showed slightly faster degradation of PCP in the presence of H₂O₂. However, free HRP loses its activity within hours of exposure to external environment while HRP encapsulated within electrospun PLGA nanofibers was able to maintain 50% of its activity after two weeks of storage. In terms of PCP removal from the solution, PLGA nanofibers with HRP showed significantly faster removal rate compared to free HRP. This has been attributed to hydrophobic surface of PLGA material which facilitated PCP adsorption. Electrospun fibers may also be used as sorbent materials for pesticide detection. Vojtech et al (2016) used electrospun polyetherimide nanofibers for sorption of hexachlorocyclohexanes (HCH) and chlorobenzene (ClB) as solid phase microextraction (SPME). Compared to commercial SPME, electrospun polyetherimide SPME shortened the extraction time for organochlorinated pesticides (HCH and CIB) from 50 to 10 minute without losing sensitivity.

Other than crops, raising farm animals also involves the use of compounds such as antibiotics and hormones. These compounds when leaked to the environment undetected may potentially disrupt the ecosystem. Pule et al (2015) constructed an electrospun fiber composite with polystyrene as the matrix for encapsulation of gold nanoparticles to be used in the detection of 17β-estradiol in dairy effluents. In the presence of 17β-estradiol, the gold nanoparticles within the matrix start to cluster which changes the color of the nanofibrous strip from white to pink. At higher concentration, the surface plasmon resonance band shift to a longer wavelength turning the color blue from pink. Color change was observable at a concentration of 100 ng/ml and the color change to pink is specific to 17β-estradiol with other compounds such as cholesterol, p,p'-DDE, deltamethrin, 4-tert-octylphenol and nonylphenol turning the probe brown.