Archive | 2021
Pesticides and removal approaches
Abstract
Abstract Pesticides are organic molecules used in agriculture, the most known being atrazine, lindane, diazinon, dichlorodiphenyltrichloroethane, and N-(phosphonomethyl) glycine (glyphosate). Farmers are the most exposed to direct harmful effects. Foods, water, and the atmosphere are regarded as indirect contact sources. Pesticides comprise three major families of organic compounds, namely herbicides, insecticides, and fungicides. Their toxicity arises from their very molecular structures, inasmuch as pesticides are intended for the elimination of undesired organisms such as weeds, insects, fungi, and other parasites for agriculture. Long-term exposure to pesticides or their ingestion was found to cause hypersensitivity, asthma and allergies, loss of coordination and memory, alteration of the visual ability, damages to the human immune system, liver, lungs, kidneys, and others. Pesticides turned out to negatively impact nontargeted species, affect fauna and plant biodiversity, aquatic and terrestrial ecosystems. Their volatility alters the atmosphere quality as well. Reportedly, they are also recognized as being responsible of leukemia and diverse cancers (brain, lymphoma, breast, prostate, ovarian, and testicular cancers). They turned out to affect the reproductive capacity by altering male and female reproductive hormone levels with unavoidable consequences like stillbirth, congenital malformations, spontaneous abortion, and infertility. So far, adsorption on solids and chemical degradation are undoubtedly the main approaches for pesticide elimination from aqueous effluents or vapor emissions. A wide variety of solids such as clay materials, zeolites, diverse activated carbons, polymers such as chitosan, their composites commonly investigated in organic pollutant removal have been tested up today. Adsorption is quite effective on organophilic materials. However, high pesticide contents in released fluids are a major shortcoming that imposes short use cycles with frequent material regenerations. Chemical degradation is a more viable alternative, more particularly through waste-free green processes not involving harmful chemicals. Chlorine-free Advanced Oxidative Processes (AOPs) appear as a judicious strategy when targeting total pesticide mineralization into CO2 with their NOx and SOx derivatives, if any. Among these, a growing interest is nowadays devoted to ozonation, which unfortunately involves high energy consumption. Suitable catalytic systems under optimum operating conditions can allow overcoming this drawback. This chapter will be focused on advances and prospects in developing low-cost oxidative processes for treating pesticide-containing effluents. An ample literature systematized herein is expected to provide scientists, researchers, and engineers with valuable findings that allow designing effective AOPs targeting complete mineralization of pesticides into CO2. The issue of ozone consumption can also be addressed by envisaging the use of solar energy where and when available.