Ionic biodegradability

By the enzymatic esterification of diglycerol with lauric acid, the corresponding monolaurate ester is obtained [84]. This is an important industrial reaction for the cosmetic, pharmaceutical and feed industries, since this ester is used as biodegradable non-ionic surfactant. In recent years, the synthesis of this and other polyglycerols with fatty acids has attracted growing interest in industry, leading also to a demand for enantiomerically and isomerically pure products. 

Adsorption is a physicochemical process whereby ionic and nonionic solutes become concentrated from solution at solid-liquid interfaces.3132 Adsorption and desorption are caused by interactions between and among molecules in solution and those in the structure of solid surfaces. Adsorption is a major mechanism affecting the mobility of heavy metals and toxic organic substances and is thus a major consideration when assessing transport. Because adsorption is usually fully or partly reversible (desorption), only rarely can it be considered a detoxification process for fate-assessment purposes. Although adsorption does not directly affect the toxicity of a substance, the substance may be rendered nontoxic by concurrent transformation processes such as hydrolysis and biodegradation. Many chemical and physical properties of both aqueous and solid phases affect adsorption, and the physical chemistry of the process itself is complex. For example, adsorption of one ion may result in desorption of another ion (known as ion exchange). 

The long-chain, fatty acid esters of sucrose are non-ionic, nontoxic, and biodegradable, and compare well in overall performance with other surface-active compounds in detergency, emulsification, and... 

Despite the fact that physico-chemical and chemical degradations were not possible, the isolation of persistent metabolites of the CnF2n+i-(CH2-CH2-0)m-H compound generated by (3 and w oxidations of the terminal PEG unit of the non-ionic blend was reported, but environmental data about this type of compound are still quite rare [49]. TSI(+) ionisation results of the industrial blend Fluowet OTN have been reported in the literature [7,51]. Actual data of non-ionic fluorinated surfactants were applied using ESI- and APCI-FIA-MS(+) and -MS-MS(+), which reported the biodegradation of the non-ionic partly fluorinated alkyl ethoxylate compounds C F2 fi-(CH2-CH2-0)x-H in a lab-scale wastewater treatment process. 

Because of their excellent biodegradability, alkylether carboxylates (AECs) (general structure CnH2 +i-0-(CH2-CH2-0)n-CH2-C00 ) are used more frequently today in households for cleaning purposes. From the structure shown in Fig. 2.11.11, mass spectra as observed in the ionisation of AES or non-ionic surfactants of the ethoxy type with equally spaced signals (Am/z 44) can be expected [22],... 

EEC, Council Directive of 31 March 1982 amending Directive 73/405/EEC on the approximation of the laws of the Member States relating to methods of testing the biodegradability of non-ionic surfactants (82/242/EEC), Official Journal of the European Communities, No. L 109/1. 

The available information about surfactant degradation under anaerobic conditions is restricted to anionic and non-ionic surfactants. Anaerobic biodegradation is strongly dependent on the chemical structure of the compound, the presence of a sufficient amount of anaerobically degrading microorganisms and a fulfilment of their growth requirements. 

Biodegradation is discussed as a key phenomenon in the (differences between marine and freshwater) occurrence and fate of non-ionic surfactants. Finally conclusions are drawn with regard to the marine fate of these compounds. 

Biodegradation of non-ionic surfactants in estuarine and marine environments... 

In conclusion, the processes dominating the environmental fate of non-ionic surfactants in estuaries are biodegradation in the water column, sorption/sedimentation and volatilisation, together with the dynamics of the estuary, in particular water residence times. 

Although the occurrence of the non-ionic surfactant nonylphenol ethoxylate (NPEO Fig. 6.7.1) and its biodegradation intermediates in the aquatic environment has attracted large interest [18] because of the potential of some biotransformation products to mimic estrogenic effects, their fate and distribution in soil environments has been only investigated in a few cases. 

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