Observations on the Relationship Between the Adsorption of Diuron and the Nature of the Adsorbent

Abstract

A scries of adtiorption experiments was carried out in order to dcterinine if ihcrc was significant compciition for adsorption sites between diuron and water. .Adsorption of diuron was miieli lower on hydrophilic matcriaLs sucli as cellulose, chitin, aluminium oxide and a soil mineral fraclion than on the less Uydrophilie ion exchange resins, lignin, carbon and a soil organic Traction. Methylation with mcihanolic HCI or diazomethane increased adsorption by the soil organic material, bul melhylation with dimethyl sulphate did not.The soil mineral fraction adsorbed considerably more diuron from petroleum spirit solution ihan from aqueous solulion, but ihe organic mailer preparation adsorbed more from aqueous than from pclroleum solution.It was concluded ihai ihcre is competition between water and diuron for adsorption liles and that diuron is a more effective competitor at soil organic matter surfaces than at soil mineral matter surlaccs. Obsenations sur la relation entn VadsoTption du diuron et la nature de VadsorbantR^sum^. Une s<^rie d'cxp^riences d'adsorption fut eflecluie pour determiner s'il y avait competition pour les sites d'adsorption eiilre le diuron ei I'eau. Sur des substances hydrophiles tellcs que cellulose, chitinr. oxydc d'aluminc ct une fraction min^rale du sol, l'adsorption du diuron eiait plus faiblr que sur des mat<^riau.\ moins hydrophiles comme des riiiines echangt-urs d'ions, la ligninr, le carbone et une I'raciion organique du sol. La m^thylation avec HCI mcthanolique on avcc le diazom^thane accrut l'adsorption des fractions organiqucs du sol, mais la mithylation avec le sulfate do dimf^thyle fut sans effet.La fraction minirale du sol adsorbe beaucoup plus dc diuron d'une solution dans lYther de p^trole que d'une solution aqueuse, tandis que la preparation de matiire orgunique adsorbe inieux d'une solution aqueuse.On conclut qu'ii y a competition entre I'rau et le diuron pour les .sites d'ad.sorption et que le diuron est tin ronipetiteur pluseflicarc sur les surfaces tic ma ticrc organique du sol que sur les surfaces dc matiere min^rale.

Degradation of contrasting pesticides by white rot fungi and its relationship with ligninolytic potential

“…These are all highly available compounds with relatively low potentials to bind to organic substrates, including fungal hyphae (Table 2) [11]. Analytical grades of each pesticide (Greyhound, Birkenhead, UK), were dissolved in methanol, and 1 ml of a stock solution dispensed into an empty 500-ml Duran bottle.…”

Equilibrium and Kinetic Studies of the Adsorption of 2,4-D and Picloram on Humic Acid

“…Numerous reports have ap-Despite the considerable amount of repeared in the literature during the past dei-search undertaken, very little attention has ade indicating that humic substances, which been paid to the-equilibrium and kinetic represent the most active fraction of organic aspect of the problem. These fundamental matter in soils, are the most active adsorbent studies are necessary for a better underfor a wide variety of herbicides (Dunigan standing of the mechanism(s) of adsorption' and Mclntosn pil Gilmour and Coleman The work described here attempts to obtain 1971; Hance 1965Hance ,1969Hayes et al 1968 separation, and purification of the HA were identical to those described previously (Khan 1971 In the present study, the data obtained gave reasonably good straight lines by plotting log X against log C. A typical Freundlich plot for adsorption of 2,4-D on humic acid at 5 C is shown in Fig. 1.…”

The processes that determine the fate of pesticides in soil

“…Hronološki posmatrano, još je Hance 1965. godine (Hance, 1965b), na osnovu svojih istraživanja i ranije publikovanih rezultata (Sherburne i Freed, 1954;Sheets, 1958;Harris i Warren, 1964;Hance, 1965a;Lampert i sar., 1965), zaključio da je za datu dozu primene različitih herbicida, fitotoksičnost veća u zemljištima sa nižim sadržajem organske materije. Ubrzo zatim, usledila su obimna istraživanja na osnovu kojih je ova zakonitost proširena na sve pesticide (Bailey i White, 1964;Upchurch, 1968).…”