Study On The Hydrophilicity Of Sodium Lignosulphonate And Its Influence On The Dispersion Stability Of Pesticides

Sodium Lignosulfonate (LS), as a kind of pesticide dispersant, can be absorbedon pesticide particles and generate space steric effect and electrostatic repulsion,increasing the stability of pesticide suspension system. However, there are many typesof pesticides, the molecular structure and hydrophilicity of which are very different.LS usually can not satisfy the dispersibility of all kinds of pesticides. Thehydrophilicity of LS have a significant impact on its dispersibility, researchergenerally agree that the hydrophilicity of LS must be adapted to that of pesticide,however there are few research in this field.In this paper, LS was separated into3fractions of different hydrophilicity bymacroporous resin. The relationship between the structure and hydrophilicity of LSwas discussed. The surface physicochemical properties of LS with differenthydrophilicity and its dispersibility on pesticides of different hydrophobicity was alsoinvestigated in this paper. The hydrophilicity matching law between LS and pesticideswas discussed and which is of help for the development and design of lignindispersants.The static adsorption capacity of LS on three macroporous resins with differentpolarity were tested, the results show that: macroporous resins NKA-9with strongpolarity displayed the better adsorption capacity than macroporous resins AB-8, andthe adsorption capacity of macroporous resins H103of non-polarity is almost to zero.The optimum adsorption time and pH of resin NKA-9and AB-8are180min and pH1.As the eluent, the eluent rate of50%methanol solution is above85%. Three fractionswih the same molecular weight and different hydrophilicity were got by macroporousresin, and the hydrophilicity regular of the three fractions were confirmed by testingwettability of water on LS surface; Three fractions with different molecularweight,<10000,10000-50000and>50000,were got by ultrafiltration. Therelationship between the structure and hydrophilicity of LS was discussed. Resultsalso shows that the content of phenolic hydroxyl group and sulfonic group account formost of the hydrophilicity of LS rather than carboxyl group. The surface physicochemical properties of6fractions of LS were tested in thispaper. The result shows that LS with less hydrophilicity has greater surface activityand wettability on paraffin and carbendazim particle surface. The Adsorptionisotherms and zeta potential of LS on pesticides carbendazim, imidaclopridacetamiprid show that, LS with less hydrophilicity has greater adsorption onpesticides; The less hydrophilicity of LS, the more effect of LS on zeta potential ofcarbendazim particles was.Influence of LS with different hydrophilicity on the stability of pesticidessuspension was investigated in this paper. The results show that: the lesshydrophilicity of LS, the larger adsorption capacity and zeta potential of carbendazimsuspension was, and the better dispersibility of LS was; LS with less hydrophilicityhave better dispersibility for imidacloprid suspension, however LS with too lagermolecular weight may cause the significantly increasing of particle size, which mayweaken the stability of imidacloprid suspension; for the acetamiprid suspension,adsorption capacity and Zeta potential have less effect on the stability of suspension,LS with smaller molecular weight has better dispersibility.In this paper three kinds of dispersants GCL4-1,GCL4-2and GCL4-CM wereselected to develop new formulation80%carbendazim WP,20%imidacloprid WP,50%acetamiprid WG.