Gel breaking-capacity reduction and reutilization of waste lithium anode coating slurry
Waste lithium anode coating slurry is hard to filtrate and also hard to be reutilized since it contains high water content,which is strongly stable with a wonderful colloid dispersion.The colloidal properties of this waste coating slurry were characterized,its high-efficiency rubber breaking separation mechanisms were discussed,and its reutilization as active carbon was also investigated.The electrostatic repulsion provided by the carboxyl anion(R-COO-)produced by the dissociation of sodium carboxymethylcellulose(CMC-Na)and the spatial resistance formed between particles by styrene-butadiene rubber(SBR)were the fundamental reasons for the colloidal stability of waste slurry.The decrease in acidity effectively suppressed the dissociation of carboxymethyl cellulose sodium(CMC-Na)in the slurry,resulting in reduced adsorption of charged groups(R-COO-)onto the surface of graphite particles.Consequently,the electrostatic repulsion between particles weakened,facilitating particle agglomeration and undermining the cross-linking effect of styrene-butadiene rubber(SBR).When pH was 2.0,the filtration constant of the waste slurry escalated to 0.0741m2/s,resulting in a remarkable 48 percentage point reduction in moisture content.X-ray three-dimensional microscopy analysis(X-CT)showed that while fine particles agglomerated and broken,the retained electrostatic repulsion could reduce the filtration resistance,promote the development of the filter cake pore structure,generate a large pore radius,and the seepage network of the long throat channel reduced the amount of water adsorbed by the filter cake pores.Moreover,the separated solid carbon material demonstrated impressive adsorption capacities of 435mg/g,0.645mg/g and 87mg/g for methylene blue,chromium(Cr6+)and COD,respectively.These values adhered to the first-rate standards set forth in the"LY/T 3279-2021".
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