Optimized Liquid-Liquid Extractive Rerefining of Spent Lubricants

Figure 5

(a) Comparison of response surfaces describing simultaneous variation of sludge yield against 𝑡 and 𝑇. (b) Against 𝑡 and 𝑟. (c) Against 𝑇 and 𝑟. Color maps are actual response surfaces while superimposed dotted mesh are the response surfaces, predicted by the multivariate process models (7) or (8).