A Polymer-based Material For Water-oil Separation And Study On Its Emulsion Breaking Property

Several technical challenges hinder industrial applications of oil-water separation products,for example,high cost of the compounds used to construct the hydrophobic coatings,peeling off of hydrophobic coatings due to weak interactions with substrate,and more importantly,poor separation performance for emulsions.Recently,effective emulsion treatment has become an important index for evaluating oil-water separation products domestically and abroad.Petroleum asphalt is a promising candidate for building hydrophobic coatings due to its low price and its own hydrophobicity.Thus,this thesis proposes a multi-step reaction strategy to chemically graft asphaltene(APT)from petroleum asphalt to melamine sponge(MS)to prepare durable strong hydrophobic sponge(MS-EP-APT),and examined its separation performance on oil-water mixture and emulsions.First,to tackle its chemical inertness,a two-step strategy was developed to functionalize asphalt using Diels-Alder reactions.We reacted asphalt with maleic anhydride to introduce a large number of reactive anhydride groups,followed by ring-opening grafting reaction using polyethyleneimine(PEI).The amino functionalization of two asphalts(QL and TH)was successfully carried out and characterized by FT-IR,water contact angle and zeta potential.Among them,PEI was grafted to TH with 41% grafting ratio.Combined with the softening point,microstructure,thermogravimetric and four-components analysis results,it was demonstrated that PEI forms cross-linked structures with activated asphalt components.Then,a strongly hydrophobic oil absorbent(MS-EP-APT)was developed using a silane coupling agent as a molecular bridge for the aminated APT and MS,which was confirmed by water contact angle,ATR-FTIR and wettability characterization.MS-EP-APT features excellent chemical stability,anti-fouling property and mechanical durability.The absorptionextrusion process was repeated for 10 cycles,and MS-EP-APT maintained high absorption capacity(91%),demonstrating its good recoverability.MS-EP-APT showed fast absorption rates as well as high absorption capacities(74 ～ 187 g/g),which already exceed most of the MS-based products currently developed.In addition,MS-EP-APT showed excellent separation efficiency(>96%)for oil-water mixtures,superior to that of many synthetic polymers and natural polymer-based materials.Finally,we assessed the ability of MS-EP-APT in treating many types of emulsions.For both surfactant-free oil-in-water(O/W)emulsions and surfactant-stabilized water-in-oil(W/O)emulsions,the transparency increased to above 80% after treatment with MS-EP-APT.However,hydrophobic materials were not very effective for separating surfactant-stabilized O/W emulsions.Under the combined influence of both the special wettability of sponges and the introduction of cationic polymers(PEI),MS-EP-APT can offer effective treatment for anionic surfactant(sodium dodecyl benzene sulfonate)stabilized emulsions,with posttreatment transparency of 97%.Based on these results,we propose the molecular mechanism of emulsion breaking.Thus,hydrophobic materials,prepared by low-cost and hydrophobic APT from crude oil,show promising potential for applications in both oil-water separation and emulsion breaking.