Preparation, Characteristics, Evaluation Of Oleoyl-Carboxymethyl Chitosan As A Coagulation Agent

Treatment and disposal of oily wastewater is presently one of the serious environmental problems contributors. Various processes have been developed to remove oil from contaminated areas. Coagulation method is widely used in the treatments of water and wastewater and well known for its capability of destabilizing and aggregating colloids.In conventional wastewater treatment systems, a biodegradable material with excellent flocculating ability for the residual oil will be advantageous. A number of natural sorbents have been studied for oil-spill clean up, e.g. chitosan. Chitosan has the high absorption capacity for the residual oil and the excellent properties such as biodegradability, hydrophilicity, biocompability, adsorption property, flocculating ability, polyelectrolisity, antibacterial property and its capacity of regeneration in a number of applications. It has been used as non-toxic floccules in the treatment of organically polluted wastewaters. However, chitosan has the excellent flocculating ability for the residual oil only in acid medium. Thus, it has become necessary to develop an efficient, environmental friendly chitosan derivative for removing the residual oil at a broader pH range. The objective of this paper was to synthesize an amphiphilic chitosan derivative as a coagulant to flocculate the residual oil from the WWOE.1. Preparation, Characteristics of Oleoyl-Carboxymethyl chitosanA novel chitosan-based polymeric surfactant, Oleoyl-Carboxymethyl chitosan (O-CMCS) was produced as a coagulation agent to clean the residual oil from the wastewater of oil extraction (WWOE). O-CMCS was synthesized with different molecular weight (MW) and degrees of substitution (DS) by reacting carboxymethyl chitosan (CMCS) with oleoyl chloride in the acetone & ice system. The FT-IR,1H--NMR, UV, TG&DSC suggest the formation of an amide linkage between amino groups of Carboxymethyl chitosan and carboxyl groups of oleic acid.These O-CMCS exhibited poor solubility in aqueous acidic solution.The solubility of O-CMCS decreases as the increase of DS and MW. The degrees of substitution (DS) of oleoyl had been investigated by PVSK colloid titration. When Ncmcs:N oleoyl chloride=1:0.5, the the degree of substitution of oleoyl was 8.7%; When Ncmcs:N oleoyl chloride=1:1, was 20.66%. So O-CMCS could be synthesized by reacting carboxymethyl chitosan (CMCS) with oleoyl chloride in the acetone & ice system. SEM was taken to prove the alterative phenomena of chitosan & O-CMCS.2. The studies of adsorption behaviour for removing the residual oil by O-CMCS from WWOEIn this section, we selected a best coagulation agent for removing the rediual oil from WWOE in chitosan and its derivative. And 90h 1:1 H-O-CMCS had shown the best performance.90h 1:1 H-O-CMCS had been tested by XRD, BET surface area test, contact angle, surface energy test. The results displayed 90h 1:1 H-O-CMCS had the lower crystallinity, larger surface area, more hydrophobic characteristics, compared with chitosan. The destabilization of oil in water was successfully actualized by the application of O-CMCS (the optimal adsorbent with a dosage of 0.2 g/L; mixing time≥3 min; the broader pH 0-7.5; the temperature≤45℃; initial concentration of residual oil≤140 mg/L), which showed a enhancement for the effective adsorption for the residue oil from WWOE. Regeneration studies had also been investigated by Roasting method and rinsing method. Both of two methods had been proved that could regenerate the adsorption capacity of 90h 1:1 H-O-CMCS for removing the residual oil from WWOE. Activated carbon and polyaluminium chloride (PAC) had been used removing the residual oil from WWOE, comgpared with 90h 1:1 H-O-CMCS.90h 1:1 H-O-CMCS had better performance than activated carbon and polyaluminium chloride (PAC). The water which was disposed by 90h 1:1 H-O-CMCS had been tested by GB.3. The studies of adsorption mechanism for removing the residual oil by O-CMCS from WWOEThe destabilization of oil-in-water is successfully performed by the application of90h 1:1 H-O-CMCS and chitosan.90h 1:1 H-O-CMCS powder shows the better performance as a coagulation agent for removing the residual oil from WWOE, compared with chitosan powder. Isotherm data can be well fitted by the Langmuir equation. The maximal adsorption capacity of 90h 1:1 H-O-CMCS for removing the residual oil qo was 714.2857 mg/g. Adsorption kinetics of residue oil onto 90h 1:1 H-O-CMCS follows the pseudo-second-order kinetic model. In this paper, we designed the reversal theory to explain the adsorption mechanism of 90h 1:1 H-O-CMCS. The significant uptake of residue oil on H-O-CMCS was further proved by SEM micrographs and the surface energy test.It was proved that H-O-CMCS was a potential biomaterial as coagulation for removing the residual oil in this paper.