Treatment Of Spent Machine Cutting Fluid

With the increase of the demand for machine cutting fluid,the mechanical spent cutting fluid become a problem in the water treatment industry because of its high COD concentration,complex composition,secret formula and biodegradability Therefore,it is important to develop highly effective new-type coagulant and flocculant and reduce property loss and environmental hazardsThis paper studied on the flocculation of spent machine cutting fluids with inorganic flocculants—PAC and PAM as well as a novel graft copolymer of chitosan P(CTS/AM/DBC)by Response Surface Methodology(RSM).The experimental results are as the following1.The flocculation of spent machine cutting fluid with PAC and PAM showed that no flocculation was observed with PAM alone,while good flocculation was got with PAC alone,however,the alum was not tight enough with sole PAC;meanwhile,combined use of PAC and PAM not only good flocculation of the experimental spent machine cutting fluid was obtained,but also more compacted alum was produced,which was easy to be separated.The second-order models on transmittance(Y)in terms of coded variable initial pH value(xi),PAC concentration(X2)and PAM concentration(x3)were given by RSM as follows,Y = 3.88-0.783x1,-0.811x2-0.09x3 +0.1521x12+0.0661x22+0.0138x32-0.0126x1x2 +0.0019x1x3 +0.0031x2x32.A novel graft copolymer of chitosan P(CTS/AM/DBC)was successfully synthesized by grafting acrylamide(AM)and dimethyl acryloyloxyethyl benzyl ammonium chloride(DBC)onto chitosan(CTS)initiated by ceric ammonium nitrate(CAN).The flocculation of spent machine cutting fluid with P(CTS/AM/DBC)was studied based on two indexes,the transmittance of treated fluid and the removal efficiency of CODcrThe optimal operating conditions of treatment of spent machine cutting fluid with P(CTS/AM/DBC)determined by the single factor experiments were as follows:initiator dosage is 0.9×10-3 mol/L,reaction temperature is 70?,reaction time is 1.0 h,m(AM):m(DBC)is 3:1,m(CTS):m(AM+DBC)is 1:2,monomer DBC addition time is 1.0 h,the addition of the P(CTS/AM/DBC)is 80/100(mL/mL),initial pH value is 7 and the settling time is 10 min.Among the above 9 factors,initiator dosage,reaction time,m(AM):m(DBC)and m(CTS):m(AM+DBC)were screened out as four main influence factors by the Plackett-Burman experiment design(PBD).Then,the Second-order models on overall satisfaction(D)in terms of initiator dosage(X1),reaction time(X2),m(AM):m(DBC)(X3)and m(CTS):m(AM+DBC)(X4)were given by RSM as follows,D =-3.60 + 2.056X3+ 2.971 X4-0.4095X22-0.3612X32-2.095X42The optimum values of the above four main factors were as the following:initiator dosage is 1.0×10-3 mol/L,reaction time is 1.0 h,m(AM):m(DBC)is 2.88:1,m(CTS):m(AM+DBC)mass ratio is 3:5.Under such optimal conditions,the transmittance of the P(CTS/AM/DBC)treated spent machine cutting fluid and the COD removal rate of the aimed spent machine cutting fluid were 82.3%and 87.59%,respectively.