Study On Biodegradability Of Cationic Amine Collectors

With the development of mineral industries, the requirement for mineral resources is increasing in China and flotation reagents are used more and more, causing more and more serious pollution. Amine cationic collectors are an important sort of flotation reagents developed in recent years. They are also used more and more. At present, the treatment of cationic amine collector is rarely reported. So, the biodegradation of the cationic amine collectors should be foud out by using the treatment of surfactant, which is to apply the theory of preparing new high-effect environment-friendly flotation reagents and flotation waste water treatment.At first, BOD5/CODCr test, Carbon Dioxide Evolution Test and Shaking Culture tests are used to study the biodegradation of six cationic amine collectors, which are analyzed and evaluated. Then their biodegradation curves are simulated by first-order kinetic model and logistic model. At last, taking ether amine 609 for example, and the IR spectra of the beginning and end samples of the biodegradation of the ether amine 609 are tested. And then compared the two figures, the final product are deduced. The results of the research are as follows.(1) BOD5/CODCr test indicates that the value of the BOD5/CODCr of 30mg/L dodecylamine,octadecylamine,ether amine 609,ether amine 601,dodecyl trimethyl ammonium chloride and dodecyl trimethyl ammonium bromide is 0.49,0.0043,0.054, 0.062,0.048 and 0.089, respectively. Cl- has a more biological inhibition than Br".(2) Carbon Dioxide Evolution Test indicates that the biodegradation degree Dm containing 20mg/L organic C of dodecylamine, octadecylamine, ether amine 609, ether amine 601, dodecyl trimethyl ammonium chloride and dodecyl trimethyl ammonium bromide is 60.27%,30.10%,54.95%,52.02%,60.35% and 68.13%, respectively. And the index of IB is 147.6%,116.0%,131.12%,123.48%,164.7% and 171.2%. And the index of RBDD is 82.03%,64.44%,76.25%,71.81%,83.01% and 86.30%, respectively.(3) Shaking Culture test indicates that biodegradation degree of 30mg/L decylamine,octadecylamine,ether amine 609,ether amine 601,dodecyl trimethyl ammonium chloride and dodecyl trimethyl ammonium bromide is 98.96%,97.87%, 97.78%,92.50%,99.73% and 99.76%, respectively. DT-90 is 12.0h,16.6h,3.95d, 5.81d,23.1h and 17.9h, respectively. And a new method to determine the concentration——heated, added acid and dissolved again, is appled to solve the problem of determination of concentration of octadecylamine in the Shaking Culture test.(4) Results and data of the three evaluation methods indicates a conclusion. In the condition of domesticated microorganism and the fully contact between the associated octadecylamine and microorganism, the order of biodegradability of six cationic amine collectors from strong to weak is dodecylamine>octadecylamine> dodecyl trimethyl ammonium bromide>dodecyl trimethyl ammonium chloride> ether amine 609>ether amine 601, while under the condition of not domesticated microorganism and no full contact between the associated octadecylamine and microorganism, the order of biodegradability of six cationic amine collectors from strong to weak is dodecylamine>dodecyl trimethyl ammonium bromide>dodecyl trimethyl ammonium chloride>ether amine 609>ether amine 601>octadecylamine.(5) The biodegradation dynamic models of 30mg/L six cationic amine collectors in Shaking Culture test are as follows. cA(DA)=26.79exp(-0.1831t) cA(OA)=24.21exp(-0.1366t) cA (EA609)=26.35 exp(-0.5627t) cA(EA601)=20.13exp(-0.4034t)The biodegradation of primary amines and ether amines follows the first-order dynamic model, while the quaternary ammonium salts follow the logistic model. And the Relevance index R2 of the dynamic model is 0.9968,0.9962,0.9964,0.9997, 0.9883 and 0.9873, respectively. The dynamic constant k is 0.1831h-1,0.1366 h-1, 0.5627d-1,0.4034d-1,while the rate of degradation r is 0.8638h-1,1.2987h-1. And k(dodecylamine)>k(octadecylamine)>k(ether amine 609)>k(ether amine 601), r(dodecyl trimethyl ammonium chloride)>r(dodecyl trimethyl ammonium bromide). (6) Degradated by microorganism in the past six days, organic N of ether amine 609 may be converted to NH4+, and CH3—,—CH2—,C—O—C also became CO2 and H2O. And the reaction equation of the degradation is as follows.In the end of the degradation in the IR spectrum, there is no peak of—COOH,—CHO or—OH. It indicates that C—O—C may be completely mineralized to CO2 and H2O.