Application Of The Multiple Retention And Drainage Aids Containing Nano TiO₂Colloids In The Wet End Of Papermaking

As we know, the paper industry is a major water user. Whitewater closure in the paperindustry is a key factor for the conservation of energy and reducing consumption, but it willresult into the accumulation of dissolved and colloidal substances （DCS）, which effects theoperation of the papermachines and reduces the paper quality. In order to control theaccumulation of DCS and improve effectively the whitewater closure proportional, in thisthesis, we researche the interaction mechanism between the nano-TiO₂and DCS stimulants,the retention and drainage effects of the nano-TiO₂complex system to DIP, removal andcontrol of DCS with the multil-component systems, the influences of the filler sorts on thefunctions of the multi-component systems.Firstly, with the determination of COD in the supernatants of mixtures of nano-TiO₂andDCS stimulants, and SEM observations, we came to the conclusions that the stimulants couldbe flocculated by the nano-TiO₂, with the adsorptions of DCS stimulants sodium laurel acidand stearic acid. When the nano-TiO₂mixed with sodium laurel acid or stearic acid, theformer adsorbed the surface of nano-TiO₂particles and the latter was been adsorbed. In thecommercial process the flocs will be carried out the whitewater cycled system, lowering theCOD. As for the fines and fillers in the pulp, the nano-TiO₂had also an effective adsorption,resulting into retention with flocculation.Using DDJ experiments and laboratory paper machine and simulating whitewater closedcycle, we have studied the retention and drainage and the removal of DCS with the differentpolymers and nano-TiO₂complex systems. AmS with the three-dimensional structure couldform the special structures with nano-TiO₂, which were favorable for the combination withthe fibers and DCS. When the nano-TiO₂dosage is0.2%, AmS dosage is0.4%, the retentionand drainage aid has the best effect and the controlling ability of DCS.It has been examined that the influences of filler sorts on the retention and drainageeffects of the multi-complex system containing nano-TiO₂, the control-effective of the DCSaccumulation. The results showed that different filler has different effects of retention anddrainage. For the our kinds of slurry with different fillers, the total retention ratio and filler retention ratio of the pulp with talc as the filler are the most high. From high to low the orderis: talcum, kaolin, titanium oxide, calcium carbonate. Drainage time order is: calciumcarbonate, talcum, titanium oxide, kaolin. Handsheets with different filler has the differentperformance characteristics but can meet the requirements of national standards for newsprint.Finally, it was analyzed that the feasibility of application of the AmS-TiO₂system in thewet end of newspaper mills, comparing the economic efficiency investigation on AmS-TiO₂system and a news-paper mill current retention and drainage aid. The results displayed thatAmS-TiO₂had a better control effective of the whitewater COD, while the concentration ofwhitewater was higher, the effective was better. Although AmS-TiO₂system price slightlyexpensive, with the control effective of COD and improve the whitewater closed cycle, reducethe sewage treatment load, The AmS-TiO₂can get better economic benefit.