The Research Of Neutral Deinking Agent And Deinking Technology

Alkaline deinking of waste paper is widely used in our country at present, but this deinking technique would blacken the waste paper that contain mechanical wood pulp, what's more, it was polluting the environment. Aiming at this disadvantage of alkaline deinking, several available and cheap surfactants was used in experiments to deink the old newspaper under neutral condition. Thus, the factors that affect the deinking was invesgated, the appropriate neutral deinking agents were chosen, the operating conditions were optimized, and the feasibility of neutral deinking was proved through the comparison of alkaline deinking. The research showed as follows:1.Using the chosen surfactants to deink old newspaper under neutral condition without adding alkaline, the results showed that single anionic surfactant ,single non-ionic surfactant and the compound of different surfactants could promote the ink particle to take off and with the increase of components the deinking effect improved. All this showed that the neutral deinking was feasible. The deinking effect improved after fatty acid added in the built system of anionic surfactant and ono-ionic surfactant.The neutral deinking agent which has the best deinking effect was ZX-1.2.Influence of different salts added in ZX-1 on deinking effect was investigated. Results showed that the whiteness of deinking pulp increased, especially when calcium chloride added the whiteness can maximally increase by 1.5% .3. Using ZX-1 as neutral deinking agent, the whiteness of neutral deinking pulp was close to the alkaline pulp's and after bleaching the whiteness could achieve the same level as alkaline pulp's . The neutral deinking pulp has better capable of bleaching.4. Through orthogonal experiments, the influences of the dosage of deinking agent, breaking time, curing time and floating time on deinking pulp's whiteness was investigated. The factors that influenced the whiteness of the pulp was listed by order :dosage of deinking agent> breaking time > curing time > floating time. Through the single factor experiment the optimum deinking technological conditions obtained as follows:dosage of deinking agent 0.3%(wt%) ,floating time 10 minutes, breaking time 30 minutes.5.This paper compared neutral deinking and alkaline deinking from deinking effect, COD of waste water and cost to validate the feasibility and practicability of neutral deinking in application. The result showed that the whiteness of neutral deinking pulp after bleaching could reach the same level as alkaline; neutral deinking had better yield; the COD of waste water treating by neutral deinking was lower than the alkaline deinking; and the process simplified. The cost of deutral deinking agent were as much as alkaline deinking agent, but alkaline deinking need a lot of additions and the cost of treating waste water was higher. Therefore the total cost of neutral deinking was less than alkaline deinking.