Study On The Adsorption And Enrichment Mechanism Of Water-based Ink Particles On Fibers During Wastepaper Recycling Process

The proportion of water-based ink printed paper is rising during the wastepaper recycling process.However,these fiber resources(water-based printing papers)are difficult to be deinked by using the conventional flotation deinking system due to the small particle size and high hydrophilicity of water-based ink particles.It is easy for them to absorb onto fibers.In present work,the essential processes of adsorption and flocculation were investigated.The effect of different temperature,time and concentration of water-based ink particles on the amount of water-based ink particles adsorption on the fiber were explored.During the experiment,in order to reduce the water-based ink on the fiber adsorption,various additives will be used on water-based ink particles to increase their particle size and hydrophobicity.Firstly,the process of secondary adsorption of water-based ink particles on the fiber was simulated to explore the influence of different concentration of water-based ink particles,temperatures and time on the adsorption amount to the fibers.The adsorption capacity of water-based ink particles on the fibers increased with the concentration arise,when the concentration of water-based ink particles is 0.4 g/L,the adsorption capacity reaches the maximum.It can be presumed that the adsorption processes are divided into two stages:the fast-stage and the slow-stage.The adsorption amount of water-based ink particles to the fibers decreased along with the increase of temperature,the adsorption amounts of water-based ink particles onto the fibers at 10,20 and 30?,were 1.63,1.43 and 1.26 mg/g respectively.Adsorption would dominate at lower temperatures while desorption would dominate at higher temperatures.Secondly,the adsorption thermodynamically and dynamically of water-based ink particles on the fiber was studied.It was apparent that the adsorption of water-based ink particles onto cellulosic fibers was fitted better to the Freundlich.Negative AH(-7.0 kJ·mol-1)indicates the exothermic nature of the adsorption process.The result of ?S=32.0 J·mol-1·K-1>0 showed that the adsorption entropy increased in this process,it indicates that the affinity of the fibers for water-based ink particles and the increase of randomness during adsorption process.The pseudo-second-order rate equation is more suitable to depict the adsorbing kinetic process of water-based ink particles onto the cellulosic fibers,The Ea value was 10.1 kJ-mol-1,diffusion mechanism is also involved in the adsorption process.Finally,the water-based ink particles were enriched with inorganic additives,organic additives and surfactants.The results show that 0.20 mol/L of CaC12 can make small ink particle size increased to 3.8?m.In the presence of fiber,0.30 mol/L of CaCl2 can increase the whiteness of pulp from 76.23%ISO to 84.23%ISO.PAC commonly used for water-based ink wastewater treatment can also increase the flocculation efficiency of water-based ink particles.When PAC concentration is 20 mg/L,the whiteness of pulp is the highest,reaching to 82.67%ISO.CPAM has a large molecular weight,so it can play a bridge role between ink particles to increase the size of water-based ink particles,when the CPAM concentration is 7 mg/L,ink particle size can increase to 0.6?m,paper whiteness can increase to 80.61%ISO;When the concentration of CTAB is 0.12 mnol/L,the particle size of water-based ink particles is 1.0 ?m,but the additive of CTAB played a negative role due to the bridging effect between the fibers and water-based ink partices.