Study On Pretreatment And Application Of Lignosulfonate

As a derivative of lignin,lignosulfonate is mainly derived from waste liquid of papermaking industry.Due to the advantages of high surface activity,good water solubility and small molecular weight,it has been widely concerned in many fields such as surfactants,cosmetics,medicine,and polymer materials.In this paper,using lignosulfonate as raw material,the application of lignosulfonate in dye dispersant,windbreak sand fixing agent,composite coating,artificial fiber board and concrete water reducing agent were studied,in order to reduce environmental pollution while realizing the high value-added utilization of lignosulfonate.Firstly,using lignosulfonate as raw material,the dye dispersant was prepared by combined treatment of separation,purification and chemical modification.The effects of different separation and purification methods and epichlorohydrin dosage on dye dispersant were investigated.Ultrafiltration could significantly improve the performance of dye dispersant.With the increase of ECH dosage,the dyeing performance of dye dispersant increased gradually,while the reduction hydrolysis rate decreased.When the dosage of ECH was 3 mmol/g,the performance of dye dispersant reached the best after ultrafiltration of 1000 molecular weight.Secondly,the performance of untreated by LS-0 and ultrafiltration（LS-1000 and LS-5000）as windbreak and sand-fixing agent was compared.LS-0 has the best water retention and moisture absorption performance,and the evaporation rate of sand sample was only 82.2%.LS-5000 showed good compressive strength and wind erosion resistance,with compressive strength and cumulative weight loss of sand grains per unit area of 365Pa and 0.97%,respectively.The three lignosulfonates with different treatments have the function of windbreak and sand fixation under different environmental conditions.Then,（1）Lignin-containing cellulose nanofibrils（LCNF）were prepared by DES treatment and high pressure homogenization from hemp stalk.LCNF has a good directional arrangement trend and a certain hydrophobicity at low concentration.In addition,the prepared LCNF showed good UV shielding and good redispersibility in water and DMSO.（2）Preparation and characterization of 5 composite coatings containing lignosulfonate,LCNF,Ag NO₃and other reagents.The composite coatings were nanoscale,with particle size distribution between 100?600 nm,and have good anti-aggregation and dispersion properties.Under the same conditions,the thermal stability and hydrophobicity of composite coatings prepared with LS-5000 were higher than those prepared with lignosulfonate.In addition,the five composite coatings have excellent UV shielding and antibacterial activity.Finally,lignosulfonate is applied in the field of artificial fiberboard and concrete water reducing agent.The Type B fiberboard with 0.5%lignosulfonate content has the best performance,and its elastic modulus（MOE）and internal bonding strength（IB）meet the national standard of medium density fiberboard.In addition,when lignosulfonate was used as concrete water reducing agent,its performance was good under the dosage of 0.8%,the water reducing rate and slump were up to 28%and 90 mm,respectively,in line with the standard of high-performance water reducing agent.