Document Type : Original Article
                            
                        
                                                    Authors
                            
                                                            
                                                                            1
                                                                        Department of Natural Resources, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, P.O. Box: 56199-13131, Ardabil, Iran                                
                                                            
                                                                            2
                                                                        Department of Paper Science and Engineering, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, P.O. Box: 49138-15739, Gorgan, Iran                                
                                                            
                                                                            3
                                                                        Tehran University, Faculty of Natural Resources, P.O. Box: 77871-31587, Karaj, Iran                                
                                                            
                                                                            4
                                                                        Department of Printing Science and Technology, Color Physics Faculty, Institute for Color Science and Technology, P.O. Box: 16688-36471, Tehran, Iran                                
                                                            
                                                                            5
                                                                        Bioprocess Technology Department, University of Borås, Borås, P.O. Box: S-501 90, Borås, Sweden                                
                            
                                                                             10.30509/jcst.2024.167278.1223
                        
                        
                            Abstract
                            In this research, it was aimed to investigate the production of a sizing agent based on lignin extracted from the soda black liquor. The crude lignin was subjected to a chemical modification process, i.e., sulfomethylation, in order to improve its reactivity ratio and to increase its solubility in water. Unmodified/ sulfomethylated lignin were mixed with starch and then, applied on the test liner papers by surface. The SEM micrograph of the treated papers surface indicated capability of soda lignin to fill the pores and to prepare for a homogeneous film on the paper surface. The roughness increased by 20 % in case of a paper treated with unmodified lignin. The lightness decreased for the paper sized with unmodified lignin compared to the control paper. The results indicated the positive effect of the chemical modification and or starch usage in improvement of the lightness and yellowness. The optical density measurement indicated higher relative values for lignin-based solutions either unmodified or modified ones. 
                        
                        
                        
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