The research is related to the development of a method for modifying cellulose fiber to improve the operational characteristics of membranes. Epichlorohydrin and triethanolamine were used as modifiers to plasticize the structure of the cellulose membrane. The consumption of modifiers, the temperature and duration of cellulose fiber modification, as well as the drying conditions of the resulting membranes on their properties were investigated. It has been shown that selected modifiers can act as plasticizers depending on the processing temperature. It was established that the resulting membranes are characterized by low productivity, but are capable of effectively reducing water color. It has been experimentally shown that the use of a modifier with a consumption of 15% allows to ensure the selectivity of color removal during filtration of a sodium humate solution at a level of more than 98%.