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Efficient approaches to eliminate or neutralize stickies is one of the topics of recent research. In the current study, some of the most conventional chemical and physical strategies in controlling these contaminants were compared. Control of micro-stickies originated from recycling of OCC using some selected physical approaches (washing, washing-flotation, flotation-washing and flotation) and some selected chemical methods by four fixing agents (Alum-PAC-pDADMAC-Cationic Starch) at 0.1-0.5-1 % dosing levels based on oven-dry weight of pulp were investigated. Electrical conductivity, TDS, turbidity, dissolved and colloidal substances (DCS) and COD were measured and compared to evaluate the efficiency of each approaches of micro-stickies removal. The results indicated that the lowest value of electrical conductivity and TDS in the physical methods was related to the flotation-washing stage and in the chemical methods was related to cationic starch (1%). The lowest value of turbidity in the physical methods was observed in the washing and washing-flotation. Furthermore, the potential of secondary stickies was the lowest in the washing stage, while the flotation method had the highest potential of secondary stickies. Among the different dosing levels of the fixing agents, the lowest level of turbidity and DCS was determined for pDADMAC with 0.1% addition level, and the lowest potential of secondary stickies was observed for Alum with 0.5% dosage. Both in the physical and chemical methods, turbidity and DCS at pH4 was more than neutral pH. In the chemical approach with cationic starch dosage at 1% and in the physical method with the washing-flotation stage, the lowest amount of COD was reached. [ABSTRACT FROM AUTHOR]

Sticky contaminants present one of the biggest technical challenges in the paper recycling process. These contaminants reduce paper strength, cause plugging of wires and felts, and stick to or deposit on machine parts affecting the runnability of the paper machine. In this study, first, the sticky deposit on doctor blades was subjected to multi-stage extraction with alcohol, acetone, toluene, and tetrahydrofuran solvents respectively. Then the nature of the resulting material and its physicochemical properties was investigated with FTIR analysis, GC-MS, TGA, XRF, SEM. The results showed that these deposite originates from the fibers, polymers such as polyvinyl acetate and styrene butadiene, which are components of hot melt adhesives, and fatty acid/resin esters. Fatty acids and resins are the most common organic compounds in stickies deposite. The possible origin of these compounds are chemical substances (saponified fatty acids), deinking steps and some resins and fatty acids used in the formulation of adhesives or more resistant resins and extractive materials related to cellulosic fibers. The identified minerals are mainly calcium, iron, silica and aluminum, which are present in the formulation of fillers and coating pigments during the papermaking process. [ABSTRACT FROM AUTHOR]