Progress 05/01/01 to 04/30/07
Outputs
OUTPUTS: Several experiments were performed in this research, mainly laboratory scale paper recycling experiments and lab scale paper sorting experiments. The results were presented at several national conferences, including the Technical Association of Pulp and Paper Industry (TAPPI) conferences, the American Chemical Society conferences, the EPA P3 conference and the Research Forum on Recycling conferences sponsored by PAPTAC and TAPPI. Some of the information was distributed through a short course delivered in 2005, titled, Hands On Workshop for Paper Recycling, sponsored by North Carolina State University (NCSU) and TAPPI. Material was also taught through a NCSU distance education course, titled, Advanced Topics in Paper Recycling. A week long course that disseminated the findings titled New Products from Renewable Sources was delivered at NCSU. Products included the following. A clear understanding of the extrusion of pressure sensitive adhesives in slotted screens. An
understanding of agglomeration deinking. An understanding of supercritical carbon dioxide extraction of wax from wax paper products. An understanding of the interactions between water and paper fibers. An understanding of the loss of paper strength in paper upon recycling. The development of a lignin sensor, stiffness sensor, color sensor for the automatic sorting of recovered paper. The lignin sensor has been commercialized and incorporated into an industrial system to sort recovered papers.
PARTICIPANTS: Collaborators not within NCSU: Mahendra Doshi and coauthors. Faculty collaborators at NCSU: Hubbe, Jameel, Rojas, Heitmann, Kadla, Ramasubramanian. Organizational partners: American Forest and Paper Association, Technical Association of Pulp and Paper Industry, MSS Sorting.
TARGET AUDIENCES: The target audience is the paper industry and all associated researchers.
PROJECT MODIFICATIONS: No significant major changes in approach occurred for this program. As new opportunities arised in paper recycling that warranted attention, the project often times accompanied these.
Impacts
Automatic Paper Sorting. One of the objectives of this research was to develop fast acting sensors that will help characterize recovered papers as part of an automated recovered paper sorting system that is efficient, fast, accurate and completely autonomous. A non-contact bending stiffness sensor for recovered paper and board has been developed. Also, a fiber optic sensor for the real time measurement of lignin content of paper was developed. A Fuzzy Logic inference system was developed to distinguish paper grades based on sensor outputs. Loss of Paper Strength on Recycling. Fiber hornification (the irreversible collapse of pores in a wood fiber upon drying decreasing the potential to produce strong paper upon recycling) was evaluated by a parameter termed hard-to-remove (HR) water content, which was defined as the ratio of water mass to fiber mass at the transition between the constant rate zone and the falling rate zone from the isothermal TGA experiments. The
results indicated that the HR water content could be used as a measurement technique for fiber hornification, showing a close correlation with the WRV over repeated drying and wetting cycles. Characterization of Water-Cellulose Interactions. Changes in pore size distribution during the drying of cellulose fibers were determined using differential scanning calorimetry (DSC) with an isothermal step melting procedure. Softwood bleached kraft pulp at various moisture ratios were generated from partial drying in a thermogravimetric analyzer (TGA) and then analyzed in a DSC. It was observed that larger pores collapse first followed by the sequential collapse of smaller pores. Adhesive Contaminant Removal. The removal of adhesive contaminants using pressure screens is a critical issue in paper recycling. The passage of PSA particles through a single 0.178 mm (0.007 inch) slot was determined versus particle dimensions and pressure difference. It was found that PSA particles with smallest
dimension greater than approximately 4 times the slot width did not pass through the slot for pressure differences of up to 80 kPa. However, a significant percentage of PSA particles with smallest dimension between the slot width and 4 times the slot width passed through the slot at moderate pressure differences. These findings provide basic information about the behavior of contaminants in paper recycling that is useful in improving current recycling operations. Supercritical Carbon Dioxide Extraction of Wax. Old corrugated containers (OCC) are an excellent source of strong, unbleached fibers for recycling. Currently, wax coated OCC (WOCC) is excluded from recycling. A new process to remove contaminants such as wax in OCC was developed using supercritical CO2 extractions. The removal of the wax was demonstrated to be 100% under certain operating conditions, with pressure being important. It has been clearly shown that the removal of wax from WOCC with CO2 is technically feasible.
However, one economic model of the process shows that the process is not economically feasible. The extent of solubility of the wax in the CO2 is the key to the major economic issues.
Publications
- What happens to cellulosic fibers when paper is made and recycled? A review, M. A. Hubbe, R. A. Venditti, O. J. Rojas, Bioresources, 2(4), 739-788 (2007).
- Environmentally acceptable technology for removing post-it note adhesive in paper recycling process, R. A. Venditti, N. A. Fadl, A. H. Basta, Appita Journal, 60(5) 378-383, 2007.
- The Effects of Adhesive Properties on the Removal of Pressure Sensitive Adhesive Contaminants in Paper Recycling, R. A. Venditti, B. E. Lucas, H. Jameel, Progress in Paper Recycling, 16(3)18-31, 2007.
- Stiffness based sorting of paper on a high speed conveyor, M. K. Ramasubramanian, R. A. Venditti, K. C. Katuri, Journal of Mechanics of Materials and Structures, 2(2), pp. 201-219, 2007. Hard to Remove Water in Cellulose Fibers Characterized by Thermal Analysis: a Model for the Drying of Wood Fibers, S. Park, R.A. Venditti, H. Jameel, and J.J. Pawlak, Tappi, 6(7), pp. 10-16, 2007.
- A Non-Contact Sensor for the Identification of Paper and Board Samples on a High-Speed Sorting Conveyor, M. K. Ramasubramanian, Richard A. Venditti and Kalyan C. Katuri, Appita Journal, 60(5) 2007.
- Studies of the Heat of Vaporization of Water Associated with Cellulose Fibers Characterized by Thermal Analysis , Sunkyu Park, Richard A. Venditti, Hasan Jameel, and Joel J. Pawlak, Cellulose, 14, pp. 195-204, 2007.
- Surface and Pore Structure Modification of Cellulose Fibers Through Enzyme Treatment, S. Park, R.A. Venditti, D.G. Abrecht, H. Jameel, J.J. Pawlak, and J.M. Lee, Journal of Applied Polymer Science, 103(6), pp. 3833-3839, 2007.
- Natural Surfactants for Flotation Deinking in Paper Recycling, R. A. Venditti, O. J. Rojas, H. Morris, J. Tucker, K. Spence, C. Austin, L. G. Castillo, 8th Research Forum on Recycling, Niagara Falls CA, September 23-26, 2007.
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Progress 01/01/06 to 12/31/06
Outputs
Recovered Paper Automatic Sorting The objective of this research is to develop fast acting sensors that will help characterize recovered papers as part of an automated recovered paper sorting system that is efficient, fast, accurate and completely autonomous. A non-contact bending stiffness sensor for recovered paper and board has been developed. Also, a fiber optic sensor for the real time measurement of lignin content of paper was refined. A study of the use of IR thermographic imaging was performed (ThermoVision A20M Infrared Camera) and it was determined that the time constant for cooling of paper samples was strongly correlated to the basis weight of the paper. The time constant was related to the thickness of the paper but showed little response to the density of the paper. A Fuzzy Logic inference system was developed to better distinguish paper grades based on some of the sensor responses listed.. Adhesive Contaminant Detection A major review of the control of
tacky deposits on a paper machine was generated and is listed in the references of this report. The review considers a variety of chemical additives that papermakers have used to combat deposit problems. The premise of this article is that knowledge of the chemistry and colloidal behavior of existing deposit-control agents can guide us in the selection, usage practices, and further development of strategies for the control of tacky deposits, especially in the case of pitch, adhesive-based stickies, and wax-like deposits. Paper Strength Loss on Recycling Fiber hornification (the irreversible collapse of pores in a wood fiber upon drying decreasing the potential to produce strong paper upon recycling) was evaluated by a parameter termed hard-to-remove (HR) water content, which was defined as the ratio of water mass to fiber mass at the transition between the constant rate zone and the falling rate zone from the isothermal TGA experiments. The results indicated that the HR water content
could be used as a measurement technique for fiber hornification, showing a close correlation with the WRV over repeated drying and wetting cycles. Characterization of Water-Cellulose Interactions Changes in pore size distribution during the drying of cellulose fibers were determined using differential scanning calorimetry (DSC) with an isothermal step melting procedure. Softwood bleached kraft pulp at various moisture ratios were generated from partial drying in a thermogravimetric analyzer (TGA) and then analyzed in a DSC. The waters with specific melting point depressions detected by DSC were used to determine the pore size distribution according to the Gibbs-Thomson equation. It was observed that larger pores collapse first followed by the sequential collapse of smaller pores. It is suggested that pore wall collapse resistance is the primary factor that determines which size pores close. The average measured pore size was calculated to be about 80 nm and reduced with drying of the
fibers. A constant pore size of about 20 nm was observed at moisture ratios below 0.3 g/g, which corresponds to one-to-two layers of non-freezing bound water tightly bound to the surface.
Impacts
The advancement of automated sorting of recovered paper will encourage the recycling of paper, avoiding paper wastes from entering landfills. The lignin sensor for sorting that has been developed has been commercialized and is in use in several automated sorting operations. The efficient removal of adhesive contaminants is the most pressing problem in paper recycling. This research has developed a methodology for evaluating test methods for adhesive concentration determinations. Paper fibers are degraded often during recycling. The research performed has determined the impact of drying and heating on the fiber degradation process. This information can be used to improve the effective recycling of paper. Finally, the interactions between water and cellulose are very critical in paper making and paper recycling. A method has been described to better understand these interactions using a simple, repeatable test, valuable to all those trying to improve the paper making
and paper recycling processes.
Publications
- Dynamic Changes in Pore Size of Cellulose Fibers During Drying Processes, S. Park, R. A. Venditti, H. Jameel, and J. J. Pawlak, 231st ACS National Meetings, March 2006, Atlanta.
- The Effects of Adhesive Properties on the Removal of Pressure Sensitive Adhesive Contaminants in Paper Recycling, R. A. Venditti, B. E. Lucas, H. Jameel, Pressure Sensitive Tape Council (PSTC) 29th Annual Technical Seminar, Las Vegas, NV, May 3-5, 2006.
- Preparation of Starch Micro-Cellular Foam for Filler Applications, Khaled El-Tahlawy, Richard Venditti, and Joel J. Pawlak, Proceedings of the 2006 Progress in Paper Physics Symposium, October 2-5, 2006, Miami, OH.
- A Novel Method to Evaluate Fiber Hornification by High Resolution Thermogravimetric Analysis, S. Park, R.A. Venditti, H. Jameel, and J.J. Pawlak, Appita Journal, 59(6), pp. 481-485, 2006.
- Changes in Pore Size Distribution During Drying of Cellulose Fibers as Measured by Differential Scanning Calorimetry, S. Park, R. A. Venditti, H. Jameel, and J. J. Pawlak, Carbohydrate Polymers, 66(1), pp. 97-103 2006.
- Control of Tacky Deposits on Paper Machines A Review, M. A. Hubbe, O. J. Rojas, and R. A. Venditti, Nordic Journal of Pulp and Paper, 21(2), pp. 154-171, 2006.
- Hard to Remove Water in Cellulose Fibers Characterized by High Resolution Thermogravimetric Analysis - Methods Development, S. Park, R. A. Venditti, H. Jameel, J. Pawlak, Cellulose, 13 (1) pp. 23-30 (2006)
- The Positive Pulse Jar (PPJ): A Flexible Device for Retention Studies, M. A. Hubbe, J.A. Heitmann, R. A. Venditti, and T. Tripattharanan, Paperi ja Puu, 88(1), 39-45, 2006.
- The Effect of Cellulase on the Pore Structure of Cellulose Fibers, S. Park, R. A. Venditti, D. G. Abrecht H. Jameel, and J. J. Pawlak, 2006 Pan Pacific Conference, June 2006, Korea.
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Progress 01/01/05 to 12/31/05
Outputs
Recovered Paper Automatic Sorting The objective of this research is to develop fast acting sensors that will help characterize recovered papers as part of an automated recovered paper sorting system that is efficient, fast, accurate and completely autonomous. A non-contact bending stiffness sensor for recovered paper and board has been developed. The static distance sensor determines the deflection of a sheet of paper spanning a gap with an air jet impinging on the topside and a distance sensor on the bottom-side, a measure of the bending stiffness of the paper. Also, a fiber optic sensor for the real time measurement of lignin content of paper was refined. The sensor is based on the principle that the fluorescence emitted by paper following absorption of visible light has a wavelength distribution determined by the chemical composition of the paper. Adhesive Contaminant Detection The objective of this research was to evaluate several different stickies test methods
for pulps from various unit operations of an old corrugated container recycling plant. The stickies test methods evaluated included several deposition tests, a solvent extraction method, two handsheet methods and two methods that utilized laboratory screening. The results of the study demonstrate a method to differentiate the test methods. Further, the results reveal the stickies concentration profile across an OCC recycle mill. Paper Strength Loss on Recycling The effects of heating and drying of bleached kraft fibers were separately investigated by measuring the water retention value (WRV) and cellulose viscosity. Heating and drying were observed to result in different changes in fibers upon treatment. Heating fibers without water removal resulted in a decrease in WRV from the never dried and air dried levels, but not as large of a decrease as drying at high temperatures. Drying at high temperatures reduced the cellulose viscosity only slightly, whereas heat treatment at high
temperatures resulted in much greater losses in cellulose viscosity. Fractionation to Upgrade Recycled Fiber Quality To understand the influence of fiber properties on the fractionation of chemical pulp in a hydrocyclone, a simple fiber model was proposed with a slip velocity equation. In the model, a novel method to estimate drag coefficient was demonstrated. This analysis predicts that fibers with higher slip velocities tend to be rejected. The results indicate that drag coefficient is the dominant variable and this was verified experimentally. Characterization of Water-Cellulose Interactions A method has been described that classifies water in a cellulosic fiber and water system. Thermogravitmetric analysis (TGA) is used to determine hard-to-remove (HR) water from an isothermal drying curve. The HR water content is defined as the moisture ratio (g of water / g of oven dried sample) of the fiber-water system at the transition between the constant rate zone and falling rate zone of
an isothermal drying curve. The TGA instrument provides tightly controlled drying conditions that allow one to distinguish small differences in drying behavior.
Impacts
The advancement of automated sorting of recovered paper will encourage the recycling of paper, avoiding paper wastes from entering landfills. The lignin sensor for sorting that has been developed has been commercialized and is in use in several automated sorting operations. The efficient removal of adhesive contaminants is the most pressing problem in paper recycling. This research has developed a methodology for evaluating test methods for adhesive concentration determinations. Paper fibers are degraded often during recycling. The research performed has determined the impact of drying and heating on the fiber degradation process. This information can be used to improve the effective recycling of paper. Finally, the interactions between water and cellulose are very critical in paper making and paper recycling. A method has been described to better understand these interactions using a simple, repeatable test, valuable to all those trying to improve the paper making
and paper recycling processes.
Publications
- Development of a Bending Stiffness Sensor for the Automated Sorting of Recovered Paper, R. A. Venditti, M. K. Ramasubramanian, Kalyan C Katuri, 2005 Engineering, Pulping, and Environmental Conference, Philadelphia, August 28-31, 2005.
- Measurement of fiber hornification using high resolution thermogravimetric analysis, Sunkyu Park, Richard A. Venditti, Hasan Jameel and Joel J. Pawlak, 2005 Engineering, Pulping, Environmental Conf. -Philadelphia, PA -August 28-31, 2005.
- Gypsum-Cellulose Interactions - a Colloidal Probe Microscopy Study, J. C. Bastidas, J. J. Pawlak, R. A. Venditti, J. A. Heitmann, M. A. Hubbe, J. F. Kadla, 13th ISWFPC in Auckland, New Zealand, May 2005.
- High Resolution Thermogravimetric Analysis of Pulp Drying, S. Park, R. A. Venditti, J. Pawlak, H. Jameel, 13th Fundamental Research Symposium, September 2005 England.
- Dynamic Measurement of Drying Behavior of Cellulose Fibers Using Thermogravimetric Analysis, H. Jameel, S. Park, R. A. Venditti, J. Pawlak, IAWPS 2005, November 2005, Japan.
- Chemical Force Microscopy of Cellulosic Fiber", J. C. Bastidas, R. A. Venditti, J. J. Pawlak, R. Gilbert, S. Zauscher, J. F. Kadla, Carbohydrate Polymers, 62, pp 369-378, 2005.
- Optical sensor for non-contact measurement of lignin content in high speed moving paper surfaces M. K. Ramasubramanian, R. A. Venditti, C. Ammineni, IEEE Sensors Journal, 5(5), pp. 1132-1139, October 2005.
- Evaluation of Various Adhesive Contaminant (Stickies) Analysis Methods: Tracking Stickies Concentrations Across Unit Operations of an Old Corrugated Container Recycling Plant R. A. Venditti, H. M. Chang, K. Copeland, Progress in Paper Recycling, 14(2), pp. 9-19, 2005.
- The Effects of Heating Without Water Removal and Drying on the Swelling as Measured by Water Retention Value and Degradation as Measured by Intrinsic Viscosity of Cellulose Papermaking Fibers E. S. Welf, R. A. Venditti, and M. A. Hubbe, Progress in Paper Recycling, 14(3), pp. 5-13, 2005.
- The Effect of Operating Variables and Fiber Properties on Fiber Fractionation Using a Hydrocyclone S. Park, R. A. Venditti, H. Jameel, J. Pawlak, M. Byrd, Journal of Pulp and Paper Science, 31(3), pp. 132-137, 2005.
- Natural Polymer Based Foam as an Opacify Agent in Coatings Films and Paper R. A. Venditti and J. J. Pawlak, US Patent Application, submitted 2005.
- Thermogravimetric Analysis of Water Associated with Cellulose Fibers, Park, Sunkyu, Venditti, R. A., Jameel, H., Pawlak, J., Society of Plastics Engineers ANTEC 2005, Boston MA, May 1-5, 2005.
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Progress 01/01/04 to 12/31/04
Outputs
Economic Analysis of Wax Removal from Old Corrugated Containers Using Supercritical Carbon Dioxide A new process to remove contaminants such as wax, stickies and sizing in waxed old corrugated containers (WOCC) was proposed using supercritical CO2 extractions (SC-CO2). In the proposed process, unpulped WOCC would be placed in a high-pressure vessel and the wax extracted using SC-CO2. The removed wax could then be recovered in a dry form and sent for recycling. The de-waxed OCC could then be sent to an OCC recycling mill for conventional repulping and cleaning steps. The economic feasibility of implementing a commercial CO2 extraction process for WOCC was determined. A preliminary basis of design was developed that identified major pieces of equipment and estimates of material flowrates and process conditions. Estimates of the capital cost, manufacturing cost, and all other associated costs were made. A return on investment and net present value of an investment were
calculated for a base case and several other price/cost scenarios. The current conclusion is that the SC-CO2 extraction of WOCC is not economically practical under the existing economic, cultural and environmental conditions. Removal of Pressure Sensitive Adhesives in Screening Operations One of the major concerns in paper recycling is the presence of pressure sensitive adhesives in the recycled material. One useful process in the paper industry to remove the pressure sensitive adhesive from the recycled material is pressurized screening. The objective of this research was to understand how adhesive formulation affects the mechanical properties of pressure sensitive adhesives, and thus their behavior in the pulper and pressure screen. The glass transition temperature, contact angle, yield strain, yield stress, and modulus were measured for each of eight different adhesive materials. Adhesive particles for each of the materials were analyzed in a pressurized single slot device with a
0.007 inches wide slot, typical slot width for industrial pressure screens. Yield strain, yield stress, and modulus were significant in determining the average particle size produced by pulping. Yield stress and particle area were significant in determining particle passage through the slot of the pressurized single slot device. Particle passage decreased as the yield stress and average particle area increased, and increased as the interaction between yield stress and average particle area increased. The mechanical properties of adhesive materials, which depend on the adhesive formulation, are important in predicting particle breakage and passage in industrial recycling operations. Further, it was of interest to determine if an extrusion or folding model could predict the passage of PSA particles through a laboratory single slot device. Both a folding and extrusion model were fitted to experimental data. The average yield stress of the PSA materials was calculated from the fits of the
data and was within the range of the independently measured yield stress values, indicating utility of either of the models.
Impacts
A new technology for the recovery of fiber from wax containing boxes has been demonstrated, making it possible to recover wax boxes. The determination of the critical economic factors for this process has been achieved and will assist those interested in the application of the technology. The effective removal of adhesive contaminants from recycled paper is critical to advancing the paper recycling industry. Several important mechanisms that determine whether an adhesive particle is removed are elucidated. This is useful information for adhesive manufacturers, recycling equipment manufauturers and paper recycling operators to improve the paper recycling process.
Publications
- A Simple Experiment to Demonstrate the Flotation Deinking Process, R. A. Venditti, J. of Chemical Education, 81(5), 693, 2004.
- Porous Fibers from Natural/Synthetic Polymer Blends J. F. Kadla, R. D. Gilbert, R. A. Venditti, S. Kubo, US Patent Number US 6,765,028 B2, July 20, 2004.
- A Compact, High Speed Lignin Sensor for the Automated Sorting of Newsprint from Mixed Waste, Vishnu Mallapragada, M. K. Ramasubramanian and Richard Venditti, Tappi Spring Technical Conference, May 2004.
- Extrusion and Folding Models for the Pasage of Pressure Sensitive Adhesive Materials Through Slotted Screening Devices in Paper Recycling R. A. Venditti, B. E. Lucas and H. Jameel, 7th Research Forum on Recycling, September 27-29, 2004, Quebec City, Canada.
- Characterization of Bound Water in Fibers Using Thermogravimetric Analysis, S. Park, R. A. Venditti, H. Jameel, J. Pawlak, Progress in Paper Physics Seminar 2004, June 2004, Norway.
- The Effect of Paper Additives on Xerographic Toner Agglomeration during the Recycling Process Chen, Junhua, Heitmann, John A., Chang, Hou-min, Hubbe, Martin A., and Venditti, Richard A., Progress in Paper Recycling, 13(4), pp 16-23, 2004
- Effects of Sugar Addition Before Drying on the Wet-Flexibility of Redispersed Kraft Fibers, Min Zhang, Martin A. Hubbe, Richard A. Venditti, and John A. Heitmann, Journal of Pulp and Paper Science, 30(1), pp. 29-34, 2004.
- Refining to Overcome Effects of Drying Unbleached Kraft Fibers in the Presence or Absence of Sugar, Min Zhang, Martin A. Hubbe, Richard A. Venditti, and John A. Heitmann, Progress in Paper Recycling, 13(2), 5-12, 2004.
- Supercritical Carbon Dioxide Extraction of Wax Coated Old Corrugated Containers: An Economic Analysis R. A. Venditti, R. D. Gilbert, J. F. Kadla, T. Bliss, Progress in Paper Recycling, 13(2), 13-19, 2004.
- The Effects of Adhesive Properties on Particle Breakage and Passage During Paper Recycling Operations B. E. Lucas, R. A Venditti, and H. Jameel, Progress in Paper Recycling, 13(2), 20-28, 2004.
- Effect of Idealized Flow Regimes during Forming on Retention Aid Performance. Part 1. Cationic Acrylamide Copolymer, T. Taweewat, M. A. Hubbe, R. A. Venditti and J. A. Heitmann, Appita J. 57 (5 ), 404-410, 2004.
- Effect of Idealized Flow Conditions on Retention Aid Performance. Part 2: Polymer Bridging, Charged Patches, and Charge Neutralization,Tripattharanan, T., Hubbe, M. A., Heitmann, J. A., and Venditti, R. A., Appita J. 57 (6): 448-454, 2004.
- Effect of Idealized Flow Regimes during Forming on Retention Aid Performance. 2. Polymer Bridging, Charged Patches, and Charge Neutralisation T. Taweewat, M. A. Hubbe, J. A. Heitmann, and R. A. Venditti, Appita J. 57 ( 6 ), 448-454, 2004.
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Progress 01/01/03 to 12/31/03
Outputs
Removal of Wax from Wax Containers. A strong need exists for the paper industry to develop methods to recycle wax-treated old corrugated containers (wax-OCC). This research evaluated a process to recycle wax-OCC by incorporating it into a conventional kraft pulping process. A pilot plant batch digester was used to cook blends of pre-consumer wax-OCC and hardwood chips. Analysis of the accepted pulps showed that the incorporation of the wax-OCC in the cooks produced pulps of similar strength and Kappa number at higher yields relative to a 100% virgin hardwood cook. The hexane extractive content of the pulp and the slide angle of resulting handsheets indicated that some, but not all, of the wax was removed from the pulp. A critical parameter affecting the wax removal efficiency was the post-pulping washing procedure. Approximately 95% wax removal was obtained for a 25% wax-OCC/hardwood chip blend digester feed, producing a pulp with approximately 1% wax content with the
procedures described herein. Recovered Paper Automatic Sorting. The objective of this research is to develop an automated waste paper sorting system that is efficient, fast, accurate, and completely autonomous. The research has consisted of developing a fast sensor system to measure the distinguishing optical characteristics of various grades of paper and an identification algorithm for paper grades using a neural network. In this project, the principles of mechatronic design are being applied to the problem of sorting mixed waste paper. Mechatronics is loosely defined as the synergistic combination of mechanical engineering with electronic and intelligent computer control in the design and manufacturing of industrial products and processes. The optical characteristics of paper used for identification include visible light fluorescence, gloss and color. Visible light fluorescence has been demonstrated to be an accurate and fast method to measure the lignin content in paper. Ongoing
work involves the miniaturizing of the sensors into a single, compact detector and the development of the neural network for decision making. Evaluation of Macro Stickies Test Methods. Pulp containing PSA was prepared in the laboratory and blended with stickie-free pulp in four different proportions. Four pulps were then dewatered and shipped to four laboratories for the evaluation of macro stickies in terms of mm2/kg with different tests. In view of the significant differences in the methods used to measure the concentration of macrostickies, it is not surprising to see considerable variations in actual values of stickies area reported by the participating groups. However, we were surprised to see excellent correlation among all methods for both laboratory as well as mill samples. As a result, any one of the methods seems to be suitable for monitoring stickies content but one cannot compare actual values from different methods as they may vary significantly.
Impacts
A new technology for the recovery of fiber from wax containing boxes has been demonstrated, making it possible to recover wax boxes. Further, sensors have been developed to assist in the automatic sorting of recovered paper, thus improving the potential for sorting technology of recovered paper. Finally, the measurment of large adhesive particles has been compared using different testing methods and recommendations on the use of these methods made.
Publications
- Comparison of Macro Stickies Measurement Methods Mahendra R. Doshi, PPR and Bill Moore, FVTC, Appleton, WI. Part 1: Kevin Copeland and Richard Venditti, NCSU, Raleigh, NC, Part 2: Hans Putz, Part 3. Thierry Delagoutte, CTP., Part 4. Carl Houtman, Freya Tan, Lisa Davie and Gregg Sauve, 2003 TAPPI Technical Conf., Oct. 26-30, Chicago Hyatt Hotel.
- Mechatronic Design and Control of a Waste Paper Sorting System for Efficient Recycling: Development of a Lignin Sensor to Distinguish Recovered Paper Grades at High Speed, M. Karanakaran, M. K. Ramasubramanian, R. A. Venditti, 2003 TAPPI Technical Conf., Oct. 26-30, Chicago Hyatt Hotel.
- Fractionation of Paper Recycling Deinking Sludge for Potential Utilization in the Production of Ethanol, R. A. Ernest, R. A. Venditti, D. S. Argyropolous, R. D. Gilbert, Abstracts of the Second Annual NC State University Undergraduate Summer Research Program Symposium, p. 28, August 7, 2003, North Carolina State University, Raleigh, NC.
- Pulping Wax Containing Old Corrugated Containers with Hardwood Chips in a Kraft Pulping Operation,E. S. Welf, R. A. Venditti, H. Jameel, and J. Renaud, Progress in Paper Recycling, 12(2), pp. 13-18, 2003.
- Changes to Unbleached Kraft Fibers Due to Drying and Recycling M. A. Hubbe, R. A. Venditti, R. L. Barbour, and M. Zhang, Progress in Paper Recycling, 12(3), pp. 11-20, 2003.
- Comparison of Macro Stickies Measurement Methods Mahendra R. Doshi, PPR and Bill Moore, FVTC, Appleton, WI. Part 1: Kevin Copeland and Richard Venditti, NCSU, Raleigh, NC, Part 2: Hans Putz, Part 3. Thierry Delagoutte, CTP., Part 4. Carl Houtman, Freya Tan, Lisa Davie and Gregg Sauve, Progress in Paper Recycling, 12(3), pp. 34-43, 2003
- Comparison of Micro Stickies Measurement Methods Part I: Sample Preparation and Measurement Methods, M. R. Doshi, A. Blanco, C. Negro, T. Delagoutte, G. M. Dorris, C. C. Castro, A. Hamann, R. D. Haynes, C. Houtman, K. Scallon, J. J. Putz, H. Johansson, R. A. Venditti, K. Copeland, H. M. Chang, Progress in Paper Recycling, 12(4), pp. 35-42, 2003.
- Comparison of Micro Stickies Measurement Methods Part II: Results and Discussion M. R. Doshi, A. Blanco, C. Negro, T. Delagoutte, G. M. Dorris, C. C. Castro, A. Hamann, R. D. Haynes, C. Houtman, K. Scallon, J. J. Putz, H. Johansson, R. A. Venditti, K. Copeland, H. M. Chang, Progress in Paper Recycling, 13(1), pp. 44-53, 2003.
- The Effect of Operating Variables on the Mass Balance of Fiber Fractionation Using a Hydrocyclone S. Park, R. A. Venditti, H. Jameel, J. Pawlak, M. Byrd, 2003 TAPPI Technical Conf., Oct. 26-30, Chicago Hyatt Hotel.
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Progress 01/01/02 to 12/31/02
Outputs
Comparison of Adhesive Detection Methods in Paper Recycling. The objective of this research was to evaluate several different macro-stickies test methods for pulps made from old corrugated containers. The stickies test methods evaluated included a deposition test, two handsheet methods and two methods that utilized laboratory screening. These tests were performed on a series of blends of recycled OCC and quaternary screen rejects as a model for highly contaminated pulps. The tests were also performed on a series of blends of virgin kraft pulp and recycled OCC as a model for pulps with low levels of contamination. The detection of stickies in handsheets using bleaching and/or dyeing techniques was found to be effective on these samples for both low and high concentrations of stickies in the pulp. Stickies detection methods with screening involved were sensitive to stickies contamination in pulps with low levels of stickies but not with pulps with high levels of
stickies. It is expected that this limitation could be remedied by using smaller sample sizes of the highly contaminated pulps. The detection of stickies via deposition on a papermachine wire was found to be effective for pulps with high concentrations of contaminants but not with low concentrations. In general, the methods using a screening step were less demanding with regard to labor and time than were the methods utilizing handsheets. Removal of Adhesives in Paper Recycling. Research has been conducted to elucidate some factors in paper recycling that affect the screening efficiency of pressure sensitive adhesive (PSA) contaminants. The results of industrial screening experiments showed that while screening effectively removes some large particles, intense forces in the screen break PSA particles and decrease screening efficiencies. The effects of papermaking components, shear, consistency, and temperature on the size (breakage) and shape of PSA particles were investigated.
Evidence of deformation and passage of PSA particles through industrial and model laboratory screens was found, indicating that removal efficiency of PSA material can be improved by lowering the pressure drops and temperatures in screening. Recycling of Wax Coated Paper. Supercritical carbon dioxide (SC-CO2) extractions of paraffin-based wax coatings from saturated and curtain-coated old corrugated containers were performed. Wax removal efficiencies of 98% and 70% for saturated and curtain-coated OCC, respectively were obtained. Decreasing the operating pressure to 200 bar decreased the extraction efficiency to approximately 50%. Gas chromatography (GC) of the wax coatings on OCC, before and after extraction with SC-CO2, showed a slight shift in the molecular weight distribution of the paraffin wax (after SC-CO2 extraction) toward higher molecular weights for both saturating wax and curtain-coating wax. There was no evidence of chemical degradation or modification of the paraffin wax
coatings by SC-CO2. It has been clearly shown that the extraction of wax from wax coated OCC is technically feasible, resulting in useful wax and fiber products.
Impacts
This research has revealed information that will allow paper recycling manufacturers to more effectively operate their machinery in order to remove contaminants. It is expected that paper recycling can be more cost effective if this information is put to use. Also, several adhesive contaminant measurement methods have been identified that can be applied to evaluate paper recycling processes. The use of these tests can also improve the cost effectiveness of paper recycling. The de-waxing of wax coated paper with carbon dioxide has been shown to be a technically viable process that could be developed and put into practice immediately. The result would be that less wax coated paper would be landfilled and more would be recycled.
Publications
- Venditti, R. A., Chang, H. M., Copeland, K., 2002. Evaluation of Various Adhesive Contaminant (Stickies) Analysis Methods for the Use in Old Corrugated Container Recycling Plants. Progress in Paper Recycling, 11(2):38-46.
- Zhang, M., Hubbe, M. A., Venditti, R. A., Heitmann, J. A. 2002. Can Recycled Kraft Fibres Benefit from Chemical Addition Before They are First Dried? Appita Journal, 55(2):135-144.
- Stauffer, T., Venditti, R. A., Gilbert, R. D., Kadla, J. F. 2002. Removing Paraffin-Based Wax Coatings from Old Corrugated Containers using Supercritical Carbon Dioxide. Journal of Applied Polymer Science, 83:2699-2704.
- Venditti, R. A., Lucas, B. E., Huo, X., Jameel, H. and Chang, H. M., 2002. Paper Recycling Factors Affecting the Screening of Pressure Sensitive Adhesives, in "Recent Advances in Paper Recycling - Stickies" Chapter 5, Doshi and Associates, 126-133.
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Progress 01/01/01 to 12/31/01
Outputs
The removal of adhesive contaminants using pressure screens is a critical issue in paper recycling. Several hypotheses have been presented to explain the passage of pressure sensitive adhesive (PSA) particles of apparently larger size than the screen openings passing through the screen. The objective of this research was to provide experimental observations to help explore these hypotheses. The passage of PSA particles through a single 0.178 mm (0.007 inch) slot was determined versus particle dimensions and pressure difference. It was found that PSA particles with smallest dimension greater than approximately 4 times the slot width did not pass through the slot for pressure differences of up to 80 kPa. However, a significant percentage of PSA particles with smallest dimension between the slot width and 4 times the slot width passed through the slot at moderate pressure differences. These particles were observed to deform and pass through the slot. Increased
temperature, which is expected to decrease the modulus of the PSA material, promoted the passage of particles through the slot. Other research in the area of stickies and toners has been performed elucidating the factors that cause these contaminants to fragment or agglomerate. We have found that cationic starch interferes with adhesive agglomeration in the same way as it does with toner agglomeration.
Impacts
These findings provide basic information about the behavior of contaminants in paper recycling that is useful in improving current recycling operations. The information will allow paper recyclers to understand how changing their incoming raw material, process conditions and process equipment will impact the removal of adhesive contaminants (a particularly troublesome contaminant) in paper recycling. The information is also useful to adhesive manufacturers in that it shows how the properties of adhesives affect their removal during paper recycling operations.
Publications
- Flanagan, J., Venditti, R. A., Jameel, H., Lucas, B. E. 2002. The Passage of Pressure Sensitive Adhesives Through a Single Slot. Progress in Paper Recycling, 11(3): 17-23.
- Huo, X., Venditti, R. A., Chang, H.M. 2001. Effect of Salts and Cationic Polymers on the Stability of Micro-Adhesive Particles. Journal of Pulp and Paper Science, 27(6): 207-212.
- Lucas, B. E., Venditti, R. A., Jameel, H. 2001. Laboratory and Pilot Plant Evaluations of Pressure Sensitive Adhesive Materials in Paper Recycling Processes. Tappi Journal, 84(5): 70.
- Stauffer, T., Venditti, R. A., Gilbert, R.D., Kadla, J. F., Montero, G. 2001. The Removal of Wax from Wax Containing Old Corrugated Containers using Supercritical CO2. Journal of Applied Polymer Science. 81: 1107-1114.
- Zeng, J., Venditti, R. A., Olf, H. G. 2001. Role of Contact Angle in 1-Octadecanol Agglomeration of Electrostatic Toners. Journal of Pulp and Paper Science, 27(3): 98-102.
- Welf, E., Venditti, R. A., 2001. The Effect of Surfactant Structure on Toner Agglomeration. Progress in Paper Recycling, 10(2): 24-34.
- Huo, X., Venditti, R. A., Chang, H. M. 2001. Use of Deposition and Extraction Techniques to Track Contaminants (Stickies) in a Papermill. Progress in Paper Recycling, 10(2): 15-23.
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