Interest has grown in bio-polymers as being environmental friendly alternatives to synthetic additives. In this work, two native chitosans with different molecular weights have been evaluated on a laboratory scale for their effectiveness for the removal of contaminants from papermaking process waters by dissolved air flotation (DAF). The use of chitosan quaternary derivatives and the use of the native chitosans in combination with anionic bentonite microparticles have also been tested. Results demonstrate a high efficiency of the native chitosan products at intermediate dosages and furthermore, their efficiency is enhanced by the combined addition of bentonite. For an equivalent removal of contaminants, the required dosage of chitosan is about half that the dosage required in absence of bentonite. Quaternary derivatives have not improved the efficiency of the native chitosan in this case. The optimum treatment would be 50 mg/L of native chitosan and 100 mg/L of bentonite where this treatment is capable of the removal of 83-89% turbidity (residual turbidity 210-320 NTU), 68-71% dissolved turbidity (residual dissolved turbidity of 22-24 NTU), 18-22% total solids (residual total solids of 2750-2900 mg/L) and 19-23% COD (1440-1525 mg/L). The low molecular weight native chitosan is more efficient than the medium molecular weight chitosan in all cases. The Focused Beam Reflectance Measurement (FBRM) is used to assess the aggregation process and to predict the separation efficiency of DAF units either with single or dual systems. The efficiency predicted through the FBRM technique is very similar to that obtained later in the DAF tests.

There is a large interest in bio-polymers as environment-friendly alternatives to synthetic additives in papermaking. In this work, the behavior of three chitosans with different molecular weights and cationic charges were investigated as flocculation additives in papermaking on two systems: calcium carbonate (GCC) and pulp/GCC suspension. Comparison was made with two traditional cationic polymers used in wet end chemistry (poly-diallyldimethyl-ammonium chloride (PDADMAC) and poly-ethylene imine (PEI)). Flocculation efficiency was evaluated by flocculation parameters (mean floc size and number of counts) and by floc behavior under shear conditions, using a focused beam reflectance measurement (FBRM) technique. Results indicated different behaviors between the three chitosans when they were used for the flocculation of GCC and pulp/GCC suspensions. Chitosans were found to be more efficient over PDADMAC and PEI for flocculating small particles of the GCC suspension, but less efficient for increasing floc sizes, regardless of their MW or CCD. Flocculation parameters for pulp/GCC suspensions suggested the flocculation behavior of chitosan was close to that of PEI, but chitosan had higher efficiency and affinity towards cellulose fibers.

Efficient end-of-life solutions play an important role in developing sustainable packaging because they contribute to reducing resource wastage and environmental impact, whilst providing economic and social benefits. This paper briefly reviews current end-of-life solutions for fibre and bio-based materials for packaging in Europe. It also addresses current research in the field, as well as standardization, legislation and socio-economic aspects related to renewable packaging in Europe. This review focuses on the following groups of packaging materials: paper and board and bioplastics. With this hierarchy, recycling, organic recovery and energy recovery are analysed with regard to the processes and technologies that offer the most sustainable end-of-life options.

Three water-soluble chitosan derivatives (ChDs)-carboxymethyl-chitosan (CCh), alkyl-chitosan (ACh), and quaternary-chitosan (QCh)-were evaluated as new materials for paper conservation. Several series of samples were prepared by coating different paper types with ChDs or methylcellulose (MC). The ChDs' effectiveness were analyzed by their effects on the strength (tensile energy absorption (TEA), double folds) and water barriers (Cobb60, contact angle (CA)). The coatings on laboratory paper showed strength improvements for the CCh/QCh coatings that were consistent with an increase in the coating weight (CW). The ACh had little effect on the strength, but developed an effective barrier to water. The coatings on printing paper were performed at a constant CW by applying two layers of the same ChD or MC, and by combining CCh or QCh in the first layer with ACh in the second layer. Homogenous coatings based on the CCh or QCh resulted in high strength improvements, comparable to MC, but only ACh coatings developed an effective barrier to water. Combinations of the CCh or QCh with ACh provided the best relationship between the strength and barrier properties and proved their effectiveness as strengthening/protective materials in the treatment of natural aged paper.

In a previous work , the flocculation efficiency of three chitosans differing by molecular weight and charge density were evaluated for their potential use as wet end additives in papermaking. According to the promising results obtained, chitosan (single system) and its combination with bentonite (dual system) were evaluated as retention aids, and their efficiency was compared with poly(diallyl dimethyl ammonium chloride) (PDADMAC) and polyethylenimine (PEI). In single systems, chitosan was clearly more efficient in drainage rate than PDADMAC and PEI, especially those with the lowest molecular weights; however, retention is considerably lower. This drawback can be overcome by using dual systems with anionic bentonite microparticles, with the optimum ratio of polymer:bentonite being 1:4 (wt./wt.). In dual systems, the differences in retention were almost negligible, and the difference in drainage rate was even higher, together with better floc reversibility. The most efficient chitosan in single systems was Ch.MMW, while Ch.LMW was the most efficient in dual systems. The flocculation mechanism of chitosan was a combination of patch formation, charge neutralization, and partial bridge formation, and the predominant mechanism depended on the molecular weight and charge density of the chitosan.