Marc Aurousseau

The printed electronics sector is experiencing significant growth driven by societal expectations. The use of cellulosic substrates is an excellent strategy that offers interesting research prospects, but also sets challenges in terms of management and recycling of these new wastes to avoid their accumulation. This work investigates the recycling ability of paper-based printed electronics (a simple RFID antenna printed on paper), containing silver particles in the functional ink, using processes already applied in conventional paper and board recycling lines. These operations, commonly used in the papermaking industry, are pulping, screening, centrifugal cleaning, and flotation. The efficiency of each unit operation was evaluated. Mass balances between the inlet and the outlet of each studied operation have been established in order to evaluate the separation efficiency of Ag and cellulosic fibers, the objective being to reuse the fibers to manufacture a recycled paper, and to recover Ag in another fraction for further valorization. The results are encouraging, with more than 70% of silver and over 80% of cellulose fibers recovered, demonstrating a higher recovery efficiency compared to typical recycling methods reported in the literature. Thus, it has been shown that existing processes used in conventional recycling lines can be adapted to efficiently separate functional materials from cellulosic fibers, offering an improvement in both metal and fibers’ recovery.

The ozone reactive flotation for deinking recovered cellulosic fibers, recently developed at lab scale, showed interesting results in terms of fiber yield and effluent pollution reduction with clas...

Enzyme cocktails of reusable, highly-stable cellulolytic enzymes play an inevitable role in bioconversion of biomass to biofuels economically. Cellulase, xylanase and β-1,3-glucanase bound silica-amine functionalized iron oxide magnetic nanoparticles (ISN-CLEAs) were prepared and used as the biocatalyst for the depolymerization of cellulosic biomass into monomeric sugar in the present study. The Fe₃O₄-NPs and Fe₃O₄@SiO₂-NH₂-NPs and ISN-CLEAs had an average hydrodynamic size of 82.2 nm, 86.4 nm and 976.9 nm respectively, which was confirmed by dynamic light scattering (DLS). About 97% of protein binding was achieved with 135 mM glutaraldehyde at 10 h of crosslinking time and successful binding was confirmed by Fourier transform infrared spectroscopy (FTIR). The ISN-CLEAs exhibited the highest thermal stability of 95% at 50 °C for 2 h and retained extended storage stability of 97% compared to 60% of its free counterpart. Besides, crosslinking allowed ISN-CLEAs reuse for at least eight consecutive cycles retaining over 70% of its initial activity. ISN-CLEAs exhibited approximately 15% increase in carbohydrate digestibility on sugarcane bagasse and eucalyptus pulp than the free enzyme.

The aim of this paper is to propose a step by step method to establish and validate a relevant, dynamical model of the activated sludge process for the paper mill industry. The model is established by considering the specificities of the effluent to be treated. It uses the biochemical oxygen demand (BOD) measurement, which allows a direct correlation between the state variables of the model and the measurements. This model is validated on a pilot plant of semi-industrial size fed with industrial paper mill effluents. The parameter estimation is based on an analysis of the sensitivities. The results are compared with a model based on chemical oxygen demand (COD) partitioning which is issued from the simplification of the activated sludge model number 1 (ASM1) model. Finally, the model dealing with BOD measurements not only shows the best performances, but is also the easiest to implement, overcoming one main obstacle to efficient monitoring and control in paper mill wastewater treatment plants.

Combined cross-linked enzyme aggregates (combi-CLEAs) of xylanase, cellulase and β-1,3-glucanase.

The current study investigates the amount of charged groups induced by sulfuric acid hydrolysis on the surface of starch nanocrystals. Conductometric titration revealed the existence of both weak and strong acidic groups. Strong acidic groups (sulfate ester groups) were present at low amounts (13.2 mmol kg⁻¹) and their concentration increased with increasing duration of hydrolysis. The amounts of weak acidic groups (carboxylic acid) were greater (32–38 mmol kg⁻¹) and the duration of hydrolysis appeared to have no effect. Negative zeta potential values were measured in the studied pH ranges (2.3 and 10). Zeta potential decreased for pH values fewer than 4, remained constant between 4 and 8, then decreased for higher values. Absolute zeta potential values were low (−6 to −29 mV) which could explain the poor suspension stability and the great tendency for particles to aggregate and settle in an aqueous medium. The increase in the pH of the suspension resulted in a lower aggregation as the mean apparent size of the particles decreased in this case. The increase in ionic strength had a similar effect, although the mechanisms involved were hypothesised to be quite different.

Starch nanocrystals (SNC), because of their interesting barrier properties, are of great interest for the formulation of biodegradable nanocomposites. Conventional production process by acid hydrolysis results in a very low yield and a heterogeneous suspension which limits the possibility of scaling up. A continuous process that includes a microfiltration step for isolating starch nanocrystals during the hydrolysis step may be a solution to increase SNC production yield. The main objectives of this study were, first, to quantify the transmission of SNC through membranes under different operating conditions and then to identify the preponderant fouling phenomenon by using simple linear fouling models.Filtration tests were run using a lab‐scale microfiltration unit. It was equipped with ceramic membranes with a nominal pore sizes of 1.4 µm and 0.8 µm. Suspensions of nanocrystals at 0.01, 0.02 and 0.04 % (w/w) were filtered in a concentration mode under different transmembrane pressures (50, 100, and 150 kPa).Particle size analysis by Dynamic Light Scattering (DLS) showed that microfiltration is an effective tool for suspension fractionation. Mean diameter of SNC particles was reduced to less than 300 nm in permeate. The transmission through the membrane depended on operating conditions and reached 37 %. The permeate flow rate decreased with time to reach a steady value. The decrease rate was higher when the feed concentration increased. Constant pressure filtration models were used to identify the preponderant fouling phenomenon during filtration and highlighted that the decrease in permeate flow was mainly due to a cake formation on membrane surface.