## 4 L-MMCF Manufacturing Process
### Pulp Dissolution  
For this step, a precise knowledge of pulp moisture content is required to determine the amount of water and NMMO to be added to lead to the desired ratio of pulp to water to NMMO. Moisture content should be determined based on the pulp ambient storage conditions as this would indicate the moisture added to the cellulose-NMMO-water solution. NMMO is commercially available as a 50% NMMO aqueous solution (C\({}_{5}\)H\({}_{11}\)NO\({}_{2}\):H\({}_{2}\)O, monohydrate). In addition, 0.2 to 2.0 wt% propyl gallate is added as a stabilising agent to reduce radical reactions (i.e., due to presence of transition metals) and ionic degradation of NMMO [2; 65; 114]. During this stage, the cellulosic pulp swells, increasing NMMO access to cellulosic chains without derivatisation (i.e., cellulose activation) [115]. The solubility of cellulose is illustrated in Figure 6; the region of complete cellulose dissolution is identified with a grey area on the phase diagram of cellulose-NMMO-water [20]. The dried, decontaminated PHK pulp sheets are sliced into strips and shredded in a disk mill to turn them into \"fluff\" pulp. This pulp has a high surface area and is easily mixed with the 50% aqueous NMMO solution at a ratio of 50 to 67% of NMMO, 20 to 30% of water, and 10 to 15% of cellulose pulp with the addition of propyl gallate (PG) stabilising agent at 110 \({}^{\circ}\)C to 120 \({}^{\circ}\)C with a pH between 10 to 12 [2; 47; 65]. Both ionic degradation (e.g., carbenium-iminium ion-induced heterolytic) and radical reactions (e.g., metal ion-induced homolytic) are reduced by the addition of PG [114; 116]. It is noted that PG can result in yellow discolouration of the resulting lyocell fibre, so alternative stabilisers, such as 2,4,5,7,8-pentamethyl-4-hydro-1,3-benzodioxin-6-ol (PBD), butylated hydroxytoluene (BHT), and tertiary butylhydroquinone (TBHQ), have also been considered towards NMMO stabilisation [117]. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Metal Scan** & **As-Received** & **PHK** & **Chelated/Bleached** & **As-Received** & **Chelated/Bleached** \\
**(mg/kg)** & **Hurd Biomass** & **Hurd** & **Hurd** & **Bast Biomass** & **PHK Bast** & **Bast** \\ \hline Aluminum, Al & 30.8 & 22.3 & 9.05 & 95.5 & 95.5 & 8 \\ Arsenic, As & \textless{}0.5 & \textless{}1 & \textless{}0.5 & \textless{}1 & \textless{}1 & \textless{}0.5 \\ Barium, Ba & 20.6 & 20.2 & 7.2 & 31.3 & 31.3 & 0.779 \\ Boron, B & 12 & 8.1 & 0.3 & 9.8 & 9.8 & 1.1 \\ Cadmium, Cd & \textless{}0.05 & \textless{}0.1 & \textless{}0.02 & \textless{}0.05 & \textless{}0.05 & \textless{}0.02 \\ Calcium, Ca & 6040 & 5560 & 932 & 4200 & 4200 & 39.1 \\ Chromium, Cr & 0.18 & 0.95 & 3.96 & 0.24 & 0.24 & 0.4 \\ Cobalt, Co & \textless{}0.1 & \textless{}0.2 & 0.08 & 0.11 & 0.11 & \textless{}0.02 \\ Copper, Cu & 3.7 & 2.7 & 1.76 & 2.2 & 2.2 & 0.77 \\ Iron, Fe & 45.2 & 43.7 & 46.3 & 96.9 & 96.9 & 7.61 \\ Lead, Pb & \textless{}0.5 & 0.8 & \textless{}0.2 & 1 & 1 & \textless{}0.2 \\ Lithium, Li & 0.5 & 0.25 & 0.06 & 0.47 & 0.47 & 1.35 \\ Magnesium, Mg & 1800 & 1300 & 190 & 1530 & 1530 & 24.8 \\ Manganese, Mn & 26.2 & 22 & 1.12 & 48.4 & 48.4 & 0.116 \\ Molybdenum, Mo & \textless{}0.5 & \textless{}1 & 0.7 & \textless{}0.5 & \textless{}0.5 & \textless{}0.05 \\ Nickel, Ni & 0.7 & 1.5 & 3 & 0.8 & 0.8 & 0.22 \\ Phosphorus, P & 232 & 134 & 2.5 & 277 & 277 & 0.5 \\ Potassium, K & 3900 & 2050 & 5 & 3590 & 3590 & \textless{}2 \\ Silicon, Si & 137 & 113 & 133 & 660 & 660 & 215 \\ Sodium, Na & 40 & 126 & 50 & 111 & 111 & 8 \\ Strontium, Sr & 20.9 & 22.6 & 4.38 & 54 & 54 & 0.38 \\ Titanium, Ti & 1.5 & 0.96 & 0.921 & 4.44 & 4.44 & 0.498 \\ Vanadium, V & 0.14 & 0.06 & \textless{}0.05 & 0.28 & 0.28 & \textless{}0.05 \\ Zinc, Zn & 2.8 & 5.6 & 2.55 & 4.8 & 21 & 0.494 \\ \hline \end{tabular}
\end{table} 
Table 4: Metal scan (mg/kg) results for Central Alberta-grown hemp hurd and bast.