Hafizur Rahman

• PhD in Chemical Engineering
• Researcher and Project Leader at FSCN Mittuniversitet

Defibration of wood chips in high-yield pulping such as CTMP production involves sulfonation of wood chips using (Na2SO3). When aiming to improve product properties, one key issue to investigate is the evenness of the sulfonation, i.e., the distribution of the sulfite (SO32-) ions. The challenge is that the inner parts of the wood chips absorb much...

Sodium sulfite is commonly used for impregnating wood chips prior to refining when producing high-yield pulps such as CTMP. The impregnation process should ideally result in evenly sulfonated lignin, i.e. similar concentrations of sulfite (SO3 ^2-) ions in all parts of each wood chip. Sulfonated lignin is known to swell the fiber wall, which is ben...

In the pulp and paper industry, about 5 Mt/y chemithermomechanical pulp (CTMP) are produced globally from softwood chips for production of carton board grades. For tailor making CTMP for this purpose, wood chips are impregnated with aqueous sodium sulphite for sulphonation of the wood lignin. When lignin is sulphonated, the defibration of wood into...

In the pulp and paper industry, about 5 Mt/y chemithermomechanical pulp (CTMP) are produced globally from softwood chips for production of carton board grades. For tailor making CTMP for this purpose, wood chips are impregnated with aqueous sodium sulphite for sulphonation of the wood lignin. When lignin is sulphonated, the defibration of wood into...

Minimizing the fiber property distribution would have the potential to improve the pulp properties and the process efficiency of chemimechanical pulp. To achieve this, it is essential to improve the level of knowledge of how evenly distributed the sulfonate concentration is between the individual chemimechanical pulp fibers. Due to the variation in...

Optimizing the fibre property distribution could increase the pulp properties as well as the process efficiency of chemimechanical pulps (CMP/CTMP). This can only be achieved with a better understanding of how evenly distributed sulphonate concentrations are between the individual CTMP fibres. Given that the quality of wood chips varies with the ch...

An underestimated problem in the rapidly growing CTMP industry is uneven sulphonation. Optimizing the unit operations before chip refining, chip washing, steaming, impregnation, and preheating improves efficiency, provides smoother fiber properties, and reduces the cost of a certain property in the final product. Impregnation is crucial to the CTMP...

To improve the competitive advantages of pulp fibre-based materials such as tissue and packaging products over fossil-based products, it is of key importance to improve the knowledge of the selectivity of the cooking process. There is also a demand to expand the fundamental scientific understanding of pulp and paper manufacturing systems because of...

Previous paper (Rahman et al. 2017) showed that the yield of softwood kraft pulp increased by the addition of either polysulfide or sodium borohydride because of higher hemicellulose retention. An increase in hemicellulose content can make dewatering more difficult as WRV of the pulp increases, but instead, an overall increase in pulp yield could i...

The effect of increasing the pulp yield by the addition of sodium borohydride (NaBH4) or polysulfide (PS) in softwood kraft cooking, i.e. enhancing the retention of glucomannan, on the physical properties of low-grammage handsheets was studied. In addition to the yield improvement, an increase in tensile index was observed, especially at lower degr...

The fractionated crude extracts and three isolated pure compounds XM-1, XM-2 and XM-3 from stem bark of Xylocarpus mollucensis were screened for their antibacterial and antifungal activities and cytotoxicity against brine shrimp nauplii. Petroleum ether, ethyl acetate (EtOAc) and methanol (MeOH) extracts and the compounds isolated from EtOAc fracti...

The triterpinoids, betulinic acid, lupeol and betulinaldehyde, were isolated from the ethyl acetate extract of the stem bark of Avicennia officinalis (Avicenniaceae) by a combination of column and preparative thin-layer chromatography over silica gel. The structures of these compounds were determined by spectroscopic analysis (UV, IR, 1H NMR, 13CNM...