Comparison of the usage of fines and PCC pigment in handsheets

Purpose This paper aims to investigate the influences of fines and precipitated calcium carbonate (PCC) pigment and their contents on the fundamental properties of handsheets and also evaluate these results in terms of mechanical and chemical data. Design/methodology/approach A design research approach has been based on the production of various laboratory handmade papers. Any of the paper additives were not added to the paper web to compare the results of the effects of fines and PCC pigment in a literal way. For this purpose, the target grammages of handsheets and the production variables such as pulp consistency, temperature and other variables of formation, pressing and drying processes were kept constant and studied meticulously. Findings This study is confirmed that with the addition of fines to the pulp of the control handsheets, an increase of up to 125% has been observed in the tensile index values, while a decrease of up to 30% has been observed with the addition of PCC pigment as filler. The tensile results have been changed depending on the pulp content and hence chemical bonds formed in the paper web. These mechanical changes have been explained by correlating with the data of FT-IR spectrums. Especially, the variations have been seen at 950–1150 cm−1, which referring to C-OH and C-O-C stretching vibrations. Originality/value The originality of this work is based on understanding and comparing the effects of fines and the effect of PCC pigment as a paper filler on the structural and chemical characteristics of laboratory-made handsheets.

A Coupled Bio-Chemo-Hydro-Mechanical Model for Bio-cementation in Porous Media

A key challenge involving microbial induced carbonate precipitation (MICP) is lack of rigorous yet practical theoretical models to predict the intricate biological-chemical-hydraulic-mechanical (BCHM) processes and the resulting bio-cement production. This paper presents a novel BCHM model based on multiphase, multispecies reactive transport approach in the framework of poroelasticity, aimed at achieving reasonable prediction of the produced bio-cement, and the enhanced geomechanical characteristics. The proposed model incorporates four key components: (i) coupling of hydro-mechanical stress/strain alterations with bio-chemical processes; (ii) stress/strain changes induced due to precipitation and growth of bio-cement within the porous matrix; (iii) spatiotemporal variability in hydraulic and stiffness characteristics of the treated medium; (iv) and velocity dependency of the attachment rate of bacteria. The fully-coupled BCHM model predicts key unknown parameters during treatment including: concentration of bacteria and chemical solutions, precipitated calcium carbonate, hydraulic properties of the solid skeleton, and in-situ pore pressures and strains. The model was able to reasonably predict bio-cementation from two different laboratory column experiments. The Kozeny–Carman permeability equation is found to underestimate permeability reductions due to bio-cementation, while the Verma–Pruess relation could be more accurate. A sensitivity analysis revealed bio-cement distribution to be particularly sensitive to the attachment rate of bacteria.

Effect of Nickel-Coated Precipitated Calcium Carbonate on Corrosion Properties of Sn-9Zn Solder

The effect of 0.5 wt. % Nickel (Ni)-coated precipitated calcium carbonate (PCC) additions on the corrosion properties of Sn-9Zn solder was investigated in 3.5% sodium chloride (NaCl) solution employing potentiodynamic polarization. The morphological differences before and after corrosion analysis have been investigated to support the findings. The scan rate used was 1 mVs−1 after stable potential developed. Slight improvement of corrosion potential (Ecorr) with a significant reduction in corrosion current (icorr) was seen for the Sn-9Zn/Ni-coated PCC compared to Sn-9Zn, indicating the kinetics of corrosion reaction was reduced. The current consumed under the passivation stage for the Sn-9Zn/Ni-coated PCC was also smaller, highlighting that further corrosion protection was improved. Microstructural observation also verified that the number and size of blackish spot clusters were reduced for the Sn-9Zn/Ni-coated PCC, revealing that Ni-PCC additions improve the overall corrosion performance of Sn-9Zn solder.

Effect of Liquid Feeding Rate on Carbonation of Precipitated Calcium Carbonate via Continuous Method

Precipitated calcium carbonate (PCC) is an innovative product generated from lime that significantly offers various functional characteristics in fulfilling numerous market demand. PCC is produced by hydrating high-calcium quicklime resulting slurry so-called milk-of-lime and reacting the slurry with carbon dioxide (CO2) via carbonation process. The resulting PCC product is extremely white and typically has a uniform narrow particle size distribution. PCC is available in various crystal morphologies and sizes, which can be tailored to optimize performance in a specific application. The final properties of the PCC can be diversified by controlling processing parameters. In this current work, effect of liquid air pressure corresponding to feeding rate on a formation of PCC was investigated. In enhancing the product yield, the quicklime was initially converted into a solution containing calcium ion (Ca2+) using natural promoter agent. Subsequently, CO2 gas was continuously supplied into the Ca-rich ionic solution, thus inducing carbonation reaction to form PCC. This present work showed the carbonation time of producing PCC was effectively reduced as a function of feeding rate from 15 minutes at 10 psi to only 7 minutes at 50 psi. The PCC yield slightly increased from 19 g to 23 g with increasing the feeding rate from 10 psi to 50 psi, respectively. Morphologically, the PCC particles were dominated by rhombohedral structures at various feeding rates with an indication of intergrowth mechanism. This current finding signified the increasing feeding rate offered a significant reduction of PCC production time that might be efficiently applied by the industrial manufacturers.

Synthesis and Characterization of Hydroxyapatite from Duck Eggshell by Wet Precipitation Process

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the most stable form of calcium phosphate and widely used in various medical applications, mainly in orthopedics and dentistry due to its close similarities with the inorganic mineral component of bone and teeth. This study aims to synthesize hydroxyapatite from duck eggshell using the precipitation method. The duck eggshell was calcined, hydrated (slaking) and underwent carbonation to form Precipitated Calcium Carbonate (PCC). Afterwards, (NH4)2HPO4 was added to produce HAp by varying the molar ratio of Ca/P by 1.67, 1.77 and 1.87 and stirring speed by 200, 250, 300rpm under basic condition (pH 10 – 11). The best results were obtained at a molar ratio of 1.77 with 200rpm stirring speed. Furthermore, the X-ray Diffraction (XRD) analysis showed that its crystals were hexagonal with sizes of 23.062nm, in the absence of other crystalline phases. Therefore, the hydroxyapatite was obtained in the agglomerates form with a specific surface area of ??55.929m2/g.

Quantitatively characterizing sandy soil structure altered by microbial-induced carbonate precipitation （MICP） using multi-level thresholding segmentation on synchrotron radiation imaging

The influences of biological, chemical, and flow processes on soil structure through microbial-induced carbonate precipitation (MICP) are not yet fully understood. In this study, we use the Kapur entropy (KE) multi-level thresholding segmentation algorithm to quantitatively characterize sandy soil structure altered by MICP treatment. A sandy soil specimen was treated by MICP and scanned by the synchrotron radiation micro-CT with a resolution of 6.5 µm. After validation, tri-level thresholding segmentation using KE successfully separated the precipitated calcium carbonate crystals from sand particles and pores. Spatial distribution of porosity, pore structure parameters, and flow characteristics were calculated for quantitative characterization. The size effect of the specimen was discovered to be a key factor affecting the performance of MICP treated soil. The results offer pore-scale insights of MICP treatment effect, and the quantitative understanding confirms the importance of the KE multi-level thresholding segmentation algorithm.

Eucalyptus Pulp Fibers with In-Situ Precipitated Calcium Carbonate – A 12-Inch Laboratory Paper Machine Study

Paper manufacturing on a global scale is a highly competitive market which requires to constantly improve the manufacturing process to be competitive. To decrease production cost paper manufactures, add filler material prior to sheet forming to replace costly wood fiber based raw material. This research project investigates the use of in-situ precipitated calcium carbonate produced in the presence of eucalyptus fiber material at a 41.0% filler level prior to beating. The in-situ filler containing eucalyptus fiber suspension was used on a 12’ (304mm) wide Laboratory Fourdrinier Paper Machine together with non-filler containing eucalyptus fiber material, and a commercial precipitated calcium carbonate filler material. The manufactured in-situ fiber suspension resulted in a higher ash retention compared to the addition of the powdered commercial PCC filler material. In addition to commercial filler material retention is improved at higher filler addition above 30%. The increased ash retention is linked to the increased micro fibrillation fiber material of the in-situ filler-fiber suspension forming neckless like particles on the fibers microfibrils. Mechanical paper properties showed an improvement for in-situ precipitated filler material compared to commercial filler material addition. Optical properties could be improved in comparison to the eucalyptus fiber without filler addition for in-situ precipitated filler material and a combination of in-situ and commercial filler material.

Three-dimensional thermomechanical converting of CTMP substrates: effect of bio-based strengthening agents and new mineral filling concept

The effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed.