Optimization of pulp production from groundnut shells using chemical pulping at low temperatures

Development of Raw Materials and Technology for Pulping-A Brief Review

Paper is one of the most significant inventions in human civilization, which considerably advanced global cultural development. Pulping is a key step in the conversion of fiber raw materials into paper. Since its inception, pulping has rapidly evolved, continually adapting to technological advancements. Researchers are constantly investigating various types of raw materials for pulping. In this review, some of the materials employed in pulping are outlined, and the fiber content, pulping method, as well as the strength of wood and non-wood crop straw as pulping raw materials are analyzed and discussed. In addition, this review explores the effects of different materials under various pulping conditions and assesses the future trends in raw material selection for pulping while considering the current global environmental pressures.

Modification of Epoxy Compositions by the Application of Various Fillers of Natural Origin

A series of composites based on epoxy resin filled with additives of natural origin were prepared to investigate the influence of such fillers on the properties of the epoxy compositions. For this purpose, the composites containing 5 and 10 wt.% of additive of natural origin were obtained using the dispersion of oak wood waste and peanut shells in bisphenol A epoxy resin cured with isophorone-diamine. The oak waste filler had been obtained during the assembly of the raw wooden floor. The performed studies include testing of samples prepared using unmodified and chemically modified additives. Chemical modification via mercerization and silanization was performed to increase the poor compatibility between the highly hydrophilic fillers of natural origin and the hydrophobic polymer matrix. Additionally, the introduction of NH₂ groups to the structure of modified filler via 3-aminopropyltriethoxysilane, potentially takes a part in co-crosslinking with the epoxy resin. Fourier Transformed Infrared Spectroscopy (FT-IR), as well as Scanning Electron Microscopy (SEM), were carried out, to study the influence of performed chemical modification on the chemical structure and morphology of wood and peanut shell flour. SEM analyses showed significant changes in the morphology of compositions with chemically modified fillers, indicating improved adhesion of the resin to lignocellulosic waste particles. Moreover, a series of mechanical (hardness, tensile strength, flexural strength, compressive strength, and impact strength) tests were carried out, to assess the influence of the application of fillers of natural origin on the properties of epoxy compositions. All composites with lignocellulosic filler were characterized by higher compressive strength (64.2 MPa-5%U-OF, 66.4%-SilOF, 63.2-5%U-PSF, and 63.8-5%SilPSF, respectively), compared to the values recorded for the reference epoxy composition without lignocellulosic filler (59.0 MPa-REF). The highest compressive strength, among all tested samples, was recorded for the composite filled with 10 wt.% of unmodified oak flour (69.1 MPa-10%U-OF). Additionally, higher values of flexural and impact strength, concerning pure BPA-based epoxy resin, were recorded for the composites with oak filler (respectively, flexural strength: 73.8 MPa-5%U-OF and 71.5 MPa-REF; impact strength: 15.82 kJ/m²-5%U-OF, 9.15 kJ/m²-REF). Epoxy composites with such mechanical properties might be considered as broadly understood construction materials. Moreover, samples containing wood flour as a filler exhibit better mechanical properties compared to those with peanut shell flour (tensile strength for samples containing post-mercerization filler: 48.04 MPa and 40.54 MPa; while post-silanization 53.53 MPa and 42.74 MPa for compositions containing 5 wt.% of wood and peanut shell flour, respectively). At the same time, it was found that increasing the weight share of flour of natural origin in both cases resulted in the deterioration of mechanical properties.

Response surface methodology for optimization of cellulose extraction from banana stem using NaOH-EDTA for pulp and papermaking

Alkaline pulping using sodium hydroxide (NaOH), also known as soda pulping, is predominantly used to extract cellulose for pulp and papermaking. The NaOH was responsible for the dissolution and removal of lignin but unfortunately, simultaneous hydrolysis of cellulose could not be avoided. Modification for improved lignin removal and cellulose stabilization are always a technical challenge for the pulp and paper industry. Therefore, ethylenediaminetetraacetic acid (EDTA) was considered as an additive to minimize cellulose hydrolysis and thus improve the total yield of cellulose pulp. Response surface methodology (RSM) with central composite design (CCD) was employed for statistical modeling and optimization of NaOH and EDTA charges for maximum pulp yield, lignin removal, and cellulose content. Analysis of variance (ANOVA) revealed a significant interaction effect of NaOH and EDTA charges on pulp yield and its cellulose content. Using the predicted optimum condition of 17.7% NaOH and 10% EDTA, pulping of banana stem at 100 ± 5 °C for 30 min resulted in increasing pulp yield, lignin removal, and cellulose content by approximately 18.5%, 1.1%, and 0.6%, respectively, as compared to pulping without EDTA. Changes in the functional groups monitored using Fourier transform infrared (FTIR) revealed the presence of ester and C–N stretching bands from cellulose extracted with NaOH/EDTA due to successful esterification of EDTA on the cellulose pulp. Further analysis on the viscosity average degree of polymerization found that the cellulose pulp extracted with NaOH/EDTA also has a higher degree of polymerization compared to the pulp extracted without EDTA. Based on these findings, it was concluded that esterification with EDTA has successfully protected the cellulose against alkaline hydrolysis by NaOH. Therefore, the addition of EDTA is a promising approach to improve the pulp yield with high degree of polymerization.

Utilization of cellulose in tobacco (Nicotiana tobacum) stalks for nitrocellulose production

This research explains the conversion of waste tobacco stalks into nitrocellulose to try to recover as much chemical potential contained in the biomass material as possible. Simple pioneering experiments were conducted using pulping tobacco stalks with a moisture content of 10.17 wt% and the soda pulping method being applied to produce cellulose pulp. The cellulose pulp was bleached using calcium hypochlorite to produce a dry white lignin-free pulp, which was subjected to nitration. The mixture used was 67% nitric acid and 98% sulphuric acid, and the acid ratio was varied between 3:7 and 7:3 v/v. Nitration time was varied between 5 and 25 min. This process produced nitrocellulose with all the various conditions. The nitrocellulose obtained with nitrogen content between 11 – 11.5% v/v was characterized using its solubility in acetone. An optimum nitrating mixture of 1:1 v/v with a nitration time of 5 min was used to produce nitrocellulose from tobacco stalks using soda pulping. The results show a great potential for tobacco farming countries to reduce their nitrocellulose import bill using this process.