Volume 7 Issue 1

In this study the optimum preparation conditions of bio-char were achieved as a by-product of the bio-oil production process from oil palm shell as an agricultural waste material. To investigate the possibility of utilizing bio-char as an adsorbent for wastewater treatment and other applications, a central composite design was applied to investigate the influence of carbonization temperatures, nitrogen flow rates, particle sizes of precursor, and duration on the bio-char yield and methylene blue adsorption capacity as the responses. Methylene blue was chosen in this study due to its wide application and known strong adsorption onto solids. Two quadratic models were developed for the responses and to calculate the optimum operating variables providing a compromise between yield and adsorption. From the analysis of variance, temperature was identified as the most influential factor on each experimental design response. The predicted yield and adsorption capacity was found to agree satisfactorily with the experimental values. A temperature of 400°C, nitrogen flow of 2.6 L/min, particle size of 1.7 mm and time of 61.42 min were found as the optimum preparation conditions and near to the optimal bio-oil production variables.

Alkaline peroxide mechanical pulping of paulownia wood harvested from exotic tree plantations in northern Iran was investigated. The fiber length, width, and cell wall thickness of this wood were measured as 0.82 mm, 40.3 μm, and 7.1 μm, respectively. The chemical composition including cellulose, lignin, and extractives soluble in ethanol-acetone, 1% NaOH, hot and cold water was determined as 49.5%, 25%, 12.1%, 26.9%, 11.4%, and 8.1% respectively. The ash content of this wood was 0.45%. Pre-washed chips were chemically treated at 70°C for 120 minutes with different combinations of three dosages (1.5, 3, and 4.5%) of hydrogen peroxide and three dosages (1.5, 3, and 4.5%) of sodium hydroxide prior to defibration. Other chemicals including DTPA, sodium silicate, and MgSO4 were constant at 0.5%, 3%, and 0.5%, respectively. The results showed that using a 1.5% hydrogen peroxide and 4.5% sodium hydroxide charge, the brightness of APMP pulp reached 68.7% ISO and higher chemical dosages did not improve the brightness; however, to produce APMP pulp with higher strength, a sodium hydroxide charge of 4.5% was needed. The tensile strength, tear strength, burst strength indices, and bulk density of the APMP pulp produced from 1.5% hydrogen peroxide and 4.5% sodium hydroxide were measured as 15.5Nm/g, 6.54mN.m2/g, 0.56kPa.m2/g, and 3.47cm3/g, respectively. The resulting pulp was bulky and is suitable for use in the middle layer of boxboard to provide the desired stiffness with a lower basis weight.

The bleaching sequences have been applied to oil palm frond soda-anthraquinone pulp. Oxygen delignification resulted in a delignification of approximately half of the kappa number. In comparison between OQP and OQPO sequences, the OQPO sequence was able to improve brightness from 75.2% ISO to 82.3% ISO. A TCF bleaching sequence involving laccase was also suitable for the frond pulp bleaching. Results indicated that laccase has a good bleaching capability. Short beating in a PFI refiner (about PFI 2000 revolutions) was sufficient to attain good pulp strength of TCF bleached pulp. There was no total organically bound chlorine in the TCF bleaching effluent. The results of this study show that soda-anthraquinone pulping and TCF bleaching is a promising alternative to produce high-quality pulp from oil palm frond for writing and printing paper.

A variety of the Leucaena genus, Leucaena diversifolia, was used for pulp and paper making by kraft and refining processes and a OD(EP)DP bleaching sequence. The same species has been suggested as an energy crop and, in fact, this species used shows a high gross heating value; besides, this variety of Leucaena has appropriate characteristics for pulp and paper making. The holocellulose content was higher than Eucalyptus globulus, and ash and lignin contents were comparable to other varieties of Leucaena. Pulps with a kappa number between 17 and 18, and 21.4 cP viscosity were obtained using an active alkali concentration of 31%. Also, paper sheets showed good strength properties, comparable or even greater than those obtained with Eucalyptus or others varieties of Leucaena at comparable refining degrees, between 30 and 40 ºSR. The pulp was successfully bleached in all cases with a kappa number below 1.5 in the EP stage and a value of brightness higher than 90%.

The potential of spherical lignin beads as an adsorbent to take up L-lysine from aqueous solution was investigated. The kinetic data were estimated by the pseudo-first-order and pseudo-second-order models. The mechanism of adsorption was also studied using the Boyd model and Webber’s intraparticle diffusion model. The equilibrium data were modeled by the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms as well. Results suggested that the adsorption kinetics can be best described by the pseudo-first-order model. The equilibrium data could be well fitted using the Langmuir isotherm model with a maximum adsorption capacity of 67.11 mg·g-1. The adsorption characteristics of the spherical lignin adsorbent proved the feasibility of its use as an alternative adsorbent for the removal of L-lysine from aqueous solution.

Fluorescent whitening agents (FWAs) are the most widely used functional chemicals for the manufacture of printing and writing grades of paper. FWAs are used as internal or external additives for the surface treatment on the size press and coater. In spite of the extensive use of FWAs, no method has been established to analyze the FWA content in process water and paper products. Samples are typically exposed to UV light in order to detect the presence of FWAs. This method is based on the fluorescence exhibited by FWAs under a UV-lamp. The observation of fluorescence with the naked eye is highly subjective. Thus, it is essential to develop a more scientific and objective to the quantitative analysis of FWA optical effects. Water and paper samples containing FWAs were prepared in a laboratory. Quantitative analysis was carried out with a spectrofluorometer, a spectrophotometer, and an image restoration microscope. Using these analytical instruments, fluorescence was observed. Regression equations were obtained from the relationship between the fluorescence intensity and the FWA optical effects of the samples.

Straw is an agricultural byproduct that can be utilized to obtain bioethanol without affecting animal or human sustinence. This process involves recovering the sugars and reducing the lignin content present through the use of ligninolytic fungi such as the basidiomycete Trametes sp. 44. Fermentation was carried out using particle sizes 4 (4.76 mm, No. 4 sieve) and 8 (2.30 mm, No. 8 sieve), and two velocities of airflow (100 and 200 mL/min). Study results showed that particle size affected the production of hydrolytic enzymes, as particle size 8 favored the expression of cellulases and hemicellulases. In addition, both aeration and particle size affected the expression of ligninolytic enzymes, as it was observed that with particle size 8 and airflow of 200 mL/min, the study detected 63 AU/mL of LiP and 11 AU/mL of MnP. In the case of laccase, the enzymatic activity detected reached 220 AU/mL using particle size 8 and an airflow velocity of 200 mL/min. Statistical analysis indicated that the treatment that produced the highest biological delignification occurred when Trametes sp. 44 was grown on corn straw at particle size 4 and airflow of 100 mL/min, conditions that yielded 34% delignification at day 12 of fermentation.

Two agricultural biomass materials, namely wheat straw and sugarcane bagasse, were pretreated with NaOH and then used as substrates for enzymatic saccharification. After the pretreatment, the increase in glucan content and the decrease in lignin content were more than 65%, while less than 20% increase occurred in xylan content. The enzymatic saccharification was initiated with solid loading 9% (w/v), and then 8%, 7% and 6% (w/v) solid was fed at 8, 24, and 48 h, respectively. The final enzyme solid loading was 9.60 FPU/g solid and 30% (w/v), respectively. At 144 h, the produced glucose, xylose, and reducing sugar concentrations for wheat straw were 81.88, 20.30, and 115.25 g/L, respectively, and for sugarcane bagasse they were 125.97, 8.66, and 169.50 g/L, respectively. The final conversions of wheat straw and sugarcane bagasse were 34.57% and 50.85%, respectively. SEM images showed that the surface structure of the two materials changed a lot via alkali-pretreatment and enzymatic hydrolysis. In summary, a high concentration sugar is produced from the two agricultural biomass materials by high solid and low enzyme loading. Compared to wheat straw, sugarcane bagasse is more suitable for use in sugar production.

Three commercial starches were evaluated in conjunction with colloidal silica and flocculant to retain precipitated calcium carbonate (PCC) filler. A unique feature of this study was the fact that the filler was pre-flocculated by a portion of starch (2kg starch/t PCC) and the rest of the starch was added after the flocculant but before the silica. The pulp used was peroxide bleached thermo-mechanical pulp (TMP). A statistical design methodology was employed and empirical process models were constructed based on the analysis of variance (ANOVA) results. The models were then employed to predict the retention and drainage. It was found that the high-charged cationic starch gave the highest retention and best drainage performance. The high-charged cationic starch S880 also resulted in stronger paper, probably because of the larger and stronger flocs produced and its higher affinity with the fiber and fines. Finally, pre-flocculation was found to provide stronger paper compared with a conventional starch/retention aid addition sequence.

Water-soluble hemicelluloses and eight alkali-soluble hemicelluloses were fractionated from bamboo (Phyllostachys pubescens Mazel) culm with hot distilled water, 2% NaOH, 2% KOH, 5% NaOH, and 5% KOH aqueous solution. The chemical structures, as analyzed employing FTIR spectrometry, suggested that all the hemicelluloses were likely to be comprised of arabinoxylans associated with lignin more or less. Thermal analysis for hemicelluloses was carried out using TG-DTG method under nitrogen atmosphere at a heating rate of 10 °C/min, and first-order kinetics was evaluated. The major pyrolysis was focused at 187-346 °C, with activation energy ranging from 23.77 to 45.02 kJ/mol. The alkali-soluble fractions, being soluble in solution only at pH higher than 5.5, presented lower thermal stability and higher values of activation energy and pre-exponential factor than the alkali-soluble fractions remaining soluble in alkaline solution at pH lower than 5.5 and insoluble in ethanol. The chemical property of the hemicellulose fractions may greatly influence the thermal characteristics.