Showing papers on "Sawdust published in 2020"

Transparent lignin-containing wood nanofiber films with UV-blocking, oxygen barrier, and anti-microbial properties

Abstract: Lignocellulose is a potential raw material for film and membrane applications, such as packaging for every day consumables or a supporting barrier layer for flexible electronics. Here, lignin-containing cationic wood nanofiber (CWNF) films were produced using sawdust as the starting material. Sawdust was directly cationized using four different aqueous solvents containing tetraethylammonium hydroxide with different carbamides (urea, methylurea, ethylurea, or dimethylurea) and glycidyltrimethylammonium chloride as the cationization agent. Cationic wood was obtained with a high cationic group content (around 1.5 mmol g−1) and yield (89–100%), and CWNFs were easily obtained by mechanical disintegration as a water suspension. The films produced using solvent-casting exhibited excellent visible-light transparence (around 80% at 600 nm), and the presence of lignin allowed high UV-adsorption (below 380 nm, transmittance was under 1%). The films showed high oxygen barrier properties (below 400 and 4000 m3 μm/m2 day atm at a relative humidity of 50 and 92%, respectively) and good mechanical strength. An antimicrobial test conducted using the disk method showed that the CWNF films exhibited bacterial anti-adhesive properties with a small inhibition zone. CWNFs are therefore potential environmentally friendly packaging materials to prevent food spoilage, or useful as a UV-absorption layer for electronic devices such as solar cells.

Efficiency of Sawdust as Low-Cost Adsorbent for Dyes Removal

Abstract: In recent years, the removal of dyes from wastewater has attracted considerable attention due to their harmful effects to ecosystem and human health. Adsorption as a facile and effective technique has been widely used to eliminate a large variety of dyes from aqueous solutions. Activated carbon is the most preferred adsorbent to treat wastewater but its use is limited because of high cost. Therefore, several low-cost and natural materials and wastes have been used as precursors for the preparation of alternative adsorbents. Among them, sawdust as an abundant and low-cost by-product has been explored as adsorbent for the removal of dyes from wastewater. This review focuses on the various sawdust used as a precursor for the preparation of activated carbons. Extensive literature information about sawdust, its compositions, activation methods, its efficiency for dyes removal, and environmental conditions effects has been reviewed. The applicability of various adsorption kinetic models and adsorption isotherm models for dye removal by sawdust-derived activated carbons has been also reported. Finally, this paper highlights the use of sawdust as base material for various composites and mixture which can be used as granular activated carbon.

Catalytic pyrolysis of pinewood over ZSM-5 and CaO for aromatic hydrocarbon: Analytical Py-GC/MS study

Abstract: A higher amount of oxygenates is the main constraint for higher yield and quality of aromatics in catalytic pyrolysis while a study of hydrocarbon production with a balance of reactive species lies importance in the catalytic upgrading of pyrolytic vapor. Catalytic pyrolysis of pinewood sawdust over acidic (ZSM-5) and basic (CaO) catalyst was conducted by means of Py-GC/MS to evaluate the effect of biomass to catalyst loading ratio on aromatic hydrocarbon production. Catalytic pyrolysis with four different biomass to catalyst ratios (0.25:1, 0.5:1, 1:1, and 2:1) and non-catalytic pyrolysis were conducted. It has been obtained that ZSM-5 showed better catalytic activity in terms of a high fraction of aromatic hydrocarbon. The ZSM-5 catalyst showed a potential on the aromatization as the yield of aromatic hydrocarbon was increased with a higher amount of ZSM-5 catalyst and the highest yield of aromatics (42.19 wt %) was observed for biomass to catalyst ratio of 0.25:1. On the other hand, basic CaO catalyst was not selective to aromatic hydrocarbon from pinewood sawdust but explored high deacidification reaction in pyrolytic vapor compared to ZSM-5 catalyst, whereas non-catalytic pyrolysis resulted in acidic species (13.45 wt %) and phenolics (46.5 wt %). Based on the results, ZSM-5 catalyst can only be suggested for catalytic pyrolysis of pinewood sawdust for aromatic hydrocarbon production.

Characteristics of pyrolysis products from pyrolysis and co-pyrolysis of rubber wood and oil palm trunk biomass for biofuel and value-added applications

Abstract: This study investigated the yields and characteristics of bio-oil, biochar and pyrolysis gas obtained from pyrolysis and co-pyrolysis of rubber wood sawdust (RWS) and oil palm trunk (OPT) by using an agitated bed pyrolysis reactor. Co-pyrolysis of RWS and OPT was performed at the mixing ratio of 50:50 (wt.). The biomass samples were pyrolyzed at temperatures of 400, 450, and 500 °C under specific conditions. The results indicated that the yields of the bio-oil, biochar and pyrolysis gas were in the ranges of 38.5-46.5, 22.27-28.68 and 30.1-36.9 wt.%, respectively. Pyrolysis of RWS at 500 °C provided the most bio-oil. Co-pyrolysis of RWS and OPT could improve the product yield and quality. The bio-oil had relatively high water content, while its pH was low. The main compounds of bio-oil were oxygenated compounds such as acetic acid, phenols and 2-Propanone, 1-hydroxy-, determined by GC-MS. The higher heating value (HHV) of bio-oil ranged from 16.1 to 20.36 MJ/kg. The biochar had high carbon content and low oxygen content in proximate and ultimate analysis, and based on FTIR. The HHV of biochar was in the range from 26.35 to 29.6 MJ/kg. The biochar also was highly porous, which was revealed by SEM and BET. The pyrolysis gas mainly contained CO, CO2, H2 and CH4, and its heating value was in the range from 3.23 to 6.7 MJ/m3. Based on these results, the RWS and OPT are alternative and challenging biomasses for conversion to biofuels and value-added products via pyrolysis.

Magnetized Tectona grandis sawdust as a novel adsorbent: preparation, characterization, and utilization for the removal of methylene blue from aqueous solution

Abstract: In the submitted research work, adsorption characteristic of magnetized Tectona grandis sawdust for methylene blue from aqueous media was explored. The prepared adsorbent was characterized by SEM/EDXS, TEM, BET, XRD, FTIR, TGA-DTG/DTA, VSM, and point of zero charge. To investigate the adsorption capacity and mechanisms prevailing for the adsorption of methylene blue, batch adsorption studies were performed by changing adsorbate/adsorbent contact time, pH, initial dye concentration, and temperature. The removal efficiency was found to be 90.8% under the optimized adsorption conditions. The optimal process parameters were 1 g/L of magnetized adsorbent, 60 min contact time, pH 8, and temperature of 30 °C for 100 mg/L MB solution. The laboratory generated adsorption data was best conformed by pseudo-second-order kinetics and Langmuir adsorption isotherm models. The maximum monolayer adsorption capacity was determined to be 172.41 mg/g. The adsorption process was established to be thermodynamically feasible and accompanying with the absorption of heat and escalation of entropy. Regeneration study revealed that magnetized Tectona grandis sawdust could be reused efficaciously up to four repeated adsorption–desorption cycles using HCl as the best desorbing agent. The magnetized Tectona grandis sawdust has been proved to be novel, efficient, and cost-effective adsorbent. The combined advantages of easy preparation, good affinity towards dyes, excellent separability, reusability, and cost-effectiveness of magnetized Tectona grandis sawdust make it a novel adsorbent.

Activated carbon from sawdust for naphthalene removal from contaminated water

Abstract: Naphthalene, simplest polycyclic aromatic hydrocarbon (PAH), is extensively liberated in aqueous systems through wastewaters of various industries. The present study proposes the removal of naphthalene from aqueous solutions inexpensively and efficiently using high quality activated carbon synthesized from waste material, sawdust. The Brunauer–Emmett–Teller(BET) N 2 surface area for sawdust activated carbon (SDAC) was over 1400 m2/g. The influence of contact time, dosage of prepared activated carbon, temperature, and pH for naphthalene adsorption has been investigated. Results were evaluated using Langmuir and Freundlich equations. Based on obtained isotherm parameters, Freundlich isotherm was found to be more favourable for naphthalene adsorption. Results revealed efficient adsorption of naphthalene with sawdust activated carbon under given conditions. Equilibrium time for the adsorption on SDAC was found to be 90 min. Samples were analysed using UV–Visible spectrophotometry. The study furnishes high quality, easily acquirable, and cheap adsorbent which is highly effective for the treatment of polycyclic aromatic hydrocarbons.

Use of low-cost natural waste from the furniture industry for the removal of methylene blue by adsorption: isotherms, kinetics and thermodynamics

Abstract: Residues from the wood industry have great potential to be used as adsorbents in the textile wastewater treatment. In this sense, this work aimed to evaluate the feasibility of removing methylene blue (MB) dye from aqueous solutions using Pinus elliottii sawdust. Initially, this material was subjected to a sequential solvent extraction to improve its adsorption capacity. After drying, it was characterized by several analytical techniques, including morphological and spectroscopic analyses. The influence of the experimental parameters on the adsorption process, such as contact time (2–240 min), pH (3.0–10.0), stirring intensity (90–210 rpm), adsorbent dosage (1.0–5.0 g L−1) and initial MB concentration (60–140 mg L−1), as well as the equilibrium, kinetics and thermodynamics were also evaluated. In general, the characterization analyses evidenced the presence of several types of oxygenated functional groups in the adsorbent chemical structure and a favorable morphology for dye removal. Regarding the adsorption process, the preliminary tests showed that all experimental parameters evaluated, in some way, interfere in the MB removal. The data set suggests that equilibrium was best described by the Freundlich model, although Fisher’s test (F) have shown that the Langmuir model could also be applied to describe the experimental results. Thermodynamics parameters, by other hand, revealed that MB dye adsorption onto the treated Pinus elliottii sawdust was spontaneous and endothermic, occurring mainly by physisorption. Concerning the removal rate, it was verified that the pseudo-second-order model better explains the kinetic data and that, according to the F test, there is a significant difference between the tested kinetic models. Finally, the data set indicated that the treated Pinus elliottii sawdust can remove about 97% of MB, and that the adsorbent used here has many of the characteristics required to be employed in the removal of cationic dyes from textile wastewater.

Activated carbon from a specific plant precursor biomass for hazardous Cr(VI) adsorption and recovery studies in batch and column reactors: Isotherm and kinetic modeling

Abstract: The main aim of this work was the development of the chemical activated carbon (AC) method from specific wood biomass, i.e., Eucalyptus camaldulensis sawdust (ECS), and this AC is proposed as a promising alternative treatment for hazardous Cr(VI) from aqueous solution. ECS waste sawdust was carbonized in two stages, i.e. 170 °C for 60 min, followed by 500 °C for 120 min under the continuous steam of nitrogen gas, and rated as an efficient method with H3PO4 activation (>80% Cr(VI) removal). Finally, activated carbon-Eucalyptus camaldulensis sawdust (AC-ECS) was selected for batch and column reactor studies and different influencing parameters, such as contact time, pH, temperature, initial Cr(VI) metal concentration, particle size, and bed height were optimized. AC-ECS was characterized through analysis by SEM, EDX, FTIR, and BET. Cr(VI) adsorption was found to be highly pH-dependent, i.e., 87% at pH 3.0. AC-ECS adsorption mechanism for Cr(VI) with experimental and maximum predicted adsorption capacities of 104 and 125 mg g−1, respectively, was best described by the Langmuir isotherm (R2 = 0.999) and pseudo-second-order kinetics (R2 = 0.999). The column study showed an improvement in the breakthrough curve time from 5595 to 12,270 min, with the respective increase of bed height from 5 to 15 cm, respectively. Column breakthrough data was found to be well fitted to the bed depth service time model. Current batch and column studies indicate that freshwater contamination with Cr(VI) can be managed by upscaling the AC-ECS as an efficient treatment solution.

Energy Utilization of Spent Coffee Grounds in the Form of Pellets

Abstract: Nowadays it is important to limit the use and combustion of fossil fuels such as oil and coal. There is a need to create environmentally acceptable projects that can reduce or even stop greenhouse gas emissions. In this article, we dealt with the objectives of energy policy with regard to environmental protection, waste utilization, and conservation of natural resources. The main objective of the research was to assess the possibility of the use of spent coffee grounds (SCG) as fuel. As a part of the solution, the processing of coffee waste in the form of pellets, analysis of calorific value and combustion in the boiler were proposed. The experiments were done with four samples of pellets. These samples were made from a mixture of wood sawdust and spent coffee grounds with ratio 30:70 (wood sawdust: spent coffee grounds), 40:60, 50:50 and 100% of spent coffee grounds. The calorific values were compared with wood sawdust pellets (17.15 MJ.kg−1) and the best lower calorific value of 21.08 MJ.kg−1 was measured for 100% of spent coffee grounds. This sample did not achieve the desired performance during the combustion in the boiler due to the low strength of the sample.

Alkali-catalyzed liquefaction of pinewood sawdust in ethanol/water co-solvents

Abstract: In this study, pinewood sawdust was liquefied in either ethanol/water co-solvents (50/50, wt./wt.) or pure water at 300 °C for 30 min and 10 wt% of feedstock loading, with or without the use of Na2CO3 or NaOH as a catalyst. The physical and chemical properties of liquefaction products (bio-crude oil and solid residue) were comprehensively characterized by FT-IR, GC-MS, elemental, GPC and TGA analyses. The results showed that the highest biomass conversion of approx. 98% was obtained in ethanol/water mixed solvents and without catalyst, along with a maximum yield of bio-crude oil (~48 wt%). The HHV of crude oil was within the range of 26–30 MJ/kg. The results indicated that the beneficial effect of ethanol on the bio-crude oil yield might be compromised by adding Na2CO3 or NaOH into the liquefaction system under investigated reaction conditions. As suggested by GPC analysis, the bio-crude oil obtained in ethanol/water co-solvents from both non-catalytic and catalytic liquefaction contained a slightly higher molecular weight than that obtained in pure water. Additionally, TGA results indicated that the boiling point distribution of bio-crude oil was only affected by ethanol addition, whereas, the effect of the catalyst was found to be minor.

Preparation and properties of hydrogel based on sawdust cellulose for environmentally friendly slow release fertilizers

Abstract: Abstract A novel hydrogel slow-release nitrogen fertilizer based on sawdust with water absorbency was prepared using grafting copolymerization. Urea was incorporated as nitrogen source in a hydrogel fertilizer. Potassium persulfate (KPS) and N,N᾽-methylenebis acrylamide (MBA) were used as the initiator and cross-linker, respectively. The structure and properties of the samples were characterized by XPS, EDS, SEM, XRD and FTIR. The effects of various salt solutions, ionic strength and pH on swelling behavior were discussed. The results showed that the largest water absorbency of the sample reached 210 g/g in distilled water. In addition, the sample had the good nitrogen release property. Thus, the novel environmentally friendly hydrogel fertilizer may be widely applied to agricultural and horticultural fields.