LSU Archives - DrToddShupe.com

New Approach to Remove Metals from Chromated Copper Arsenate (CCA)-Treated Wood

October 1, 2018 / Leave a Comment

Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated using binary acid solutions consisting of acetic, oxalic, and phosphoric acids in a microwave reactor. Formation of an insoluble copper oxalate complex in the binary solution containing oxalic acid was the major factor for low copper removal. Furthermore, the possible complexation of acetic/oxalic acid in the organic phase, the decomposition of oxalic acid in acetic acid at high temperatures, and the promotion of the formation and precipitation of the copper oxalate by phosphoric acid may induce an antagonistic effect which adversely influenced the effectiveness of the copper extraction. It was found that the addition of acetic acid into phosphoric acid enhanced the chromium recovery rate of the mixed acid solution. This synergistic effect of mixed acetic acid and phosphoric acids is considered one of the most interesting and significant discoveries in the study.

Our recent studies on removal of CCA elements from spent CCA-treated wood have focused on the application of the microwave energy to facilitate acid extraction. A preliminary study (Yu et al. 2009) has shown: (1) microwave-assisted acid extractions with oxalic, acetic, and phosphoric acids have reduced the reaction times from hours to minutes compared to the conventional methods, (2) oxalic acid effectively removed arsenic and chromium but not copper, (3) acetic acid extraction was highly effective for the removal of arsenic and copper but not for chromium, and (4) extraction using phosphoric acid was less effective as compared to both oxalic and acetic acids. These results indicated that none of the individual acids were able to effectively remove all three CCA elements simultaneously, but showed a potential complementary effect for extraction. For instance, oxalic acid removed chromium very effectively but not copper, and acetic acid effectively extracted copper but not chromium. The results strongly suggested the opportunity for a two-acid process by either a synergistic extraction effect of the combined acids or a two-step process of consecutive acid extraction. In this study, two acids were mixed, and the extraction potential was evaluated. The acids studied were oxalic, acetic, and phosphoric. The objectives of the study were to develop a cost-effective microwave-based dual acids extraction system to maximize removal of CCA elements from spent-CCA-treated wood. This was addressed by optimizing of the acid combinations and concentration, extraction times, and reaction temperature to minimize any environment impact.

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science. Shupe worked as a professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Study of Moso Bamboo’s Permeability and Mechanical Properties

May 15, 2018 / Leave a Comment

Microwave Treatment of Bamboo

In this article, moso bamboo blocks were first treated with hydrochloric acid solvents with different concentrations or microwave treatments with various microwave output power and treatment durations. The results showed that the crystalliferous region of cellulose of moso bamboo blocks formed porous or swelling type structures under hydrochloric acid pretreatment conditions; the mechanical strength of the moso bamboo decreased when the percentage of hydrochloric acid pretreatment solvents increased from 0 to 3%. When the moso bamboo blocks were treated with microwave, the internal water was transformed into steam, and the water vapor destroyed the cell walls of the vessel, sieve tube, and parenchyma cells in the moso bamboo block, resulting in a significant improvement in the permeability of moso bamboo. In order to ensure that the moso bamboo samples did not burn by microwave heating, the samples had to be immersed in water. The process of water gasification inside the moso bamboo was not violent. Therefore, the mechanical strength of the moso bamboo had decreased only slightly, and a weak relationship was found between the mechanical strength of the moso bamboo samples and the microwave treatment durations.

Previous Bamboo Research

There are more than 1200–1500 species of bamboo in the world, and 90% of the bamboo in Asia are found in Southeast Asia.¹Moso bamboo (Phyllostachys pubescens mazei ex H. de Lebaie) accounts for ≈70% of the total bamboo forest.² With the advancement of science and technology and the tight supply of timber, the bamboo industry has been developing rapidly in China since the 1990s. Now, many new methods are required for the processing of bamboo to make it durable, inexpensive and usable. Therefore, detailed studies are needed to aid and promote its application in the modern world.^3-6 As is well known, the cellulose in mature moso bamboo is ≈40– 60%; the hydroxyl groups in cellulose molecules could easily lead to the formation of hydrogen bonds between the oxygen containing groups. These hydrogen bonds combine to make many cellulose molecules forming a crystalline structure. Because about two-thirds of the cellulose is distributed in the outer region of the green moso bamboo, this region has excellent physical and mechanical properties.^7,8 In previous studies, we found that the composite materials, made of the moso bamboo green blocks, were unable to achieve satisfactory bond quality.⁹ The poor bond quality was caused by two problems.

Bamboo Permeability

The primary reason for this problem is that the distribution of the main tissue system (the vessel, sieve tube, and parenchyma cells) in moso bamboo is longitudinal, with no horizontal transmission systems.¹⁰According to the theory of mechanical adhesion, the adhesive that is spread on the moso bamboo block surface enters exposed pores (cell cavities), where it is solidified and anchored.¹¹ Because the glue surface of bamboo lamination usually occurs in the horizontal direction of bamboo blocks, and the moso bamboo blocks have no horizontal transmission system (cell cavities), the bond quality is poor. The outer sections of moso bamboo green blocks have poor wettability of the adhesive to each other. It is difficult for the adhesive to spread well on the moso bamboo block surface. Low permeability of bamboo blocks causes many problems during moso bamboo manufacturing. Impregnating low permeability moso bamboo blocks with preservatives or resins is extremely difficult. Thus, in this study, moso bamboo blocks were first treated with hydrochloric acid solvents with different concentrations or microwave treatment with different microwave output power and varying treatment durations; and then, the rates of water absorption and water loss were quantified. The objective of this study was to evaluate the effects of hydrochloric acid and microwave treatments on the permeability and mechanical properties of the moso bamboo blocks.

To read more please visit our publication: Study of moso bamboo’s permeability
and mechanical properties

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science. Shupe worked as a professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Characterization of Microwave Liquefied Bamboo Residue

May 12, 2018 / Leave a Comment

Microwave Liquefaction System

Bamboo raw feedstocks with large particle size (20−80 mesh) were subjected to a microwave liquefaction system, and the liquefied products were separated into biopolyols and liquefied residues. Biopolyols were first analyzed by gas chromatography mass spectrometry (GC−MS), and the main components were sugar derivatives with 2−4 hydroxyl groups and phenolic compounds derived from lignin. The residues were collected and evaluated for potential use in the production of nanofibrillated cellulosic fibers. Results show that liquefied residue content as well as its physicochemical properties varied with respect to particle size, liquefaction temperature, and reaction time. It was also found that residues from liquefaction reaction with the minimum residue content in this study still exhibited traced fiber structure with remaining cellulose attached with recondensed lignin. Pure white cellulose fibers were extracted from the residues with yield of 65.61% using a combination of bleaching and acid hydrolysis treatment. Nanofibrillated cellulosic fibers were generated by given the purified cellulose fibers to high-intensity ultrasonic treatment. The resulted nanofibrillated cellulosic fibers had a range of 4−18 nm in diameter and length of 550 nm or longer, indicating the nanofibers obtained from liquefied bamboo residues hold great potential in reinforcing polymeric matrix materials. The successful isolation of nanofibrillated cellulosic fibers from liquefied residues offers a novel approach to make full use of the liquefied bamboo for value-added green products.

Biomass Feedstock

Biomass is widely considered as an important feedstock because of its renewability, ease of degradation, and availability. According to Perlack and Stokes, the current biomass resource availability annually was about 1.37 × 109 dry tons from forestlands and croplands.¹ Recently, utilization of biomass for bioenergy or biochemicals has attracted great attention.²⁻⁶ For the production of biopolyols or biobased polymers, pyrolysis and liquefaction are two common pathways. However, liquefaction has more potential in converting biomass into valuable products because of its mild reaction conditions compared to pyrolysis.⁷⁻⁹ Liquefaction of biomass using organic solvents under conventional heating sources, such as oil has been carried out before, and the liquefied products have been also evaluated for the preparation of polyurethane foams^10,11 and phenolic resins.^12,13 Usually, in the conventional liquefaction system, inefficient thermal conduction on the surface of the feedstocks results in ineffective energy utilization, and very fine feedstock grinding (smaller than 200 mesh) was required because fine particles increase overall heat transfer in a certain extent.

Particle Size

However, this requires large amount of energy for size reduction, which in turn increases the whole energy consuming in the entire system. The application of microwave irradiation to wood liquefaction has been recently reported.¹⁴ Results have shown that microwave-assisted liquefaction could convert fine grinding wood feedstock into biopolyols with a high conversion yield (>90%) in minutes.¹⁵⁻¹⁷ This is mainly due to the fact that heating by microwave is direct and volumetric and thus results in efficient biomass conversion. Because of the benefits of microwave heating in wood liquefaction, various lignocellulosic such as wheat straw lignin,¹⁸ bamboo,^19,20 sugarcane bagasse,²¹ and corn stover²²have been subjected to microwave-assisted liquefaction system for the production of biopolyols for alternatives of petroleum products. However, in all these studies only fine grinding feedstocks were used as raw materials, the attempts of using large particles has not been investigated.

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science. Shupe worked as a professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Antifungal Activities of Three Supercritical Fluid Extracted Cedar Oils

May 1, 2018 / Leave a Comment

Port-Orford cedar (Chamaecyparis lawsoniana), Alaska yellow cedar (Chamaecyparis nootkatensis), and Eastern red cedar (Juniperus virginiana) were submitted to supercritical fluid extraction with CO₂ (SCC) and Soxhlet extracted (SE) with hexane. The components in the extracted oils were identified by GC-MS. The oils were evaluated against two common wood decay fungi, brown-rot fungus (Gloeophyllum trabeum) and white-rot fungus (Trametes versicolor). The SCC extraction yields of J. virginiana, C. nootkatensis, and C. lawsoniana were 3.27%, 3.22%, and 3.29%, respectively. The SE yields of J. virginiana, C. nootkatensis, and C. lawsoniana were 0.80%, 0.71%, and 1.52%, respectively. The statistical analysis showed that SCC extracted cedar oils had higher antifungal activities than SE cedar oils against both fungi. In vitro studies showed that C. nootkatensis oils have the strongest antifungal activity, followed by C. lawsoniana, and J. virginiana oil.

Natural Wood Durability

The relationship between chemical composition and durability in wood was first reported by Hawley et al. (1924). Some heartwood has the inherent ability to resist biological degradation, often referred to as ‘‘natural durability’’ or ‘‘decay resistance’’ (Eaton and Hale 1993). Meanwhile, the relation between extractive content of heartwoods and their fungal tolerance is well established (see recent publications: Chedgy et al. 2007; Lim et al. 2007; Mburu et al. 2007; Kusuma and Tachibana 2008). Three North American important commercial wood species, Port-Orford cedar (Chamaecyparis lawsoniana), Alaska yellow cedar (Chamaecyparis nootkatensis), and Eastern red cedar (Juniperus virginiana) are known to have significant natural durability. Cedar species have been reported to have special bioactivity against termites and wood decay fungi (Liu 2004; Gao et al. 2008). Evaluations on antifungal properties (Gao et al. 2008), biocidal application (Dolan et al. 2007), and termiticidal activities (Liu 2004) of C. lawsoniana extracts have been reported. A chemical ecological study of the components of the essential oil of J. virginiana from different habitats was performed by Setzer et al. (1992). Volatile oil from J. virginiana, consisting primarily of cedrene (a terpene) and cedral has been used in perfumery (Heide et al. 1988; Semen and Hiziroglu 2005) and as an insect repellent. J. virginiana oil has been widely used in a very broad range of products owing to its unique properties, such as odor and repellency or toxicity to many pests.

Antibiotic Activity of Cedar Extractives

In addition, the antibiotic activities of C. nootkatensis have been studied extensively. For example, antimicrobial activity of essential oil from C. nootkatensis has been tested against anaerobic bacteria and yeast (Johnston et al. 2001). Heartwood extractives from C. nootkatensis have been tested for resistance to termites and fungi (Taylor et al. 2006). The composition of the leaf oil from C. nootkatensis has also been reported (Andersen and Syrdal 1970; Cheng and Von 1970). In most of these studies, conventional Soxhlet extraction (SE) was used, which is time consuming and requires organic solvents. Some bioactive components in cedar oils could be affected during SE. Supercritical CO₂ (SCC) extraction has several advantages in extracting non-polar components of complex mixtures of natural products. The low viscosity and high diffusivity of SCC can result in higher extraction efficiencies and CO₂ can be easily removed from the extract, leaving an extract that is uncontaminated by any solvent residue. However, SCC of these three cedar oils has been rarely reported (Eller and King 2000). The antifungal activities of these SCC-extracted oils has not been compared. The objectives of this research are to compare the extraction efficiency between hexane SE and SCC extraction, identify the main chemical components by GC-MS, compare the chemical composition of the extracts obtained by the two methods, and evaluate the antifungal activities of the SCC extracts of the three cedar woods.

To read more please visit our publication: Antifungal activities of three supercritical fluid extracted cedar oils

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science. Shupe worked as a professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Market Potential for Reclaiming CCA from Decommissioned Utility Poles

April 15, 2018 / Leave a Comment

Green Spray Foam

In the area of recycling of spent chromated copper arsenate (CCA)-treated wood, most studies to date have focused on methods of removing/extracting the residual preservative from the wood matrix. It is well recognized that exposure of CCA-treated wood to an acid solution can reverse the CCA fixation process thereby converting the CCA elements into their water-soluble form. The economic viability of the process is enhanced because it can be integrated with other technologies and products (e.g., “green” spray foam insulation, etc.). The market for the “green” CCA is the same as for traditional CCA-the wood treating industry, principally utility poles and pilings. A market research study was conducted to determine the suitability of spent CCA-treated wood as a source for recycled, “green” CCA for manufacturing “green” spray-foam insulation. Specifically, we wanted to discern the attitudes and overall perspectives of buyers/sellers (i.e., utilities and wood treating companies) of CCA preservatives and treated wood products, disposal methods and costs for decommissioned CCA-treated wood, and understand perceptions of and willingness-to-pay for “green” CCA preservatives extracted from the technologies used in this research. Results show that 60% of wood preservative treating respondents and 60% of electric utility company respondents are somewhat or greatly interested in using out-of-service utility poles as feedstock for “green insulation” as part of a new potential business venture.

Louisiana State University CCA Research

Preservative-treated wood plays a substantial role in the infrastructure of the nation. Virtually all of the preservative-treated wood that is installed is eventually decommissioned and landfilled. The goal of on-going research at Louisiana State University Agricultural Center (LSU AgCenter) is to reclaim the preservative in decommissioned preservative-treated wood and utilize the preservative-free wood as a raw material for bio-polyols which can be used to produce spray foam insulation. In the area of recycling of spent chromated copper arsenate (CCA)-treated wood, most studies to date have focused on methods of removing/extracting the residual preservative from the wood matrix. It is well recognized that exposure of CCA-treated wood to an acid solution can reverse the CCA fixation process thereby converting the CCA elements into their water-soluble form. Thus, acid extraction using different acids and a wide range of reaction conditions has been extensively studied for removal of CCA from out-of service CCA-treated-wood. However, acid extraction processes are slow and requires a large treating space and a large amount of acid solution.

Conventional Extraction

Furthermore, conventional acid extraction requires sequential extraction or a two-step extraction process to attain complete removal because none of the individual acids are able to effectively remove all three CCA elements simultaneously. Therefore, a cost-effective acid extraction method is lacking. The core innovation of the LSU technology involves the novel approach of microwave energy for binary acid solutions consisting of oxalic acid combined with either acetic or phosphoric acids. Our previous bench top research has shown that the addition of acetic acid into phosphoric acid enhanced the metal recovery rate of the mixed acid solution. This synergistic effect of mixed acetic acid and phosphoric acids is considered one of the most interesting and significant discoveries of the core invention. The minimal reaction conditions for extracting the maximum percentage of metals were 2.75% phosphoric acid, 0.5% acetic acid, and 130˚C. The total recovery rate approached 100% for arsenic, 96.7% for chromium, and 98.6% for copper in a one step process. We can obtain virtually complete removal of all three metals at slightly more aggressive reaction conditions. The economic viability of the process is enhanced because it can be integrated with other technologies and products (e.g., “green” spray foam insulation, etc.).

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science. Shupe worked as a professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

LSU