In Yang

Environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper and/or boron salts

Novel biocides, such as copper azole (CuAz) and ammoniacal copper quaternary (ACQ), are extensively used as substitutes for chromate copper arsenate (CCA) in wood preservation. However, the expense of these biocides has necessitated the development of cost-effective and environmentally friendly wood preservatives. This study was conducted to investigate the effectiveness against decaying fungi of the preservatives formulated with enzymatic-hydrolyzed okara (OK), which is an organic waste produced from the manufacture of tofu, CuCl(2) (CC) and/or Na(2)B(4)O(7).10H(2)O (B). With the addition of NH(4)OH as a dissociating agent, the addition of OK facilitated the target retention of most of the OK/CC and OK/CC/B preservative formulations in wood blocks. The OK-based wood preservatives (OK-WPs) were stable against hot-water leaching. When compared with control and CC-treated wood blocks, the leached wood blocks treated with OK/CC and OK/CC/B formulations showed excellent decay resistance against both Postia placenta and Gloeophyllum trabeum, especially when OK was hydrolyzed by Celluclast at a loading level of 0.1 ml/g. Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray (SEM-EDX) spectrometry analyses demonstrated that preservative complexes, such as OK-CC and OK-CC-B, existed in the wood blocks treated with OK/CC and OK/CC/B formulations. This study results support the potential application of OK-WPs as environmentally friendly wood preservatives capable of replacing CuAz and ACQ.

Efficacy of wood preservatives formulated from okara with copper and/or boron salts

As a substitute for high-cost copper azole (CuAz) and alkaline copper quaternary (ACQ) wood preservatives, alternative wood preservatives were formulated with okara, which is an organic waste from the production of tofu, and copper chloride and/or borax. Each preservative was used in treatment of wood blocks in a reduced-pressure method to measure its treatability. The treated wood blocks were placed in hot water for 3 days to examine the stability of the preservatives against hot-water leaching. The preservatives successfully penetrated into wood blocks, probably due to the use of ammonium hydroxide as a dissociating agent. However, the stability of okara-based preservatives dropped as the concentration of acid in the solutions used for hydrolysis of okara increased. The treatability and leachability of the preservatives were not affected by hydrolysis temperature but were negatively affected by the addition of borax. Leached wood blocks treated with okara-based preservatives and exposed to decay fungi Gloeophyllum trabeum and Postia placenta over 12 weeks showed good decay resistance. Okara-based wood preservatives can protect wood against fungal attack as effectively as CuAz, and have potential for use as environmentally friendly wood preservatives.

Effects of Various Factors on the Durability of Pellets Fabricated with Larix kaempferi C. and Liriodendron tulipifera L. sawdust

ABSTRACT This study was conducted to investigate the effects of sawdust size and moisture content, pelletizing temperature and time on the durability of the pellets fabricated with larch and tulip tree sawdust. The durability of larch-pellet was significantly higher than that of tulip tree-pellet. For the larch-pellets, the durability of the pellets fabricated with > 18 mesh sawdust was higher than that of 8 ∼ 18 mesh sawdust. With the increases of pelletizing temperature and time, the durabilities of larch- and tulip tree-pellets steadily improved. The durabilities of larch- and tulip tree-pellets also increased as the moisture content of sawdust increased. In the comparison of durabilities between commercial pellets and larch- or tulip tree-pellets, the pellets fabricated with larch and tulip tree sawdusts in our study were less denser than commercial pellets, but the durability of most larch-pellets was satisfied with the 1st-grade pellet standard designated by Korea Forest Research Institute. In addition, the durability of tulip tree-pellets were higher than that of the 3rd-grade pellet standard. From the scanning electron microscopic observation of larch- and tulip tree-pellets, the gap between the sawdusts of each pellet was reduced with the increases of pelletizing temperature and time. In particular, it was visually confirmed that the surface of the pellets made with the pelletizing temperature of 180°C for 3 min did not differ from that of commercial pellets. Keywords : larch, tulip tree, pellet, durability, scanning electron microscope

Adhesive Properties of Medium-Density Fiberboards Fabricated with Rapeseed Flour-Based Adhesive Resins

This study examined the adhesive properties of adhesives formulated with rapeseed flour (RSF), a by-product of edible oil and bio-diesel manufacture, for medium-density fiberboards (MDFs). The RSF was hydrolyzed by sulfuric acid (AC-RSFH) and sodium hydroxide (AK-RSFH) solutions of 3%, 5%, and 7%. Phenol–formaldehyde (PF) prepolymers were prepared with formaldehyde to phenol molar ratios of 1.5, 1.8, and 2.1 (1.5-, 1.8-, and 2.1-PF). RSF-based adhesives were formulated by cross-linking 35% AC-RSFH, 35% AK-RSFH, and 30% PF prepolymers on a solid weight basis. The mechanical strength and dimensional stability of the MDFs were improved by decreasing the concentration of RSF-hydrolytic agents. The properties of the MDFs bonded with RSFH/1.8-PF resins were superior to those of RSFH/1.5- or 2.1-PF resins. These results suggest that RSF can be used as a raw material for environment-friendly adhesives used in MDF production.

Effect of the addition of binders on the fuel characteristics of wood pellets.

본 연구는 낙엽송과 백합나무 톱밥을 이용한 펠릿의 제조 과정에서 바인더로 일정량의 유채박, 커피부산물,수피, 솔방울, 리그닌 분말을 첨가하여 바인더의 종류 및 첨가량이 내구성을 포함한 펠릿의 품질에 미치는 영향을 알아보기 위하여 수행하였다. 바인더와 함께 제조한 펠릿의 품질은 국립산림과학원에서 고시한 목재 펠릿 품질 규격 1등급 기준을 대부분 상회하였으며, 일부 과다한 양의 바인더를 첨가하여 제조한 펠릿에서만 높은 회분함량으로 2~3등급 기준을 만족하는 것으로 조사되었다. 바인더 종류 및 첨가량에 따른 펠릿의 내구성은 리그닌,유채박 그리고 커피부산물을 첨가하여 제조한 펠릿에서 우수하였으며, 백합나무 펠릿은 첨가량의 증가와 함께 내구성도 향상되었다. 한편 낙엽송 펠릿의 경우 첨가량의 증가에 따른 내구성 향상 효과는 크지 않았으며, 수피와 솔방울을 바인더로 사용하였을 때 첨가량의 증가와 함께 내구성이 감소하였다. 제조된 펠릿의 광학/전자현미경 관찰을 통하여 바인더의 종류에 따른 차이를 명확하게 확인할 수 없었으나, 첨가량에 따른 차이는 명확하게 관찰 할 수 있었다. 결과를 종합하면, 바인더의 첨가는 목재 펠릿의 품질 향상에 대부분의 항목에서 기여하였으며, 특히 커피부산물을 바인더로 사용하여 제조한 펠릿의 경우 모든 품질에서 뚜렷한 향상을 확인할 수 있었다. 향후 저렴한 바인더의 안정적인 확보가 이루어진다면 바인더의 첨가로 인하여 연료적 품질이 향상된 목재 펠릿의 상용화가 가능할 것으로 확신한다.

Antifungal efficacy of environmentally friendly wood preservatives formulated with enzymatic‐hydrolyzed okara, copper, or boron salts

Okara, an organic waste product obtained from soy milk production, was used with copper chloride or sodium borate to formulate new wood preservatives as a substitute for expensive wood preservatives, such as copper-azole-based preservatives and ammoniacal copper quaternary. Before formulating the preservatives, okara was hydrolyzed by enzymes (cellulase, pectinase, and protease) to augment penetration and fix the biocide salts of the preservatives into wood blocks. The preservatives were injected into wood blocks by vacuum pressure to measure the treatability of the preservatives. The treated wood blocks were placed in hot water for 3 d to measure leachability. The treatability and leachability of the preservatives were affected by the type and loading amount of enzymes and the addition of sodium borate into okara-based wood preservative formulations. The treatability and leachability of the preservatives formulated with copper chloride and okara hydrolysates were 63.38 and 3.15%, and those of the preservatives with copper chloride, okara hydrolysates, and sodium borate were 61.47 and 3.32%, respectively. Despite the hot water leaching, wood blocks treated with preservatives formulated with 2% cellulase, pectinase, and protease hydrolyzed okara, CuCl(2), and sodium borate showed only 1.98% average weight loss against Fomitopsis palustris over 12 weeks. Microscopic observation revealed how okara-based preservatives work in wood blocks. Okara has potential as a raw material for cost-effective and environmentally friendly wood preservatives.

Evaluating The Water Resistance of Wood Adhesives Formulated with Chicken Feather Produced from Poultry Industry

본 연구는 주원료로 도계부산물인 닭털의 NaOH 가수분해물, 경화제로 닭털의 H2SO4 가수분해물 및 폼알데히드계가교제를 반응시켜 접착제를 제조하고, 이에 대한 물성 및 내수성 실험을 통하여 닭털의 목질계 판상재용 접착제의 원료화 가능성을 확인하기 위하여 수행하였다. 닭털은 주로 케라틴계 단백질로 구성되어 있었으며, 중금속의 함유량이 매우 낮거나 검출되지 않았다. 알칼리에 대한 닭털의 가수분해율은 수용액 내의 NaOH 농도가 증가함에 따라 계속 증가하였으나, 과도한 가수분해에 따른 단백질 고유의 접착능 손실을 최소화하고 적정한 가수분해 조건을 찾기 위하여 닭털의 가수분해제 내의 NaOH 농도를 5%, 7.5%, 10%로 결정하였다. 접착제의 조성을 보면, 고형분 함량을 기준으로 70%의 닭털 NaOH 가수분해물 또는/그리고 경화제로 닭털의 H2SO4 가수분해물 및 30%의 가교제로 조제하였는데, 이접착제의 고형분 함량은 가수분해 조건 및 가교제의 종류에 따라 28.3 - 44.8% 범위에 존재하였다. 이 접착제의 점도는 상온에서 전반적으로 높았으나, 50℃에서 측정한 결과 분사형 접착제로서 적용이 가능한 것으로 조사되었다. 접착제의 내수성을 비교하기 위하여 측정된 열수 불용해율은 5% 농도의 NaOH 수용액에서 반응시킨 닭털의 알칼리 가수분해물(CF-AK-5%)에 경화제로 5% 농도의 H2SO4 수용액에서 반응시킨 닭털의 산가수분해물(CF-AC-5%)을 고형분함량 기준 10% 이상 첨가하여 제조하고 경화시킨 접착제에서 높았다. 또한 접착제 제조시 고형분 함량을 기준으로 30%가 첨가된 가교제별 열수 불용해율은 phenol-formaldehyde (PF), melamine-urea-formaldehyde (MUF), formalin 순으로 조사되었다. 닭털 접착제의 열수 불용해율을 섬유판 제조에 사용되고 있는 석유화학계 합성수지와 비교한 결과, CF-AC-5%에 가교제로 PF를 그리고 경화제로 CF-AC-5%를 첨가하여 조제한 접착제는 기존 멜라민-요소수지의 열수불용해율과 통계학적으로 차이가 없었으며, 가교제로 PF를 사용한 모든 접착제와 고형분 함량을 기준으로 55%의 CF-AK-5%, 15%의 CF-AC-5% 그리고 가교제로 30%의 MUF와 함께 제조한 접착제는 기존 요소수지를 대체할 수 있는 것으로 조사되었다. 이 결과를 토대로 적정한 조건에서 가수분해한 닭털은 목질계 판상재용 접착제의 원료로 사용이 가능할 것으로 판단된다.

Effect of Torrefaction Condition on The Chemical Composition and Fuel Characteristics of Larch wood

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and 270℃ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the

Effect of Diluted H2SO4 and NaOH Treatment on Chemical Composition of Larch and Yellow Poplar

본 연구에서는 산 및 알칼리 처리가 목질계 바이오매스의 주요 화학조성 변화에 미치는 영향을 확인하기 위해 H2SO4와 NaOH를 각각 1.0 wt%와 2.0 wt% 수용액으로 제조한 후 국내 주요 수종인 백합나무와 낙엽송에 상온에서 72시간 침지 처리하였다. 리그닌, 주요 구성당, 원소분석 등 화학적 특성 분석을 수행하고 그 결과를 통계 프로그램을 이용하여 분석하였다. 그 결과 동일한 화학적 처리에도 수종에 따라 95% 유의수준에서 유의한 결과를 확인하였다. 백합나무는 산 처리에 민감한 변화를 보이는 반면에 낙엽송에서는 알칼리 처리에서 유의한 결과를 얻을 수 있었다. 두 수종 모두에서 glucose보다는 헤미셀룰로오스에 미치는 영향이 큰 것으로 분석되었으며, 바이오매스의 에너지량과 밀접한 관계가 있는 H/C와 O/C 비율을 이용한 Van Krevelen 다이어그램에서는 산 또는 알칼리 처리 종류에 관계없이 수종에 따라 상반된 결과를 확인하였다. 이러한 결과는 바이오매스 종류에 따라 각기 다른 최적화된 바이오에너지 생산 공정이 필요함을 의미하며, 목재펠릿과 같은 고형 바이오연료 생산의 경우 바이오매스 내 헤미셀룰로오스 및 리그닌 함량 변화로 인하여 내구성에 영향을 미칠 것으로 분석되었다.

Development of Adhesive Resins Formulated with Rapeseed Flour Hydrolyzates for Laminated Veneer Lumber and Its Performance Evaluation

ABSTRACT Due to the increase of oil price and the environmental issue such as the emission of volatile organic compounds, the necessity for developing alternative resins of petroleum-based adhesive resins, which have extensively been used for the manufacture of wood-based products, has been speculation since the early 1990. In our study, rapeseed flour (RSF), which is the by-product of bio-diesel produced from rapeseed, were hydrolyzed by enzymes. As a crosslinking agents of the RSF hydrolyzates, phenol-formaldehyde prepolymers (PF) were prepared. The RSF hydrolyzates and PF were mixed to complete the formulation of RSF-based adhesive resins, and the resins were applied to make the laminated veneer lumber (LVL). The physical and mechanical properties of the LVL were measured to examine whether RSF can be used as raw materials of adhesive resins for the fabrication of LVL or not. The average moisture content and soaking delamination rate of the LVL bonded with RSF-based adhesive resins exceeded the minimum requirement of KS standard. Moreover, thermal analysis of the RSF-based resins showed similar tendencies except for the RSF-based adhesive resins formulated with pectinase-hydrolyzed RSF. The bending strengths of the LVL were higher than that of the LVL made with commercial PF resins. These results showed the potential of RSF as a raw material of alternative adhesives for the production of LVL. Further works on the optimal conditions of RSF hydrolysis and spreading characteristics for RSF-based adhesive resins is required to improve the adhesive performance of RSF-based resins. Keywords : rapeseed flour (RSF), laminated veneer lumber (LVL), enzyme hydrolyzates, alter-native adhesives.