한지의 천연염색에 사용되는 염재에 대한 조사와 더불어 국내 18개 한지 업체에서 제작한 천연염색 한지의 색 특성과 색 견뢰도를 평가하였 다. 이들 업체에서 구매한 천연염색 한지는 모두 33종으로 선염이 29종, 후염이 4종이며, 자체 제작한 한지는 후염법에 의해 황색계 11종 및 청색계 1종이었다. 업체에서 제작한 천연염색 한지의 염색에 사용된 염재는 소목과 쪽(각 5종), 치자 및 황토(각 4종), 감물(3종), 오리나무와 숯(각 2종) 그 외 홍화, 호두나무, 가죽나무, 쑥이 각각 1종씩으로 모두 선염법 염색하였으며, 특히 소목, 치자, 쪽이 많았다. 후염법으로는 옻과 개망초만이 행해지고 있었다. 14종의 미염색 한지(순지)의 색상은 2.2Y~6.9Y로 백색에 대한 색차는 8.9~18.2였다. 자외선을 72시간 조사하여도 Y색상은 변하지 않았으나, 원지에 대한 72시간 조사 후의 색차는 0.5~4.2(평균 2.2)로 미염색 한지도‘눈에 띄게 차이가 있다’ 수준으로 색이 변화됨을 알 수 있었다. 전체 천연염색 한지의 색상은 B(쪽-2종), PB(쪽-4), R(소목-2, 홍화-1), RP(소목-2), Y(옻-3, 오리-3, 치자-5, 황칠-1, 괴화-1, 정향-1, 울금-1, 쑥-1, 황벽-1), GY(황벽-1), YR(가죽-1, 감-3, 황토-4, 호두-1, 옻-1, 개망초-1), Black 계열(소목(철매 염)-1, 숯-2)이었다. 72시간 자외선 조사 후 다른 색상으로 변색된 천연염색 한지는 선염법에서는 I-소목(1.2R→0.6YR), C-홍화(6.6R→1.3Y), B-소목(7.4R→3.1YR), H-소목(9.1RP→0.1YR), C-소목(9.6RP→6.2R), 후염법에서는 m-황벽(0.3GY→2.3Y)이었다. 72시간 자외선 조사 후 색 견뢰도는 울금이 가장 불량하였으며, 치자, 황벽, 홍화, 소목, 괴화도 좋지 않았으나, 황토, 쪽, 숯, 그리고 황색계에서는 오리나무와 옻이 비교적 우수하였다. 특히 쪽, 오리나무, 옻, 황토, 숯에 의한 천연염색 한지는 미염색 한지보다 우수한 색 견뢰도를 나타내었다. 대체로 천연염색 한지의 염착량은 화학염색 한지보다 낮으나 청색계의 쪽 염색 한지의 일부는 염착량도 높고, 색 견뢰도 우수하였다.

The world is transitioning towards sustainable agriculture, which includes reducing chemical fertilizers and increasing the adoption of eco-friendly materials. Red clay, known for its colloidal properties, adsorption, and ion exchange capabilities, has become eco-friendly due to its non-toxic nature. However, when red clay is applied in its insoluble powdered form, its absorption by plants is limited. Processed red clay (PRC) was developed to overcome these limitations, and microbial formulations containing Lactobacillus fermentum (MFcL) were applied alongside it. Chlorophyll content and fluorescence values decreased over time after cucumber transplantation. However, co-application of PRC and MFcL resulted in higher chlorophyll content than PRC alone, suggesting that this combination could alleviate plant growth reduction caused by stress. Although the total yield of cucumbers was highest in the NF group, yield per plant increased by more than 10% in the PRC treatment compared to NF. Additionally, yield was higher when PRC was applied alongside MFcL than with MFcL alone. While the proportion of marketable fruits decreased over time in the NF treatment, it increased in the PRC treatment. Soil analysis revealed that PRC application increased soil pH by 3% and available silicon content by 7.6% compared to NF, while available phosphate levels decreased by 13%. Analysis of microbial density in the soil showed that bacteria levels significantly increased by 2-fold in PRC+MFcL compared to NF, while actinomycetes decreased by 1.5-fold. In conclusion, PRC treatment positively influenced cucumber growth, and co-application with microbial fertilizers demonstrated a synergistic effect.

Empty fruit bunch (EFB) char was used to remove NOx and odorous substances. The physicochemical properties of the EFB chars were altered by steam or KOH treatments. The Brunauer-Emmett-Teller surface area and porosity were measured to determine the properties of the modified EFB chars. The deNOx and adsorption test for hydrogen sulphide and acetaldehyde were performed to determine the feasibility of the modified EFB chars. The KOH-treated EFB (KEFB) char revealed higher deNOx efficiency than with commercial activated carbon. The Cu-impregnated EFB char also had high deNOx efficiency at temperatures higher than 150°C. The KEFB char showed the highest hydrogen sulphide and acetaldehyde adsorption ability, followed by the steam-treated EFB char and untreated EFB char. Moreover, the product prepared by sulfonation of EFB char showed excellent performance for esterification of palm fatty acid distillate for biodiesel production.

Biochar obtained from the thermal conversion of biomass has high potential as a substitute material for activated carbon and other carbon-based materials because it is economical, environmentally friendly, and carbon-neutral. The physicochemical properties of biochar can also be controlled by a range of activation methods such as physical, chemical, and hydrothermal treatments. Activated biochar can be used as a catalyst for the catalytic pyrolysis of a biomass and as an absorbent for the removal of heavy metal ions and atmospheric pollutants. The applications of biochar are also expanding not only as a key component in producing energy storage materials, such as supercapacitors, lithium ion batteries, and fuel cells, but also in carbon capture and storage. This paper reviews the recent progress on the activation of biochar and its diverse present and future applications.

As a replacement for activated carbon, biochar was synthesized and used for the adsorptive removal of formaldehyde and nitrogen oxide. Biochar was produced from the fast pyrolysis of the red marine macro alga, Pyropia tenera. The P. tenera char was then activated with steam, ammonia and KOH to alter its characteristics. The adsorption of formaldehyde, which is one of the main indoor air pollutants, onto the seaweed char was performed using 1-ppm formaldehyde and the char was activated using a range of methods. The char activated with both the KOH and ammonia treatments showed the highest adsorptive removal efficiency, followed by KOH-treated char, ammonia-treated char, steam-treated char, and non-activated char. The removal of 1000-ppm NO over untreated char, KOH-treated char, and activated carbon was also tested. While the untreated char exhibited little activity, the KOH-treated char removed 80% of the NO at 50°C, which was an even higher NO removal efficiency than that achieved by activated carbon.

Refuse-derived fuel (RDF) produced using municipal solid waste was pyrolyzed to produce RDF char. For the first time, the RDF char was used to remove aqueous copper, a representative heavy metal water pollutant. Activation of the RDF char using steam and KOH treatments was performed to change the specific surface area, pore volume, and the metal cation quantity of the char. N2 sorption, Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and Fourier transform infrared spectroscopy were used to characterize the char. The optimum pH for copper removal was shown to be 5.5, and the steam-treated char displayed the best copper removal capability. Ion exchange between copper ions and alkali/alkaline metal cations was the most important mechanism of copper removal by RDF char, followed by adsorption on functional groups existing on the char surface. The copper adsorption behavior was represented well by a pseudo-second-order kinetics model and the Langmuir isotherm. The maximum copper removal capacity was determined to be 38.17 mg/g, which is larger than those of other low-cost char adsorbents reported previously.

급속열분해 기술은 바이오매스를 수송용 연료와 고품질의 석유화학 생산물로 업그레이드 할 수 있는 바이오오일을 만드는 유망한 수단으로 주목 받고 있다. 이러한 기대에도 불구하고 연료와 석유 화학 생산물의 상업성은 바이오오일의 높고 잘 변하는 점도, 많은 수분과 산소 함량, 낮은 발열량 및 산 성도와 같은 상당히 바람직하지 않은 특징 때문에 한계가 있다. 그래서 본 연구는 가압증류를 통해 바 이오오일의 품질 개선을 목표로 수행하였다. 가압증류에 따른 바이오오일의 특성 변화를 알아보기 위하 여 0.8～1.4 mm 크기의 굴참나무(Quercus variabilis) 시료 600 g을 465℃에서 1.6초 동안 급속열분해 하여 바이오오일을 제조하고, 감압증류(100hPa) 온도는 대조구, 40℃, 50, 60, 70 및 80에서 각각 30분 간 처리하였다. 급속열분해를 통해 생산된 바이오오일, 바이오차 및 가스는 각각 62.6 wt%, 18.0 및 19.3으로 나타났다. 또한 온도별로 생성된 바이오오일은 수분함량 0.9∼26.1 wt%, 점도 4.2∼11.0 cSt, 발열량 3,893∼5,230 kcal/kg 및 pH 2.6∼3.0 수준으로 긍정적 효과가 나타났다. 이러한 바이오오일 품 질개선에도 불구하고 점도는 반대로 증가했으며 여전히 높은 산소 함량, 낮은 발열량 및 산성도 때문에 바이오오일을 실용적인 연료로 사용하기 위해서는 지속적으로 품질 개선이 필요하다.