• Journal of Korean Society on Water Environment
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• 제37권6호
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• pp.483-492
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• 2021

This study evaluated the removal efficiencies of methylene blue (MB) and humic acids (HA) using a rice husk (RH) biochar and powdered activated carbon (PAC). The pseudo-second-order model better presented the adsorption of MB and HA onto a RH biochar than the pseudo-first-order model. Furthermore, better description of the adsorption behavior of MB and HA by the Langmuir isotherm model (R² of the RH biochar: MB = 0.986 and HA = 0.984; R² of PAC: MB = 0.997 and HA = 0.989) than the Freundlich isotherm model (R² of the RH biochar: MB = 0.955 and HA = 0.965; R² of PAC: MB = 0.982 and HA = 0.973) supports the assumption that monolayer adsorption played key roles in the removal of MB and HA using the RH biochar and PAC. Batch experiments were performed on the effects of dosage, temperature, and pH. For all experiments, PAC showed higher efficiencies than RH biochar and MB adsorption efficiencies were higher than those of HA. Adsorption efficiencies increased with increasing amounts of adsorbents and temperature. As the pH increased, adsorption efficiencies of MB were increased while adsorption efficiencies of HA were decreased.

• Computers and Concrete
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• 제33권6호
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• pp.707-724
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• 2024

This paper proposes a study of cement replacement with rice husk ash (RHA) and eggshell ash (ESA) for enhanced mechanical properties of geopolymer (GP) concrete with and without admixture. The main objective is to investigate the mechanical properties of GP with various replacement levels of Pozzolana Portland cement by RHA and ESA. The GP resistance to durability is examined and impact of ash materials on concrete's durability performance is determined. The environmental benefits of using agricultural waste materials in GP manufacturing minimize cement usage and CO2 emissions. The goal is to assess value of RHA-ESA of building material, paving stones for structures to lessen environmental impact. The novelty lies in use of ESA and RHA as partial replacements for cement and investigation of admixtures to enhance concrete properties, and reduce environmental impact. The research contributes by introducing a novel approach to reducing cement consumption by using ESA and RHA to address environmental concerns. It also explores the potential benefits of admixtures improving concrete performance and reducing environmental pollution. A study is carried with and without impacts of admixture to find compressive strength of GP cubes. The cement has been replaced by RHA and ESA in the range of (2.5%+7.5%, 5%+5%, 7.5%+2.5) by weight of cement for M20 mix. The compressive strength (CS) and split tensile strength (STS) at 7days, 14 days and 28 days is obtained as 21 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 24 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 28 N/mm2 at 7.5%RHA+2.5%ESA and 2.8 at 7.5%ESA respectively with normal curing condition.

• Journal of the Korean Wood Science and Technology
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• 제12권4호
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• pp.36-46
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• 1984

In order to investigate the inhibitory index (I) and the effects of hot water extraction treatments and addition of accelerators on the index in hardening of Korean lignocellulosics, portland cement (Type I) and water system, hydration tests were carried out on 8 Korean lignocellulosics, namely, Pinus densiflora, Pinus rigida, Pinus koraiensis, Abies holophylla, Larix leptoiepis, Populus alba-glandulosa, rice husk and rice stalk with or without hot water extraction or chemical additives. The inhibitory index of Pinus densiflora and Pinus rigida found to be suitable under limited conditions for composite without any treatment. With hot water treatment rice husk, Pinus koraiensis, Larix leptolepis, and A hies holophylla were reclassified from not suitable to suitable under limited conditions. Combining hot water extraction with chemical addition of accelerator, calcium chloride of magnesium chloride, Populus alba-glandulosa, Larix leptolepis, and Pinus rigida became highly suitable.

• Clean Technology
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• 제20권3호
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• pp.205-211
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• 2014

Biomass-based plastics containing the biomass content higher than 25 wt% have been considered as environment-friendly materials due to their effects on the reduction in the $CO_2$ emission and petroleum consumption as well as biodegradability after use. This article described the effect of the additions of oxo-biodegradable additive, 4 kinds of plant biomass, unsaturated fatty acid, citric acid in the properties of polyethylene films. Bio films were prepared using a variety of biomasses and tested for feasibility as a food packaging film. Mechanical properties such as tensile strength and percent elongation at break were evaluated. Husk biomasses from such as corn, soybean, rice, and wheat were pulverized using air classifying mill (ACM) and four different types of packaging films with thickness of $50{\mu}m$ were prepared using the pulverized biomass and low density polyethylene/linear low density polyethylene. The packaging film with wheat husk biomass was found to have greater mechanical properties of elongation and tensile strength than the other samples. Biodegradability of bio film was measured to be 51.5% compared to cellulose.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.26-27
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• 2015

The purpose of this study was to investigate the compressive strength property into concrete using rice straw ash.. In an effort to evaluate the effects of rice straw ash as mineral admixture, rice straw ash was mixed with cement at the mixture ratio of 0, 5, 10 and 15% relative to the cement weight. When the mixture ratio of rice straw ash was 10%, the highest compressive strength was observed, while the strength tended to decrease when the mixture ratio of rice straw ash was 15% even if it exhibited higher compressive strength than the plain. And it was observed that compressive strength of concrete containing rice husk ash was a similar a compressive strength of concrete containing silica fume.

• Research in Plant Disease
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• 제20권4호
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• pp.289-294
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• 2014

Rice samples including paddy, husk, brown rice, blue-tinged rice, broken rice, discolored rice and polished rice were collected from rice processing complexes(RPC) nationwide to determine the contamination of fungi and mycotoxins on rice during 2010-2013. Among the samples, paddy rice had the highest frequencies of fungal and Fusarium occurrence, and the frequencies decreased along with milling as husk was the next. Blue-tinged rice or discolored rice was similar with brown rice for fungal occurrence, and polished rice showed the lowest frequency. Among Fusarium species, F. graminearum species complex occupied 87% in 2012 but did 35-39% in 2011 and 2013. Aspergillus and Penicillium species appeared at low frequency in most samples but occurred at higher frequency in certain RPC samples. Alternaria, Nigrospora, and Epicoccum species occurred similarly to the pattern of total fungi. The rice samples from 2010-2012 were analyzed for the occurrence of Fusarium mycotoxins including deoxynivalenol, nivalenol, zearalenone, and other trichothecenes. The most highly contaminated sample was discolored rice in terms of frequency, level, ratio of simultaneous contamination with multiple toxins, followed by blue-tinged rice.

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.507-518
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• 1998

세계에서 가장 주된 곡물중의 하나인 벼의 생산은 세계의 주된 폐기물 즉 왕겨와 볏짚을 발생시킨다. 1993년 기준으로 세계 벼 생산량은 5억톤이며 이중 10∼20%를 왕겨로 보고 있다. 국내의 경우 1997년에 5백 45만톤으로 16∼18%를 왕겨로 추정하고 있다. 따라서 농산폐기물의 효율적 이용이 절박한 실정이다.(중략)

• Korean Journal of Environmental Agriculture
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• 제28권2호
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• pp.158-164
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• 2009

Biosorption uses adsorbents derived from non-living biomass and removes toxic metals from industrial wastewater. The objective of this research was to evaluate the potential of low cost biosorbents to remove heavy metal ions (Cd, Cu, Pb and Zn) from aqueous solutions using chemically modified rice husk and saw dust (Pseudotsuga menziesi, Quercus, Populus). Batch-type adsorption experiments were carried out using rice husk and saw dust treated with NaOH and/or tartaric acid in artificial wastewater 100 mg metal/L). The experimental results showed that the adsorption specificity of each biosorbent was Pb > Cu > Cd > Zn irrespective of the types of biosorbents. The adsorption capacity of Pb and Cu onto NaOH-treated sawdust was increased 2${\sim}$3 times compared to the untreated one. In addition, the tartaric acid treatment increased the adsorption capacity of rice husk for Zn and Cd approximately 5${\sim}$10 fold compared to the untreated one. Surface conditions and changes in functional groups by chemical modification of each biosorbent were confirmed by SEM and FT-IR. Overall, the results show that chemical modification increases the metal removal capacity of rice bran and sawdust.

• Magazine of the Korea Concrete Institute
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• 제11권2호
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• pp.115-125
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• 1999

The purpose of this experimental research is to investigate the properties of workability and strength of the concrete containing admixtures such as silica fume, fly ash, ground granulated blast-furnace slag, and rice husk ash. For this purpose, the workability and the strength of the concrete containing each admixture were tested and analyzed according to the unit weight of binder and the replacement ratio of each admixture. As a result, considering their workability and strength, the existence of minimum binder weight and optimum replacement ratio of concrete containing admixture to plain concrete were obtained for each admixture.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.309-312
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• 2010

본 연구에서는 유동층반응기를 이용하여 왕겨의 탄화반응을 수행하였다. 탄화반응은 내경 40mm, 높이 1.8m의 유동층을 사용하였으며, 분산판은 다공성 스테인레스스틸을 사용하였다. 탄화반응은 질소를 이용하여 수행하였다. 왕겨 주입입자 크기는 직경 2.0mm, 0.715mm, 0.359mm, 0.194mm를 각각 사용하였으며, 유동층의 온도는 $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$에서 탄화특성을 측정하였다. 또한 유동층의 매질로는 직경 1.0mm의 Co-Mo-Fe/$Al_2O_3$ 촉매를 사용하였으며, 탄화물은 유동층상부에 설치된 사이크론에 의하여 포집 분리 되었다. 탄화온도, 유속, 입자크기 등 조업변수에 따른 생성 탄소체의 물성을 규명하여 최적 조업조건을 제시하였다.