The present study focuses on the adsorption of organic matter mainly COD from pretreated landfill leachate of Lamdeng Khunou Solid Waste Management Plant, Manipur, India through the employment of H3PO4 treated activated carbon derived from Parkia speciosa (Petai) pods (PPAC). The adsorbent was analyzed for morphological and surface characterization by various methods including, Field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray Analysis (EDAX), Brunauer–Emmett–Teller (BET) surface area and pH at zero point charges ( pHZPC). The impacts of adsorption processes such as initial pH, temperature, equilibrium time and dose of adsorbent were considered to evaluate the performance of PPAC. At 20 °C, PPAC showed maximum COD removal of 93% within 90 min contact time, at optimum pH 2. Adsorption kinetic was able to explain by Lagergren’s pseudo-second-order equation and intraparticular diffusion models suggesting the combined behavior of both the physical and chemical adsorption of COD on PPAC. Through thermodynamics and isotherm studies, the adsorption of COD on PPAC is revealed to be exothermic with maximum monolayer coverage of 200 mg COD/g PPAC. The performance of the PPAC adsorbent is also compared with other existing reported adsorbents for treating leachate.

The understanding of water vapor sorption and equilibrium in food samples is crucial in the formulation of foods and in their storage stability. In this study, the moisture sorption isotherms of yacon powder was measured by using gravimetric method at 25℃, 35℃, and 45℃ under the relative humidity ranging from 11% to 75%, and nine different isotherm models were used to fit the experimental data and to analyze water vapor sorption on yacon powder. The experimental results showed that water vapor sorption for yacon powder followed a type III shape over the humidity range. The BET monolayer moisture contents values were slightly higher than the values predicted by the GAB model. The monolayer moisture content increased slightly as temperature increased. The surface areas for monolayer moisture sorption decreased with increasing temperature and blanching reduced these values. Through quantifying the relative percentage error (E), coefficient of determination (R2), standard error (SE), and root mean square (RMS) of the isotherm models relative to data, Halsey model was identified to be the best-fitting isotherm to describe the water sorption process in yacon powder.

야콘 분말의 이상적인 저장조건을 규명하기 위한 기초자료로서 저장상대습도(11-75%) 및 온도(25℃, 35℃, 45℃)에 따른 생 및 데친 야콘 분말의 흡습에 미치는 영향을 조사하고 그 특성을 모델링하였다. 생 및 데친 야콘 분말의 등온흡습곡선은 type III 곡선을 나타내었으며, 데친 시료의 평형수분함량은 생 시료에 비해 낮은 것으로 나타났다. GAB식으로부터 예측한 대부분의 단분자층 수분함량은 BET식으로부터 예측한 값보다 낮은 것으로 나타났으며, 생 및 데친 시료의 값은 유사하거나 일정한 패턴의 차이는 발견되지 않았다. 실험이 수행된 조건하에서 GAB와 Halsey 모델이 생 및 데친 야콘 분말의 흡습특성을 가장 잘 예측할 수 있는 것으로 확인되었다. 이러한 실험결과는 야콘의 건조가공 및 저장의 최적조건을 도출하기 위한 중요한 자료로 사용될 수 있을 것으로 판단된다.

볶음온도에 따른 옥수수 분말의 흡습특성을 구명하기 위하여, 옥수수 낟알을 160, 180, 200, 220, 240℃에서 20분간 볶은 후 분쇄하고, 20℃에서 각 분말의 수분활성도(aw) 0.11, 0.33, 0.53, 0.75, 0.90에 따른 평형수분함량(EMC)을 측정하여 등온흡습곡선을 작성하였다. 볶은 옥수수 분말의 등온흡습곡선은 aw 증가에 따른 EMC 증가가 전형적인 sigmoid 형태를 보였으며, aw 0.53 이상의 영역에서는 동일 aw에서 볶음온도가 고온일수록 높은 EMC를 나타내었다. 옥수수 분말의 등온흡습곡선은 볶음온도의 뚜렷한 영향이 없이 Oswin, Caurie, Henderson, Halsey 모델로 설명이 가능하였으며, 가장 적합한 모델은 Oswin인 것으로 나타났다. 단분자층 수분함량은 전범위의 aw영역에서 GAB 방정식으로 예측할 수 있었으며, 볶음온도가 높아짐에 따라 증가하는 경향을 보여서 180℃에서는 0.043 kg H2O/kg solids, 240℃에서는 0.053 kg H2O/kg solids을 각각 나타내었다. 이로써 옥수수의 볶음온도가 분말의 20℃ 흡습특성에 영향을 미치는 것으로 확인되었다.

Laboratory sorption isotherm batch studies have been attempted to elucidate interaction of synthetic pyrethroids (bifenthrin and permethrin) with sediments and their fractions. As a nonlinear isothermal model, the Freundlich equation was applied to sorption results obtained from sediments to investigate the relationship between synthetic pyrethroids and sediments containing different amounts of organic carbon. Results demonstrated that the sorption capabilities of bifenthrin and cis- and trans-permethrin was in the order of bifenthrin, cis-permethrin and trans-permethrin, respectively, indicating that adsorbed bifenthrin was the most stable followed by cis- and trans-permethrin in all sediments. Their sorption capability was closely related to organic carbon contents in sediments. Higher sorption was observed in sediments containing higher organic carbon contents. Sorption study extended into the fractions, clay and humic acids, extracted from a sediment, indicated that higher sorption capacity in humic acids occurred than in the clay of both examined bifenthrin and permethrin. This study demonstrates the sorption of synthetic pyrethroids with sediments, and will help in the understanding of the transport and fate of synthetic pyrethroids existing in field sediments.