• Environmental Engineering Research
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• v.21 no.2
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• pp.152-163
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• 2016

Present study investigates the potential of cassava peel and rubber tree bark for the removal of Cr (VI) from aqueous solution. Removal efficiency of more than 99% was obtained during the kinetic adsorption experiments with dosage of 3.5 g/L for cassava peel and 8 g/L for rubber tree bark. By comparing popular isotherm models and kinetic models for evaluating the kinetics of mass transfer, it was observed that Redlich-Peterson model and Langmuir model fitted well ($R^2$ > 0.99) resulting in maximum adsorption capacity as 79.37 mg/g and 43.86 mg/g for cassava peel and rubber tree bark respectively. Validation of pseudo-second order model and Elovich model indicated the possibility of chemisorption being the rate limiting step. The multi-linearity in the diffusion model was further addressed using multi-sites models (two-site series interface (TSSI) and two-site parallel interface (TSPI) models). Considering the influence of interface properties on the kinetic nature of sorption, TSSI model resulted in low mass transfer rate (5% for cassava peel and 10% for rubber tree bark) compared to TSPI model. The study highlights the employability of two-site sorption model for simultaneous representation of different stages of kinetic sorption for finding the rate-limiting process, compared to the separate equilibrium and kinetic modeling attempts.

• Research in Plant Disease
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• v.24 no.3
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• pp.237-241
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• 2018

A circular bark with a 30 cm width was artificially removed from the trunk of a 250-year-old zelkova tree (Zelkova serrata) heavily damaged by artificial girdling in Sunchang, Jeonbuk Province in March of 2005. The debarked area was cleaned approximately 10 days after artificial girdling and bark margins with 2 cm width above and below the girdled portion were cut off to promote wound callus formation. Nine pieces of fresh bark (width 8 cm, length 35 cm, thickness 0.5 cm) were then prepared from branches of neighbor zelkova trees broken by heavy snowfalls and pasted onto the girdled portion of the tree, after which a Vaseline dressing was applied to water-proof the area and rubber bars were used to hold the implants to the trunk. Two pieces of the implanted fresh barks were successfully grafted onto the girdled area and the damaged tree has been vigorously growing over 13 years. To our knowledge, this is the first case of successful bark implantation to cure a 250-year-old zelkova tree heavily damaged by artificial girdling. This bark implantation technique will be utilized for the conversation and management of heavily damaged big and old trees in the future.