The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization.However,these materials would be inevitably aged by natural forces after entering into the environment,while there ar...The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization.However,these materials would be inevitably aged by natural forces after entering into the environment,while there are seldom studies reported the aging effects of zero-valent iron modified biochar.In this work,the hydrogen peroxide and hydrochloric acid solution were applied to simulate aging conditions of zero-valent iron modified biochar.According to the results,the adsorption capacity of copper(II)contaminants on biochar,zero-valent iron modified biochar-1,and zero-valent iron modified biochar-2 after aging was decreased by 15.36%,22.65%and 23.26%,respectively.The surface interactions were assigned with chemisorption occurred on multi-molecular layers,which were proved by the pseudo-second-order and Langmuir models.After aging,the decreasing of capacity could be mainly attributed to the inhibition of ion-exchange and zero-valent iron oxidation.Moreover,the plant growth and soil leaching experiments also proved the effects of aging treatment,the zero-valent iron modified biochar reduced the inhibition of copper(II)bioavailability and increased the mobility of copper(II)after aging.All these results bridged the gaps between bio-adsorbents customization and their environmental behaviors during practical agro-industrial application.展开更多
Iron-modified corn straw biochar was used as an adsorbent to remove phosphorus from agricultural runoff. When agricultural runoffs with a total phosphorus （TP） concentration of 1.86 mg.L-1 to 2.47 mg.L-1 were filter...Iron-modified corn straw biochar was used as an adsorbent to remove phosphorus from agricultural runoff. When agricultural runoffs with a total phosphorus （TP） concentration of 1.86 mg.L-1 to 2.47 mg.L-1 were filtered at a hydraulic retention time of 2 h through a filtration column packed with the modified biochar, a TP removal efficiency of over 99% and an effluent TP concentration of less than 0.02mg.L-1 were achieved. The isotherms of the phosphorus adsorption by the modified biochar fitted the Freundlich equation better than the Langmuir equation. The mechanism of the phosphorus adsorbed by the modified biochar was analyzed by using various technologies, i.e. scanning electron microscopy （SEM）, X-ray diffraction （XRD） analysis, X-ray photoelectron spectroscopy （XPS）, and Fourier transform infrared spectroscopy （FTIR）. The results indicated that the surface of the modified biochar was covered by small iron granules, which were identified as Fe304. The results also showed that new iron oxides were formed on the surface of the modified biochar after the adsorption of phosphorus. Moreover, new bonds of Fe- O-P and P-C were found, which suggested that the new iron oxides tend to be Fe5（PO4）4（OH）3. Aside from removing phosphorus, adding the modified biochar into soil also improved soil productivity. When the modified biochar-to-soil rate was 5%, the stem, root, and bean of broad bean plants demonstrated increased growth rates of 91%, 64%, and 165%, respectively.展开更多
基金The authors appreciate the support from the National Natural Science Foundation of China(Grant No.22264025)the Yunnan Province Education Department Scientific Research Foundation Project(Grant No.2022J0136)the Applied Basic Research Foundation of Yunnan Province(Grant Nos.202201AS070020,202201AU070061).
文摘The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization.However,these materials would be inevitably aged by natural forces after entering into the environment,while there are seldom studies reported the aging effects of zero-valent iron modified biochar.In this work,the hydrogen peroxide and hydrochloric acid solution were applied to simulate aging conditions of zero-valent iron modified biochar.According to the results,the adsorption capacity of copper(II)contaminants on biochar,zero-valent iron modified biochar-1,and zero-valent iron modified biochar-2 after aging was decreased by 15.36%,22.65%and 23.26%,respectively.The surface interactions were assigned with chemisorption occurred on multi-molecular layers,which were proved by the pseudo-second-order and Langmuir models.After aging,the decreasing of capacity could be mainly attributed to the inhibition of ion-exchange and zero-valent iron oxidation.Moreover,the plant growth and soil leaching experiments also proved the effects of aging treatment,the zero-valent iron modified biochar reduced the inhibition of copper(II)bioavailability and increased the mobility of copper(II)after aging.All these results bridged the gaps between bio-adsorbents customization and their environmental behaviors during practical agro-industrial application.
文摘Iron-modified corn straw biochar was used as an adsorbent to remove phosphorus from agricultural runoff. When agricultural runoffs with a total phosphorus （TP） concentration of 1.86 mg.L-1 to 2.47 mg.L-1 were filtered at a hydraulic retention time of 2 h through a filtration column packed with the modified biochar, a TP removal efficiency of over 99% and an effluent TP concentration of less than 0.02mg.L-1 were achieved. The isotherms of the phosphorus adsorption by the modified biochar fitted the Freundlich equation better than the Langmuir equation. The mechanism of the phosphorus adsorbed by the modified biochar was analyzed by using various technologies, i.e. scanning electron microscopy （SEM）, X-ray diffraction （XRD） analysis, X-ray photoelectron spectroscopy （XPS）, and Fourier transform infrared spectroscopy （FTIR）. The results indicated that the surface of the modified biochar was covered by small iron granules, which were identified as Fe304. The results also showed that new iron oxides were formed on the surface of the modified biochar after the adsorption of phosphorus. Moreover, new bonds of Fe- O-P and P-C were found, which suggested that the new iron oxides tend to be Fe5（PO4）4（OH）3. Aside from removing phosphorus, adding the modified biochar into soil also improved soil productivity. When the modified biochar-to-soil rate was 5%, the stem, root, and bean of broad bean plants demonstrated increased growth rates of 91%, 64%, and 165%, respectively.
