The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorptio...The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g^-1 and 8.2 mg·g^-1 for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr（VI） was endothermic when studied by varying temperature from 20℃ to 50℃ for both activated and functionalized adsorbents.展开更多
Aims In plant eco-physiology,less negative(enriched)carbon 13(^(13)C)in the leaves indicates conditions of reducing leaf gas exchange through stomata,e.g.under drought.In addition,^(13)C is expected to be less negativ...Aims In plant eco-physiology,less negative(enriched)carbon 13(^(13)C)in the leaves indicates conditions of reducing leaf gas exchange through stomata,e.g.under drought.In addition,^(13)C is expected to be less negative in non-photosynthetic tissues as compared with leaves.However,these relationships inδ^(13)C from leaves(photosynthetic organs)to branches,stems and roots(non-photosynthetic organs)are rarely tested across multiple closely related tree species,multiple compartments,or in trees growing under extreme heat and drought.Methods We measured leaf-to-root^(13)C in three closely related desert acacia species(Acacia tortilis,A.raddiana and A.pachyceras).We measuredδ^(13)C in leaf tissues from mature trees in southern Israel.In parallel,a 7-year irrigation experiment with 0.5,1.0 or 4.0 L day1 was conducted in an experimental orchard.At the end of the experiment,growth parameters andδ^(13)C were measured in leaves,branches,stems and roots.Important Findings Theδ^(13)C in leaf tissues sampled from mature trees was ca.-27‰,far more depleted than expected from a desert tree growing in one of the Earth's driest and hottest environments.Across acacia species and compartments,δ^(13)C was not enriched at all irrigation levels(-28‰to ca.-27‰),confirming our measurements in the mature trees.Among compartments,leafδ^(13)C was unexpectedly similar to branch and rootδ^(13)C,and surprisingly,even less negative than stemδ^(13)C.The highly depleted leafδ^(13)C suggests that these trees have high stomatai gas exchange,despite growing in extremely dry habitats.The lack ofδ^(13)C enrichment in nonphotosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.展开更多
文摘The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g^-1 and 8.2 mg·g^-1 for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr（VI） was endothermic when studied by varying temperature from 20℃ to 50℃ for both activated and functionalized adsorbents.
基金funded by the Benoziyo Fund for the Advancement of ScienceMr and Mrs Norman Reiser,together with the Weizmann Center for New Scientists+1 种基金the Edith&Nathan Goldberg Career Development Chair.D.U.was funded by Ariovich scholarship and by the scholarship of the environmental science school of the Hebrew University.G.W.thanks the Arava Drainage Authority and the Israeli Ministry of Science and Technology(MOST)for their continued support.The study used data available through the TRY initiative on plant traits(http://www.try-db.org,data request 8968).The TRY initiative and database is hosted,developed and maintained by J.Kattge and G.Bonisch(Max Planck Institute for Biogeochemistry,Jena,Germany)TRY is currently supported by DIVERSITAS/Future Earth and the German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig.
文摘Aims In plant eco-physiology,less negative(enriched)carbon 13(^(13)C)in the leaves indicates conditions of reducing leaf gas exchange through stomata,e.g.under drought.In addition,^(13)C is expected to be less negative in non-photosynthetic tissues as compared with leaves.However,these relationships inδ^(13)C from leaves(photosynthetic organs)to branches,stems and roots(non-photosynthetic organs)are rarely tested across multiple closely related tree species,multiple compartments,or in trees growing under extreme heat and drought.Methods We measured leaf-to-root^(13)C in three closely related desert acacia species(Acacia tortilis,A.raddiana and A.pachyceras).We measuredδ^(13)C in leaf tissues from mature trees in southern Israel.In parallel,a 7-year irrigation experiment with 0.5,1.0 or 4.0 L day1 was conducted in an experimental orchard.At the end of the experiment,growth parameters andδ^(13)C were measured in leaves,branches,stems and roots.Important Findings Theδ^(13)C in leaf tissues sampled from mature trees was ca.-27‰,far more depleted than expected from a desert tree growing in one of the Earth's driest and hottest environments.Across acacia species and compartments,δ^(13)C was not enriched at all irrigation levels(-28‰to ca.-27‰),confirming our measurements in the mature trees.Among compartments,leafδ^(13)C was unexpectedly similar to branch and rootδ^(13)C,and surprisingly,even less negative than stemδ^(13)C.The highly depleted leafδ^(13)C suggests that these trees have high stomatai gas exchange,despite growing in extremely dry habitats.The lack ofδ^(13)C enrichment in nonphotosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.
