Kinetic modelling of a diesel-polluted clayey soil bioremediation process

A mathematical model is proposed to describe a diesel-polluted clayey soil bioremediation process. The reaction system under study was considered a completely mixed closed batch reactor, which initially contacted a soil matrix polluted with diesel hydrocarbons, an aqueous liquid-specific culture medium and a microbial inoculation. The model coupled the mass transfer phenomena and the distribution of hydrocarbons among four phases (solid, S; water, A; non-aqueous liquid, NAPL; and air, V) with Monod kinetics. In the first step, the model simulating abiotic conditions was used to estimate only the mass transfer coefficients. In the second step, the model including both mass transfer and biodegradation phenomena was used to estimate the biological kinetic and stoichiometric parameters. In both situations, the model predictions were validated with experimental data that corresponded to previous research by the same authors. A correct fit between the model predictions and the experimental data was observed because the modelling curves captured the major trends for the diesel distribution in each phase. The model parameters were compared to different previously reported values found in the literature. Pearson correlation coefficients were used to show the reproducibility level of the model.Se propone un modelo matemático para describir un proceso de biorremediación de suelos arcillosos contaminados con diesel. El sistema de reacción en estudio se consideró un reactor discontinuo cerrado completamente mixto, que inicialmente entró en contacto con una matriz de suelo contaminada con hidrocarburos diesel, un medio de cultivo específico líquido acuoso y una inoculación microbiana. El modelo acopló los fenómenos de transferencia de masa y la distribución de hidrocarburos entre cuatro fases (sólido, S; agua, A; líquido no acuoso, NAPL; y aire, V) con la cinética de Monod. En el primer paso, se utilizó el modelo que simula las condiciones abióticas para estimar solo los coeficientes de transferencia de masa. En el segundo paso, se utilizó el modelo que incluía tanto la transferencia de masa como los fenómenos de biodegradación para estimar los parámetros biológicos cinéticos y estequiométricos. En ambas situaciones, las predicciones del modelo fueron validadas con datos experimentales que correspondían a investigaciones previas de los mismos autores. Se observó un ajuste correcto entre las predicciones del modelo y los datos experimentales porque las curvas de modelado capturaron las principales tendencias para la distribución del diesel en cada fase. Los parámetros del modelo se compararon con diferentes valores reportados previamente encontrados en la literatura. Se utilizaron coeficientes de correlación de Pearson para mostrar el nivel de reproducibilidad del modelo

New alkyl imido niobium complexes supported by guanidinate ligands: synthesis, characterization and migratory insertion reactions

A series of guanidine proligands, 2-(4-(tertbutyl) phenyl)-1,3-diisopropylguanidine (1), 2-(4-bromophenyl)- 1,3-diisopropylguanidine (2), 2-(4-methoxyphenyl)-1,3- diisopropylguanidine (3), and 2,2′-(1,4-phenylene)bis(2′,3- diisopropylguanidine) (4), has been reacted with [NbBz3(NtBu)] (5) through a protonolysis reaction to obtain new monoguanidinate-supported dibenzyl niobium complexes, {NbBz2(NtBu)[(4-tBuC6H4)NC(NiPr)(NHiPr)]} (6), {NbBz2(NtBu)[(4-BrC6H4)NC(NiPr)(NHiPr)]} (7), {NbBz2(NtBu)[(4-MeOC6H4)NC(NiPr)(NHiPr)]} (8), and the dinuclear complex {[NbBz2(NtBu)]2[(C6H4)(NC(NiPr)- (NHiPr))2]} (9). Complexes 6, 8, and 9 were structurally characterized. These neutral complexes contain a η2-benzyl ligand coordinated to the metal center. Insertion migratory reactions with isocyanides resulted in the formation of bis-κ2-iminoacyl species, {Nb(NtBu)(tBuNCCH2Ph)2[(4-tBuC6H4)NC(NiPr)(NHiPr)]} (10), {NbBz2(NtBu) (tBuNCCH2Ph)2[(4- BrC6H4)NC(NiPr)(NHiPr)]} (11), {Nb(NtBu)(tBuNCCH2Ph)2[(4-MeOC6H4)NC(NiPr)(NHiPr)]} (12), and the dinuclear complex {[Nb(NtBu)(tBuNCCH2Ph)2]2[(C6H4)(NC(NiPr)(NHiPr))2]} (13), when tBuNC was used. The analogous reaction using XyNC (Xy = 2,6-Me2C6H3) led to the formation of vinylamido species, {Nb(NtBu)[N(2,6- Me2C6H3)CHCHPh][BzCN(2,6-Me2C6H3)][(4-tBuC6H4)NC(NiPr)(NHiPr)]} (14), {Nb(NtBu)[N(2,6-Me2C6H3)- CHCHPh][BzCN(2,6-Me2C6H3)][(4-BrC6H4)NC(NiPr)(NHiPr)]} (15), {Nb(NtBu)[N(2,6-Me2C6H3)CHCHPh]- [BzCN(2,6-Me2C6H3)][(4-MeOC6H4)NC(NiPr)(NHiPr)]} (16), and {[Nb(NtBu)[N(2,6-Me2C6H3)CHCHPh]- [BzCN(2,6-Me2C6H3)]]2[(C6H4)[NC(NiPr)(NHiPr)]2]} (17), through a proposed 1,2-hydrogen shift mechanism from an iminoacyl intermediate similar to those obtained from the insertion of tBuNC. Complex 17 was structurally characterized

Revista Temas Agrarios Volumen 26; Suplemento 1 de 2021

1st International and 2nd National Symposium of Agronomic Sciences: The rebirth of the scientific discussion space for the Colombian Agro.1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano