Kinetic studies for nitrate adsorption on granular chitosan–Fe(III) complex

<p>In this study, a generalized kinetic equation was proposed to simulate adsorption behaviors in batch systems and several useful kinetic equations were deduced. The results indicated that the amount of nitrate uptake increased rapidly in the initial stage, followed by a slower process until adsorption equilibrium was reached after approximately 1.5 h. The rate constant was a function of the initial nitrate concentration. The adsorption and desorption rate constants quantitatively reflected the adsorption and desorption reactions at the solid/solution interface. The adsorption and desorption processes for nitrate adsorption followed identical reaction order. The kinetic parameters (adsorption and desorption rate constants, half-time and instantaneous rate) provided by these kinetic equations are of significant importance for the understanding of adsorption mechanisms.</p

Nickel Oxide Grafted Andic Soil for Efficient Cesium Removal from Aqueous Solution: Adsorption Behavior and Mechanisms

An andic soil, akadama clay, was modified with nickel oxide and tested for its potential application in the removal of cesium from aqueous solution. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD) results revealed the nickel oxide was successfully grafted into akadama clay. N₂ adsorption–desorption isotherms indicated the surface area decreased remarkably after modification while the portion of mesopores increased greatly. Thermogravimetric-differential thermal analysis (TG-DTA) showed the modified akadama clay had better thermostability than the pristine akadama clay. Decreases in cation exchange capacity (CEC) and ζ-potential were also detected after the modification. Adsorption kinetic and isotherm studies indicated the adsorption of Cs⁺ on the modified akadama clay was a monolayer adsorption process. Adsorption capacity was greatly enhanced for the modified akadama clay probably due to the increase in negative surface charge caused by the modification. The adsorption of Cs⁺ on the modified akadama clay was dominated by an electrostatic adsorption process. Results of this work are of great significance for the application of akadama clay as a promising adsorbent material for cesium removal from aqueous solutions

Library coverage estimations and sequence diversity of 16 S rRNA.

<p>Library coverage was calculated as C = 1-<i>n</i>/<i>N</i>, where <i>n</i> is the number of OTUs without a replicate, and <i>N</i> is the total number of sequences. The numbers in parentheses are lower and upper 95% confidence intervals for the Chao 1 estimators. The Shannon index = , where <i>p_i</i> = <i>n_i</i>/<i>N</i>, <i>n_i</i> is the number of OTUs with <i>i</i> individuals, and <i>N</i> is the total number of individuals.</p

Relative abundances of dominant phylogenetic groups in sediments derived from Caohai and Waihai sampling sites.

<p>Phylogenetic groups accounting for <1% of all classified sequences are summarized as “other” in the figure.</p

Quantitive analysis of 16 S rRNA, <i>amoA</i>, and <i>nosZ</i> gene in the sediments (computed in dry weight).

<p>Black bars represent Caohai and grey bars represent Waihai. Error bars represent standard deviation from three independent experiments.</p

Principal components analysis (PCA) and Redundancy analysis (RDA) with of bacterial communities as affected by sediment properties, based on the relative abundance of dominant bacterial phyla and proteobacterial classes.

<p>Total-N represents NH₃-N+NO₂⁻-N+NO₃⁻-N. Abbreviations in figure: Temp, temperature; <i>Actinobac.</i>, <i>Actinobacteria</i>; <i>Alphapro.</i>, <i>Alphaproteobacteria</i>; <i>Betapro.</i>, <i>Betaproteobacteria</i>; <i>Deltapro.</i>, <i>Deltaproteobacteria</i>; <i>Gammapro</i>.,<i>Gammaproteobacteria</i>; <i>Acidobac.</i>, <i>Acidobacteria</i>; Unclassified bac., Unclassified bacteria; Unclassified <i>Pro.</i>, Unclassified <i>Proteobacteri</i>a. <i>Epsilonpro</i>., <i>Epsilonproteobacteri</i>a.</p

Phylogenetic trees with the (a) <i>amoA</i> and (b) <i>nosZ</i> representative sequences (OTUs) from Dianchi Lake sediments (Sampled in Dec. of 2010).

<p>The numbers on the branch nodes represent percentage of bootstrap resamplings based on 1000 replicates (only ≥50% are shown). The scale bar indicates the number of nucleotide substitutions per site. The relative abundance of each OTU (comprising 2 or more clones) in the <i>amoA</i> or <i>nosZ</i> clone library is shown in parentheses. Additional symbols for abundance are (▪) Caohai and (▴) Waihai.</p

Community analysis using principal coordinate analysis (PCoA) of weighted UniFrac distance matrix.

<p>Community analysis using principal coordinate analysis (PCoA) of weighted UniFrac distance matrix.</p