Historical variations in climate and landscape configuration are the main aspects known to generate and maintain diversity. Taxa associated with open habitats within broader forest contexts are often ...overlooked in studies of Neotropical biogeography. We investigated the evolutionary and demographic history of lizards in the Cnemidophorus lemniscatus species group, which encompasses three described species - one unisexual and two bisexuals - restricted to open environments in Amazonia. We also explored the geographic ecology of the group using critical ecophysiological traits as proxies for sensitivity or resilience to environmental change. To that end, we delimited the main lineages within the group, estimated their divergence times, and asked if these lineages have experienced changes in effective population size. We recovered six lineages, three of which correspond to C. cryptus, C. lemniscatus, and C. gramivagus, and three yet unnamed species. We recovered divergence events during the Late Miocene and signs of recent population expansion for at least one of the species (the parthenogenetic C. cryptus). This pattern corroborates the ancient emergence of the Amazonian open areas, followed by a high and recent dynamism during the Pleistocene. Conserved traits related to high thermal tolerance and broad thermal tolerance ranges likely facilitated niche tracking and establishment in open ecosystems during Pleistocene climatic fluctuations. Our results bring insights regarding how these species might be influenced, and even favoured, by human-induced environmental changes in the contemporary timescale.
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•NaOH-activated carbon was produced from guava seeds (AC–GS).•AC–GS exhibited microporous feature (85%) and SBET of 2573.6m2g−1.•Kinetic, isotherm and thermodynamic studies for ...amoxicillin removal were evaluated.•AC–GS presented maximum monolayer adsorption capacity of 570.48mgg−1 at 25°C.
We report the preparation and characterization of NaOH-activated carbon of high surface area produced from guava seeds (AC–GS) and its application for amoxicillin (AMX) adsorption. The AC–GS was fully characterized from the N2 adsorption and desorption isotherms, scanning electron microscopy (SEM), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), Boehm titration and pHPZC. Additionally, the kinetics, equilibrium and thermodynamic parameters on the adsorption of AMX onto AC–GS were evaluated. The AC–GS showed BET surface area of 2573.6m2g−1 and microporous features (85%), presenting average pore diameter of 1.96nm, which are suitable for AMX adsorption. The experimental adsorption data were modelled using several kinetic (pseudo-first order, pseudo-second order and Elovich) and isotherm (Freundlich, Langmuir, Redlich–Peterson and Dubinin–Radushkevich) models, which suggested that the adsorption of AMX onto AC–GS occurs predominantly by chemisorption showing a maximum monolayer adsorption capacity of 570.48mgg−1 (pH=4.0; T=25°C), which stands out compared to various adsorbents found in literature. Additionally, the thermodynamic parameters revealed the spontaneity of AMX adsorption (ΔG°=−1.915kJmol−1 at 298K) and its endothermic characteristic (ΔH°=21.33kJmol−1), evidencing the high-efficiency of AC–GS for AMX adsorption and its great potential for organic pollutants removal.
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•A NaOH-activated carbon was prepared from macadamia nut shells.•The ACM showed BET surface area of 1524m2g−1 and microporous feature (78.2%).•Kinetic and equilibrium studies were ...applied for tetracycline removal.•The ACM presented maximum monolayer adsorption capacity of 455.83mgg−1.
A NaOH-activated carbon was prepared from macadamia nut shell using the impregnation ratio of 3:1 (NaOH:char) (wt:wt). The obtained material (ACM) was characterized by several techniques and methodologies such as, N2 adsorption–desorption isotherms, SEM, FT-IR, Boehm titration, and pHpzc. The results demonstrated that the ACM is composed mainly of micropores (78.2%), presenting BET surface area of 1524m2g−1. Through the SEM and FT-IR analysis it could be observed that significant changes occurred on the material surface after the activation procedure. According to Boehm titration, the ACM has on its surface a majority of basic groups which is in agreement with the obtained pHpzc value of 8.74. The ACM was applied for tetracycline (TC) removal in order to assess its potential as an adsorbent. Thus, adsorption studies were carried out and several kinetic and isotherm models were employed. The isotherm model which best fitted to experimental data was Temkin, while the best fitted kinetic model was Elovich. ACM showed maximum monolayer adsorption capacity (Qm) of 455.33mgg−1. The intraparticle diffusion and film diffusion mechanisms were studied by the equations of Weber & Morris and Boyd, respectively. According to the results, the limiting step of the adsorption of TC onto ACM is influenced by intraparticle diffusion and by film diffusion.
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•Spherical carbon was obtained from hydrothermal treatment (HT) of sucrose.•HT in conjunction with subsequent KOH activation produced activated carbon (AC).•AC has a BET surface area ...of 1534m2g−1 and 82.6% of micropores.•The Methylene Blue maximum monolayer adsorption capacity on AC was 704.2mgg−1.
This work reports the synthesis of activated carbon (AC) obtained by KOH chemical activation of spherical carbon (SC) produced from hydrothermal treatment (HT) of sucrose. Scanning electron microscopy was used to characterize the morphology and the sphere sizes of SC, which showed average diameter of 2.86μm. SC showed low values of BET surface area (SBET) and total volume of pores (VT), whereas AC presented characteristics of microporous materials with SBET and VT of 1534m2g−1 and 0.765cm3g−1, respectively. FT-IR analysis and Boehm method indicated that the AC surface has essentially acid functional groups, which was confirmed by pHPZC values of 3.0. The adsorption equilibrium data of Methylene Blue (MB) onto AC were best fitted to the Redlich–Peterson model. The maximum adsorption capacity monolayer was of 704.2mgg−1, which showed to be high compared to other ACs reported in the literature. The kinetic data showed better fit to the pseudo-first-order model at low MB concentration, and with the increasing of concentration, to the pseudo-second-order and Elovich models. Thermodynamic parameters indicated that MB–AC adsorption process is spontaneous and endothermic.
► Use of NaOH as activating agent in the coconut activated carbon production. ► NaOH promotes the microporosity development of the char. ► Microporous characteristics of the activated carbon allow ...that it adsorbs high amount of methylene blue (916.26
mg
g
−1).
Activated carbons (ACs) of coconut shell produced by NaOH activation at impregnation ratios of NaOH:char (w/w) equal to 1:1 (AC-1), 2:1 (AC-2) and 3:1 (AC-3) were prepared. The properties of these carbons, including BET surface area, pore volume, pore size distribution, and pore diameter, were characterized from N
2 adsorption isotherms. It was found that the ACs are essentially microporous and that the BET surface area was in order of 783 m
2
g
−1 for AC-1, 1842 m
2
g
−1 for AC-2, and 2825 m
2
g
−1 for AC-3. Scanning electron microscopy images showed a high pore development while Boehm method and Fourier-transform infrared spectroscopy spectra indicated the presence of acid functional groups which was confirmed by pH drift method. The adsorption equilibrium and kinetics of methylene blue (MB) onto AC-3 were carried out. Experimental data were fitted to the four isotherm models (Langmuir, Freundlich, Toth and Redlich–Peterson), and was found that Langmuir model presented the best fit, showing maximum monolayer adsorption capacity of 916
mg
g
−1. The kinetic studies showed that experimental data follow pseudo-second-order model. The mechanism of the adsorption process was described from the intraparticle diffusion model. The AC-3 has a high surface area and showed to be an efficient adsorbent for removal of MB from aqueous solutions.
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