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Purpose: This research aimed to develop activated carbons from tobacco by double (thermal-physical) and triple activations (thermal-chemical-physical) for high-efficiency removal of Cd 2+ ., Methods: The adsorbents were characterized by their chemical composition, point of zero charge (pH PZC ), SEM, FT-IR, BET, and BJH. The subsequent adsorption studies were conducted: optimal conditions (CCD on adsorbent dose versus pH of Cd 2+ solution), kinetics, equilibrium, thermodynamics, and desorption studies., Results: The activated carbons have irregular and heterogeneous morphology, surface functional groups COO-, C-O, C-O-C, C=O and O-H, pH PZC of 11.11 and 10.86, and enhanced SSA (especially for CT NaOH + CO 2  = 103.40 g m -2 ). The optimal conditions for Cd 2+ adsorption occur using 4.0 g L -1 , pH from 3.0 to 7.0, with most of the Cd 2+ adsorbed in the first 10-20 min. The goodness of the fit found for pseudo-first order, pseudo-second order, intraparticle diffusion, Langmuir, Freundlich, Dubinin-Radushkevich, Sips, and Temkin suggest the occurrence of Cd 2+ chemisorption and physisorption in mono and multilayers. The values of ∆G° < 0 kJ mol -1 indicate that the observed phenomena are energetically favorable and spontaneous; the values of ∆H° < 0 and the effective desorption rates (58.52% and 44.64%) suggest that the adsorption of Cd 2+ is ruled mainly (but not only) by physical interactions., Conclusion: Our excellent results on Cd 2+ removal allow us to state that tobacco use as a raw material for adsorbent development is a renewable and eco-friendly technique, allowing the production of highly effective activated carbons and providing an adequate destination for this waste., Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-021-00740-8., Competing Interests: Conflict of interestThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© Springer Nature Switzerland AG 2021.)

Although not considered poisonous and with natural occurrence, Zn contamination is mainly related to anthropic actions. This research aim was to develop, from crambe wastes, adsorbents with high adsorption capacity of Zn 2+ . The crambe biomass was modified with H 2 O 2 , H 2 SO 4 and NaOH 0.1 mol L -1 , resulting in four crambe-based adsorbents: C. in natura (unmodified), C. H 2 O 2 , C. H 2 SO 4 and C. NaOH. These were studied by determination of their chemical components, SEM, FTIR, pH PZC , thermal stability (by TG/DTG curves), SSA, pore volume and pore diameter (by BET and BJH). Adsorption studies were also carried out to evaluate its Zn removal capacity. Evaluations were taken on adsorbent dose and the influence of the pH, as well as studies on adsorption kinetics and equilibrium. These results were evaluated by pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, Langmuir, Freundlich, Dubinin-Radushkevich and Sips (linear and nonlinear models). Results show that the crambe-based adsorbents may have functional groups such as hydroxyls, amides, carbonyls and carboxylates, which may be responsible for the Zn 2+ adsorption. The materials have heterogeneous structure, allowing the occurrence of mono and multilayer adsorption of Zn. The finest results point out the occurrence of mono and multilayer of Zn 2+ (evidenced by Sips-nonlinear model), with an increase in Q sat of 72% (C. H 2 O 2 ), 22% (C. H 2 SO 4 ) and 80% (C. NaOH). The developed crambe adsorbents have low cost of production (since the raw material is until now a solid waste) and have high removal ratio of Zn 2+ from waters, being a promising technology., Competing Interests: Conflict of interestThe authors of the aforementioned article confirm that there is no conflict of interest that are directly or indirectly related to the research., (© Springer Nature Switzerland AG 2020.)

The validation of chromatographic methods is a costly process, however necessary, especially with regard to the validation of methods that accurately determine concentrations of pesticides in different environmental compartments. This research aimed at the development and validation of a simple and fast method for the determination of chlorpyrifos concentrations in water by means of a gas chromatograph with electron capture detection (GC/ECD), and to investigate chlorpyrifos dynamics of adsorption in a Rhodic Ferralsol in Southern Brazilian conditions. The developed chromatographic method was based in EPA 8141 method. Parameters to be checked for method validation were: Selectivity/specificity, linearity, precision, accuracy, robustness, limit of detection (LOD) and limit of quantitation (LOQ). Were employed the following methodologies for the validation process: ANVISA Resolution 899, DOQ-CGCRE-008 and FDA Bioanalytical Method Validation Guide. Also, through laboratory tests, the sorption dynamics of chlorpyrifos in Rhodic Ferralsol was evaluated. Thus, the soil was contaminated with increasing concentrations of chlorpyrifos, which were subjected to solid-liquid extraction with SPE cartridge Chromabond® C18 ec. The obtained results were submitted to the models of Langmuir, Freundlich, Dubinin-Radushkevich and Sips. By this method, chlorpyrifos peaks are obtained at 16.9 min, demonstrating practicality and low cost. This method exhibits precision and sensitivity, with satisfactory LQ and LQ values. The models of Langmuir, Freundlich, Dubinin-Radushkevich and Sips suggest the occurrence of simultaneous adsorption in mono and multilayer of chlorpyrifos in Rhodic Ferralsol colloids, as well as the predominance of a chemical, high energy binding process (irreversible). However, the chemisorption of chlorpyrifos is more related to the good fit found for Dubinin-Radushkevich sorption energy values (9.861 and 11.079 KJ mol -1 ) and Q m values estimated by Langmuir (485.55 and 389.61 μg g -1 for linear and nonlinear model)., Competing Interests: Conflict of interestThe authors declare no conflict of interests., (© Springer Nature Switzerland AG 2020.)

This work aimed to evaluate, on a spatial and temporal scale, the effect of the flow on the concentrations of Cu and Zn in sediments from two water bodies (the Alvorada and Mandaguari Rivers). Five sediment-sampling periods were conducted, under four different streams in each sampling point (shallow/fast (SF), shallow/slow (SS), deep/fast (DF), deep/slow (DS)). Each sampling point represented the spring, the middle, and the mouth of the evaluated rivers. Some climatic variables were also evaluated, such as monthly temperature and rainfall. In addition, temperature, pH, dissolved oxygen (DO), and total solids were evaluated. Cu and Zn concentrations were obtained by FAAS. Cu and Zn levels are affected by the speed and depth of the water column. The quality of the sediments is affected by human activities in the surroundings, and according to legislation, levels of Cu and Zn in sediments offer risks of medium and high effects to aquatic biota. The highest accumulation of Cu in sediments occurs during October (221 mg kg -1 ) and December 2015 (225 mg kg -1 ), which coincides with the period of implantation of the soybean crop in the region, as well as the rain period. The increase of Cu in these periods suggests the occurrence of erosion. It can be concluded that Cu and Zn are found in large quantities in sediments, offering risk to the aquatic organisms. Cu levels exhibited direct relation with the sampling periods, with higher concentrations in rainy periods, while Zn concentrations suffer influence of the water column velocity and depth.

Due to intense agricultural and industrial activities, the environment has been affected by increasing amounts of pollutants, such as lead, a toxic heavy metal. When introduced to the environment, toxic metals are distributed and incorporated into the liquid medium, sediments, and aquatic biota; bioaccumulating. This research aimed to identify and quantify the levels of toxic metals present in the waters and sediments of Toledo River, compare the obtained results with legislation and other studies, as well as to evaluate the possible pollutant sources of the water body. Six water and sediment samples were taken at seven strategic sites. The concentrations of Cu, Zn, Fe, Mn, Cd, Pb, and Cr in water were compared to the maximum limits established by Brazilian legislation IN CONAMA No. 357/05, for class II fresh waters. The sediment samples were submitted to nitroperchloric digestion, and then the total concentrations of the metals were determined by flame atomic absorption spectrometry (FAAS). The toxicological quality of the Toledo River has been considerably affected by the activities carried out in its surroundings, such as extensive areas of agriculture, pig farming and industrial areas, causing concentrations of Cd, Fe, and mainly Pb, which is observed at concentrations higher than value allowed by the legislation.

The removal of Cr 3+ from water solutions by biosorbents from the rind, endosperm, and endosperm + episperm of the Jatropha curcas was evaluated. Adsorption tests were performed in batch systems for evaluating the influence of the solution's pH, adsorbent mass, contact time, initial Cr 3+ concentrations, and solution temperature during the adsorption process. Kinetic, adsorption isotherm, and thermodynamic studies were performed to investigate the mechanisms that control adsorption. Ideal conditions for the adsorption process included pH of the solution of 5.5 and 8 g L -1 adsorbent mass, within 60 min time contact between adsorbent and adsorbate. Maximum adsorption capacities by Langmuir model for rind, endosperm, and endosperm + episperm of the J. curcas were, respectively, 22.11, 18.20, and 22.88 mg g -1 , with the occurrence of chemosorption in mono and multilayers. Results show that the biosorbents obtained from J. curcas have a high potential to recuperate Cr 3+ from contaminated water sources.