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The production and consumption of cassava (Manihot esculenta) occur in several places worldwide, producing large volumes of waste, mostly in the form of bark. This study sought to bring a new purpose to this biomass through producing activated carbon to use as an adsorbent to remove the herbicide Diuron from water. It was observed that the carbon contains the functional groups of methyl, carbonyl, and hydroxyl in a strongly amorphous structure. The activated carbon had a surface area of 613.7 m2 g−1, a pore volume of 0.337 cm3 g−1, and a pore diameter of 1.18 nm. The Freundlich model was found to best describe the experimental data. It was observed that an increase in temperature favored adsorption, reaching a maximum experimental capacity of 222 mg g−1 at 328 K. The thermodynamic parameters showed that the adsorption was spontaneous, favorable, and endothermic. The enthalpy of adsorption magnitude was consistent with physical adsorption. Equilibrium was attained within 120 min. The linear driving force (LDF) model provided a strong statistical match to the kinetic curves. Diffusivity (Ds) and the model coefficient (KLDF) both increased with a rise in herbicide concentration. The adsorbent removed up to 68% of pollutants in a simulated effluent containing different herbicides. Activated carbon with zinc chloride (ZnCl2), produced from leftover cassava husks, was shown to be a viable alternative as an adsorbent for the treatment of effluents containing not only the herbicide Diuron but also a mixture of other herbicides. [ABSTRACT FROM AUTHOR]

The powdered biomass of paddle cactus (Tacinga palmadora), a rustic plant of great occurrence in the driest regions of Brazil, was evaluated as a low-cost adsorbent to treat textile effluents containing crystal violet (CV) dye. The powdered paddle cactus (PPC) was mainly composed by lignin and holocellulose, as well as, a variety of functional groups. Best results for CV adsorption were found using an adsorbent dosage of 0.5 g L−1 at solution pH equivalent to 10.0. Fast adsorption kinetics was verified, being the equilibrium reached within 100 min, and the curves were well modeled by the pseudo-first-order model. The isotherms were well-represented by the Langmuir model. The maximum adsorption capacity was 228.74 mg g−1 at 328 K. The estimated thermodynamics parameters were ΔG0T = 328K of –9.08 kJ mol−1, ΔH0 of 12.44 kJ mol−1, and ΔS0 of 0.065 kJ mol−1 K−1. In addition, PPC was able to treat a simulated textile effluent containing organic and inorganic compounds, reaching 93% of color removal efficiency. These findings show that powdered paddle cactus can be applied as potential low-cost adsorbent to treat textile effluents containing CV. [ABSTRACT FROM AUTHOR]

In this work, Moringa oleifera seed husk (MOSH) and Moringa oleifera seed pulp (MOSP) were converted via a green route into efficient biosorbents for biosorption of Acid Blue 9 (AB9) synthetic dye from the wastewater. The textural properties, morphologies, and structures of both biosorbents were analyzed using Fourier infrared spectroscopy (FTIR), N 2 adsorption/desorption isotherms, pH of point-zero-charge (pH PZC), and scanning electron microscope (SEM). The characterization results showed that the biosorbents have heterogeneous surfaces with a diversity of functional groups. The experimental data of biosorption kinetics were best described by the nonlinear Avrami fractional. The isothermal empirical data were supported by the nonlinear Liu equation, and the maximum biosorption capacities of MOSH and MOSP at 55 °C for AB9 synthetic dye are 329.5 mg g–1 and 694.2 mg g–1, respectively. The evaluation of thermodynamic parameters showed that the biosorption processes of both biosorbents were spontaneous, endothermic, and occurred by physisorption. The availability, low-cost, high adsorption capacity, and fast adsorption kinetics of MOSH and MOSP make them alternative, promising, and attractive green biosorbents for removal AB9 synthetic dye from aqueous solutions. [Display omitted] • Green preparation of highly efficient biosorbents. • Moringa oleifera seed (husk and pulp) were utilized as biosorbents. • Functional groups have a notable influence on the adsorption process. • MOSH and MOSP present adsorption capacities of 329.5 and 694.2 mg g−1. • Biosorption process are described by Liu isothermal and Avrami kinetic models. [ABSTRACT FROM AUTHOR]

• A novel adsorbent from Physalis peruviana chalice was developed. • The adsorbent was able to a successful adsorb 2,4-D. • Statistical physics models indicate that adsorption occurs due to physisorption. In this study, the chalice generated from the production of the Physalis peruviana fruit was subjected to a treatment with sulfuric acid and applied in the adsorption of 2,4-Dichlorophenoxyacetic acid (2,4-D). The precursor, and the treated material before and after the adsorption, were analyzed by different techniques. After the acid treatment, it was found that the surface was changed from a smooth to an irregular surface with the presence of cavities with irregular size. The adsorption was favored at pH = 2 and with a dosage of 0.8 g L−1. The pseudo-second-order model was the best to represent kinetic data. The isothermal experiments were well represented by the Langmuir and Tóth models, reaching a high capacity of 244 and 320 mg g−1, respectively. The computed thermodynamic values show that the 2,4-D adsorption was spontaneous and exothermic. Overall, this study indicates that the Physalis peruviana chalice treated with strong acid presents great potential as an alternative material for the adsorption/removal of 2,4-D herbicide from liquid effluents. [ABSTRACT FROM AUTHOR]