Microporous activated carbon from the fruits of the invasive species Hovenia dulcis to remove the herbicide atrazine from waters

Novel activated carbon from Magonia pubescens bark: characterization and evaluation of adsorption efficiency

In this work, the synthesis of activated carbon from the bark of the Magonia pubescens (known as Tingui) and its efficiency in the removal of diclofenac sodium through batch adsorption tests and physical-chemical characterizations were investigated. The phytotoxicity of this material was also evaluated through germination and root growth of Lactuca sativa seeds. According to the experimental design performed for the synthesis of Tingui carbon, the optimized temperature and residence time for the production of this adsorbent were 550 °C and 120 min, respectively. The equilibrium time was reached in 600 minutes and the theoretical model that best fitted the kinetic data was the Elovich model. The BET was the best fit for the adsorption isotherm data.This indicates that the adsorption process of sodium diclofenac by activated carbon can occur by two different mechanisms, monolayer and/or multilayer adsorption, depending on the conditions employed in the process, such as temperature and adsorbate concentration. The thermodynamic study showed that the process was favorable and spontaneous in the temperature range evaluated. Furthermore, the characterizations showed by TG/DTG and FTIR analyses that the temperature throughout the process had a marked impact on the degradation of the organic constituents of the biomass and the appearance of distinct functional groups that contributed to the adsorption process of diclofenac sodium. Finally, the toxicity tests recognized that this adsorbent does not affect the germination of L. sativa species. Thus, this adsorbent may become a novel and viable option to be used in the removal of sodium diclofenac.

The production of activated biochar using Calophyllum inophyllum waste biomass and use as an adsorbent for removal of diuron from the water in batch and fixed bed column

The Calophyllum inophyllum species annually produces a large volume of cylindrical fruits, which accumulate on the soil because they do not have nutritional value. This study sought to enable the use of this biomass by producing activated biochar with zinc chloride as an activating agent for further application as an adsorbent in batch and fixed bed columns. Different methodologies were used to characterize the precursor and the pyrolyzed material. Morphological changes were observed with the emergence of new spaces. The carbonaceous material had a surface area of 468 m² g^-1, D_p = 2.7 nm, and V_T = 3.155 × 10^-1 cm³ g^-1. Scientific and isothermal studies of the adsorption of the diuron were conducted at the natural pH of the solution and adsorbent dosage of 0.75 g L^-1. The kinetic curves showed a good fit to the Avrami fractional order model, with equilibrium reached after 150 min, regardless of the diuron concentration. The Liu heterogeneous surface model well represented the isothermal curves. By raising the temperature, adsorption was encouraged, and at 318 K, the Liu Q_max was reached at 250.1 mg g^-1. Based on the Liu equilibrium constant, the nonlinear van't Hoff equation was employed, and the ΔG° were < 0 from 298 to 328 K; the process was exothermic nature (ΔH⁰ = -46.40 kJ mol^-1). Finally, the carbonaceous adsorbent showed good removal performance (63.45%) compared to a mixture containing different herbicides used to control weeds. The stoichiometric column capacity (q_eq) was 13.30 and 16.61 mg g^-1 for concentrations of 100 and 200 mg L^-1, respectively. The length of the mass transfer zone was 5.326 cm (100 mg L^-1) and 4.946 cm (200 mg L^-1). This makes employing the leftover fruits of the Calophyllum inophyllum species as biomass for creating highly porous adsorbents a very effective and promising option.

Functional Bimetal/Carbon Composites Co/Zr@AC for Pesticide Atrazine Removal from Water

Atrazine is a toxic and refractory herbicide that poses threats to human health and the ecological environment. In order to efficiently remove atrazine from water, a novel material, Co/Zr@AC, was developed. This novel material is prepared by loading two metal elements, cobalt and zirconium, onto activated carbon (AC) through solution impregnation and high-temperature calcination. The morphology and structure of the modified material were characterized, and its ability to remove atrazine was evaluated. The results showed that Co/Zr@AC had a large specific surface area and formed new adsorption functional groups when the mass fraction ratio of Co²⁺:Zr⁴⁺ in the impregnating solution was 1:2, the immersion time was 5.0 h, the calcination temperature was 500 °C, and the calcination time was 4.0 h. During the adsorption experiment on 10 mg/L atrazine, the maximum adsorption capacity of Co/Zr@AC was shown to be 112.75 mg/g and the maximum removal rate was shown to be 97.5% after 90 min of the reaction at a solution pH of 4.0, temperature of 25 °C, and Co/Zr@AC concentration of 60.0 mg/L. In the kinetic study, the adsorption followed the pseudo-second-order kinetic model (R² = 0.999). The fitting effects of Langmuir and Freundlich isotherms were excellent, indicating that the process of Co/Zr@AC adsorbing atrazine also conformed to two isotherm models, so the adsorption of atrazine by Co/Zr@AC had multiple effects including chemical adsorption, mono-molecular layer adsorption, and multi-molecular layer adsorption. After five experimental cycles, the atrazine removal rate was 93.9%, indicating that Co/Zr@AC is stable in water and is an excellent novel material that can be used repeatedly.

Transformation of Residual Açai Fruit (Euterpe oleracea) Seeds into Porous Adsorbent for Efficient Removal of 2,4-Dichlorophenoxyacetic Acid Herbicide from Waters

Brazil's production and consumption of açai pulp (Euterpe oleracea) occur on a large scale. Most of the fruit is formed by the pit, which generates countless tons of residual biomass. A new purpose for this biomass, making its consumption highly sustainable, was presented in this study, where activated carbon (AC) was produced with zinc chloride for later use as an adsorbent. AC carbon formed by carbon and with a yield of 28 % was satisfactorily used as an adsorbent in removing the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Removal efficiency was due to the highly porous surface (Vp = 0.467 cm³ g^-1; Dp = 1.126 nm) and good surface área (SBET = 920.56 m² g^-1). The equilibrium data fit the Sips heterogeneous and homogeneous surface model better. It was observed that the increase in temperature favored adsorption, reaching a maximum experimental capacity of 218 mg g^-1 at 328 K. The thermodynamic behavior indicated a spontaneous, favorable, and endothermic behavior. The magnitude of the enthalpy of adsorption was in agreement with the physical adsorption. Regardless of the herbicide concentration, the adsorbent displayed fast kinetics, reaching equilibrium within 120 min. The linear driving force (LDF) model provided a strong statistical match to the kinetic curves. AC with zinc chloride (ZnCl₂), created from leftover açai biomass, is a potential alternative as an adsorbent for treating effluents containing 2,4-D.