Iron-bearing mining reject as an alternative and effective catalyst for photo-Fenton oxidation of phenol in water.

In this work, iron-bearing mining reject was employed as an alternative and potential low-cost catalyst to degrade phenol in water by photo-Fenton strategy. Various techniques, including SEM-EDS, BET, FTIR, and XRD, were applied to evaluate the material's properties. Process parameters such as hydrogen peroxide concentration, catalyst dosage, and pH were studied to determine the optimum reaction conditions ([catalyst] = 0.75 g L-1, [H2O2] = 7.5 mM, and pH = 3). Phenol degradation and mineralization efficiencies at 180 and 300 min were 96.5 and 78%, respectively. These satisfactory results can be associated with the iron amount present in the waste sample. Furthermore, the material showed high catalytic activity and negligible iron leaching even after the fourth reuse cycle. The degradation behavior of phenol in water was well represented by a kinetic model based on the Fermi function. The iron-bearing mining reject can be considered a potential photo-Fenton catalyst for phenol degradation in wastewater.

Removal of dyes from water using Citrullus lanatus seed powder in continuous and discontinuous systems.

The objective of this study is to develop a low-cost biosorbent using residual seeds of the Citrullus lanatus fruit for the removal of cationic dyes. Physicochemical parameters such as pH, adsorbent mass, contact time, and temperature were evaluated for their effects on dye removal. The biosorbent is composed of lignin and cellulose, exhibiting a highly heterogeneous surface with randomly distributed cavities and bulges. The adsorption of both dyes was most effective at natural pH with a dosage of 0.8 g L-1. Equilibrium was reached within 120 min, regardless of concentration, indicating rapid kinetics. The Elovich model and pseudo-second-order kinetics were observed for crystal violet and basic fuchsin dye, respectively. The Langmuir model fitted well with the equilibrium data of both dyes. However, the increased temperature had a negative impact on dye adsorption. The biosorbent also demonstrated satisfactory performance (R = 43%) against a synthetic mixture of dyes and inorganic salts, with a small mass transfer zone. The adsorption capacities for crystal violet and basic fuchsin dye were 48.13 mg g-1 and 44.26 mg g-1, respectively. Thermodynamic studies confirmed an exothermic nature of adsorption. Overall, this low-cost biosorbent showed potential for the removal of dyes from aqueous solutions.

In this work, a novel biosorbent was developed using residual Citrullus lanatus fruit seeds that can efficiently remove cationic dyes from aqueous solutions. The biosorbent's composition includes lignin and cellulose, and its surface structure is highly heterogeneous, consisting of randomly distributed cavities and bulges. The biosorbent demonstrated a rapid and efficient adsorption capacity for both crystal violet and basic fuchsin, regardless of dye concentration. Moreover, the biosorbent was successfully employed in the treatment of a synthetic mixture containing several dyes and inorganic salts. Finally, the application of the biosorbent in continuous adsorption showed a low zone of mass transfer and high breakthrough time, indicating it to be an excellent material for fixed-bed operation. Overall, this study provides a low-cost and efficient alternative for the removal of dyes from aqueous solutions, with promising practical applications.

Applying bottom ash as an alternative Fenton catalyst for effective removal of phenol from aqueous environment.

In this study, coal bottom ash from a thermoelectric plant was tested as an alternative Fenton catalyst for phenol degradation in water. The effect of operating parameters such as initial pH, catalyst dosage and H2O2 concentration were evaluated. The characterization results indicated that the material has a mesoporous structure, with active species (Fe) well distributed on its surface. Under the optimal reaction conditions (6 mM H2O2, 1 g L-1 of catalyst and pH = 3), 98.7% phenol degradation efficiency was achieved in 60 min, as well as 71.6% TOC removal after 150 min. Hydroxyl radical was identified as the main oxidizing agent involved on the cleavage of the phenol molecule. After four consecutive reuse cycles, phenol degradation efficiency was around 80%, indicating good reusability and stability of the catalyst. Therefore, the obtained results demonstrated that the bottom ash presents remarkable activity for application in the Fenton reaction towards phenol degradation.

Application of green-synthesized cadmium oxide nanofibers and cadmium oxide/graphene nanosheet nanocomposites as alternative and efficient photocatalysts for methylene blue removal from aqueous matrix.

For the first time, cadmium oxide (CdO) nanofibers (NFs) and graphene nanosheet (GNS)-doped CdO nanocomposites (NCs) have been synthesized by a simple green route using green tea (Camellia sinensis) extract, for subsequent application as photocatalysts for methylene blue (MB) removal from an aqueous matrix. In addition, the materials were tested as working electrodes for supercapacitors. The prepared samples were analyzed by FESEM, UV-Vis spectroscopy, FTIR, and X-ray diffraction (XRD). FESEM revealed that the obtained NPs and NCs show fiber-shaped nanostructure. FTIR confirmed the presence of biomolecules on CdO and carbon compounds on CdO/GNS, while XRD exhibited the cubic crystalline structure of obtained NPs and NCs. The Rietveld refinement using XRD data was performed to ascertain the crystallographic characteristics of the produced samples and look into lattice imperfections. UV-Vis spectroscopy evaluated the optical bandgap energies of CdO and CdO/GNS NCs. The CdO/GNS NCs demonstrated a fast cleavage of the dye molecule under UV irradiation, resulting in 97% removal in 120 min. In addition, CdO/GNS NCs showed remarkable chemical stability as an electrode material, with a high specific capacitance of 231 F g-1 at a scan rate of 25 mV s-1. These observed NCs characteristics are higher when compared to pristine CdO NPs. Finally, we found that the investigated NCs showed enhanced multifunctional properties, such as photocatalytic and supercapacitor characteristics, which can be useful in practical applications.

Augmented degradation of dyed organic pollutant using Fe2O3 supported on char formed from poultry slaughterhouse waste.

In this work, a novel support for an iron-based catalyst was prepared and employed for Ponceau 4R degradation by photo-Fenton reaction. To this, poultry waste was used for producing char, which was subsequently used to prepare the Fe2O3/Char composite. Process parameters, including catalyst dosage, pH, and hydrogen peroxide concentration, were investigated. The characterization analysis indicated that the textural properties of the composite were improved after impregnation with Fe2O3. The composite exhibited excellent catalytic activity, achieving a decolorization efficiency of 97% at 45 min and 81.06% organic carbon removal at 300 min. In addition, the material showed acceptable performance after four consecutive cycles. Furthermore, a scavenger test was performed to investigate the major reactive species involved in the Ponceau 4R oxidation, and a plausible mechanism for the respective reaction was projected. Therefore, the results of this research demonstrate that this material can be used as a potential catalyst for the abatement of dyed molecules from wastewater.

Enhanced UV-light driven photocatalytic performance of magnetic CoFe2O4/TiO2 nanohybrid for environmental applications.

In this work, CoFe2O4/TiO2 nanostructure was prepared through a facile and effective solvothermal route for efficient use in the degradation of the Erionyl Red A-3G model pollutant under ultraviolet irradiation. Characterization analysis indicated the successful heterojunction among the precursors. The composite presented band gap value of 2.75 eV, being smaller than that of the pristine TiO2, as well as mesoporous structure. The catalytic activity of nanostructure was investigated by employing a 22 factorial experimental design with 3 central points. The optimized reaction conditions were set as pH = 2 and catalyst dosage = 1.0 g L-1 for an initial pollutant concentration of 20 mg L-1. The prepared nanohybrid presented remarkable catalytic activity, reaching color removal efficiency of 95.39% after 15 min, as well as total organic carbon (TOC) removal of 69.4% after 120 min. The kinetic studies of TOC removal followed the pseudo-first order model, with a rate constant of 0.10 min-1. Moreover, the nanostructure presented magnetic behavior, being easily separated from the aqueous medium through the use of a simple external magnetic field.

Remarkable photocatalytic performances towards pollutant degradation under sunlight and enhanced electrochemical properties of TiO2/polymer nanohybrids.

In this work, TiO2-based nanocomposites containing polyaniline (PANI), poly(1-naphthylamine) (PNA), and polyindole (PIN) were synthesized by effective and simple routes and posteriorly employed as photocatalysts and supercapacitors. Characterization techniques such as XRD, FTIR, FESEM, UV, and PL were employed to investigate the structural, morphological, and optical properties of materials. XRD analysis confirmed the successful formation of TiO2 and TiO2/polymer nanocomposites. PANI, PNA, and PIN polymers were well distributed on the surface of TiO2 nanoparticles and were investigated/explored from the FESEM analysis. The visible light absorption and the recombination rate of photogenerated charge carriers were confirmed by the UV-Vis and PL analysis. The photocatalytic properties of the nanocomposites were investigated towards malachite green (MG) dye degradation under sunlight. The dye degradation efficiency followed the order TiO2/PNA > TiO2/PANI > TiO2 > TiO2/PIN. The higher efficiency of TiO2/PNA can be associated with its smaller bandgap energy compared to the other materials. Electrochemical properties of materials were also examined by cyclic voltammetry and galvanostatic charge-discharge measurements using a three-electrode experiment setup in an aqueous electrolyte. TiO2/PNA nanocomposite showed higher supercapacitor behavior compared to the other materials due to higher electrical conductivity of PNA and redox potential of TiO2 (pseudocapacitance).

Preparation of alumina-supported Fe-Al-La composite for fluoride removal from an aqueous matrix.

Using groundwater for human consumption is an alternative for places with no nearby surface water resources. Fluoride is commonly found in groundwater, and the consumption of this water for a prolonged time in concentrations that exceed established limits by WHO and Brazilian legislation on water potability (1.5 mg L-1) can cause harmful problems to human health. For this reason, fluoride removal is an important step before water consumption. In this work, activated alumina was impregnated with Fe-Al-La composite and employed for the first time as an adsorbent for fluoride removal from an aqueous environment. XRD, SEM/EDS, FT-IR, and point of zero charge were used to characterize the prepared adsorbent. The adsorptive performance of adsorbent material was investigated by employing a 23-central composite design (CCD), and the obtained experimental conditions were pH = 6.5 and adsorbent dosage = 3.0 g L-1. A maximum adsorption capacity of 8.17 mg g-1 at 298 K and pH = 6.5 was achieved by Langmuir isotherm to describe the adsorption. The kinetic model that better described experimental data was Avrami, with the kav parameter increasing with the initial concentration from 0.076 to 0.231 (min-1)nav. The nature of adsorption was found to be homogeneous, and it occurs in a monolayer. The fluoride removal performance for the prepared adsorbent was higher than granular activated alumina, showing that supporting Fe-Al-La at the alumina surface increased its fluoride adsorption capacity from 16 to 42% at the same experimental conditions. Finally, the influence of co-existing ions Cl-, SO42-, and NO3- was evaluated in fluoride adsorption, and the material presented great selectivity to fluoride. Thus, Fe-Al-La/AA adsorbent is a promising material for fluoride removal from water.

Poly(1-Napthylamine) Nanoparticles as Potential Scaffold for Supercapacitor and Photocatalytic Applications.

Herein, we explore the supercapacitor and photocatalytic applications of poly(1-naphthylamine) (PNA) nanoparticles. The PNA nanoparticles were synthesized by using polymerization of 1-naphthylamine and characterized with several techniques in order to understand the morphological, structural, optical and compositional properties. The structural and morphological properties confirmed the formation of crystalline nanoparticles of PNA. The Fourier-transform infrared (FTIR) spectrum revealed the successful polymerization of 1-naphthylamine monomer to PNA. The absorption peaks that appeared at 236 and 309 nm in the UV−Vis spectrum for PNA nanoparticles represented the π−π* transition. The supercapacitor properties of the prepared PNA nanoparticles were evaluated with cyclic voltammetry (CV) and galvanostatic charge−discharge (GCD) methods at different scan rates and current densities, respectively. The effective series resistance was calculated using electrochemical impedance spectroscopy (EIS), resulting in a minimum resistance value of 1.5 Ω. The highest specific capacitance value of PNA was found to be 255 Fg−1. This electrode also exhibited excellent stability with >93% capacitance retention for 1000 cycles, as measured at 1A g−1. Further, the prepared PNA nanoparticles were used as an effective photocatalyst for the photocatalytic degradation of methylene blue (MB) dye, which exhibited ~61% degradation under UV light irradiation. The observed results revealed that PNA nanoparticles are not only a potential electrode material for supercapacitor applications but also an efficient photocatalyst for the photocatalytic degradation of hazardous and toxic organic dyes.

Adsorption kinetics and equilibrium of Ni2+, Cu2+, Co2+, and Ag+ on geopolymers derived from ashes: application to treat effluents from the E-Coat printing process.

Geopolymers were obtained from ashes through an alternative geopolymerization process and applied to remove Ni2+, Cu2+, Co2+, and Ag+ from synthetic aqueous media and real effluents. The study in synthetic solutions revealed that pseudo-second-order and general order models were the best to fit the kinetic curves. To represent the equilibrium curves, Langmuir and Freundlich were the most adequate. The geopolymer derived from bottom ash (GHA) was superior to adsorb Cu+2, Co+2, and Ag+1 than the geopolymer derived from fly ash (GFA). GHA reached adsorption capacities of 279.5, 288.2, and 462.8 mg g-1 for Co+2, Cu+2, and Ag+1, respectively. Otherwise, GFA was the best for Ni+2 removal, with an efficiency of 95% in low concentrations. In treating real effluents of the E-coat printing process, both GHA and GFA were efficient, with the removal of higher than 85% for all the metals. In brief, it can be stated that GFA and GHA prepared are promising materials to remove metals from aqueous media (synthetic and real), presenting fast adsorption kinetics, high adsorption capacity, and high metal removal percentage.

Remarkable sunlight-driven photocatalytic performance of Ag-doped ZnO nanoparticles prepared by green synthesis for degradation of emerging pollutants in water.

In this work, Ag-doped ZnO nanoparticles (NPs) were synthesized by a simple green method using a toxic agent-free route for photocatalytic purposes, toward methylene blue (MB) removal in water under sunlight irradiation. The effects of operating parameters, such as catalyst dosage, dye concentration, and pH, on the MB removal efficiency, were investigated. The presence of Ag on the ZnO structure resulted in superior catalytic activity compared to the pure ZnO sample. High removal efficiency for MB, corresponding to 95%, was obtained in 30 min of reaction time only, using Ag-doped ZnO NPs. This result can be related to its smaller bandgap energy (1.92 eV) when compared to the ZnO sample (2.85 eV). The material presented a satisfactory level of reusability after three consecutive cycles. In addition, a reaction mechanism for MB photodegradation onto Ag-doped ZnO NPs under sunlight irradiation was suggested. Overall, the catalyst prepared via the green route in this work exhibited excellent photocatalytic activity under sunlight for MB degradation in an aqueous solution.

Application of biowaste generated by the production chain of pitaya fruit (Hylocereus undatus) as an efficient adsorbent for removal of naproxen in water.

Pharmaceutical compounds are a serious problem in the environment. They cause damage to the aquatic, animal, and human organisms and soon became considered emerging pollutants where their removal is extremely urgent. Among the techniques used, adsorption has been used with success, where several adsorbent materials, including those from residual biomass, have been used to remove these pollutants. In this study, the skins of the pitaya fruit (Hylocereus undatus) productive chain were carbonized with ZnCl2 to obtain activated carbon and later used in the adsorption of the drug naproxen (NPX) in a batch system. The Freundlich model demonstrated a better adjustment for the equilibrium isotherms. A high adsorption capacity for NPX (158.81 mg g-1) was obtained at 328 K, which can be attributed to the remarkable textural properties of the adsorbent, besides certain functional groups present on its surface. Thermodynamic studies confirmed the endothermic nature of the adsorption process (∆H0 = 0.2898 kJ mol-1). The linear driving force model (LDF) presented a good statistical adjustment to the experimental kinetic data. The application of the material in the treatment of simulated wastewater composed of various pharmaceutical drugs and salts was very promising, reaching 75.7% removal. Therefore, it can be inferred that the application of activated carbon derived from pitaya bark is highly promising in removing the NPX drug and treating synthetic mixtures containing other pharmaceutical substances.

Effective removal of non-steroidal anti-inflammatory drug from wastewater by adsorption process using acid-treated Fagopyrum esculentum husk.

In this work, buckwheat husks (Fagopyrum esculentum) were modified by acid treatment and posteriorly employed to remove the ketoprofen in batch adsorption. The characterization results indicated that a more irregular surface with new empty spaces was generated after acid treatment. The adsorptive process was favored at acidic pH = 3. The dosage of 0.85 g L-1 was fixed for the kinetic and isothermal tests, obtaining good removal and capacity indications. The kinetic studies were better represented by pseudo-second-order, obtaining an experimental capacity of 74.3 mg g-1 for 200 mg L-1 of ketoprofen. An increase in temperature negatively affected the adsorption isotherm curves, resulting in a maximum capacity of 194.1 mg g-1. Thermodynamic results confirmed the exothermic nature of the process with physical forces acting. The adsorbent presented high efficiency in treating a synthetic effluent containing different drugs and salts, 71.2%. Therefore, adsorbent development from buckwheat husks treated with a strong acid is an excellent alternative, given the good removal results and the low cost for its preparation.

Effective adsorptive removal of textile pollutant using coal bottom ash with high surface area obtained by alkaline fusion route.

In this work, coal bottom ash was modified by alkaline fusion route in order to improve its pore properties and make it a potential adsorbent to remove crystal violet dye from aqueous medium. The solids were characterized and posteriorly subjected to kinetic, isotherm, and thermodynamic studies, as well as regenerated and reused for five adsorption tests. The alkaline fusion step resulted in the amorphization of material and generation of high surface area (102 m 2 g -1) and pore volume (0.180 cm 3 g-1), resulting in superior performance compared to the raw material. Kinetic and equilibrium studies showed that the adsorption process was better adjusted by the pseudo-second order and Langmuir models, respectively. The maximum adsorption capacity at equilibrium was 177. 37 mg g-1, with the adsorptive step occurring spontaneously and endothermically. The adsorbent maintained notable levels of dye removal after five consecutive cycles of thermal regeneration and reuse. Besides, the adsorbent was able to remove 64% of the colour of simulated industrial wastewater. Therefore, the alkaline fusion step proved to be a route capable of transforming the coal bottom ash into an adsorbent with improved textural and adsorptive properties.

Development of activated carbon from Schizolobium parahyba (guapuruvu) residues employed for the removal of ketoprofen.

Schizolobium parahyba species can be found in all of South America, producing several residues that can be a major opportunity to develop activated carbon. This work presents the investigation regarding the development of a high specific surface activated carbon (981.55 m2 g-1) and its application in the adsorption of ketoprofen from the aqueous media. The ketoprofen molecules were better adhered to the adsorbent surface under acidic conditions (pH = 2), being the ideal adsorbent dosage determined as 0.7 g L-1, resulting in satisfactory values. It was found that the system reached equilibrium in 200 to 250 min depending on the initial concentration studied, achieving an adsorption capacity of 229 mg g-1. The general order was the most suitable model for describing the experimental data, with an R2 ≥ 0.9985 and MSR ≤ 63.40 (mg g-1)2. The equilibrium adsorption found that the temperature increases the adsorption capacity, achieving 447.35 mg g-1 at 328 K. Besides that, the Tóth model was the most suitable for describing the isotherms R2 ≥ 0.9990 and MSR ≤ 25.67 (mg g-1)2, indicating a heterogeneous adsorbent. The thermodynamic values found that the adsorption of ketoprofen is spontaneous (average ΔG0 of - 32.79 kJ mol-1) and endothermic (ΔH0 10.44 kJ mol-1). The treatment of simulated effluent with the developed adsorbent was efficient, removing 90% of ketoprofen, ibuprofen, and salts. It was found that the adsorbent is reaming its adsorption capacity up to the 5th cycle, progressively decreasing the adsorption capacity until the adsorption does not occur past the 12th cycle. Overall, the results demonstrated that the activated carbon from residual biomass of the Schizolobium parahyba species could be an excellent alternative in obtaining an effective adsorbent to treat wastewater-containing drugs.

Woody residues of the grape production chain as an alternative precursor of high porous activated carbon with remarkable performance for naproxen uptake from water.

Activated carbon prepared from grape branches was used as a remarkable adsorbent to uptake naproxen and treat a synthetic mixture from aqueous solutions. The material presented a highly porous texture, a surface area of 938 m2 g-1, and certain functional groups, which were key factors to uptake naproxen from effluents. The maximum adsorption capacity predicted by the Langmuir model for naproxen was 176 mg g-1. The thermodynamic study revealed that the adsorption process was endothermic and spontaneous. The linear driving force (LDF) model presented a good statistical adjustment to the experimental decay data. A suitable interaction pathway of naproxen adsorption onto activated carbon was proposed. The adsorbent material was highly efficient to treat a synthetic mixture containing several drugs and salts, reaching 95.63% removal. Last, it was found that the adsorbent can be regenerated up to 7 times using an HCl solution. Overall, the results proved that the activated carbon derived from grape branches could be an effective and sustainable adsorbent to treat wastewaters containing drugs.

Effective adsorptive removal of atrazine herbicide in river waters by a novel hydrochar derived from Prunus serrulata bark.

In this work, a novel and effective hydrochar was prepared by hydrothermal treatment of Prunus serrulata bark to remove the pesticide atrazine in river waters. The hydrothermal treatment has generated hydrochar with a rough surface and small cavities, favoring the atrazine adsorption. The adsorption equilibrium time was not influenced by different atrazine concentrations used, being reached after 240 min. The Elovich adsorption kinetic model presented the best adjustment to the kinetic data. The Langmuir model presented the greatest compliance to the isotherm data and indicated a higher affinity between atrazine and hydrochar, reaching a maximum adsorption capacity of 63.35 mg g-1. Thermodynamic parameters showed that the adsorption process was highly spontaneous, endothermic, and favorable, with a predominance of physical attraction forces. In treating three real river samples containing atrazine, the adsorbent showed high removal efficiency, being above 70 %. The hydrochar from Prunus serrulata bark waste proved highly viable to remove atrazine from river waters due to its high efficiency and low precursor material cost.

Optimization of ketoprofen adsorption from aqueous solutions and simulated effluents using H2SO4 activated Campomanesia guazumifolia bark.

This study used the bark of the forest species Campomanesia guazumifolia modified with H2SO4 to absorb the anti-inflammatory ketoprofen from aqueous solutions. FTIR spectra confirmed that the main bands remained after the chemical treatment, with the appearance of two new bands related to the elongation of the carbonyl group present in hemicellulose. Micrographs confirmed that the surface started to contain a new textural shape after acid activation, having new pores and cavities. The drug adsorption's optimum conditions were obtained by response surface methodology (RSM). The adsorption was favored at acidic pH (2). The dosage of 1 g L-1 was considered ideal, obtaining good indications of removal and capacity. The Elovich model very well represented the kinetic curves. The isotherm studies indicated that the increase in temperature negatively affected the adsorption of ketoprofen. A maximum adsorption capacity of 158.3 mg g-1 was obtained at the lower temperature of 298 K. Langmuir was the best-fit isotherm. Thermodynamic parameters confirmed the exothermic nature of the system (ΔH0 = -8.78 kJ mol-1). In treating a simulated effluent containing different drugs and salts, the removal values were 35, 50, and 80% at 15, 30, and 180 min, respectively. Therefore, the development of adsorbent from the bark of Campomanesia guazumifolia treated with H2SO4 represents a remarkable alternative for use in effluent treatment containing ketoprofen.

Synthesis of geopolymers from fly and bottom ashes of a thermoelectrical power plant for metallic ions adsorption.

A series of geopolymers were synthesized from fly and bottom ashes of a thermoelectrical power plant located in the Brazilian southern, aiming to add value for these wastes. The geopolymers were prepared in conventional and ultrasound-assisted ways and used to uptake Ag+, Co2+, Cu2+, and Ni2+ from aqueous solutions. All materials were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and N2 adsorption isotherms (BET and BJH methods). The results revealed that the geopolymers obtained from the conventional method presented slightly higher values of surface area and total pore volume. However, in some cases, the adsorption potential was better for the ultrasound synthesized materials. The geopolymers prepared from both methods presented good adsorption performance concerning Ag+ and Cu2+, Co2+ and Ni2+. The removal percentages were higher than 90%. In addition, the adsorption capacities were within the literature range. These findings show that the ultrasound technique is not essential to improve the geopolymers production process compared to the conventional process, which generated material with better performance for heavy metals adsorption. Besides, it was possible to aggregate value for fly and bottom ashes, generating promising adsorbent materials.

One step acid modification of the residual bark from Campomanesia guazumifolia using H2SO4 and application in the removal of 2,4-dichlorophenoxyacetic from aqueous solution.

The residual bark of the tree species Campomanesia guazumifolia was successfully modified with H2SO4 and applied to remove the toxic herbicide 2.4-dichlorophenoxyacetic (2.4-D) from aqueous solutions. The characterization techniques made it possible to observe that the material maintained its amorphous structure; however, a new FTIR band emerged, indicating the interaction of the lignocellulosic matrix with sulfuric acid. Micrographs showed that the material maintained its irregular shape; however, new spaces and cavities appeared after the acidic modification. Regardless of the herbicide concentration, the system tended to equilibrium after 120 min. Using the best statistical coefficients, the Elovich model was the one that best fitted the kinetic data. The temperature increase in the system negatively influenced the adsorption of 2.4-D, reaching a maximum capacity of 312.81 mg g-1 at 298 K. The equilibrium curves showed a better fit to the Tóth model. Thermodynamic parameters confirmed the exothermic nature of the system (ΔH0 = -59.86 kJ mol-1). As a residue obtained from urban pruning, the bark of Campomanesia guazumifolia treated with sulfuric acid is a promising and highly efficient alternative for removing the widely used and toxic 2.4-D herbicide from aqueous solutions.