The worrying energy and climate situations make it necessary to face a transition to a carbon-neutral economy. In this context, green hydrogen plays a crucial role in the future energy landscape. Besides other technologies, thermochemical water splitting represents a promising route for renewable hydrogen generation, using thermosolar energy as the primary energy source. In this study, different types of perovskites La0.8Me0.2NiO3 +/-delta (Me = Al, Ba and Ca) were synthesised via reactive grinding. Their redox performance was evaluated under different thermal reduction temperatures (1200-800 degrees C), obtaining materials with hydrogen production values ranging from 4.51 to 5.31 cm3STP/gactive material & sdot;cycle when the reduction was performed at 800 degrees C, exceeding those already reported values for similar materials at higher temperatures. In order to obtain suitable configurations for their implementation in solar reactors, powdered perovskites were shaped into macrostructures such as pellets, reticulated porous ceramic (RPC) structures and thin films deposited over ceramic monoliths. Compared to powdered materials, the macrostructures exhibited higher hydrogen production attributed to enhanced gas-solid contact and more efficient heat transfer within the structures. The best performance was obtained by La0.8Ca0.2NiO3 +/-delta supported as a thin layer over the ceramic monolithic structure, with productions up to 14.91-16.33 cm3STP/gactive material & sdot;cycle using thermal reduction temperatures of 800 and 1000 degrees C, respectively. These results confirm that shaping strategies enhance the already remarkable redox activity of perovskites and enable their integration into volumetric solar reactors. This represents a significant step forward in the development of scalable green hydrogen production systems based on renewable solar thermal energy.

The production of green hydrogen is one of the main targets of current energy and environmental policies. In this context, thermochemical water splitting is one of the potential methodologies that enable its production. This process is based on the thermal reduction of a metal oxide, followed by its re-oxidation with water releasing hydrogen. The main problem of this process, which hinders its full-scale application, is that reducing the metal oxide usually requires very high temperatures (>1500 degrees C). To decrease this reduction temperature, non-stoichiometric oxides such as perovskites have been proposed. In a previous work, the authors have presented La1-xSrxMeO3 +/-delta (x = 0.2-0.4; Me = Mn, Fe and Co) perovskites as active materials decreasing the operation temperature to 1400 degrees C. However, those perovskites showed a significant lack of stability upon cycling, limiting their use in a future scale-up of the process. In this work, we present a multi-substituted perovskite type A(1-x)A'xB1-yB'O-y(3 +/-delta) (La0.6Sr0.4Co0.2Fe0.8O3 +/-delta, named LSCF) as redox material with increasing stability and remarkable activity in the hydrogen production cycles even at temperatures below 1000 degrees C. This material was synthesised by reactive grinding as a green synthesis method optimising the variables of the process. Three reduction temperatures for the thermochemical water splitting were evaluated in the range 800-1200 degrees C at the same oxidation temperature of 800 degrees C. LSCF perovskite has been used in powder form with a H-2 production of 5.22 cm(3)STP/g(material)cycle when the reduction was performed at 800 degrees C and 6.83 cm(3)STP/g(material)cycle when this reduction step was performed at 1000 degrees C. Afterwards, the LSCF was shaped into two different macroporous structures looking for a potential scaling-up of the process: reticulated porous ceramic structure (RPC) and a ceramic monolith structure with straight and well-ordered channels in which the perovskite forms a thin layer over the internal channels surface. The macroscopic structures exhibited good activity and stability working isothermally at 800 degrees C under N-2 atmosphere, reaching H-2 productions higher than 10 cm(3)STP/g(material)cycle. Particularly, the monolithic structure, characterised by its open macroporosity improves the heat transfer phenomena and the contact between the gas-phase and the perovskite, obtaining a stable hydrogen production under isothermal conditions of 17 cm(3)STP/g(material)cycle at 800 degrees C. That could be increased up to 32.5 cm(3)STP/g(material)cycle when the reduction step of the thermochemical water splitting is performed at 1000 degrees C. To the best of our knowledge, this is the higher value obtained for hydrogen production by a perovskite in this application at this reaction conditions. These results confirm the LSCF as a potential material for green hydrogen production by low-temperature thermochemical cycles.

Highly dispersed iron catalysts on rice husk silica are obtained by deposition-precipitation assisted by hydrolysis with urea, controlling the hydrolysis (OH/metal molar ratio 5:1) up to pH 4.5 and low load of Fe3+ as active phase (0.25-5 %). X-ray diffraction analysis presumes a good dispersion of the metallic phase, while H2 temperature-programmed reduction suggests a reducibility from 49 to 100 % (5 to 0.25%wt Fe). Thermogravimetric analysis reveals good thermal stability of the catalysts. The IR analysis evidences the equivalent to Si-O-Fe interaction through a reduction in the bands of silanol groups, and an in situ diffuse reflectance infrared spectroscopy study with carbon monoxide on the reduced catalysts confirms the high dispersion of the metal phase in the catalysts. The catalytic activity was investigated in the wet oxidation reaction of phenol (5 x 10(-4) M) with H2O2. The catalysts achieve phenol conversions >80 % and high selectivity to CO2 (37-52 %) in just 20 min, which greatly exceeds the catalyst obtained by conventional impregnation, which only achieves 54 % conversion and 26 % selectivity.

This study aimed to produce and characterise laminar biochar from Guadua angustifolia Kunth culms longitudinal cuts by TiO 2 sedimentation deposit with photocatalytic activity against bacteria; several ages and height positions culms served to produce longitudinal cuts, fibre and parenchyma compositions; longitudinal cuts containing the highest fibre were transformed into laminar biochar by modified pyrolysis; biochar TiO 2 deposited served to evaluate the photocatalytic activity against Escherichia coli 226 and Salmonella Typhimurium 211, the highest fibre percentages for longitudinal cuts were MM, BM, TJ, TD, and DM (ranging from 59.50 to 63.78 %), among these, BM, MD and TD showed the highest thermal stability, with decomposition temperatures between 341.65 and 345.85 ºC. Elastic modulus in bending (E) for these cuts exceeded 3.06 GPa, indicating their mechanical strength. TiO 2 deposited on the laminar biochar exposed to UV 253nm generated > 50 % inactivation of both bacteria after 30 min of exposure (photocatalytic activity).

Solar-driven thermochemical water splitting has the potential to transform concentrated solar energy into green hydrogen and other solar fuels. In this work, La0.8Ca0.2MeO3 +/-$ (Me = Co, Ni, Fe and Cu) perovskites have been synthesised by a modified Pechini method and evaluated as materials for hydrogen production by two step thermochemical water splitting cycles. Performing the thermal reduction at temperatures of 1200 and 1000 degrees C, while the oxidation is done at 800 degrees C, allows a remarkable and stable hydrogen production after 5 consecutive cycles. However, the perovskites suffer changes in the structure after each redox cycle, with potential effects in the long-term cyclic operation. On the contrary, the isothermal thermochemical cycles at 800 degrees C produce a stable amount of hydrogen with each consecutive cycle maintaining the perovskite structure. This hydrogen production ranges from 3.60 cm3 STP/gmaterial$cycle for the material with the lowest productivity (La0.8Ca0.2FeO3 +/- d) to 5.02 cm3 STP/gmaterial$cycle for the one with the highest activity (La0.8Ca0.2NiO3 +/- d). Particularly the Ni-based material shows the highest H2 productivity accompanied by very good material stability after 15 consecutive cycles, being possible to combine with current solar thermal facilities based on concentrated solar power technologies like plants with central receivers.(c) 2023 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Solar-driven thermochemical water splitting has the potential to transform concentrated solar energy into green hydrogen and other solar fuels. In this work, La0.8Ca0.2MeO3±δ (Me = Co, Ni, Fe and Cu) perovskites have been synthesised by a modified Pechini method and evaluated as materials for hydrogen production by two step thermochemical water splitting cycles. Performing the thermal reduction at temperatures of 1200 and 1000 °C, while the oxidation is done at 800 °C, allows a remarkable and stable hydrogen production after 5 consecutive cycles. However, the perovskites suffer changes in the structure after each redox cycle, with potential effects in the long-term cyclic operation. On the contrary, the isothermal thermochemical cycles at 800 °C produce a stable amount of hydrogen with each consecutive cycle maintaining the perovskite structure. This hydrogen production ranges from 3.60 cm3 STP/gmaterial·cycle for the material with the lowest productivity (La0.8Ca0.2FeO3±δ) to 5.02 cm3 STP/gmaterial·cycle for the one with the highest activity (La0.8Ca0.2NiO3±δ). Particularly the Ni-based material shows the highest H2 productivity accompanied by very good material stability after 15 consecutive cycles, being possible to combine with current solar thermal facilities based on concentrated solar power technologies like plants with central receivers.

The presence of antibiotics in the environment has raised concerns due to their potential negative effects on ecosystems. Conventional water treatment methods are ineffective at removing antibiotics. This study aims to investigate the efficiency of Fenton-like processes catalyzed by delaminated clay and layered double hydroxides impregnated with Fe or Cu for the degradation of amoxicillin. The catalysts were obtained by synthesizing delaminated clay and layered double hydroxides and subsequently impregnating them with Fe or Cu. The characterization of catalysts involved X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), N2 adsorption-desorption, and X-ray photoelectron spectroscopy (XPS). Catalytic activity was assessed by varying the concentration of hydrogen peroxide, the initial concentration of amoxicillin, and the amount of catalyst. The determination of byproducts was done by high-performance liquid chromatography (HPLC) with a quadrupole time-of-flight mass spectrometer (QqTof). The study found that layered double hydroxides impregnated with Fe or Cu were able to remove 100% of amoxicillin in just 20 min. The study identified 16 byproducts, indicating a degradation process. Under all of the studied conditions, the copper catalysts showed the highest percentage of amoxicillin removal.

Selective CO methanation from H2-rich stream has been regarded as a promising route for deep removal of low CO concentration and catalytic hydrogen purification processes. This work is focused on the development of more efficient catalysts applied in practical conditions. For this purpose, we prepared a series of catalysts based on Ru supported over titania and promoted with small amounts of Rh and Pt. Characterization details revealed that Rh and Pt modify the electronic properties of Ru. The results of catalytic activity showed that Pt has a negative effect since it promotes the reverse water gas shift reaction decreasing the selectivity of methanation but Rh increases remarkably the activity and selectivity of CO methanation. The obtained results suggest that RuRh-based catalyst could become important for the treatment of industrial-volume streams.

Antibiotics and pesticides, as well as various emerging contaminants that are present in surface waters, raise significant environmental concerns. Advanced oxidation processes, which are employed to eliminate these substances, have demonstrated remarkable effectiveness. However, during the degradation process, by-products that are not completely mineralized are generated, posing a substantial risk to aquatic ecosystem organisms; therefore, it is crucial to assess effluent ecotoxicity following treatment. This study aimed to assess the toxicity of effluents produced during the removal of amoxicillin and glyphosate with a Fenton-type process using a laminar structure catalyzed with iron (Fe) and copper (Cu). The evaluation included the use of Daphnia magna, Selenastrum capricornutum, and Lactuca sativa, and mutagenicity testing was performed using strains TA98 and TA100 of Salmonella typhimurium. Both treated and untreated effluents exhibited inhibitory effects on root growth in L. sativa, even at low concentrations ranging from 1% to 10% v/v. Similarly, negative impacts on the growth of algal cells of S. capricornutum were observed at concentrations as low as 0.025% v/v, particularly in cases involving amoxicillin–copper (Cu) and glyphosate with copper (Cu) and iron (Fe). Notably, in the case of D. magna, mortality was noticeable even at concentrations of 10% v/v. Additionally, the treatment of amoxicillin with double-layer hydroxides of Fe and Cu resulted in mutagenicity (IM ≥ 2.0), highlighting the necessity to treat the effluent further from the advanced oxidation process to reduce ecological risks.

A Colombian bentonite is successfully pillared with Al, Al-Fe, Al-Cu and Al-Fe-Cu polyhydroxications in solid state. The effect of the Fe and Cu content on the physicochemical properties of the pillared bentonite was evaluated using characterization techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and textural analysis (nitrogen physisorption). The Box-Behnken statistical experiment design was used to determine the optimal parameters of the independent variables hydrogen peroxide (0.120-0.144 M), catalyst load (0.5-1.5 g/L) and type of catalyst (PILC FeCu1, FeCu5, FeCu10) in the catalytic oxidation (CWPO) of amoxicillin. The optimized conditions of hydrogen peroxide (0.137 M) and catalyst loading (0.7 g/L) were used to compare the catalytic performance of the catalysts with 1%, 5% and 10% Al-Fe, Al-Cu and Al-Fe-Cu reaching a removal between 91% and 100% of amoxicillin at T and ambient pressure. The rate constants determined allowed the identification of the best catalyst of each series to study the degree of mineralization and choose the best catalyst: the pillared clay with AlFeCu10, with a TOC removal of 24.6% after 2 h of reaction. After three cycles of reuse, the catalyst maintained its catalytic activity in removing amoxicillin without leaching any metal.

Aluminum based perovskites, La0.8Al0.2MeO3-6 (Me = Co, Ni, Fe, Cu), were synthesized following the Pechini method at different pHs and evaluated for hydrogen production by water splitting in a two-step thermochemical cycle. The pH of the synthesis medium showed a critical influence in the redox properties of the aluminum-based perovskites during the thermochemical cycle. Both the thermal reduction and the hydrolysis step produce irreversible changes in the crystalline structure of La0.8Al0.2MeO3-6 perovskites prepared at acid pH, avoiding the cyclability of the material and a stable production of hydrogen during consecutive cycles. However, these changes are not observed when the perovskites were synthesized at basic pH and operated at isothermal conditions at 800 & DEG;C. In this case, the materials keep the crystalline structure leading to stable hydrogen production during consecutive cycles. Among all the studied materials, the nickel-based La0.8Al0.2MeO3-6 perovskites exhibited the best hydrogen productivity per cycle, 4.4 cm3 STP /g(material).cycle (Standard Temperature and Pressure conditions), which is a remarkable result considering that the thermochemical water splitting is conducted under isothermal conditions at just 800 ?. Moreover, this result is accompanied with a good performance of the perovskite in terms of solar to fuel efficiency (being 0.46 the ratio between the potential energy recovery from the produced hydrogen and the solar heat required for its production), comparable or even higher than values reported in the literature for other metal oxides. These results confirm the La0.8Al0.2MeO3-6 perovskite as an auspicious material for a full-scale H2 production from water splitting by solar-driven thermochemical cycles at low temperatures.

The aim of this work was to clarify the effect of the support on CO selective methanation with Ru/TiO2 catalysts. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity should be ascribed to anatase:rutile ratio, RuO2 +TiO2 solid solution formation, as well as the metal content and the thermal treatment used. All these characteristics result in active and selective catalysts in which the suppression of the reverse water gas shift reaction was observed. The catalytic performance must be explained by both the formation of more active Ru species as a result of support influence and the higher Ru dispersion. The study allows to conclude that for CO activation the role of support surface hydroxyls seems to be determinant for both the activity and selectivity of Ru/TiO2 catalysts.

Low-density polyethylene (LDPE) sheets (3.0 ± 0.1 cm) received sequential treatment, first by the action of direct-current low-pressure plasma (DC-LPP) with a 100% oxygen partial pressure, 3.0 × 10−2 mbar pressure, 600 V DC tension, 5.6 cm distance, 6-min treatment. Then, sheets were submitted to TiO2 photocatalysis at UV radiation at 254 nm (TiO2/UV) with a pH value of 4.5 ± 0.2 and a TiO2 concentration of 1 gL−1. We achieved a complementary effect on the transformation of LDPE films. With the first treatment, ablation was generated, which increased hydrophilicity. With the second treatment, the cavities appeared. The changes in the LDPE sheets’ hydrophobicity were measured using the static contact angle (SCA) technique. The photocatalytic degradation curve at 400 h revealed that the DC-LPP photocatalysis sequential process decreased SCA by 82°. This was achieved by the incorporation of polar groups, which increased hydrophilicity, roughness, and rigidity by 12 and 38%, respectively. These sequential processes could be employed for LDPE and other material biodegradation pretreatment.

The purpose of this study was to demonstrate that methanol addition after glucose depletion has a positive effect on improving rPOXA 1B production under the control of pGap in P. pastoris. Four different culture media (A, B, C and D) were used to culture P. pastoris X33/pGapZαA-LaccPost-Stop (clone 1), containing a previously optimized POXA 1B synthetic gene coding for P. ostreatus laccase, which after glucose depletion was supplemented or not with methanol. Enzyme activity in culture media without methanol (A, B, C and D) was influenced by media components, presenting activity of 1254.30 ± 182.44, 1373.70 ± 182.44, 1343.50 ± 40.30 and 8771.61 ± 218.79 U L−1, respectively. In contrast, the same culture media (A, B, C and D) with methanol addition 24 h after glucose depletion attained activity of 4280.43 ± 148.82, 3339.02 ± 64.36, 3569.39 ± 68.38 and 14,868.06 ± 461.58 U L−1 at 192 h, respectively, representing an increase of approximately 3.9-, 2.4-, 3.3- and 1.6-fold compared with culture media without methanol. Methanol supplementation had a greater impact on volumetric enzyme activity in comparison with biomass production. We demonstrated what was theoretically and biochemically expected: recombinant protein production under pGap control by methanol supplementation after glucose depletion was successful, as a feasible laboratory production strategy of sequential carbon source addition, breaking the habit of utilizing pGap with glucose.

Aluminum pillared clay (Al-PILC) was synthesized and impregnated with Co(II) nitrate (1.0, 3.0 and 6.0 wt.% cobalt), using an incipient wetness impregnation method. The obtained solids were characterized by XRF, XRD, N2 adsorption–desorption at 77 K and point of zero charge. This is the first study using cobalt impregnated in a pillared clay (Co/Al-PILC) as a catalyst for sunset yellow (SY) degradation, with bicarbonate-activated hydrogen peroxide (BAP) as the oxidizing agent. The influence of the amount of H2O2, the H2O2/NaHCO3 molar ratio, and the amount of Co impregnated in Al-PILC on azo dye oxidation in an aqueous solution was studied. The toxicity of by-products formed after dye oxidation with the BAP system was explored in an anaerobic digestion test. Total decolorizations were obtained for the reactions carried out with three cobalt impregnated catalysts, with 8 times the stoichiometric dose of H2O2 and H2O2/NaHCO3 molar ratios of 0.25 and 4.0. Textural properties of Co (1.0 wt.%)/Al-PILC can be related to its good catalytic performance in the oxidation of SY, using the BAP system, as it preserved 68.8% of the SBET and 66.0% of the microporous area of support. The concentration of leached cobalt in the tests, with the catalysts impregnated with 1.0 and 3.0 wt.% cobalt, was lower than the detection limit (< 0.01 mg/L), which indicated that the active phase was very stable at a basic pH. By-products generated during the oxidation of SY in the BAP system did not inhibit the specific methanogenic activity in anaerobic digestion. This is the first study using cobalt impregnated in a pillared clay (Co/Al-PILC) as a catalyst for an azo-dye degradation, with bicarbonate-activated hydrogen peroxide (BAP) as the oxidizing agent. Total decolorizations were obtained for the reactions carried out under the conditions studied. However, total carbon and nitrogen removals were low.

The modified tannin by Mannich reaction was investigated for wastewater treatment. The removal of heavy metals, such as copper, chromium and mercury, in industrial wastewater was evaluated through the coagulation–flocculation technique, using modified Acacia tannin (MAT) as a coagulant agent. The successful tannin modification was evaluated by infrared spectopometry (FTIR), nuclear magnetic resonance (NMR); monitoring the removal of heavy metals was performed by atomic absorption (AA) and a direct mercury analyzer (DMA). Additionally, the parameters of water quality, total suspended solids (TSS), turbidity and chemical oxygen demand (COD) were assessed. Different doses of MAT were evaluated (375 ppm, 750 ppm, 1250 ppm and 1625 ppm) and three different levels of pH (4, 7 and 10). The highest percentages of removal obtained were copper 60%, chromium 87%, mercury 50%–80%, COD 88%, TSS 86% and turbidity 94%, which were achieved with the dose of 375 ppm of MAT at pH 10. The coagulation–flocculation process with the modified Acacia tannin is efficient for the removal of conventional parameters and for a significant removal of the metals studied.

The catalytic oxidation of aqueous crystal violet (CV) solutions was investigated using Ni and Fe catalysts supported over Mg–Al oxides synthesized by the autocombustion method. The influence of temperature, loading, and selectivity were studied in the catalytic wet air oxidation (CWAO) of CV. The kind of metal had an important contribution in the redox process as significant differences were observed between Fe, Ni, and their mixtures. The catalysts with only Fe as active phase were more efficient for the oxidation of CV under normal conditions (T = 25 °C and atmospheric pressure) compared to those containing Ni, revealing the influence of the transition metal on catalytic properties. It was found that iron-containing materials displayed enhanced textural properties. The synthesis of Fe/MgAl catalysts by the autocombustion method led to solids with excellent catalytic behavior, 100% CV degradation in eight hours of reaction, 68% selectivity to CO2, and significant reduction of chemical oxygen demand (COD).

Laccases (E.C. 1.10.3.2) are multicopper oxidases of great importance in the industry due to their non-specificity and high oxidative potential. Laccases are useful to bleach synthetic dyes, oxidize phenolic compounds and degrade pesticides, among others. Hence, the objective of this work was to optimize low cost culture media for recombinant (rPOXA 1B) laccase production from Pleurotus ostreatus in Pichia pastoris. To this end, low cost nitrogen sources were studied, such as malt extract, isolated soy protein and milk serum. Following, two central composite designs (CCD) were performed. In CCD-1 different concentrations of glucose USP (0–13.35 gL-1), protein isolated soy protein (5–25 gL-1), malt extract (3.5–17.5 gL-1) and (NH4)2SO4 (1.3–6.5 gL-1) were evaluated. In CCD-2 only different concentrations of glucose USP (7.9–22 gL-1) and isolated soy protein (15.9–44.9 gL-1) were evaluated. CCD-2 results led to a One Factor Experimental design (OFED) to evaluate higher isolated soy protein (20–80 gL-1) concentrations. In all designs, (CCD-1, CCD-2 and OFED) CuSO4 (0.16 gL-1) and chloramphenicol (0.1 gL-1) concentrations remained unchanged. For the OFED after sequential statistical optimization, an enzyme activity of 12,877.3 ± 481.2 UL−1 at 168 h was observed. rPOXA 1B activity increased 30.54 % in comparison with CCD-2 results. Final composition of optimized media was: 20 gL-1 glucose USP, 50 gL-1 isolated soy protein 90 % (w/w), 11.74 gL-1 malt extract, and 4.91 gL-1 (NH4)2SO4. With this culture media, it was possible to reduce culture media costs by 89.84 % in comparison with improved culture media previously described by our group.

Industrial development has increased wastewater (WW) volume; generating contamination and disturbing ecosystems, because of breeching disposal parameters. In this work, Coloured Laboratory Wastewater (CLWW), (1500.00 colour units, CU) was separately submitted to two secondary treatments. For the first one CLWW was treated for three cycles C1, C2 and C3 with P. pastoris X33/pGAPZαA-LaccPost-Stop producing rPOXA 1B laccase, immobilized in calcium alginate beads. For the second-one, rPOXA 1B enzyme concentrate was used (three processes: P1, P2, and P3). Both treatments were carried out in a 15 L reactor with 10 L effective work volume (EWV) with 72 h hydraulic retention time. C1, C2, and C3 effluents were flocculated and filtered through quartzite sand, while P1, P2, and P3 effluents were only filtered through quartzite sand. The mixture of secondary effluents was submitted to a tertiary treatment with Chlorella sp. For C1, C2, C3, P1, P2, and P3, CU removal was of 99.16, 99.58, 99.53, 96.72, 97.05 and 96.47%, respectively. Discharge parameters, total organic carbon (TOC), inorganic carbon (IC), chemical oxygen demand (COD) and biological oxygen demand (BOD5) decreased, although they reached different final values. After the tertiary treatment (144 h) effluent discharge parameters were reduced to 34 ± 4 CU, TOC to 6.6 ± 0.9 mg L−1 and COD to 155 ± 4 mg L−1. It was demonstrated that secondary treatments (immobilized recombined cells or recombinant enzyme concentrate) combined with Chlorella sp., (tertiary treatment) attained a considerable removal of discharge parameters, demonstrating a promissory alternative for CLWW sequential treatment.

Agricultural waste management for the production of materials with specific uses is important for the remediation of certain environmental problems. Rice husk, an abundantly agricultural waste in Colombia, could be a low cost adsorbent for molecules such as dyes or heavy metals in effluent streams. In this research, we address the production and characterization of rice husk ash obtained by chemical activation with phosphoric acid as an adsorbent material. The physical-chemical properties of the materials were evaluated using different characterization techniques, such as close analysis, iodine number, adsorption of methylene blue, adsorption-desorption of nitrogen, analysis of the functional groups on the surface of the adsorbent through infrared spectroscopy (ftir), as well as an analysis of the morphology with scanning electron microscopy (sem). The materials have a surface area around 320 m2/g, which decreases depending on the amount of acid used in the activation. The pore size in the studied samples ranged between 4 and 12 nm, which suggest that mesoporous solids were obtained. Regarding the adsorption of methylene blue, results show that the production of the activated ashes from rice husk as adsorbent materials is viable, presenting a new opportunity for the use of materials considered as agricultural waste.