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This study investigated the application of adsorption with activated carbons (ACs) and photodegradation to reduce the concentration of triclosan (TCS) in aqueous solutions. Concerning adsorption, ACs (Darco, Norit, and F400) were characterised and batch experiments were performed to elucidate the effect of pH on equilibrium. The results showed that at pH = 7, the maximum adsorption capacity of TCS onto the ACs was 18.5 mg g -1 for Darco, 16.0 mg g -1 for Norit, and 15.5 mg g -1 for F400. The diffusional kinetic model allowed an adequate interpretation of the experimental data. The effective diffusivity varied and increased with the amount of TCS adsorbed, from 1.06 to 1.68 × 10 -8  cm 2  s -1 . In the case of photodegradation, it was possible to ensure that the triclosan molecule was sensitive to UV light of 254 nm because the removal was over 80 % using UV light. The removal of TCS increased in the presence of sulfate radicals. It was possible to identify 2,4-dichlorophenol as one of the photolytic degradation products of triclosan, which does not represent an environmental hazard at low concentrations of triclosan in water. These results confirm that the use of AC Darco, Norit, and F400 and that photodegradation processes with UV light and persulfate radicals are effective in removing TCS from water, reaching concentration levels that do not constitute a risk to human health or environmental hazard. Both methods effectively eliminate pollutants with relatively easy techniques to implement., Competing Interests: Declaration of competing interest The 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., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Chlorpheniramine (CPM) and Ciprofloxacin (CIP) adsorption onto a granular (GAC) and pelletized activated carbon (PAC) analyzing the physicochemical mechanisms involved using the carbon's characterization were studied. Adsorption isotherm studies were performed at temperatures of 25 °C at pH values of 4, 7 and 9 and at 45 °C at a pH of 7. The characterization demonstrated that GAC has a predominantly acid character due to its predominantly negative surface charge and acidic site concentration alongside the characteristic bands detected in the X-ray Photoemission Spectroscopy (XPS) study. On the other hand, PAC presented a mostly basic character due to its positive surface charge and basic site concentrations. The adsorption isotherm studies demonstrated that the Freundlich isotherm better described the equilibrium data with an average deviation percentage of 7.45 and 6.74 for GAC and PAC. The temperature and desorption studies demonstrated that the adsorption process occurs through a chemisorption mechanism, and the pH study alongside the GAC and PAC characterization demonstrated that the mechanisms involved are a combination of electrostatic interactions and pi-pi interactions between the CPM and CIP molecules and the carbon's surface. These results demonstrate that the adsorption process of these pharmaceutical compounds is done through a combination of physical and chemical interactions., Competing Interests: Declaration of competing interest The 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., (Copyright © 2023 Elsevier Inc. All rights reserved.)

This work presents a one-step synthesis methodology for preparing a hydrochar (HC) doped with TiO 2 (HC-TiO 2 ) for its application on the degradation of crystal violet (CV) using UV and visible radiation. Byrsonima crassifolia stones were used as precursors along with TiO 2 particles. The HC-TiO 2 sample was synthesized at 210 °C for 9 h using autogenous pressure. The photocatalyst was characterized to evaluate the TiO 2 dispersion, specific surface area, graphitization degree, and band-gap value. Finally, the degradation of CV was investigated by varying the operating conditions of the system, the reuse of the catalyst, and the degradation mechanism. The physicochemical characterization of the HC-TiO 2 composite showed good dispersion of TiO 2 in the carbonaceous particle. The presence of TiO 2 on the hydrochar surface yields a bandgap value of 1.17 eV, enhancing photocatalyst activation with visible radiation. The degradation results evidenced a synergistic effect with both types of radiation due to the hybridized π electrons in the sp 2 -hybridized structures in the HC surface. The degradation percentages were on average 20% higher using UV radiation than visible radiation under the following conditions: [CV] = 20 mg/L, 1 g/L of photocatalyst load, and pH = 7.0. The reusability experiments demonstrated the feasibility of reusing the HC-TiO 2 material up to 5 times with a similar photodegradation percentage. Finally, the results indicated that the HC-TiO 2 composite could be considered an efficient material for the photocatalytic treatment of water contaminated with CV., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jonathan M. Sanchez-Silva reports financial support was provided by National Council on Science and Technology., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Metformin consumption for diabetes treatment is increasing, leading to its presence in wastewater treatment plants where conventional methods cannot remove it. Therefore, this work aims to analyze the performance of advanced oxidation processes using sulfate radicals in the degradation of metformin from water. Experiments were performed in a photoreactor provided with a low-pressure Hg lamp, using K 2 S 2 O 8 as oxidant and varying the initial metformin concentration (C A0 ), oxidant concentration (C ox ), temperature (T), and pH in a response surface experimental design. The degradation percentages ranged from 26.1 to 87.3%, while the mineralization percentages varied between 15.1 and 64%. Analysis of variance (ANOVA) showed that the output variables were more significantly affected by C A0 , C ox, and T. Besides, a reduction of C A0 and an increase of C ox up to 5000 μM maximizes the metformin degradation since the generation of radicals and their interaction with metformin molecules are favored. For the greatest degradation percentage, the first order apparent rate constant achieved was 0.084 min -1 . Furthermore, while in acidic pH, temperature benefits metformin degradation, an opposite behavior is obtained in a basic medium because of recombination and inhibition reactions. Moreover, three degradation pathways were suggested based on the six products detected by HPLC-MS: N-cyanoguanidine m/z = 85; N,N-dimethylurea m/z = 89; N,N-dimethyl-cyanamide m/z = 71 N,N-dimethyl-formamide m/z = 74; glicolonitrilo m/z = 58; and guanidine m/z = 60. Finally, it was shown that in general the toxicity of the degradation byproducts was lower than the toxicity of metformin toward Chlamydomonas reinhardtii., Competing Interests: Declaration of competing interest The 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., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Chili seeds (CS) represent one of the most abundant residues in Mexico due to the high production and consumption. In this work, CS were used as raw material for the production of low-cost adsorbents for the removal of methylene blue from water. The adsorbents were synthesized from a hydrothermal treatment (based on a surface response experiment design) and characterized texturally by assessing changes in their properties. The mass yield (%R), carbon content (%C), and the second order adsorption rate constant (k 2 ) were derived in relation to a list of input variables (e.g., the reaction temperature, residence time, and water/biomass ratio). Accordingly, those output variables were affected most sensitively by temperature and/or residence time, while changes of the water/biomass ratio were insignificant. Besides, an increase in the reaction temperature favored the degradation of the lignocellulosic material with increases in the carbon fixation. The adsorption capacity of methylene blue (MB) by the hydrochars depended drastically on the oxygen/carbon ratio. As such, the maximum adsorption capacity value of 145 mg g -1 was attained at the initial MB concentration of ~3000 μM (optimal oxygen/carbon value of 0.43). On the other hand, the maximum partition coefficient (K D ) was estimated as 2.96 μM -1  mg g -1 with the initial/equilibrium concentrations of 20.5/6.93 μM. The performance evaluation between different studies, when made in terms of K D , suggests that the tested hydrochar should be one of the best adsorbents to treat methylene blue, especially at near-real environmental conditions (e.g., below micromolar levels)., Competing Interests: Declaration of competing interest The 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., (Copyright © 2020 Elsevier Inc. All rights reserved.)

This study investigated the adsorption of two endocrine-disrupting chemicals, bisphenol A (BPA) and S (BPS), from water using activated carbon clothes (ACCs), as-received and oxidized, in the absence and presence of bacteria, analyzing both kinetic and equilibrium adsorption data. Kinetic study of the different systems showed that the adsorption rate was affected both by the oxidation of the adsorbent and by the presence of bacteria. Bisphenol adsorption kinetics followed a second-order kinetic model, with rate constants between 0.0228 and 0.0013 g min -1  mol -1 . ACC was a much better adsorbent of E. coli compared to granular activated carbons, achieving 100% adsorption at 24 h. ACC oxidation reduced the adsorption capacity and the adsorbent-adsorbate relative affinity due to the decrease in carbon surface hydrophobicity. Conversely, the presence of bacteria in aqueous solution increased the ACC surface hydrophobicity and therefore enhanced the adsorption capacity of BPA and BPS on ACC, which was 33% and 24%, respectively. In all cases, more BPS than BPA was removed due to the greater dipolar moment of the former. Results found show that activated carbon clothes in the presence of bacteria can be an adequate process to remove bisphenol A and S from different aqueous systems., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Gamma radiation has been used to induce the degradation of compounds used as plasticizers and herbicides such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) in aqueous solution, determining the dose constants, removal percentages, and radiation-chemical yields. The reaction rate constants of hydroxyl radical (HO), hydrated electron (eaq(-)) and hydrogen atom (H) with these pollutants were also obtained by means of competition kinetics, using 3-aminopyridine and atrazine as reference compounds. The results indicated that the elimination of these pollutants with gamma radiation mainly follows the oxidative pathway through reaction with HO radicals. The degradation by-products from the five pollutants were determined, detecting that the hydroxylation of the corresponding parent compounds was the main chemical process in the degradation of the pollutants. Moreover, a high decrease in the chemical oxygen demand has been observed for all pollutants. As expected, the degradation by-products generated by the irradiation of PA, BPA and DPA showed a lower toxicity than the parent compounds, however, in the case of 2,4-D and MCPA irradiation, interestingly, their by-products were more toxic than the corresponding original compounds., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The main aim of this study was to investigate the single, competitive, and dynamic adsorption of phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two activated carbons with different chemical natures and similar textural characteristics. The adsorption mechanism was also elucidated by analyzing the influence of solution pH and ionic strength. The activated carbons demonstrated high adsorption capacity to remove all micropollutants due to the presence of active sites on their surfaces, which increase dispersive interactions between the activated carbon graphene layers and the aromatic ring of pollutants. The adsorption capacity of the activated carbons increased in the order: DPA

The aim of this study was to determine the effectiveness of oxidation processes based on UV radiation (UV, UV/H2O2, UV/K2S2O8, and UV/Na2CO3) to remove bisphenol A (BPA) from aqueous solution. Results showed that UV radiation was not effective to remove BPA from the medium. The addition of radical promoters such as H2O2, K2S2O8, or Na2CO3 markedly increased the effectiveness of UV radiation through the generation of HO(•), SO4(•-), or CO3(•-)/HCO3(•) radicals, respectively. The reaction rate constants between BPA and HO(•), SO4(•-), and CO3(•-)/HCO3(•) radicals were k(HO(•)BPA)=1.70±0.21×10(10)M(-1)s(-1), k(SO4(•-)BPA)=1.37±0.15×10(9)M(-1)s(-1) and k(CO3(•-)/HCO3(•)BPA)=3.89±0.09×10(6)M(-1)s(-1), respectively. The solution pH had a major effect on BPA degradation with the UV/H2O2 system, followed by UV/K2S2O8, and UV/Na2CO3 systems. All oxidation systems in this study showed 100% effectiveness to remove BPA from wastewater, due to its large content of natural organic matter (NOM), which can absorb UV radiation and generate excited triplet states ((3)NOM*) and various reactive oxygen species. With all three systems, the total organic carbon in the medium was markedly decreased after 5 min of treatment. The toxicity of byproducts was higher than that of BPA when using UV/H2O2, similar to that of BPA with the UV/Na2CO3 system, and lower than that of BPA after 40 min of treatment with the UV/K2S2O8 system., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The objective of this work was to compare the effectiveness of conventional technologies (adsorption on activated carbon, AC, and ozonation) and technologies based on advanced oxidation processes, AOPs, (UV/H(2)O(2), O(3)/AC, O(3)/H(2)O(2)) to remove phthalates from aqueous solution (ultrapure water, surface water and wastewater). Diethyl phthalate (DEP) was chosen as a model pollutant because of its high water solubility (1,080 mg/L at 293 K) and toxicity. The activated carbons showed a high adsorption capacity to adsorb DEP in aqueous solution (up to 858 mg/g), besides the adsorption mechanism of DEP on activated carbon is governed by dispersive interactions between π electrons of its aromatic ring with π electrons of the carbon graphene planes. The photodegration process showed that the pH solution does not significantly affect the degradation kinetics of DEP and the first-order kinetic model satisfactorily fitted the experimental data. It was observed that the rate of decomposition of DEP with the O(3)/H(2)O(2) and O(3)/AC systems is faster than that with only O(3). The technologies based on AOPs (UV/H(2)O(2), O(3)/H(2)O(2), O(3)/AC) significantly improve the degradation of DEP compared to conventional technologies (O(3), UV). AC adsorption, UV/H(2)O(2), O(3)/H(2)O(2), and O(3)/AC showed a high yield to remove DEP; however, the disadvantage of AC adsorption is its much longer time to reach maximum removal. The best system to treat water (ultrapure and natural) polluted with DEP is the O(3)/AC one since it achieved the highest DEP degradation and TOC removal, as well as the lower water toxicity., (Copyright © 2012 Elsevier B.V. All rights reserved.)