Corn Cobs' Biochar as Green Host of Salt Hydrates for Enhancing the Water Sorption Kinetics in Thermochemical Heat Storage Systems.

Heat storage technologies are essential for increasing the use of solar energy in the household sector. Their development can be achieved by designing new storage materials; one way is to impregnate a porous matrix with hygroscopic salts. In this article, the possibility of using biochar-based composite sorbents to develop promising new heat storage materials for efficient thermal storage is explored. Biochar-based composites with defined salt loadings (5, 10, 15, and 20%) were produced by impregnating MgSO4 into a biochar matrix derived from corn cobs. The new materials demonstrated a high water sorption capacity of 0.24 g/g (20MgCC). After six successive charging-discharging cycles (dehydration/dehydration cycles), only a negligible variation of the heat released and the water uptake was measured, confirming the absence of deactivation of 20MgCC upon cycling. The new 20MgCC composite showed an energy storage density of 635 J/g (Tads = 30 °C and RH = 60%), higher than that of other composites containing a similar amount of hydrate salt. The macroporous nature of this biochar increases the available surface for salt deposition. During the hydration step, the water molecules effectively diffuse through a homogeneous layer of salt, as described by the intra-particle model applied in this work. The new efficient biochar-based composites open a low-carbon path for the production of sustainable thermal energy storage materials and applications.

Unveiling the Potential of Corn Cob Biochar: Analysis of Microstructure and Composition with Emphasis on Interaction with NO2.

In the context of sustainable solutions, this study examines the pyrolysis process applied to corn cobs, with the aim of producing biochar and assessing its effectiveness in combating air pollution. In particular, it examines the influence of different pyrolysis temperatures on biochar properties. The results reveal a temperature-dependent trend in biochar yield, which peaks at 400 °C, accompanied by changes in elemental composition indicating increased stability and extended shelf life. In addition, high pyrolysis temperatures, above 400 °C, produce biochars with enlarged surfaces and improved pore structures. Notably, the highest pyrolysis temperature explored in this study is 600 °C, which significantly influences the observed properties of biochars. This study also explores the potential of biochar as an NO2 adsorbent, as identified by chemical interactions revealed by X-ray photoelectron spectroscopy (XPS) analysis. This research presents a promising and sustainable approach to tackling air pollution using corn cob biochar, providing insight into optimized production methods and its potential application as an effective NO2 adsorbent to improve air quality.

Ceramic hydroxyapatite foam as a new material for Bisphenol A removal from contaminated water.

Ceramic hydroxyapatite foam (CF-HAP) was prepared by combining slip-casting and foaming methods. The prepared CF-HAP was characterized by scanning electron microscopy (SEM), physisorption of N2, Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results of the specific surface area and SEM analyses revealed that the used shaping method provides CF-HAP with a wide range of porosity including macro and mesopores. Based on FTIR and XRD analyses, the CF-HAP is similar to pure well-crystallized hydroxyapatite. The adsorption results revealed that 94% of the BPA with a concentration of (40 mg/L) was effectively removed from the water and that the maximum adsorption capacity was higher in acidic than in basic medium. The thermodynamic studies indicated that the adsorption reaction was spontaneous and endothermic in nature. The adsorption capacity increased with the temperature and the BPA is chemisorbed on the ceramic foam. The isotherm data fitted slightly better with the Liu than with the Freundlich and Langmuir models suggesting that the adsorption was homogeneous and occurred only in the monolayer. The adsorption process depends largely on the BPA concentration and the results fitted well with the pseudo-first-order model. This confirms that the interaction between the BPA and the CF-HAP was mainly chemical in nature. The FTIR analysis of the used and fresh CF-HAP showed that all the hydroxyl and phosphorus bands characteristic of the hydroxyapatite shifted after adsorption of Bisphenol A. This suggests that the adsorption of Bisphenol A occurred in the sites of the hydroxyapatite. Therefore, it can be concluded that the CF-HAP has the potential to be used as an adsorbent for wastewater treatment and purification processes.

Catalytic wet air oxidation of high BPA concentration over iron-based catalyst supported on orthophosphate.

The catalytic performance of Fe supported on nickel phosphate (NiP) was evaluated for the removal of bisphenol A (BPA) by catalytic wet air oxidation (CWAO) at 140 °C and 25 bar of pure oxygen pressure. The prepared NiP and Fe/NiP materials were fully characterized by XRD, N2-physisorption, H2-TPR, TEM, and ICP analysis. Iron (Fe/NiP) impregnation of NiP support enhanced the BPA removal efficiency from 37.0 to 99.6% when CWAO was performed. This catalyst was highly stable given the operating conditions of acidic medium, high temperature, and high pressure. The Fe/NiP catalyst showed an outstanding catalytic activity for oxidation of BPA, achieving almost complete removal of BPA in 180 min at a concentration of 300 mg/L, using 4 g/L of Fe/NiP. No iron leaching was detected after the CWAO of BPA. The stability of Fe/NiP was performed over three consecutive cycles, noting that BPA conversion was not affected and iron leaching was negligible. Therefore, this catalyst (Fe/NiP) could be considered as an innocuous and effective long-lasting catalyst for the oxidation of harmful organic molecules.

Porous carbon materials derived from olive kernels: application in adsorption of organic pollutants.

Adsorption of organic pollutants (OPs), bisphenol A, and diuron, from aqueous solutions onto porous carbon materials (CMs) prepared from olive kernels, have been investigated. The effects of initial pH, initial OP concentration, temperature, and contact time on the adsorption capacity were studied. The adsorption of bisphenol A and diuron onto CMs was found to be optimal at pH 5.6 and 6.9, respectively. It was noticed that the adsorption of those organic pollutants from aqueous solution declined with increasing temperature and the process is exothermic. The rate of adsorption followed the second order kinetic equation. The equilibrium results showed that Langmuir model fits well with the data. The maximum adsorption capacities obtained using the best CM were 476 and 434 mg g-1 for BPA and diuron, respectively. The results showed that CMs made from olive kernels are an excellent and inexpensive biomass waste-derived sorbent. Graphical abstract.

Microwave assisted green synthesis of Fe2O3/biochar for ultrasonic removal of nonsteroidal anti-inflammatory pharmaceuticals.

Iron oxide/biochar (Fe2O3/biochar) was prepared by green synthesis via a microwave to evaluate ultrasound-assisted adsorption capacity of Nonsteroidal Anti-inflammatory Drugs (NSAIDs) (salicylic acid, naproxen, and ketoprofen) from the water. Several techniques of characterization, including, Fourier transform infrared spectrometry, scanning electron microscopy, EDS analysis, N2 adsorption-desorption, X-ray diffraction, and Raman spectrometry were applied. The adsorption of NSAIDs onto Fe2O3/biochar was performed using an ultrasonic bath. The effects of batch adsorption under various experimental parameters such as contact time (0-120 min), initial concentration (10-500 mg L-1) and pH (2-12) were tested. The obtained Fe2O3/biochar specific surface area, mesopore volume/micropore volume, and pores size were equal to 786 m2 g-1, 0.409 cm3 g-1, and 1.534 cm3 g-1, respectively. The pseudo-second-order model could describe better all NSAID adsorptions onto Fe2O3/biochar. The Langmuir model agreed well with the NSAID adsorptions and the maximum adsorption capacities reached 683 mg g-1, 533 mg g-1 and 444 mg g-1 for salicylic acid, naproxen, and ketoprofen, respectively. Fe2O3/biochar can be used as an excellent adsorbent for the treatment of NSAIDs in water.

Correction: Microwave assisted green synthesis of Fe2O3/biochar for ultrasonic removal of nonsteroidal anti-inflammatory pharmaceuticals.

[This corrects the article DOI: 10.1039/D0RA00617C.].

New amino group functionalized porous carbon for strong chelation ability towards toxic heavy metals.

Herein, ethylenediamine functionalized porous carbon (PC-ED/1.5) was synthesized, then characterized by various methods and finally used as a functional material for Cu(ii) and Pb(ii) ion removal from water. XPS revealed the presence of numerous functionalities within the surface of PC including -NH and C-N-C groups. Furthermore, S BET, RS, XRD and FTIR analyses confirmed the changes implemented on the PC surface. Thereafter, a systematic study was implemented to analyze the interactions of the PC-ED/1.5 surface with Cu(ii) and Pb(ii) heavy metal ions. Hence, adsorption experiments showed that the PC-ED/1.5 exhibits maximum adsorption capacities of 123.45 mg g-1 and 140.84 mg g-1 for Cu(ii) and Pb(ii), respectively. Moreover, in situ electrostatic interactions occurring between the divalent cation and the PC-ED/1.5 functional groups was investigated. The mechanism involves chelation processes, electrostatic interactions and mechanical trapping of the metal ions in the adsorbent pores. Interestingly, a synergistic effect of the pores and surface active sites was observed. Finally, by using alginate bio-polymer we prepared membrane films of PC-ED/1.5 which showed long-term stability, regeneration capabilities and high mass recovery.

Structured carbon foam derived from waste biomass: application to endocrine disruptor adsorption.

In this paper, a novel structured carbon foam has been prepared from argan nut shell (ANS) was developed and applied in bisphenol A (BPA) removal from water. The results showed that the prepared carbon foam remove 93% of BPA (60 mg/L). The BPA equilibrium data obeyed the Liu isotherm, displaying a maximum uptake capacity of 323.0 mg/g at 20 °C. The calculated free enthalpy change (∆H° = - 4.8 kJ/mol) indicated the existence of physical adsorption between BPA and carbon foam. Avrami kinetic model was able to explain the experimental results. From the regeneration tests, we conclude that the prepared carbon foam has a good potential to be used as an economic and efficient adsorbent for BPA removal from contaminated water. Based on these results and the fact that the developed structured carbon foam is very easy to separate from treated water, it can serve as an interesting material for real water treatment applications.

High extent mass recovery of alginate hydrogel beads network based on immobilized bio-sourced porous carbon@Fe3O4-NPs for organic pollutants uptake.

This work goes inside the understanding of organic pollutants adsorption mechanism over network alginate hydrogel beads based on immobilized bio-sourced PC@Fe3O4-NPs (PC@Fe3O4-NPs@Alginate) and highlights its high extent mass recovery in aqueous media. The samples were successfully synthesized, we previously developed porous carbon (PC), which, was used to elaborate PC@Fe3O4-NPs via simple in situ coprecipitation (PC@ Fe3O4-NPs), which was encapsulated by alginate-Ca2+ via the blend crosslinking method. The structural, textural, chemical and morphological proprieties of as prepared materials were studied by XRD, FTIR, Raman spectroscopy, nitrogen adsorption-desorption, XPS, SEM and TEM. The adsorption kinetic and isotherm data were well fitted to the pseudo-second-order and Langmuir models. Magnetic particles exhibited an excellent ability to adsorb methylene blue (MB) from aqueous solutions with maximum MB adsorption capacity of 180.42 mg g-1 (PC@Fe3O4 NPs powder) and 49.66 mg g-1 (beads based PC@Fe3O4-NPs@Alginate). Response surface methodology was used to optimize the removal efficiency of MB from aqueous solution and optimum parameters were determined. Magnetic beads based PC showed good magnetic propriety, long-term stability, regeneration capabilities and high extent mass recovery.

Combined Methane Energy Recovery and Toxic Dye Removal by Porous Carbon Derived from Anaerobically Modified Digestate.

Valorization of agri-food organic waste in order to reach zero waste using cleaner methods is still a challenge. Therefore, both anaerobic co-digestion (ACD) (biological process) and adsorption (physicochemical process) were used in combination for this objective. ACD allows the activation of biodegradable organic matter by microbial action and produces a digestate (co-product). This coproduct was used as a raw material to produce porous carbon having a high specific surface area after chemical treatment using sulfuric acid and thermal activations at temperature T = 350 °C. The resulted material was used for the preparation of core-shell particles with a core made of porous carbon and a shell consisting mainly of alginate and a calcium ion layer. The final core-shell particles were then used for dye treating wastewater and solving the solid-liquid separation problem in the adsorption process. We show here that in the ACD process, significant bio-methane potential (BMP) was produced. Furthermore, the data indicate that 153 L CH4 kg·SV-1 of BMP was produced under optimum conditions of pH = 8 and inoculum/load ratio = 1.2. The overall results concerning the methylene blue (MB) adsorption from water onto the core-shell particles show the occurrence of a maximum adsorbed amount equal to 26.178 mg g-1, and good agreement was found between the experimental adsorption data with pseudo-second-order and Langmuir theoretical models. The response surface methodology coupled with the central composite design has allowed the identification of optimal conditions for MB removal and has led to the elucidation of adsorption mechanism and the regeneration of the adsorbent without the occurrence of the solid/liquid separation problem.

Carbon microspheres derived from walnut shell: Rapid and remarkable uptake of heavy metal ions, molecular computational study and surface modeling.

Carbon microspheres were synthesized under nitrogen flow from walnut shells (WS) and then used as an adsorbent for the removal of Pb (II), Cu(II), Cr(III) and Cd(II) metals. The prepared material was characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, Brounauer-emett-teller surface, Fourier transform infrared and Raman spectroscopy. SEM micrographs showed homogenous sphere-like structure with an average diameter of 4.55 µm. The prepared carbon microspheres exhibit selective and rapid removal of hazardous metals from synthetic water samples. The effects of solution pH, contact time and temperatures on the removal process have been systematically investigated. The material used in this present work present the highest adsorption capacities ever reported for Cr(III), Pb(II), Cd(II) and Cu(II) at an optimum pH of 5, the adsorption capacities reached 792, 638, 574 and 345 mg g-1 for Cr(III), Pb(II), Cd(II) and Cu(II), respectively. Density functional calculations (DFT) showed an agreement with the adsorption process results, Cr(III) had stronger binding ability to the OH and/or COOH functional groups followed by Pb, Cu and Cd. The adsorption mechanism was discussed based on the experimental and theoretical results. Finally, the response surface methodology was used to optimize the adsorption conditions.

Reusable bentonite clay: modelling and optimization of hazardous lead and p-nitrophenol adsorption using a response surface methodology approach.

In this work, bentonite clay (BC) calcined at 500 °C was used as an adsorbent (BC-500) for the adsorption of Pb2+ and p-nitrophenol. The ability of BC-500 for the removal of Pb2+ and p-nitrophenol has been investigated. The adsorption studies tailored well the pseudo-first-order and the Langmuir model for Pb2+ and p-nitrophenol both. In addition, the optimal removal of Pb2+ and p-nitrophenol was found at pH 5 for Pb2+ and pH 6 for p-nitrophenol. However, the change of temperature (20-60 °C) was found to have a negative effect on the adsorption process on BC-500. Based on the Dubinin-Radushkevich model the adsorption occurs via a physical process. Accordingly, the adsorption mechanism was proposed using N2-physisorption analysis before and after adsorption of Pb2+ and p-nitrophenol. The reusability of BC-500 was examined and the outcomes recommended that BC-500 had good potential as an economic and proficient adsorbent for Pb2+ or p-nitrophenol from contaminated water. Finally, the experimental Pb2+ and p-nitrophenol removal efficiency were found to be 90.93 ± 2.15% and 98.06 ± 1.87% while the predicted value by model equals 91.28 ± 1.68 and 97.24 ± 2.54, respectively, showing that the predicted model values are in good agreement with the experimental value.

Kinetics, equilibrium, statistical surface modeling and cost analysis of paraquat removal from aqueous solution using carbonated jujube seed.

This paper reports the removal of paraquat from an aqueous solution using prepared carbonated jujube seed (JS/HSO-700). JS/HSO-700 was characterized by XPS, TGA, FTIR, N2 physisorption, SEM, and Raman techniques. FTIR revealed the presence of active species on the JS/HSO-700 surface. The removal rate of paraquat was investigated as a function of multiple operational factors such as contact time, adsorbent dose and solution pH. Adsorption mechanism was fully investigated based on FTIR, Raman, and BET analyses before and after adsorption. Response surface methodology modeling using central composite design was performed to statistically optimize the adsorption conditions. The experimental paraquat removal efficiency was found to be 96.7 ± 2.02%, whereas the predicted value of the model was 94.31 ± 4.43%, showing that the predicted model values are in good agreement with the experimental value. Finally, cost analysis was performed to confirm the cost of the adsorbent based on energy consumption and reagent costs.

Correction: Reusable bentonite clay: modelling and optimization of hazardous lead and p-nitrophenol adsorption using a response surface methodology approach.

[This corrects the article DOI: 10.1039/C9RA00079H.].

Steam activation of waste biomass: highly microporous carbon, optimization of bisphenol A, and diuron adsorption by response surface methodology.

Highly microporous carbons were prepared from argan nut shell (ANS) using steam activation method. The carbons prepared (ANS@H2O-30, ANS@H2O-90, and ANS@H2O-120) were characterized using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared, nitrogen adsorption, total X-ray fluorescence, and temperature-programmed desorption (TPD). The ANS@H2O-120 was found to have a high surface area of 2853 m2/g. The adsorption of bisphenol A and diuron on ANS@H2O-120 was investigated. The isotherm data were fitted using Langmuir and Freundlich models. Langmuir isotherm model presented the best fit to the experimental data suggesting micropore filling of ANS@H2O-120. The ANS@H2O-120 adsorbent demonstrated high monolayer adsorption capacity of 1408 and 1087 mg/g for bisphenol A and diuron, respectively. The efficiency of the adsorption was linked to the porous structure and to the availability of the surface adsorption sites on ANS@H2O-120. Response surface method was used to optimize the removal efficiency of bisphenol A and diuron on ANS@H2O-120 from aqueous solution. Graphical abstract ᅟ.

Toward new benchmark adsorbents: preparation and characterization of activated carbon from argan nut shell for bisphenol A removal.

The use of argan nut shell as a precursor for producing activated carbon was investigated in this work. Two activated carbons AC-HP and AC-Na were prepared from argan nut shell by chemical activation method using phosphoric acid (H3PO4) and sodium hydroxide (NaOH), respectively. Textural, morphological, and surface chemistry characteristics were studied by nitrogen physisorption, TGA, SEM, TXRF, FTIR, XRD, and by determining the pHPZC of the AC-HP. The adsorption experiments revealed that AC-HP was more efficient in adsorption of BPA due to high specific surface area (1372 m2/g) compared to AC-Na (798 m2/g). The obtained adsorption data of BPA on AC-HP correlated well with the pseudo-second-order model and the Langmuir isotherm (Qmax = 1250 mg/g at 293 K). The thermodynamic parameters (ΔG° < 0, ΔH° < 0, and ΔS° < 0) indicate that adsorption of BPA on AC-HP was spontaneous and exothermic in nature. The regeneration of AC-HP showed excellent results after 5 cycles (95-93%). This work does not only provide a potential way to use argan nut shell but also represents a sustainable approach to synthesize AC-HP, which might be an ideal material for various applications (energy storage, catalysis, and environmental remediation).