Search

Living organisms are at great risk from the highly toxic metal cadmium (II). It is not allowed to be in industrial effluent or drinking water that is dumped into cadmium-containing water bodies. It has been classified as a carcinogen by the IARC and the US EPA. Thus, it is essential to discover a practical and economical technique for removing cadmium from an aqueous solution. In the present work, a novel and easy-to-prepare component of graphene oxide/orange peel/chitosan composite (GO-OP-CS) was prepared and examined using various analytical techniques as a hybrid product with improved physicochemical properties and metal ion Cd(II) adsorption capabilities. The results showed that Cd (II) ion adsorption occurred initially fairly fast and that a pH of 6 was optimal for both adsorption and removal of Cd (II) ions. The thermodynamic analysis revealed that the adsorption of Cd(II) is spontaneous and exothermic. The experimental results showed that the functional groups present on the adsorbent surfaces (such as hydroxyl, carboxyl, epoxy, amine, and so on) led to the improvement of the Cd(II) metal's ability to absorb. This novel composite exhibited a high adsorption capacity (qmax) of 537.63 mg/g. The results of the toxic Cd(II) sorption using the synthesized composite showed that its adsorption kinetics and sorption isotherm confirmed the pseudo-second-order and Langmuir models, respectively. The proposed method is also reliable for Cd(II) sorption for preconcentration and remediation before Cd testing from genuine samples, such as wastewater, digested tobacco, and e-battery samples. [ABSTRACT FROM AUTHOR]

Alternanthera philoxeroides (AP) is a typical invasive plant. The quick spread of AP biomass may cause serious threat to ecological balance and biodiversity of the local area. However, AP has a high content of potassium, making it possible for preparing biochar through a self-activation process. In this study, AP biomass was employed to prepare porous carbon through a simple one-step pyrolysis. The effect of pyrolysis temperature (T) and carrier gas flow rate (v) onto the target carbon was intensively discussed. The obtained carbon were employed as adsorbents for methylene blue (MB) adsorption. Results showed that both of the T and v played great influence on the porous structure of the obtained biochar. Higher pyrolysis temperature and lower carrier gas flow rate were in favor of the formation of micropore and mesopore. The biochar obtained from 900°C pyrolysis temperature and 20 cm3 min−1 carrier gas flow rate (BC/900–20) possessed a satisfying specific surface area (825.6 m2 g−1) through the direct one-step pyrolysis, verifying the existence of pyrolysis gas self-activation and inorganic salt template self-activation effect. The maximum adsorption capacities calculated from Langmuir model were 424.9 mg g−1 for BC/900–20, which was comparable to that of the adsorbents reported recently. [ABSTRACT FROM AUTHOR]

Magnetic biochar (Fe3O4-BCPP) was prepared by using iron oxide nanoparticles, and biochar which is obtained from pomegranate peel. The Fe3O4-BCPP were characterized by Brunauer-Emmett-Teller analysis, X-ray diffraction analysis, scanning electron microscopy, and vibrating sample magnetometer. The adsorption properties of Fe3O4-BCPP for sulfadiazine in water were investigated. The Fe3O4-BCPP had good adsorption properties and separated well from aqueous solution by a permanent magnet due to superparamagnetic property and magnetic saturation value. Therefore, Fe3O4-BCPP has potential application for the removal of sulfadiazine from water samples. [ABSTRACT FROM AUTHOR]

Petroleum hydrocarbons, including alkanes ranging from C10 to C32, have been recognized as priority organic water contaminants with a toxic impact on ecosystems. Therefore, the removal of these contaminants is of utmost importance to protect humans, plants and animals. In this work, biochar derived from the dead leaves of the widely-distributed seagrass Halodule uninervis (SGC) was prepared through biomass pyrolysis at 800°C and characterized using SEM, FTIR, TGA and surface area analysis. The prepared SGC was investigated for adsorptive removal of total petroleum hydrocarbons (TPHs) and individual alkane hydrocarbons (C10 to C32) from water contaminated with crude oil. The SGC displayed good removal efficiency, adsorption capacity and recyclability toward these hydrocarbons. Using the SGC, 98.8% of the TPHs were removed within 300 minutes with an adsorption capacity of 23.5 mg/g. The adsorption results were tested with the most commonly used isotherm and kinetics models. The hydrocarbon adsorption data for the SGC fit the Langmuir and Freundlich isotherms, which indicates non-uniformity of the adsorbent and a predominance of multilayer adsorption of the hydrocarbons onto the prepared SGC adsorbent. The performance and reusability of the prepared SGC adsorbent were promising, losing only 22% of its hydrocarbon removal efficiency after the 3rd cycle. [ABSTRACT FROM AUTHOR]

We evaluated the potential application of tobacco as a low-cost raw matter for the development of a new and ecological activated biochar, with the aim of chlorpyrifos adsorption. This was performed by means of characterization and testing the efficiency of the activated biochar based on tobacco from seized cigarettes. Chemically and thermally activated biochar were produced with different chemical modifying agents (ZnCl2 and NaOH). The treatments improved the features of adsorbent structure, with an increase of 1775x in SSA of AB-ZnCl2. The adsorption of chlorpyrifos by the activated biochar seems to occur partially by chemical and partially by physical interactions between the pesticide and the surface functional groups O–H, C–H, C=O, C–C, C–H, and C–O. The good adjustments may indicate the adsorption of mono and multilayer. The materials show great results for removal of chlorpyrifos with an estimate qm of 683.30 and 1602.40 µg g−1 for Langmuir, respectively, found for AB and for AB-ZnCl2. This way, the production of activated biochar can be an excellent alternative for the destination and use of tobacco from seized cigarettes, allowing its use in remediation and decontamination of water. [ABSTRACT FROM AUTHOR]

An efficient adsorbent was derived from Sargassum boveanum macroalgae (BCM) through a thermal pyrolysis process. It was characterized and investigated for the removal of 2,4,6–Trichlorophenol (TCP) from the aqueous solution. The effects of adsorbent mass, adsorbate concentration, and contact time were examined. The maximum removal efficiency and adsorption capacity were 100% and 175 mg g−1, respectively. The adsorption fitted Freundlich model and followed pseudo-second order kinetics. It was also found that the adsorption process was spontaneous, endothermic, and thermodynamically favorable. This study indicated that BCM adsorbent can remove 60% of TCP from the high saline seawater and it is reusable for three times. [ABSTRACT FROM AUTHOR]

Poly(acrylamide)-rice husk biochar [p(AAm)-RHB] hydrogel composites (HBC-RH) were used to eliminate phenols. The characterization of prepared composite was investigated by using SEM, TEM, TGA DSC, and FTIR. Based on our findings, the highest removal of phenol and p-nitrophenol (PNP) was found as 82.2% and 84.6% in 50 mg/L solution at pH = 7, respectively. The results revealed that the kinetic data were best fitted by pseudo-first-order for phenol and pseudo-second-order for PNP. To be concluded that the Temkin model perfectly described the removal of phenol and HBC-RH can be widely applied for various containments. [ABSTRACT FROM AUTHOR]

Dried (nonactivated) and water-soaked (activated) pecan shells were pyrolyzed at 450°C for 1 h. The pecan shells were heated in a reduced oxygen environment and cooled under positive pressure of nitrogen. Batch sorption experiments were done to evaluate the biochar's ability to adsorb lead from aqueous solution. Several characterization analyses were performed including FT-IR, elemental analysis, SEM, EDX, and BET. Nonactivated pecan shell biochar (NPSB) has an adsorption capacity of 36.5 mg/g and the water-activated pecan shell biochar (WPSB) adsorbs 61% more lead with a capacity of 58.6 mg/g. The yield of the WPSB is marginally higher than NPSB (34.8% and 33.7%, respectively); however, there are significant differences in the surface morphology. NPSB has a total surface area of 25.48 m2/g. Of this, 29.74% is micropore volume. After water activation, WPSB's total surface area increases to 41.51 m2/g and the micropore volume was significantly reduced. [ABSTRACT FROM AUTHOR]

Plant biochars were prepared by slow pyrolysis of Mentha plant waste to remove cationic dye methylene blue (MB) from aqueous solution. The biochars were characterized by X-Ray diffraction, IR-spectroscopy, thermogravimetric analysis, scanning electron microscope, cyclic voltammetry (CV), Brunauer-Emmett-Teller analysis, and zeta potential analyzer. Adsorption isotherms and kinetics applied on the MB dye removal by biochars showed monolayer chemisorption of MB dye. Present investigation revealed that removal of MB dye was due to synergistic action of chemisorption coupled with reductive electron transfer mechanisms. CV test showed a reversible, coupled redox reaction at interface of MB dye and biochar particles. [ABSTRACT FROM AUTHOR]

Rice straw presents a good potential as feedstock to prepare biochar. In this study, two different pyrolysis methods, that is, slow pyrolysis and direct pyrolysis are applied to carbonize the rice straw in muffle furnace. SEM and TEM images indicate that both samples display porous structure, while BET data confirm that biochars from direct pyrolysis process own higher specific surface area and pores volume than that from slow pyrolysis. Two samples are employed to metal ions Pb(II), Cu(II), Mn(II), and Cr(III) sorption from aqueous solution. The influence of reaction time, pH, and metal ions initial concentration on sorption are evaluated. [ABSTRACT FROM AUTHOR]

In the present investigation, date seed-derived biochar was applied as economic and effective sorbent for remediation of reactive dye from contaminated solutions. Biochar produced at 350°C through pyrolysis process exhibited reactive black 5 (REB5) sorption capacity 2.7 times higher than virgin date seeds. The surface of biochar was analyzed through Fourier transform infrared and scanning electron microscope data. The maximum REB5 uptake determined through the Langmuir model was found to be 113.4 mg/g. The REB5 sorption kinetics were accurately described by the pseudo-first-order model than pseudo-second-order model. Thermodynamic parameters indicated that REB5 sorption was spontaneous, feasible, and endothermic process. [ABSTRACT FROM AUTHOR]

In a multicomponent systems, the adsorption of Pb2+, Cu2+, and Ni2+ by date seed biochar exhibited competitive behavior. Compared to single component systems, the adsorption capacities of each ion were reduced by 48-75% in both batch and column experiments. Surface complexation with carboxyl and hydroxyl functional groups played a major role in the removal mechanism. Ion exchange mechanism accounted for 37-40% of the total adsorption compared to 57-72% in single component systems. Modified Langmuir isotherm best described the systems. Adsorption capacities and selectivity follow the order: Pb2+> Cu2+> Ni2+. Multi-stage sequences system is recommended to avoid premature exhaustion of biochar. [ABSTRACT FROM AUTHOR]

The activated biochar (ABC) was prepared, characterized and examined the feasibility of removing ethylparaben (EP) from aqueous solution. The characterization results showed that ABC possessed multi-porous structure and high surface area. The adsorption isotherm was well fitted the Langmuir isotherm and the adsorption kinetic followed the pseudo-second-order model. The maximum adsorption capacity of EP onto ABC was 349.65 mg/g at 298 K. The adsorption capacity maintained 90.82% after five successive adsorption/desorption cycles. ABC possessed high adsorption capacity, usability and stability, which indicating that ABC has great potential to be a promising adsorbent for removal of EP from aqueous solution. [ABSTRACT FROM AUTHOR]

The carboxyl-modified biochar derived from palm fiber was prepared through pyrolysis and oxidation. The adsorption behavior for Pb(II), Cu(II) and Cd(II) on the carboxyl-modified biochar was systematically investigated. The experimental results demonstrated that the carboxyl-modified biochar exhibited impressive adsorption performance owing to its multi-porous structure and abundant adsorption sites on the surface. The maximum adsorption capacities for Pb(II), Cu(II) and Cd(II) reached 218.5, 132.1 and 79.9 mg/g, respectively. The adsorption kinetics and isotherm could be well described by the pseudo-second-order model and the Langmuir isotherm model, respectively. After five successive adsorption/desorption cycles, the removal efficiency was still more than 90%, 86% and 83% for Pb(II), Cu(II) and Cd(II), respectively. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the efficiency of typical heavy metals in electroplating sludge in terms of different phosphorus dosages (0.5 wt.%, 1 wt.% and 3 wt.%), initial pH (2, 3, 4, 5 and 6) and adsorption times (1, 3, 5, 7 and 12 h) of biochar. The heavy metal speciation was determined after adsorption to estimate the stability of ion-adsorption precipitation. Results show that phosphorus-modified biochar enhances the removal efficiency of heavy metals. Low mobility of heavy metal speciation was investigated. It is also shown that initial pH has a significant impact on the heavy metal speciation after adsorption. [ABSTRACT FROM AUTHOR]

Biochar is increasingly used as a low-cost and effective adsorbent for heavy metals in wastewater. Herein, biochar pyrolyzed from rice straw was employed as an adsorbent for the removal of Th(IV) from aqueous solutions. The sorption of Th(IV) on biochar was strongly dependent on pH, but independent on ionic strength at pH < 6.4. The inner-sphere complexation dominated the sorption mechanism of Th(IV) on biochar. The competition for Th(IV) between aqueous or surface-adsorbed cations/anions and functional groups of biochar was pivotal for Th(IV) sorption. The thermodynamic data suggested that Th(IV) sorption was a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

A novel magnetic biochar was prepared via pyrolysis method and modification. The influence factors of contact time, initial concentration, temperature, and pH on the adsorption were investigated. The experimental results exhibited that the adsorption ability of methyl salicylate onto biochar was higher than that of phenol and para-chlorophenol under the same condition, which may be owing to the effect of hydrogen bonding, hydrophobicity, and π-π interaction. The maximum adsorption capacities of phenol, para-chlorophenol and methyl salicylate were 62.6, 131.6, and 169.7 mg/g at 298 K, respectively. This magnetic biochar exhibited high reusability (retained 82.1% after five cycles) and sharply magnetic performance (21.4emu/g). [ABSTRACT FROM AUTHOR]

Three types of magnetic biochars (MBC1, MBC2, and MBC3) were synthesized from biochar using NaBH4as a reducing agent of Fe(II) to Fe(0) to remove copper(II) ions from different wastewaters. Based on the research it was found that removal of copper(II) ions by MBC1 occurs with a yield of 99.8% for the concentration 50 mg/dm3and decreases to 71.7% at 200 mg/dm3. The maximum pH sorption was found at pH 5. The highest correlation coefficient values (65.55 mg/g) were obtained for the Langmuir isotherm model. Application of 0.5 mol/dm3HNO3as a desorbing agent gives the highest desorption percentage 98.92%. [ABSTRACT FROM AUTHOR]

Magnetic biocomposite (MB) was fabricated by co-precipitation of palm seed-based biochar in the presence of Fe3O4particles. The MB sorption behaviour was investigated using nickel as the target pollutant. The MB characterisation revealed that its maintained micro-mesoporous character and high saturation magnetisation (65.8 Am2/kg) enable it to be separated from a solution using a magnet. The nickel removal efficiency of MB, 87% (28 mg/g), was achieved at pH 3; however, this was reduced to 45–75% (15–24 mg/g) in the presence of competing ions. The isotherms and kinetics studies revealed a monolayer interaction via a two-stepped sorption mechanism. [ABSTRACT FROM AUTHOR]

Farmyard manure (FYM-BC) and poultry manure (PM-BC) derived biochars were applied as adsorbents to remove Cd2+from water. Results indicated that PM-BC was a more efficient adsorbent than FYM-BC at all experimental conditions. Maximum Cd2+adsorption was observed at pH 4, temperature 318 K and contact time 1 h, regardless of biochar type. The Langmuir model predicted maximum adsorption capacity of 90.09 mg g−1for PM-BC. The data fitting to pseudo-second-order model proposed chemisorption of Cd2+onto biochars. Thermodynamics indicated that adsorption was spontaneous and endothermic. Post-adsorption analysis provided evidences of strong chemical interactions between biochars’ functional groups and Cd2+ions. [ABSTRACT FROM PUBLISHER]

The surface of wheat straw-based biochar was modified by a pretreatment using H3PO4. Biochars with different surface characteristics were obtained and characterized. Their reducing and sorption capacities for aqueous Cr(VI) were evaluated. The removal of Cr(VI) were enhanced with an increase in biochar surface acidity. The sorption performance was related to the equilibrium concentration. Oxygen-containing groups were involved in Cr(III) complexation, some of which were formed due to Cr(VI) oxidation. The competitive sorption of proton was evident for over protonated biochars at low range. Biochar porosity also played a role. The influences of other factors were also discussed. [ABSTRACT FROM PUBLISHER]

The extraction of pollutants from water using activated biochar materials is a low cost, sustainable approach for providing safe water in developing countries. The adsorption of copper ions, Cu(II), onto pyrolyzed and activated dried banana peel was studied and compared with the adsorption of copper ions onto a commercial activated carbon, F-400. Both the physical and chemical properties of the banana peel and activated carbon were measured. Pyrolysis of dried banana peels resulted in the formation of a large, porous surface area adsorbent with strongly negative surface charges. Screening studies, which were designed to evaluate the effect of the mass of the adsorbent, pH of the solution, tumbling time, and initial Cu(II) concentration were conducted for each adsorbent. Equilibrium adsorption data were also analyzed, and the Freundlich isotherm resulted in a better fit than the Langmuir isotherm. The degree of favorability of adsorption of Cu(II) ions and adsorption capacity were 1.25 and 351.1 mg/g for pyrolyzed banana peel, respectively. The sorption kinetics fit a pseudo-second order equation. The mechanism of adsorption of metal ions on pyrolyzed banana peel followed ion exchange and electrostatic interactions resulting in the complexation of adsorbed ions. [ABSTRACT FROM AUTHOR]

This study examined the ability of two sugarcane bagasse biochars to remove lead from water. The sorption of lead by biochars made from raw (BC) and anaerobically digested sugarcane bagasse (DBC) was compared with a commercial activated carbon (AC) using batch sorption experiments. DBC was a more effective sorbent of lead from water than AC, and far more effective than BC. The maximum lead sorption capacity of DBC (653.9 mmol kg-1) was about double that of AC (395.3 mmol kg-1) and about twenty times higher than that of BC (31.3 mmol kg-1). Post-sorption characterizations using X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the enhanced sorption of lead by DBC was at least partly related to a precipitation mechanism, while surface adsorption was the principal mechanism of sorption of lead onto BC. These results suggest that biochars made from bagasse and other agricultural residues may be effective alternative, low-cost environmental sorbents of lead or other metals. In addition, the enhanced lead sorption ability of the digested bagasse biochar introduces the possibility of developing a novel carbon production method to use anaerobic digestion as a means of biological activation to create high-efficiency sorbents. [ABSTRACT FROM AUTHOR]