Activated carbon (AC)/CoFe
2
O
4
nanocomposites, MAC-1 and MAC-2, were prepared by a simple pyrolytic method using a mixture of iron(III)/cobalt(II) benzoates and iron(III)/cobalt(II) oxalates, ...respectively, and were used as efficient adsorbents for the removal of amoxicillin (AMX) and paracetamol (PCT) of aqueous effluents. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The sizes of cobalt ferrite nanoparticles formed from benzoates of iron(III)/cobalt(II) and oxalates of iron(III)/cobalt(II) precursors were in the ranges of 5–80 and 6–27 nm, respectively. The saturation magnetization (
M
s
), remanence (
M
r
) and coercivity (
H
c
) of the MAC-2 nanocomposites were found to be 3.07 emu g
−1
, 1.36 emu g
−1
and 762.49 Oe; for MAC-1, they were 0.2989 emu g
−1
, 0.0466 emu g
−1
and 456.82 Oe. The adsorption kinetics and isotherm studies were investigated, and the results showed that the as-prepared nanocomposites MAC-1 and MAC-2 could be utilized as an efficient, magnetically separable adsorbent for environmental cleanup. The maximum sorption capacities obtained were 280.9 and 444.2 mg g
−1
of AMX for MAC-1 and MAC-2, respectively, and 215.1 and 399.9 mg g
−1
of PCT using MAC-1 and MAC-2, respectively. Both adsorbents were successfully used for simulated hospital effluents, removing at least 93.00 and 96.77% for MAC-1 and MAC-2, respectively, of a mixture of nine pharmaceuticals with high concentrations of sugars, organic components and saline concentrations.
In this work, Norway spruce bark was used as a precursor to prepare activated biochars (BCs) via chemical activation with potassium hydroxide (KOH) as a chemical activator. A Box-Behnken design (BBD) ...was conducted to evaluate and identify the optimal conditions to reach high specific surface area and high mass yield of BC samples. The studied BC preparation parameters and their levels were as follows: pyrolysis temperature (700, 800, and 900 °C), holding time (1, 2, and 3 h), and ratio of the biomass: chemical activator of 1: 1, 1.5, and 2. The planned BBD yielded BC with extremely high SSA values, up to 2209 m
·g
. In addition, the BCs were physiochemically characterized, and the results indicated that the BCs exhibited disordered carbon structures and presented a high quantity of O-bearing functional groups on their surfaces, which might improve their adsorption performance towards organic pollutant removal. The BC with the highest SSA value was then employed as an adsorbent to remove Evans blue dye (EB) and colorful effluents. The kinetic study followed a general-order (GO) model, as the most suitable model to describe the experimental data, while the Redlich-Peterson model fitted the equilibrium data better. The EB adsorption capacity was 396.1 mg·g
. The employment of the BC in the treatment of synthetic effluents, with several dyes and other organic and inorganic compounds, returned a high percentage of removal degree up to 87.7%. Desorption and cyclability tests showed that the biochar can be efficiently regenerated, maintaining an adsorption capacity of 75% after 4 adsorption-desorption cycles. The results of this work pointed out that Norway spruce bark indeed is a promising precursor for producing biochars with very promising properties.
•Biochar with a high surface area (1473 m2g−1) was produced with mesoporous features.•The biochar successfully removed emerging pollutants from synthetic wastewater.•DFT calculation successfully ...elucidated the diphenol adsorption mechanism on biochar.•The HOMO-LUMO energy gap explored the electron properties of the diphenol-biochar system.•The mechanism suggested π electrons at high-energy states with stable π–π conjugation.
Thermal pyrolysis synthesized activated biochar from the Pinus elliottii sawdust (PS) at 600° C. The obtained activated biochar (PB600) was used for the removal of three diphenols, catechol (CAT), resorcinol (RES), and hydroquinone (HYD), which are utilized mainly in different industries. The PB600 was characterized by several analytical techniques. The BET surface area of 1473 m2.g−1 and a total pore volume of 0.707 cm3 g−1 was obtained. The functional groups and amount of acidic and basic groups on the biochar were determined by FTIR and Bohem titration, respectively. From the isotherm studies, it was obtained that the maximum adsorption capacities (Qmax) based on the Liu isotherm model were 419.8 (CAT 45 °C), 263.8 (RES 40 °C), and 500.9 mg g−1 (HYD 25 °C). The values of thermodynamic parameters demonstrated that CAT, RES, and HYD adsorption processes were spontaneous, exothermic, and energetically favorable, and the magnitude of ΔH° was compatible with physisorption. The CAT, RES, and HYD adsorption mechanism onto the biochar is followed by porous filling, π-π interactions, and hydrogen bonds. Subsequently, PB600 biochar was employed as a potential adsorbent for treating simulated industrial effluents in a complex matrix simulating a real industrial effluent, and the overall removal attained up to 95.97 %. In concert with the experimental results, the electronic properties of the developed adsorption systems, including frontier molecular orbitals, charge density difference, and partial density of states, were studied by the density functional theory (DFT) approach to explore the mechanism of adsorption on the activated biochar surface.
Display omitted
Activated carbons from Brazil nutshells were produced by ZnCl2-activation at different biomass: ZnCl2 ratios of 1.0:1.0 and 1.0:1.5 at 600 °C and the samples were denominated as ...BNS1.0 and BNS1.5, respectively. The obtained activated carbons were used in the adsorption of acetaminophen (paracetamol) and for the treatment of synthetic hospital effluents. Several analytical techniques were used to characterize the activated carbons. The N2 isotherms presented the SBET values of the BNS1.0 and BNS1.5 are very high, 1457 and 1640 m2 g−1, respectively. The FTIR and Boehm titration analysis demonstrated the presence of several surface functional groups on both ACs surfaces, which can influence the acetaminophen adsorption. The adsorption studies revealed that the maximum adsorption capacities (Qmax) are very high for both ACs; however, the BNS1.5 capacity is higher (411.0 mg g−1) than that of BNS1.0 (309.7 mg g−1). The thermodynamic assessments revealed that the process of acetaminophen adsorption is spontaneous, energetically favorable, and exothermic, and the magnitude of enthalpy is compatible with physisorption. Besides, it suggests that the acetaminophen adsorption on both ACs is dominated by van der Walls forces and microporous filling mechanism. The use of activated carbons for treatment of synthetic hospital effluents, containing different pharmaceuticals as well as organics and inorganic salts, presented a high percentage of removal (up to 98.83%). The adsorbent was magnificently regenerated up to 74% with a mixture of 0.1 mol L−1 NaOH + 20% EtOH solution and can be reused up to four cycles ensuring sustainable use of proposed adsorbent for acetaminophen removal from aqueous media. In the light of these results, it is possible to say that Brazil nutshell is an excellent raw material to prepare efficient ACs which can be successfully used in the treatment of real hospital effluents.
In this study, avocado seed was successfully used as raw material for producing activated carbons by conventional pyrolysis. In order to determine the best condition to produce the activated carbons, ...a 2
2
full-factorial design of experiment (DOE) with three central points was employed by varying the temperature and time of pyrolysis. The two evaluated factors (temperature and time of pyrolysis) strongly influenced the
S
BET
, pore volumes, hydrophobicity–hydrophilicity ratio (HI) and functional groups values; both factors had a negative effect over
S
BET
, pore volumes and functional groups which means that increasing the values of factors leads to decrease of these responses; on the other hand, with regards to HI, both factors caused a positive effect which means that increasing their values, the HI has an enhancement over its values. The produced activated carbon exhibited high specific surface areas in the range of 1122–1584 m
2
g
−1
. Surface characterisation revealed that avocado seed activated carbons (ASACs) have hydrophilic surfaces and have predominantly acidic groups on their surfaces. The prepared ASACs were employed in the adsorption of 25 emerging organic compounds such as 10 pharmaceuticals and 15 phenolic compounds which presented high uptake values for all emerging pollutants. It was observed that the activated carbon prepared at higher temperature of pyrolysis (700 °C), which generated less total functional groups and presented higher HI, was the activated carbon with higher sorption capacity for uptaking emerging organic contaminants. Based on results of this work, it is possible to conclude that avocado seed can be employed as a raw material to produce high surface area and very efficient activated carbons in relation to treatment of polluted waters with emerging organic pollutants.
Porous activated carbons (ACs) prepared from a lignocellulosic waste, Caesalpinia ferrea seed pod wastes (CF) were utilised for removing captopril pharmaceutical from synthetic hospital effluents and ...aqueous effluents. Chemical activation using ZnCl2 was performed. It was utilised the following proportions CF-Biomass: ZnCl2 (1: 0.5, 1:1 and 1:1.5, obtaining CFAC.0.5, CFAC.1.0, and CFAC.1.5 activated carbons. These mixtures were pyrolysed at 600 °C in a conventional furnace. The ACs were characterised by FTIR, hydrophobic/hydrophilic ratio (HI), CHN/O elemental analysis, Boehm titration, surface areas (SBET), total pore volumes, and pore size distribution. These analyses show that the ACs presents several functional groups on AC surfaces and there is a predominance of hydrophilic surfaces. All the activated carbons prepared presented surface area 1050–1480 m2 g−1. Regarding the adsorption process, the kinetics data were fitted to General-order kinetic model and equilibrium of adsorption data were well represented by and Liu isotherm model. The maximum adsorption capacity of 535.5 mg g−1 was obtained at 25 °C for the sample CFAC.1.5. The thermodynamic studies have shown that the adsorption process of captopril is spontaneous and favourable. The employment of the ACs for treating simulated effluents, with different emerging contaminants, showed an excellent removal (up to 97.67%). This result is evidence that Caesalpinia ferrea seed pod wastes were a high-efficiency precursor for AC preparation and that such activated carbons could be used for treating hospital effluents containing pharmaceuticals.
•Caesalpinia ferrea seed pods were used as carbon source for preparation of activated carbon.•Efficient removal of captopril pharmaceutical from hospital effluents was obtained.•Maximum captopril sorption capacity of 776.2 mg g−1.•The several functional groups of ACs surface leads to a hydrophilic surface of ACs.
Activated carbons (ACs) prepared from tucumã seed (Astrocaryum aculeatum) were used for 2-nitrophenol removal from aqueous solutions. The ACs were characterized by elemental analysis, FTIR, N
2
...adsorption/desorption isotherms, TGA, hydrophobicity/hydrophilicity balance, and total of acidic and basic groups. The ACs showed to have hydrophilic surfaces and they presented high specific surface areas (up to 1318 m
2
g
−1
). In batch optimization studies, maximum removal was obtained at pH 7, contact time of 30 min, adsorbent dosage 1.5 gL
−1
and temperature of 50°C. The general-order kinetic model and Liu isotherm model best fit the kinetic and equilibrium adsorption data with a maximum adsorption capacity of 1382 mg g
−1
at 50°C. Effect of temperature and thermodynamic studies revealed that the adsorption processes of 2-nitrophenol onto ACs are dependent on temperature and are exothermic and spontaneous, respectively. About the applicability of the ACs for treating simulated effluents, the tucumã seed-activated carbon showed an excellent outcome in the treatment of simulated effluents, evidencing its high efficiency for phenolic compound adsorption. Tucumã seed-ACs showed to be cost effective and highly efficient adsorbents for efficient removal of 2-nitrophenol from aqueous solutions.
Display omitted
•Facile single-step synthesis of new magnetic activated carbon materials was carried out at 600 °C.•The combinations of ZnCl2/NiCl2 simultaneously provide excellent textural ...properties and high magnetization.•Maximum SBET and saturation magnetization of 1281 m2 g−1 and 13.29 emu g−1, respectively was attained.•The Qmax of 199.3 and 335.4 mg g−1 for nicotinamide and propranolol, respectively, was achieved.•The efficient total removal of simulated hospital effluents of 99.1 % was obtained.
The present research describes the synthesis of new nanomagnetic activated carbon material with high magnetization, and high surface area prepared in a single pyrolysis step that is used for the carbonization, activation, and magnetization of the produced material. The pyrolysis step of tucumã seed was carried out in a conventional tubular oven at 600 °C under N2-flow. It was prepared three magnetic carbons MT-1.5, MT-2.0, MT-2.5, that corresponds to the proportion of biomass: ZnCl2 always 1:1 and varying the proportion of NiCl2 of 1.5, 2.0, and 2.5, respectively. These magnetic nanocomposites were characterized by Vibrating Sample Magnetometer (VSM), X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, hydrophobic/hydrophilic balance, CHN/O elemental analysis, modified Boehm titration, N2 adsorption-desorption isotherms; and pHpzc. All the materials obtained presented Ni particles with an average crystallite size of less than 33 nm. The MT-2.0 was employed for the removal of nicotinamide and propranolol from aqueous solutions. Based on Liu isotherm, the Qmax was 199.3 and 335.4 mg g−1 for nicotinamide and propranolol, respectively. MT-2.0 was used to treat simulated pharmaceutical industry effluents attaining removal of all organic compounds attaining up to 99.1 % of removal.
Concrete slurry is an abundant, cheap, and commonly found waste all over the world where construction activities take place; concrete slurry, which is rich in calcium and metallic oxides, could be ...successfully employed in the phosphate (P) removal from aqueous media.
For the first time, the effect of the carbonation process on concrete adsorbent properties and how it can influence on the removal of phosphate ions in aqueous media are studied. Besides, the potential applicability of P loaded concrete adsorbent is also evaluated.
The results showed that a non-carbonated sample was more effective in the P removal, due to higher releasing of calcium (Ca2+) in comparison to carbonated sample. The dissolved Ca2+ from the dissolution of calcium hydroxide (Ca(OH)2), calcium carbonate (CaCO3), and calcium oxide (CaO) are preferably precipitated by phosphates in high pH solution, reflecting in a high initial adsorption rate.
General order kinetic and Liu isotherm provided better-fitting models for the adsorption behavior of P onto both non-carbonated and carbonated concrete samples. Phosphate removal was mainly ruled by chemical adsorption through inner-sphere complexation and P precipitation on the surface of the adsorbent containing Ca2+ as an essential ion in the adsorption mechanism. Compared with other phosphate adsorbents, both non-carbonated and carbonated concrete showed to be economical and efficient adsorbent.
The non-carbonated sample gave a high adsorption capacity of P (47.6 mg g−1) and presenting fast and high initial adsorption, reaching 72% of P removal within 5 min (min) at 22 °C, while carbonated showed adsorption capacity of 30.6 mg g−1, at the same experimental conditions. Therefore, concrete slurries can be used widely as an inexpensive phosphate-recovery adsorbent.
Besides, the application of these P loaded waste as potential fertilizers in soil can be an exciting and environmentally approach for reusing this solid-waste. The environmental analysis highlighted that the adsorbents did not leach out chemicals above the allowable limits, preconized by The Food and Agriculture Organization of the United Nations (FAO) for irrigation waters. However, aspects related to monitoring the presence and mobility of heavy metals on soil must be better addressed and monitored.
Display omitted
•The effect of the concrete carbonation on adsorption properties was investigated.•Non-carbonated concrete presented better adsorption properties.•The dissolved Ca2+ played an important role in the phosphate adsorption.•Non-carbonated and carbonated were efficient adsorbents for phosphate adsorption.•The P loaded concrete could be applied as potential fertilizers in soil.
Natural clay was grafted with 3-aminopropyl-trietoxisilane (APTES) for obtaining an organic-inorganic hybrid material. This material was successfully used as adsorbent for removal of Acid Red 1 ...(AR-1) and Acid Green 25 (AG-25) anionic dyes from aqueous solutions. This work demonstrates the effect of APTES concentration on the hydrophobic/hydrophilic characteristics and optical properties of the amino-functionalized materials. The adsorption capacity of the resultant hybrid materials were studied using anionic dyes. The physico-chemical properties of the materials was determined by several analytical techniques. It appears that the modified samples were more hydrophilic than the natural clay for ratios from 1.0 up to 2.0, due to the presence of amino group (—NH2) located at the end of the chain. The characterization data showed that APTES was successfully grafted on to the external as well as interlayer and broken edges of montmorillonite. Transmission electron microscopic images confirmed that the morphology of amino-functionalized material changed from sheet-like in the natural clay material to a conglobulated structure. The amino-functionalized material exhibited a surface area 6-times (SBET = 13.31 m2/g) lower than natural clay (SBET = 86.10 m2 g−1; Vtol = 0.126 cm3 g−1 and Dp = 4.72 nm). The total pore volume (Vtol = 0.041 cm3 g−1) and average pore diameter (Dp = 10.2 nm) was found to be 2-times lower than clay. Adsorption followed the general-order kinetic model for both dyes. Liu isotherm model was observed to be best fit and it displayed Qmax as 364.1 and 397.0 mg g−1 for AR-1 and AG-25, respectively at 50.0 °C. Electrostatic interaction was the main mechanism involved in the adsorption process. The Mrt-APTES0.5 seemed to be a good adsorbent for the treatment of synthetic effluents. The removal percentage of effluent A and B were 97.94% and 95.94%, respectively.
Display omitted
PDF
