Here, Box-Behnken design (BBD) approaches were utilised to optimise synthesis methodology for the chitosan-calcite rich adsorbent (CCM) made from fishery-food waste material (crab carapace), using ...low-temperature activation and potassium hydroxide (KOH). The effect of activation temperature, activation time and impregnation ratio was studied. The final adsorbent material was evaluated for its phosphorus (P) removal efficiency from liquid phase. Results showed that impregnation ratio was the most significant individual factor as this acted to increase surface deacetylation of the chitin (to chitosan) and increased the number of amine groups (–NH
2
) in the chitosan chain. P removal efficiency approached 75.89% (at initial P concentration of 20 mg/L) under optimised experimental conditions, i.e. where the impregnation ratio for KOH:carapace (g/g) was 1:1, the activation temperature was 105 °C and the activation time was 150 min. Predicted responses were in good agreement with the experimental data. Additionally, the pristine and CCM material were further analysed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Brunauer-Emmett-Teller technique (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Characterisation showed enhancements in surface chemistry (introducing positively charged amine groups), textural properties and thermal stability of the CCM.
Municipal wastewater is a valuable source of phosphorus (P) for the production of fertilizing products, such as microalgae (MA), crab carapace material (CCM), P salt produced by chemical leaching of ...sludge (P salt CL), and sewage sludge ash produced by pyrolysis and the incineration of sludge (SSA PI). This study compares the P availability of these fertilizing products in three planting substrates (S1, S2, and S3) during a four-month growth period of perennial ryegrass. The unfertilized control in substrate S3 had a high and available P that masked the effect of the added fertilizing products. The P salt CL fertilizer exhibited the lowest shoot dry matter in the alkaline S2 substrate. Still, it can be used as a good source of P in both acidic and alkaline substrates, given that its shoot P content was among the highest in all substrates tested. The organic-rich fertilizing products, MA and CCM, are better suited for acidic substrates since a pronounced reduction in the shoot yield and P content was seen in the alkaline S2 substrate. In contrast, for the SSA PI fertilizer, the very small differences in shoot dry matter and P content in S1 compared to S2 indicated that it is suitable for both acidic and alkaline substrates. Four months were needed to observe the maximum shoot yields treated with these P fertilizing products. Considering that the substrate solution P (using Rhizons) for the P salt CL and MA fertilizers proved to be similar to shoot P uptake, Rhizon extraction could be used for assessing P bioavailability. The chemical composition of novel products indicated their potential to deliver not only P, but also other nutrients to plants. However, concentrations of inorganic contaminants in all products, except CCM, pointed out a possibility to pollute the environment by applying these fertilizers.
The usage of pharmaceuticals (PhCs) as an integral part of human healthcare is growing globally. However, as most current wastewater treatment plants (WWTPs) are not designed for the removal of PhC ...residues, effective and cost-efficient new technologies are required to meet this challenge. Adsorption has proven to be an efficient method, however, traditional adsorbents e.g., activated carbons and ion-exchange resins are often excessively costly. Therefore, there is a growing interest in novel low-cost adsorbents, which have a high affinity toward PhCs. This review focussed on two priority pharmaceutical classes, metformin (MF) a biguanide, and macrolides (e.g., clarithromycin, erythromycin, azithromycin) and assesses isotherm, kinetic and thermodynamic studies (and modelling), as well as the adsorption mechanisms with discussion on some identified mistakes and inconsistencies. The review also sought to identify gaps in knowledge that should be priorities for future investigations. The review indicated maximum adsorption capacities from Langmuir isotherm were found to be 0.34–278 mg/g for MF and 7.56–340 mg/g for macrolides. Data showed kinetics to be well represented by the pseudo-second order model and that mass transfer was predominantly controlled by both film and intraparticle diffusion. However, there was little information in the literature on the mechanisms involved in adsorption of these compounds, or involving dynamic conditions or real-world application (real effluents in environmentally relevant concentrations). Therefore, future priorities should include scale-up, effluent studies, and cost-analysis and environmental impact (e.g., Life Cycle Analysis). These are required to assess the commercial viability of the adsorbents for PhCs removal in WWTP applications.
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•A review of metformin (biguanides) and macrolides removal from water by adsorption using various adsorbents.•Major effect of pH on adsorption mechanisms.•Incomplete and misinterpreted kinetic, isotherm and thermodynamic modelling.•Lack of utilisation of characterisation techniques to determine the governing adsorption mechanisms.•Economic and larger scale technical applicability of the process must be assessed.
This paper investigates the ability of the phosphoric acid functionalized Prunus armeniaca stones biochar (AsPhA) prepared by thermochemical activation to remove lead (Pb2+), cadmium (Cd2+), nickel ...(Ni2+), naproxen and chlorophenols from aqueous wastes. The engineered biochar was characterized using the Scanning Electron Microscopy, Energy-dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy and Brunauer, Emmett and Teller technique. The batch studies were performed by varying the initial pH of the solution (2–9), adsorbent dosage (0.2–10gL−1), contact time (5–60min), temperature (22, 32 and 42°C) and initial adsorbate concentration (5–500mgL−1). With the optimal process conditions, the adsorption efficiency was over 95% (100mgL−1). The results were fitted with three kinetic and three equilibrium theoretical adsorption models. The adsorption process has good correlation with pseudo-second-order reaction kinetics. Adsorption mechanism was found to be controlled by pore, film and particle diffusion, throughout the entire adsorption period. The monolayer adsorption capacities were found to be 179.476, 105.844 and 78.798mgg−1 for Pb2+, Cd2+ and Ni2+, respectively. Thermodynamic parameters such as Gibbs energy, enthalpy and entropy were also calculated. Additionally, preliminary results indicated a strong affinity of the biochar for selected organic micropollutants: naproxen and chlorophenols. Based on desorption study results, biochar was successfully regenerated in 3cycles with diluted phosphoric acid produced as a waste stream during washing of the biochar after thermochemical activation. The experimental results were applied in a two-stage completely stirred tank reactor design. Cost estimation of AsPhA production substantiated its cost effectiveness and adsorption costs of selected pollutants were 5 times lower than with the commercial activated carbons. Based on the low-cost and high capacity, engineered biochar can be used as a highly efficient eco-friendly adsorbent for removal of heavy metal and organic micropollutants from wastewaters systems.
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•Engineered biochar for heavy metals and organic micropollutants removal was studied.•Production cost and properties suggest that it can be a promising green adsorbent.•The adsorption capacity with 179.48mgg−1 mainly depends on the surface chemistry.•Adsorption mechanisms were detailed analyzed.•A novel biochar could be applied into slurry reactor wastewater treatment systems.
Plum stones, as a part of industrial and municipal organic waste, were used as a precursor for preparation of a low-cost activated carbon. Engineered, thermochemically-modified adsorbent was used to ...remove lead (Pb2+), cadmium (Cd2+), nickel (Ni2+) and chlorophenols from an aqueous solution. The characterization of the medium was performed using standard instrumental analysis. Additionally, the assessment included the influence of pH, adsorbent dosage, temperature, contact time and initial metal concentration on the separation efficiency in the batch-operational mode. With optimal working conditions, the process efficiency of over 95% was accomplished. The equilibrium and kinetic studies of adsorption were done. The pseudo-second order model described the adsorption kinetics best. The maximum adsorption capacity of the engineered adsorbent for Pb2+, Cd2+ and Ni2+ ions was calculated from the Langmuir isotherms and found to be 172.43 mg g−1, 112.74 mg g−1 and 63.74 mg g−1, respectively. Preliminary results indicate a strong affinity of the separation medium for chlorophenols. Thermodynamic parameters such as Gibbs energy, enthalpy and entropy were calculated. Regeneration of the saturated adsorbent was conducted, with diluted phosphoric acid produced as a waste stream, during the washing of the adsorbent after activation. Based on the desorption study results, the activated carbon was successfully regenerated in 3 cycles. Mutual influence of ions was analyzed in multicomponent systems. The real system production and operational costs analysis confirmed a possibility for a successful implementation of the highly efficient, eco-friendly engineered adsorbent in the field of cost-effective wastewater treatment.
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•Heavy metals and chlorophenols removal on green-activated carbon were studied.•High specific surface area (879 m2 g−1) activated carbon was prepared.•The adsorption capacity with 172.43 mg g−1 mainly depends on the surface chemistry.•A novel activated carbon could be applied into wastewater treatment.•Our approach is simple and inexpensive with the production cycle without any waste.
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•“Acid catalyst” functionalised carbonous adsorbent for pharmaceutical removal is studied.•Importance of phosphate and phosphonate surface groups on the adsorbent is ...highlighted.•Detailed instrumental analysis of adsorption mechanisms is presented.•High adsorption capacities for all pharmaceuticals (23.332 mg g−1 for ibuprofen) was found.•Adsorption mechanisms can be explained by H-bonding, π–π and n–π electron donor–acceptor interactions.
А highly effective adsorbent (PPhA) was designed using “acid catalyst” functionalisation and tested for six emerging PhCs (sulfamethoxazole (SMX), carbamazepine (CBZ), ketoprofen (KP), naproxen (NPX), diclofenac (DCF) and ibuprofen (IBF)) in a batch study. Characterisation results (BET, SEM, FTIR, XRD and pHzpc) showed that the functionalisation process generates a microporous material with a multitude of new functional groups (such as phosphate and phosphonate) present on the surface. Adsorption capacity reached near maximum within 10 min while equilibrium was obtained in 60 min. Findings suggest that the mass transfer was governed mainly by intraparticle diffusion processes through formation of H-bonds, π–π and n–π electron donor–acceptor interactions. A pH influence study showed that electrostatic interactions played a minor role in the overall removal mechanism. The magnitude of E was <8 kJ mol−1 for all studied PhCs, indicating that adsorption is mainly due to physisorption. Equilibrium data were best represented by the Freundlich model and the theoretical monolayer adsorption capacities were 17.193, 17.685, 19.265, 17.657, 21.116 and 23.332 mg g−1 for SMX, CBZ, KP, NPX, DCF and IBF, respectively. Based on these results, this PPhA is proposed as an excellent adsorbent for PhC removal.
Diclofenac (DCF), naproxen (NPX) and ibuprofen (IBF) are three of the most commonly used non-steroidal anti-inflammatory drugs (NSAIDs) worldwide. They are widely detected in natural waters due to ...their persistence in wastewater treatment, and their removal is desirable in future wastewater management worldwide. In this study, “acid catalyst” functionalisation and subsequent carbonisation were adopted to synthesise a P-doped microporous carbonous adsorbent (CScPA) for NSAID removal. The CScPA was evaluated in depth for its adsorption performance (i.e., isotherms, kinetics and thermodynamics of adsorption at lab-scale). The CScPA had a large surface area (791.1 m2/g) and good porosity (0.392 cm3/g), which facilitated a high maximum adsorption capacity of 62.02 mg/g for a NSAID mixture. Thermodynamic data indicated that the adsorption of these NSAIDs was an endothermic process determined by physisorption (low-energy interactions). XPS analysis revealed the specific interactions involved in the adsorption process, including π-π and n-π electron donor-acceptor (EDA) interactions and hydrogen (H-) bonding. The Freundlich isotherm and Elovich kinetic model provided the best fit to the experimental results, which indicated surface heterogeneity (of the CScPA) and cooperative adsorption mechanisms. The adsorption process was shown to have potential to be applied to real wastewater effluent containing NSAIDs at low environmentally relevant concentrations (removal reached > 90% at 10 μg/L). Analysis of different implementation and cost related factors suggested that the CScPA has the potential for use with “real-world” water matrices, offering a sustainable treatment process for pharmaceutical remediation in wastewater.
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•“Acid catalyst” functionalisation was applied to synthesise a P-ordered adsorbent.•An adsorption capacity of 5.6 mg/g was achieved using real wastewater effluent.•Adsorption mechanisms were governed by pore filling, EDA interactions and H-bonding.•O- and P-containing functionalities were responsible for the adsorption interactions.•A treatment cost of ∼0.24 $/m3, indicated the economic viability of using the adsorbent.
Metformin (MF) is widely used in the prevention and treatment of Type 2 diabetes and gestational diabetes. Following its medical administration, it may pass through the body and be introduced into ...the wastewater treatment system. However, conventional treatment plants are ineffective in removal of MF from wastewater resulting in its introduction into the aquatic environment. Novel and effective methods of MF removal are therefore required to prevent contamination of natural waters. In this work, a magnetised iron-biochar composite derived from brewery waste (magnetic brewery spent grain; MBSG) was generated and evaluated for its ability to remove MF from aqueous media. Response surface methodology (RSM) was applied to identify optimal adsorption parameters. Extensive instrumental characterisation including XPS, FTIR, EPR, Raman spectroscopy and SQUID were used in conjunction with kinetic, isotherm and thermodynamic studies to determine that H-bonding, electrostatic attraction and so-called π-π (electron donor-acceptor) EDA interactions were the mechanisms involved in the adsorption processes. Modelling showed that the MF adsorption was best described by both the Langmuir and the Freundlich models, with the value of qmax = 15.2 mg/g governed by the pseudo-second order kinetic model; and it was a spontaneous (∆G = −17.7 kJ/mol) and endothermic (∆H =38.5 kJ/mol) process. Desorption studies were conducted to evaluate the potential for regeneration and reuse of the material. These demonstrated citric acid (0.2 M) to have significant potential as a regenerative reagent, but that further optimisation is required. This work revealed that MBSG could be a sustainable and effective adsorbent for the removal of aqueous MF in water treatment.
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•Spent grain from breweries is used as low-cost precursor for synthesis of a magnetic biochar composite.•Magnetic biochar composite used for the remediation of emerging metformin from water.•ϒ-Fe3O4 nanoparticles (crystalline magnetite) were detected on biochar surface.•Low enthalpy (<50 kJ/mol) with characterisation indicated dominant physisorption.•Adsorption mechanisms were governed by pore filling, H-bonding and so-called π-π EDA interactions.
Development, characterization and evaluation of the efficiency of cost-effective medium for the removal of Pb2+, Cd2+ and Ni2+ from aqueous systems, as a novel, eco-friendly solution for wastewater ...remediation were done. The precursors for low-cost adsorbent were lignocellulosic raw materials (sweet/sour cherry kernels), as industrial byproducts and components of organic solid waste. Activated carbon synthesis was carried out by thermochemical conversion (H3PO4, 500 °C) in the complete absence of inert atmosphere. Characterization of the activated carbon was performed by elemental analysis, FTIR, SEM, EDX and BET. BET surface area corresponds to 657.1 m2 g−1. The evaluation also included the influence of pH, contact time, solute concentration and adsorbent dose on the separation efficiency in the batch operational mode. The equilibrium and kinetic studies of adsorption were done. The maximum adsorption capacity of the activated carbon for Cd2+ ions was calculated from the Langmuir isotherm and found to be 198.7 mg g−1. Adsorption of Pb2+ and Ni2+ were better suitable to Freundlich model with the maximum adsorption capacity of 180.3 mg g−1 and 76.27 mg g−1, respectively. The results indicate that the pseudo-second-order model best describes adsorption kinetic data. Based on desorption study results, activated carbon was successfully regenerated with HNO3 for 3 cycles. In order to provide the results for basic cost-effective analysis, competing ion-effects in a real sample have been evaluated.
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•Pb2+, Cd2+ and Ni2+ removal on cherry kernels activated carbon were studied.•Low-cost activation develops large pore volume with 657.1 m2 g−1 surface area.•The sorption capacity with 171.4 mg g−1 mainly depends on the surface chemistry.•The produced adsorbent could be applied into wastewater treatment.•Our approach was simple and inexpensive.
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