Emerging contaminants (EC's) are pollutants of growing concern. They are mainly organic compounds such as: pesticides, pharmaceuticals and personal care products, hormones, plasticizers, food ...additives, wood preservatives, laundry detergents, surfactants, disinfectants, flame retardants, and other organic compounds that were found recently in natural wastewater stream generated by human and industrial activities. A majority of ECs does not have standard regulations and could lead to lethal effects on human and aquatic life even at small concentrations. The conventional primary and secondary water treatment plants do not remove or degrade these toxic pollutants efficiently and hence need cost effective tertiary treatment method. Adsorption is a promising method worldwide for EC removal since it is low initial cost for implementation, highly-efficient and has simple operating design. Research has shown that the application of different adsorbents such as, activated carbons(ACs), modified biochars (BCs), nanoadsorbents (carbon nanotubes and graphene), composite adsorbents, and other are being used for EC's removal from water and wastewater. The current review intends to investigate adsorption process as an efficient method for the treatment of ECs. The mechanism of adsorption has also been discussed.
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•Emerging contaminant removal.•Activated carbon and biochar.•Nanoadsorbent.•Composites.•Clays and other adsorbents.
In the adsorption literature, the Van't Hoff equation is used in different manners without any criteria about the concepts of physical-chemistry of equilibrium for calculation of thermodynamic ...parameters of adsorption. Indeed, the equilibrium constant (K) should be dimensionless for being used in the Van't Hoff equation. However, this is not a simple adjustment of units, as being spread in the literature, to become K dimensionless. In this paper, it will be calculated the equilibrium constants using numeric examples and show the flaws of the thermodynamics calculations, when the value of K is wrongly calculated, and what are the expected results of the changes in enthalpy (ΔH°) and changes in the entropy (ΔS°) that are spread in the literature.
•Determination of thermodynamic parameters by using Van't Hoof equation.•The correct equilibrium constant for determination of thermodynamic parameters of adsorption.•Use of nonlinear equilibrium isotherms at several temperatures to obtain the K.
•Cellulose-g-poly-(acrylamide-co-acrylic acid) adsorbent was prepared by grafting.•Single adsorption of toxic inorganic pollutants on adsorbent was investigated.•Various adsorption kinetic and ...isotherm models were fitted with experimental data.•Equilibrium data was best suited and explained by Langmuir isotherm model.•Adsorption kinetics from faster to slowest was found as Cu2+ > Cd2+ > Zn2+> Pb2+.
Cellulose biopolymer was functionalized by free graft copolymerization and used as a new adsorbent to eliminate toxic inorganic pollutants from wastewater. Functional graft copolymers from cellulose were characterized by FT-IR spectroscopy, XRD, TGA, and SEM-EDX techniques.Cellulose-g-poly-(acrylamide-co-acrylic acid) polymer adsorbent showed high adsorption capacities for the Cd2+, Cu2+, Pb2+ and Zn2+ toxic metal ions, which were evidenced by the comparison with unmodified cellulose-richsamples. Cellulose-g-poly-(acrylamide-co-acrylic acid) polymer adsorbent was optimized with various adsorption parameters such as the effect of pH, contacttime, temperature, and metallic ions concentration. The maximum monolayer capacity qm calculated for Cd2+, Cu2+, Pb2+, Zn2+ were 101.73, 61.84, 209.64, and 55.04 mgg−1 respectively. Thus, these results proved that cellulose-g-poly-(acrylamide-co-acrylic acid) graft copolymer adsorbent from cellulose-rich biomass could potentially be used for the removal of pollutants from wastewater.
The aim of this article is to review and present the state of the arte about the status of toxic elements (TEs) in soils and assess the potential risk using single and total complex pollution indices ...in a global scale. We compiled, integrated, and analyzed soil TE pollution data over almost a decade through key maps, which have not been reviewed up to date. All the in-situ and ex-situ remediation treatments have been also reviewed, illustrated, and compared, for the first time. The future perspectives have been discussed and summarized. This review demonstrates that the cornerstone maps and integrated information provide reliable geographical coordinates and inclusive information on TEs pollution, particularly in China. In-situ treatment approaches for TEs polluted soils are more cost-effective and applicable than ex-situ treatment trials. Selecting a feasible remediation strategy should to take the extent of contamination, treatment objectives, site characteristics, cost-efficiency, and public suitability into account. The summarized findings in this review may help to develop innovative and applicable methods for assessing the global soil pollution by TEs. Also, these findings may help to develop innovative, applicable, and feasibly economic methods for sustainable management of TEs contaminated soils to mitigate the environmental and human health risk.
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•Assessment of complex soil indices is crucial for soil quality investigation.•Maps are favorable for geographical coordinate and toxic element (TE) concentration.•Various decontamination strategies have been established for TE contaminated soils.•In situ treatments of TE contaminated soils is more cost-effective than ex-situ ones.•Contaminated soil data is essential for the selection of the best treatment strategy.
This review discusses the imminent threat that microplastics (MPs) associated with pharmaceuticals represent to the aquatic environment and public health. We initially focused upon recognizing and ...stressing that MPs are ubiquitous pollutants. The influence of environmental factors, such as pH, mechanical stress, and photodegradation, are examined, aiming to elucidate how both substances might associate, what are their simultaneous degradation pathways and, to understand the interactions between MPs and pharmaceuticals. Mathematical tools, such as modeling and simulations, are presented in detail, aiming to improve how information is interpreted. Furthermore, it is exhibited that MPs sorption and interaction behavior towards organic contaminants play an important role in understanding its dynamics in the environment, as well as their possible interactions with pharmaceuticals that are summarized. At last, MPs and pharmaceuticals toxicity and bioaccumulation are presented.
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•Weathering heavily influence MPs sorption of organic contaminants.•Understanding MPs sorption modeling can improve further data interpretation.•MPs and pharmaceuticals, when combined, present increased toxicity.•MPs influence on pharmaceuticals degradation in the environment remains unclear.
Tetracycline (TC) is one of the antibiotics that is found in wastewaters. TC is toxic, carcinogenic, and teratogenic. In this study, the tetracycline was removed from water by adsorption using ...dioxide silicon nanoparticles (SiO2 NPs) biosynthesized from the extract of Nerium oleander leaves. These nanoparticles were characterized using SEM-EDX, BET-BJH, FTIR-ATR, TEM, and XRD. The influences of various factors such as pH solution, SiO2 NPs dose, adsorption process time, initial TC concentration, and ionic strength on adsorption behaviour of TC onto SiO2 NPs were investigated. TC adsorption on SiO2 NPs could be well described in the pseudo-second-order kinetic model and followed the Langmuir isotherm model with a maximum adsorption capacity was 552.48 mg/g. At optimal conditions, the experimental adsorption results indicated that the SiO2 NPs adsorbed 98.62% of TC. The removal of TC using SiO2 NPs was 99.56% at conditions (SiO2 NPs dose = 0.25 g/L, C0 = 25 mg/L, and t = 40 min) based on Box–Behnken design (BBD) combined with response surface methodology (RSM) modelling. Electrostatic interaction governs the adsorption mechanism is attributed. The reusability of SiO2 NPs was tested, and the performance adsorption was 85.36% after the five cycles. The synthesized SiO2 NPs as promising adsorbent has a potential application for antibiotics removal from wastewaters.
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•SiO2 nanoparticles were biosynthesized from an extract of Nerium oleander leaves.•SiO2 NPs is efficient adsorbent to remove tetracycline from water.•The maximum quantity adsorbed was 552.48 mg/g.•SiO2 NPs have excellent reusability using 0.1 M NaOH.•The TC removal was 99.56% using BBD-RSM in optimal conditions.
The water reservoirs are getting polluted due to increasing amounts of micropollutants such as pharmaceuticals, organic polymers and suspended solids. Powdered activated carbon (PAC) has been proved ...to be a promising solution for the purification of water without having harmful impacts on the environment. Parameters such as PAC dosing, wastewater hardness, the effect of coagulant and flocculant were evaluated in a batch scale study. These parameters were further applied on a pilot plant scale for the performance evaluation of PAC based removal of micropollutants concerning the contact time and PAC dosing with main focus on recirculation of PAC sludge. The obtained optimum dose was 10–20 mg/L providing 84.40–91.30% removal efficiency of suspended solid micropollutants (MPs) and this efficiency increased to 88.90–93.00% along with coagulant which further raised by the addition of polymer and recirculation process at batch scale. On pilot plant scale, the concentration in contact reactor and PAC removal effectiveness of dissolved air flotation, lamella separator and sedimentation tank were compared. Constant optimisation resulted in a concentration ranging from 2.70 to 3.40 g/L at dosing of PAC 10 mg/L, coagulant 2.00 mg/L and polymer 0.50 mg/L. PAC doses of 10–20 mg/L with 15–30 min contact time proved best for above 70–80% elimination. The recirculation system has also proved an efficient technique because the PAC's adsorption capacity was practically completely used. Small PAC dosages yielded high micropollutants elimination.
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•The application of PAC for advanced wastewater treatment at lab and pilot plant scale.•Testing of suitable type and dosing amount of PAC, coagulant (FeCl3) and flocculant (polymer).•The optimisation of operational units of pilot plant setup for efficient removal of micropollutants.•The effect of recirculation process for obtaining effective results at minimum energy inputs and cost.•The removal efficiency of micropollutants from influent and effluent of WWT was more than 80%.
Rare earth elements (REEs) have gained considerable attention due to their unique properties and their use in huge range of industrial applications. They are widely used in different sectors such as, ...nuclear energy, metallurgy, medicine, chemical engineering, electronics, and computer manufacturing. As a result, the recovery of REEs is a significant issue that needs appropriate attention. There are many methods to recover REEs such as precipitation, filtration, solvent extraction etc. but these methods are not economically attractive. Among the available methods, adsorption has gained wider attention because of its simplicity, high efficiency and low cost. This review article presents the recently published literature (after 2013) regarding the removal of rare earth metals from aqueous solution by different low cost adsorbents. For this purpose, best applying model (isotherm, kinetic), thermodynamic studies and other factors which influence the adsorption process (such as the effect of solution pH, contact time, temperature and adsorbent's dose) are also discussed.
•Adsorbents for Rare earths recovery•Equilibrium, kinetic, thermodynamic modeling•Enthalpy-entropy compensation
In the present study, zinc chloride (ZnCl2) followed by acid treating was employed for the fabrication of activated biochar from pomegranate husk (APHBC) for 2,4-dichlorophenol (2,4-DCP) adsorption ...from an aqueous solution. The batch adsorption experiments were carried out as a function of solution pH, APHBC dose, initial 2,4-DCP concentration, contact time, and ionic strength. The APHBC showed a well-developed pore with specific surface areas of 1576 m2/g due to explosive characteristics of ZnCl2. In addition, the XRD analysis showed that the diffraction peaks between 15 and 35° corresponded to amorphous carbon. The pore size distribution results showed that APHBC was dominantly mesoporous materials. The pHpzc value of APHBC was 6.15 ± 0.15. According to batch experiments, the optimum adsorption conditions were pH of 3.0, contact time 60 min, APHBC dose of 1.75 g/L and without ionic strengths. The absorption capacity of 2,4-DCP at the initial concentration of 150.0 mg/L promptly decreased from 259.5 ± 12.9 to 74.5 ± 3.7 mg/g as the APHBC dose increased from 0.50 to 2.00 g/L. The isotherm and kinetics study of 2,4-DCP adsorption by APHBC revealed that Liu and Avrami fractional-order well fitted with experimental data, respectively.
•APHBC is prepared from pomegranate husk using ZnCl2 for 2,4-DCP adsorption.•APHBC had a total pore volume of 0.83 cm3/g and a surface area of 1576.0 m2/g.•APHBC presented high adsorption capacity of 2,4-DCP.•Microporous filling and hydrogen bonds are predominant in 2,4-DCP adsorption by APHBC.•The –OH group is the crucial functional group affecting the 2,4-DCP adsorption.
The ubiquitous appearance of nonsteroidal anti-inflammatory drugs (i.e., naproxen) in water bodies has raised enormous concerns among general public. Development of promising materials for ...eliminating such contaminants from water environment has attracted much attention in the scientific community. In this study, three (direct, post-treated and pre-treated) methods were developed to prepare biochars (800-PSB, 800-800-PSB, and 190-800-PSB, respectively) derived from the wastes of peanut shells (PS). They were thoroughly characterized by various important properties (i.e., porosity and superficial functional group) and applied to remove naproxen drug from water. Results indicated that although the pre- and post-treatments had a slight effect on the surface area of biochars (i.e., 571 m2/g for 800-PSB, 596 m2/g for 800-800-PSB, and 496 m2/g for 190-800-PSB), such treatments remarkably improved the adsorption capacity of biochar. The maximum adsorption capacity of biochar (obtained from the Langmuir model) towards naproxen in solution at 25 decreased in the following order: 800-800-PSB (324 mg/g) > 190-800-PSB (215 mg/g) > 800-PSB (105 mg/g). The thermodynamic study demonstrated that the adsorption was spontaneous and exothermic. Depending the preparation process, the contribution of each mechanism in the adsorption process was dissimilar. The overall adsorption mechanism was regarded as pore filling, π-π interaction, hydrogen bonding formations, n-π interaction, van der Waals force, and electrostatic attraction. Two methods used to identify the important role of π-π interaction were proposed herein. The possible desorption and reuse of laden-biochars were investigated by the chemical and thermal methods. The prepared biochar samples can serve as potential carbonaceous porous adsorbents for effectively removing naproxen from water media.
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•Different carbonization processes were applied to convert biomass into biochars.•Biochars were applied to remove naproxen from water and wastewater.•Biochar produced from interrupted pyrolysis exhibited excellent adsorption capacity.•Adsorption mechanism was explored and proposed from various experimental data.•Pore filling and π-π interaction played a proper role in adsorption mechanism.
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