Activated carbon (AC) can help overcome toxicity of pollutants to microbes and facilitate soil bioremediation. We used this approach to treat a Histosol and an Alluvial soil historically contaminated with PCB (4190 and 1585 mg kg−1, respectively; primarily tri-, tetra- and pentachlorinated congeners). Results confirmed PCB persistence; reductions in PCB extractable from control and AC-amended soils were mostly due to a decrease in tri- and to some extent tetrachlorinated congeners as well as formation of a bound fraction. Mechanisms of PCB binding by soil and AC were different. In addition to microbial degradation of less chlorinated congeners, we postulate AC catalyzed dechlorination of higher chlorinated congeners. A large decrease in bioavailable PCB in AC-amended soils was demonstrated by greater clover germination and biomass. Phytotoxicity was low in treated soils but remained high in untreated soils for the duration of a 39-month experiment. These observations indicate the utility of AC for remediation of soils historically contaminated with PCB. Activated carbon promotes remediation of soils historically contaminated with PCB.

Batch adsorption experiments were carried out to study the adsorptive removal and diffusion mechanism of para-chlorophenol (p-CP) onto Calgon Filtrasorb 400 (F400) activated carbon. The external mass transfer resistance is negligible in the adsorption process carried out under different conditions in batch operation. Intraparticle diffusion model plots were used to correlate the batch p-CP adsorption data; three distinct linear sections were obtained for every batch operation. The textural properties of F400 activated carbon showed that it has a large portion of supermicropores, which is comparable to the size of the p-CP molecules. Due to the stronger interactions between p-CP molecules and F400 micropores, p-CP molecules predominantly diffused and occupied active sites in micropore region by hopping mechanism, and eventually followed by a slow filling of mesopores and micropores. This hypothesis is proven by the excellent agreement of the intraparticle diffusion model plots and the textural properties of F400 activated carbon.

Polyfluoroalkyl compounds (PFCs) are widely used in industry and consumer products. These products could end up finally in landfills where their leachates are a potential source for PFCs into the aqueous environment. In this study, samples of untreated and treated leachate from 22 landfill sites in Germany were analysed for 43 PFCs. ΣPFC concentrations ranged from 31 to 12,819 ng/L in untreated leachate and 4-8060 ng/L in treated leachate. The dominating compounds in untreated leachate were perfluorobutanoic acid (PFBA) (mean contribution 27%) and perfluorobutane sulfonate (PFBS) (24%). The discharge of PFCs into the aqueous environment depended on the cleaning treatment systems. Membrane treatments (reverse osmosis and nanofiltrations) and activated carbon released lower concentrations of PFCs into the environment than cleaning systems using wet air oxidation or only biological treatment. The mass flows of ∑PFCs into the aqueous environment ranged between 0.08 and 956 mg/day.

Actually, there is a growing interest in finding efficient low-cost materials that allow the removal of chemical substances from water in order to decrease the environmental impact. The use of nanoscale systems is a new area of investigation for the elimination of polluting agents from water among other useful applications in science and technology. In this work, removal of indigo blue in water solutions has been evaluated using Fe/Cu nanoparticles and composites of C/Fe–Cu nanoalloy. The first composite was using carbon obtained by pyrolysis of sewage sludge with Fe/Cu nanoparticles (MCL-NP); the second one was made with commercial activated carbon and Fe–Cu nanoparticles (CAC-NP). Synthesis of materials were carried out by the sodium borohydride reduction of FeSO4[Symbol: see text]7H2O and CuSO4[Symbol: see text]5H2O aqueous mixture. Batch adsorption and isotherm experiments were carried out in order to know the behavior of each adsorbent material employed. The experimental data were adjusted to Langmuir, Freundlich, and BET models.

The feasibility of using recycled granular tire rubber (GTR) to remove molinate from contaminated water bodies was evaluated in this study. Adsorption equilibrium data was well described by a linear isotherm, and the adsorption was completely reversible. Breakthrough curves showed column efficiencies of approximately 40%, based on total capacity, and complete bed regeneration was achieved using clean water. The effluent from the regeneration step was successfully decontaminated using a defined bacterial mixed culture, capable of molinate mineralization. It was shown that this treated water can be used for regenerating a subsequently saturated bed. The GTR adsorbent showed two important features: complete reversibility towards molinate adsorption and stability along successive adsorption/bio-regeneration cycles. Common adsorbents, such as activated carbons and resins, loose performance very quickly under the same conditions, due to irreversible adsorption.

Sorption equilibrium of phenol and aniline onto the granular activated carbon and hyperreticulated un-functionalized polymeric resin (MN200) was investigated in single and binary component aqueous systems. Higher loading was obtained for aniline than phenol onto both sorbents, which is probably due to hydrophobic difference between both solutes and the greater electronic density of the aromatic ring of the aniline. Granular activated carbon reported larger uptake than resin MN200 for both solutes, which may be attributed to the better physical properties of the granular activated carbon, for instance, larger surface area. The experimental sorption could be properly described by the Langmuir and Freundlich isotherms. Five models for predicting the binary equilibrium sorption isotherm were compared in order to determine the best fit model to correlate binary experimental data: the extended Langmuir isotherm with and without a constant interaction factor, a simplified model based on the single equilibrium factors, the empirical extended Freundlich isotherm and the modified extended Langmuir equation, which considers the synergistic interactions between sorbate-sorbate and not only the competition between them defined by the extended Langmuir model. The modified extended Langmuir model provides the best agreement between predicted and experimental data indicating that the synergistic interactions between solutes play an important role in the binary phenol/aniline sorption system.

The adsorption of pentachlorophenol (PCP) from aqueous solutions using pristine multi-walled carbon nanotubes (MWCNTs) was studied kinetically and thermodynamically. The results showed that MWCNTs are good adsorbents for the elimination of PCP from aqueous solutions in a very short time compared with activated charcoal. The kinetics study showed that the adsorption of PCP is mainly due to the diffusion of PCP from the aqueous phase to the solid phase beside intra-particle diffusion. This intra-particle diffusion was more significant for activated charcoal compared with MWCNTs. The equilibrium adsorption of PCP at different temperatures was studied, and the adsorption isotherms were well described using different adsorption models. Thermodynamics study showed that the adsorption process was product-favored (enhanced) as the temperature decreased.

Microwave (MW) is applied to enhance pentachlorophenol (PCP) removal using zerovalent iron (ZVI, Fe⁰) or granular activated carbon (GAC) as the dielectric media. Applying MW energy at 700 W for 20 s, the results show that Fe⁰ is capable of enhancing the CB removing 2.7 times (91% vs. 34 %) than GAC. Because Fe⁰ has higher dielectric loss (39.5 F/m vs. 8.3 F/m), it absorbs more MW energy to speed up the oxidation rate resulting in a faster temperature rise than GAC. Thus, in the presence of MW, Fe⁰ is superior to GAC for PCP removal. Additionally, excessive MW exposure will damage the surface structure of either Fe⁰ or GAC causing excessive electric charges to accumulate in the media that brings about the phenomenon of sparks.

Cadmium-contaminated soils can be re-used and also produce biomass energy if we plant soybeans or other biomass crops in the contaminated sites. In this study, two soils with pH values of 5.9 and 6.7 were artificially spiked to make their final total concentration as CK (about 1.0), 3.0, and 5.0 mg Cd kg⁻¹. Different amendments were mixed with these artificially Cd-contaminated soils to study the effect on the growth and Cd uptake of soybean, which include control (without amendment addition), powder-activated carbon (1%), and biosolids (sludge, 5%), respectively. Three kilograms of the treated soils was added into each pot and sowed 10 seeds of soybean (Leichardt species). The experiment was conducted in a 25°C greenhouse and controlled the soil water contents in the levels of 50-70% water holding capacity during the experimental period. Plants were harvested after growing for 90 days, and their fresh weights, dry weights, and plant heights were determined and recorded. Compared with the lower pH soil (5.9), soybeans were higher and have higher fresh weights and dry weights when growing in the higher pH soil (6.7). For most of the treatments, the two amendments had no significant effects on the plant heights of soybeans. For 3.0 or 5.0 mg Cd kg⁻¹ soil, the application of biosolids has significant effect on increasing the fresh weights and dry weights of soybeans (p < 0.05). However, there were no specific effects of applying activated carbons on the fresh weights and dry weights of soybeans.