Nitrogen-doped activated carbon from activation of polyaniline for efficient adsorption of organic pollutants

Nitrogen addition increases the ecological and human health risks of PAHs in different fractions of soil in sewage-irrigated area

Ultra-high molecular weight poly(vinylamine) polyelectrolyte-functionalized 3D graphene oxide composite aerogels with pH-adaptability for the multi-selective adsorption of organic pollutants

The edible and non-edible varieties of mushroom can be used as a green adsorbent and can be used in modified and natural form for the adsorption of dyes, pollutants and heavy metals. However, the use of edible mushroom varieties in the adsorption of pollutants is not judicious because edible mushrooms have good nutritive and medicinal properties and can be used for consumption. Recent research is thus focused on the utilization of spent mushrooms. Spent mushroom substrate, generated as waste by mushroom industries after the harvesting of mushroom, and hence, is the source of immobilized mushroom mycelium. The species of mushroom Agaricus, Pleurotus, Lentinus, Calocybe are efficient adsorbents with 70–90% removal of pollutants in laboratory conditions. Spent mushroom substrates can also remove pollutants such as dyes, heavy metals, pesticides and fungicides in laboratory conditions with comparable efficiency as mushroom. Chemisorption and physisorption processes are involved in the adsorption. The data of adsorption are well fitted to Langmuir isotherm, revealing the involvement of monolayer adsorption irrespective of the use of mushroom fruit bodies or spent mushroom substrate. Fourier-transform infrared spectroscopic analysis reveal the presence of carboxyl, hydroxyl, amino group in the adsorption of pollutants, dyes and heavy metals.

The unique morphology and structure of carbon nanotubes (CNTs) keep attracting a great number of researchers to explore the novel properties of these materials. The special structure of CNTs determines its physical and chemical properties, mainly reflected in its novel electrical, mechanical properties and excellent adsorption performance. This review summarizes the adsorption properties of CNTs and their properties related to the adsorption of various heavy metal ions, organic and inorganic pollutants from large volumes of aqueous solutions. CNTs is a kind of potential environmental material. This article also put forward future opportunities for CNTs application in environmental systems.

Adsorption of organic pollutants (OPs), bisphenol A, and diuron, from aqueous solutions onto porous carbon materials (CMs) prepared from olive kernels, have been investigated. The effects of initial pH, initial OP concentration, temperature, and contact time on the adsorption capacity were studied. The adsorption of bisphenol A and diuron onto CMs was found to be optimal at pH 5.6 and 6.9, respectively. It was noticed that the adsorption of those organic pollutants from aqueous solution declined with increasing temperature and the process is exothermic. The rate of adsorption followed the second order kinetic equation. The equilibrium results showed that Langmuir model fits well with the data. The maximum adsorption capacities obtained using the best CM were 476 and 434 mg g-1 for BPA and diuron, respectively. The results showed that CMs made from olive kernels are an excellent and inexpensive biomass waste-derived sorbent. Graphical abstract.

X-ray powder diffraction studies were performed with propyl-, dodecyl-, and dodecyldiam-monium bentonites saturated with aqueous mixtures of eleven organic pollutants at concentrations of 0.01 to 100%. The alkylammonium salt treatment separated the montmorillonite unit layers, which increased the interlamellar volume and exposed the interlamellar surfaces for adsorption of the organic pollutants. Washing the salt-treated clays with distilled water removed excess, physically adsorbed alkylammonium ions that could interfere with adsorption of the organic pollutants. Adsorption isotherms conducted at organic pollutant concentrations of 100 and 1000 mg/liter indicated the three alkylammonium montmorillonites, especially propylammonium montmorillonite, were effective adsorbents from aqueous solution, but to a lesser extent than adsorbents currently used in the water and wastewater fields.

Microplastics (MPs) are persistent tiny pieces of plastic material in the environment that are capable of adsorbing environmental organic pollutants from their surroundings. The interaction of MPs with organic pollutants alters their environmental behavior, i.e., their adsorption, degradation and toxicity, etc. Polyethylene (PE) is the most widely used plastic material. The environmental weathering of PE results in changes to its surface chemistry, making the polymer a much better vector for organic pollutants than virgin PE. In this study, a laboratory-accelerated weathering experiment was carried out with a virgin PE film and an oxidatively degradable PE (OXO-PE) film, i.e., PE modified by the addition of a pro-oxidant catalyst. The degradation of PE and OXO-PE was assessed through Fourier transform infra-red (FTIR) spectroscopy and their wettability was measured by contact angle (CA) measurements. Their thermal properties and morphology were studied using thermogravimetric analyses (TGA) and scanning electron microscopy (SEM), respectively. Further, the adsorption of two model organic pollutants onto weathered and virgin PE was analyzed. Triclosan (TCS) and methylparaben (MeP) were chosen as model organic pollutants for the adsorption experiment due to their frequent use in the cosmetics industry, their uncontrolled release into the environment and their toxicity. The adsorption of both model pollutants onto PE and OXO-PE MP was analyzed by using gas chromatography with a flame ionization detector (GC-FID). The adsorption of MeP onto OXO-PE was higher than onto PE MPs. However, TCS showed insignificant adsorption onto PE and OXO-PE. When both pollutants were present simultaneously, the adsorption of TCS onto both PE and OXO-PE was significantly influenced by the presence of MeP. This result demonstrates that the adsorption behavior of one pollutant can be significantly altered by the presence of another pollutant. Both the effect of weathering on the adsorption of organic pollutants as well as the interaction between organic pollutants adsorbing onto MPs is highly relevant to actual MP pollution in the environment, where MPs are exposed to weathering conditions and mixtures of organic pollutants.

Graphene-based adsorbents show great potential for application in the field of environmental pollution treatment due to their unique two-dimensional structure, high specific surface area, and tunable surface chemistry. This paper reviews the research on the application of graphene and its derivatives as novel adsorbents in the field of wastewater treatment in recent years, focusing on the preparation and functionalization of graphene-based adsorbents, as well as their adsorption performance and mechanism of action in the removal of inorganic and organic pollutants, and provides an outlook on the future directions of the research on graphene-based adsorbents. The analysis in this paper focuses on the functionalization of graphene-based adsorbents by introducing magnetic particles, hybridization with other materials, and grafting with polymers. The modified graphene-based adsorbents showed significant adsorption and removal of pollutants and were easy to recycle and regenerate. The adsorption of pollutants on graphene-based adsorbents is mainly carried out through π–π interaction, hydrogen bonding, and electrostatic interaction, which is related to the structure of the pollutants. Future research directions on graphene-based adsorbents should focus on in-depth adsorption mechanism studies and the development of cost-effective graphene-based adsorbents for wastewater treatment.

The studies on microplastics are significant in the world. According to the literature, microplastics have greatly specific surface areas, indicating high adsorption capacities for highly toxic pollutants in aquatic and soil environments, and these could be used as adsorbents. The influencing factors of microplastic adsorption, classification of microplastics, and adsorption mechanisms using microplastics for adsorbing organic, inorganic, and mixed pollutants are summarized in the paper. Furthermore, the influence of pH, temperature, functional groups, aging, and other factors related to the adsorption performances of plastics are discussed in detail. We found that microplastics have greater advantages in efficient adsorption performance and cost-effectiveness. In this paper, the adsorptions of pollutants by microplastics and their performance is proposed, which provides significant guidance for future research in this field.

Adsorption of common greywater pollutants and nutrients by various biochars as potential amendments for nature-based systems: Laboratory tests and molecular dynamics

A review of the adsorption of organic pollutants on mesoporous carbons and carbon/silica hybrids

To determine the competitive adsorption characteristics and influencing factors of chlorinated and aromatic hydrocarbons on the aquifer medium, toluene, benzene, 1,2−dichloropropane, and 1,2,3−trichloropropane (TCP) were selected as typical pollutants for adsorption tests. The results showed that the adsorption process of pollutants on the aquifer medium conformed to the first−order kinetic and Henry linear model equation, and the adsorption capacity decreased in the order of toluene, benzene, 1,2−dichloropropane, and TCP. Benzene promoted the adsorption of toluene on the aquifer medium, while toluene reduced the adsorption of benzene conversely. 1,2−dichloropropane restrained the adsorption of TCP, and TCP had no significant effect on the adsorption of 1,2−dichloropropane. The adsorption capacity of TCP on the aquifer increased with the concentration of toluene. TCP acted as a stimulus for the adsorption of toluene when the initial concentration of toluene was lower than 2 mg/L. In contrast, TCP served as an inhibitor for the adsorption of toluene on the aquifer medium. Furthermore, the adsorption of all pollutants increased with decreasing medium size. The promotion rates for aromatic and chlorinated hydrocarbons were 7.2~41.1% and 2.7~27.1%, suggesting that the promotion effect on aromatic hydrocarbons was stronger than that on chlorinated hydrocarbons. Natural organic matter (NOM) inhibited the adsorption of pollutants on the aquifer medium (especially for high concentrations of chlorinated hydrocarbons), and the adsorption rate increased by more than 60% when OM decreased from 0.25% to 0.08%. Clay minerals improved the adsorption of organic pollutants in different compound pollution systems, and montmorillonite exhibited a stronger promoting effect than kaolin.

Engineering carbon materials for organic pollutant removal via adsorption and photodegradation: A review

Is clay-polycation adsorbent future of the greener society? In silico modeling approach with comprehensive virtual screening

Organogel adsorbents are widely used for the adsorption of hard-to-degrade organic pollutants in wastewater due to their natural affinity to the organic phase in water. In this study, phenolic xerogels (PF) synthesised in the ethylene glycol inorganic acid system are used as a backbone and superhydrophobic phenolic xerogels (ASO-PF) are obtained by grafting aminosilanes onto the PF backbone via the Mannich reaction. The modified ASO-PF not only retains the pore structure of the original PF (up to 90% porosity), but also has excellent superhydrophobic properties (water contact angle up to 153°). Owing to the unique pore structure, ASO-PF has excellent compression properties, cycling 50% compression deformation more than 10 times without being damaged, with a maximum compression deformation of up to 80%. A squeeze–suction–squeeze approach is proposed for selective adsorption of organic pollutants in homogeneous solutions based on the recyclable compression properties of ASO-PF. The ASO-PF is put under negative pressure by squeezing, and when the pressure is released, the adsorbed liquid enters the ASO-PF, where the organic pollutants are retained by the adsorption sites in the skeleton, and then the remaining water is discharged by squeezing. This breathing ASO-PF holds great promise for organic pollutant adsorption and recovery applications.