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This work studies the interaction of organic nanoparticles (ON) with various dyes in aqueous solution, to elucidate the role of ON on transport and fate of dyes in the environment, and on dyes removal from wastewater. Studied dyes are Acid Red 66 (AR66), Methylene Blue (MB), Reactive Black 5 (RB5), and Reactive Violet 5 (RV5). ON are extracted from organic matter of anthropogenic origin through resuspension of its colloidal fraction, and successive filtration and dialysis of the obtained suspension. Mechanisms of interaction are investigated initially through three-dimensional excitation emission matrix (3DEEM) analysis. Obtained data indicate that dynamic interactions occur strongly between dye molecules and ON aggregates. 3DEEM spectra of mixed samples containing ON together with one of the tested dyes, present a shape similar to the one of ON alone, but each of them is characterized by specific differences in terms of peaks quenching and shift. The analysis of these singularities suggests that dye molecules are bound to the functional groups of ON through H-bonds, according to the following steps: i) dyes reach the surface of ON aggregates; ii) the molecules pass through the hydrophilic surface of ON aggregates, and reach their hydrophobic core; iii) the dyes are sequestrated into the hydrophobic core of ON aggregates. Nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies analysis confirm the formation of supramolecular aggregates with stable micellar hydrophobic structure, mainly consisting of aliphatic fractions of ON, which explain the disappearance of aromatic groups signals from dyes.

Digestate, as an urban solid waste, was considered as an innovative adsorbent for colorant polluted wastewater. Batch adsorption experiments were carried out using digestate as an adsorbent material to remove various dyes belonging to different categories. The removal rate and adsorption capacity of dyes were evaluated and the dose of digestate, contact time, and initial dye concentration were studied. The maximum removal rate was approximately 96% for Methylene Blue. The equilibrium time for the Methylene Blue was 4 h, while for other dyes, a longer contact time was required to reach the equilibrium. The suspicion of colloidal matter release into the solution from solid fraction of the digestate led to the investigation of the consequence of a washing step of the digestate adsorbent upstream the adsorption experiment. Washed and not washed adsorbents were tested and the differences between them in terms of dye removal were compared. Moreover, experimental data were fitted by pseudo-first order, pseudo-second order, and intra-partial diffusion kinetic models as well as Langmuir, Freundlich, and Sips isotherm models. The results from fitted models showed that the adsorption of various dyes onto the digestate was mostly well fitted by the Langmuir isotherm and pseudo-second-order kinetic model.

Activated carbons were prepared from sewage sludge by chemical activation with pyrolusite (PAC) to develop an efficient adsorbent for phosphate removal from aqueous solution. One percent (wt.) pyrolusite addition was proved to have an important effect on pore formation of the produced carbon. PAC showed 17.06% larger Brunauer–Emmett–Teller (BET) surface area than the sewage sludge-based activated carbon without modification (SAC). The adsorption results showed that the phosphate removal by PAC was 13% higher than SAC's. The adsorption experiments also showed that PAC had very good performance with high phosphate removal rate (ca. 90%) in a wide pH range (pH = 4–8), and could be stable after 30 min reaction. Adsorption isotherm and kinetics studies demonstrated that phosphate adsorption onto the modified adsorbent was well fitted by the Langmuir isotherm and could be described by the pseudo-second-order kinetic model. The modified sewage sludge-based activated carbons were effective and alternative adsorbents for the removal of phosphorus from aqueous solution due to their considerable adsorptive capacities and the low-cost renewable sources.

The concept of natural organic matter of anthropogenic origin is introduced and its characteristics and interaction with chemical pollutants are investigated by adopting several distinct analytic methodologies. Scanning electron microscopy indicates that the used sample of anthropogenic organic matter (AOM) has an amphiphilic nature, which allows its supramolecular organization in water. Fourier transform infrared spectroscopy, in turn, gives a clear indication about the presence of polysaccharide markers, lipidic and amidic fractions, and suggests the absence of free organic acid. AOM sample and AOM mixed with dye sample were examined by the three-dimensional excitation-emission matrix fluorescence spectra and the nuclear magnetic resonance mono-dimensional spectra. The results highlighted the interactions occurring between the AOM and the reactive dye, selected as a representative chemical pollutant. Electron Spin Resonance confirms that the used AOM is able to completely include the dye in its structure. Overall, the obtained results indicate that the fate, transport, and toxicity of pollutants in the environment can be drastically influenced by the presence of AOM.

Sewage sludge-based activated carbon is proved to be an efficient and low-cost adsorbent in treatment of various industrial wastewaters. The produced carbon had a well-developed pore structure and relatively low Brunauer–Emmett–Teller (BET) surface area. Adsorptive capacity of typical pollutants, i.e. copper Cu(II) and methylene blue (MB) on the carbon was studied. Adsorptions were affected by the initial solution pH, contact time and adsorbent dose. Results showed that adsorption of Cu(II) and MB on the produced carbon could reach equilibrium after 240 min. The average removal rate for Cu(II) on the carbon was high, up to 97% in weak acidic conditions (pH = 4–6) and around 98% for MB in a very wide pH range (pH = 2–12). The adsorption kinetics were well fitted by the pseudo-second order model, and both Langmuir and Freundlich isotherm models could well describe the adsorption process at room temperature. The theoretical maximum adsorption capacities of Cu(II) and MB on sewage sludge-based activated carbon were 114.94 mg/g and 125 mg/g, respectively. Compared with commercial carbon, the sewage sludge-based carbon was more suitable for heavy metal ions’ removal than dyes’.

In view of the circulation cooling water (CCW) quality for refining and petrochemical enterprises, distillates obtained from shale gas produced water after alkali precipitation, filtration and multi-effect evaporation required further purification to remove NH

An ionic liquid hybrid monolithic capillary column was prepared within 7 min via photoinitiated free-radical polymerization of an ionic liquid monomer (1-butyl-3-vinylimidazolium-bis[(trifluoromethyl)sulfonyl]imide); VBIMNTF2) and a methacryl substituted polyhedral oligomeric silsesquioxane (POSS-MA) acting as a cross-linker. The effects of composition of prepolymerization solution and initiation time on the porous structure and electroosmotic flow (EOF) of monolithic column were investigated. The hybrid monolith was characterized by scanning electron microscopy and FTIR. Owing to the introduction of a rigid nanosized POSS silica core and ionic liquids with multiple interaction sites, the monolithic column has a well-defined 3D skeleton morphology, good mechanical stability, and a stable anodic electroosmotic flow. The hybrid monolithic stationary phase was applied to the capillary electrochromatographic separation of various alkylbenzenes, phenols, anilines and polycyclic aromatic hydrocarbons (PAHs). The column efficiency is highest (98,000 plates/m) in case of alkylbenzenes. Mixed-mode retention mechanisms including hydrophobic interactions, π-π stacking, electrostatic interaction and electrophoretic mobility can be observed. This indicates the potential of this material in terms of efficient separation of analytes of different structural type.

In view of the circulation cooling water (CCW) quality for refining and petrochemical enterprises, distillates obtained from shale gas produced water after alkali precipitation, filtration and multi-effect evaporation required further purification to remove NH3-N and COD. Illumination, adsorption, photocatalysis after adsorption equilibrium (AP) and integration of adsorption and photocatalysis (IOAP) were carried out to optimize the distillates treatment. AP and IOAP treatments were feasible for the simultaneous removal of NH3-N and COD from the target distillate, while IOAP treatment had much better adaptability and practicability due to its economic cost and easy operation. In IOAP, the removal rate of COD and NH3-N was high up to 59.0% and 88.9%, respectively, under Xenon lamp illumination (25 A) for 60 min with 10 g/L zeolite. The residual concentration of COD and NH3-N were 73.9 mg/L and 23.0 mg/L, respectively, which could well meet the CCW quality. Furthermore, the results of zeolites characterization (SEM-EDX, BET and FTIR) and kinetics analysis showed that the removal of COD in IOAP process mainly depended on the effect of photocatalysis excited by zeolite, while the removal of NH3-N was in virtue of the synergistic effect of photocatalysis and adsorption.

Two traditional pretreatment methods were adopted for the pretreatment of shale gas produced water in view of facilitation for subsequent treatment processes. The research was focused on alkali precipitation due to its better performance on shale gas produced water pretreatment compared with flocculation. Agitating time, settling time, stirring speed, dosage of coagulant aids were determined by optimal configuration. The results showed that adding together with 1.0 g/L NaOH and 2.0 g/L Na2CO3 under 200 rpm stirring for 5 min and after 30 min settling, suspended solids (SS) in the effluent could drop below 20 mg/L and concentration of hardness ion could be less than 150 mg/L, which was well met the water quality to facilitate the following single or multiple-effect evaporation. The optimized alkaline pretreatment method towards produced water had excellent adaptability and practicability with economic cost and easy operation. It had significant potential and could be widely used in the shale gas produced water pretreatment process.

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