Effect of Dissolved Organic Matter on Agglomeration and Removal of CuO Nanoparticles by Coagulation

Effects of dissolved organic matter on the environmental behavior and toxicity of metal nanomaterials: A review

Metal nanomaterials (MNMs) have been released into the environment during their usage in various products, and their environmental behaviors directly impact their toxicity. Numerous environmental factors potentially affect the behaviors and toxicity of MNMs with dissolved organic matter (DOM) playing the most essential role. Abundant facts showing contradictory results about the effects of DOM on MNMs, herein the occurrence of DOM on the environmental process change of MNMs such as dissolution, dispersion, aggregation, and surface transformation were summarized. We also reviewed the effects of MNMs on organisms and their mechanisms in the environment such as acute toxicity, oxidative stress, oxidative damage, growth inhibition, photosynthesis, reproductive toxicity, and malformation. The presence of DOM had the potential to reduce or enhance the toxicity of MNMs by altering the reactive oxygen species (ROS) generation, dissolution, stability, and electrostatic repulsion of MNMs. Furthermore, we summarized the factors that affected different toxicity including specific organisms, DOM concentration, DOM types, light conditions, detection time, and production methods of MNMs. However, the more detailed mechanism of interaction between DOM and MNMs needs further investigation.

Enhanced removal of phosphate using pomegranate peel-modified nickel‑lanthanum hydroxide

In this work, a bimetallic Ni/La nanoparticle-laded biosorbent was fabricated from pomegranate fibers by solvothermal synthesis method. The material exhibited a high-efficient phosphate removal capability. The results of the characterization analysis showed that the surface of pomegranate fibers was rough and evenly coated with Ni and La after modification, and the specific surface area of Ni-La@Peel increased to 50.20 m²/g, providing a large number of adsorption sites for phosphate removal. The maximum phosphate removal rate of adsorbent was higher than 97% in a wide pH range (3.7-10.8). The maximum adsorption capacities of Ni-La@Peel were 226.55 mg-P/g and 220.31 mg-P/g under alkaline and acidic conditions, respectively, as calculated using the Langmuir model. Meanwhile, all the results were consistent with the Langmuir isothermal (R² = 0.99) and kinetic pseudo-second order models (R² = 0.99), indicating that the phosphate removal mechanism of Ni-La@Peel was mainly related to homogeneous chemisorption. Experimental results showed that in the presence of other anions, such as chloride, sulfate, nitrate, bromide and fluoride, the adsorption capacity of phosphate was only reduced by about 10% compared to the blank sample individually. In addition, the phosphate removal efficiency of Ni-La@Peel remained 82.05% at 7th adsorption-desorption cycle. These findings show that Ni-La@Peel is a promising material for purification of phosphate-containing wastewater.

Wastewater Treatment Processes: Part I

Cheap and plentiful, water was for centuries a manufacturing tool that industry took for granted [...]

Synthesis of the Hydrophobic Cationic Polyacrylamide (PADD) Initiated by Ultrasonic and its Flocculation and Treatment of Coal Mine Wastewater

In this study, a new type of hydrophobic cationic polyacrylamide P (AM-DMC-DABC) (PADD) was synthesized by ultrasonic (US)-initiated polymerization, which is used for the separation and removal of coal mine wastewater. The acrylamide (AM), methacryloyloxyethyl trimethyl ammonium chloride (DMC) and acryloyloxyethyl dimethylbenzyl ammonium chloride (DABC) were used as monomers to prepare). The factors that affecting the US initiated polymerization of PADD were analyzed. Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR) and scanning electron microscopy (SEM) were used to characterize the chemical structure, thermal decomposition performance and surface morphology of the polymers. FT-IR and 1H NMR results showed that PADD was successfully synthesized. In addition, irregular porous surface morphology of PADD were observed by SEM analysis. Under the optimum conditions (pH = 7.0, flocculant dosage = 16.0 mg/L), the excellent flocculation performance (turbidity removal rate (TR) = 98.8%), floc size d50 = 513.467 μm, fractal dimension (Df) = 1.61, flocculation kinetics (KN0) = 27.24 × 10−3·s−1) was obtained by using high-efficiency flocculant PADD. Zeta potential analysis was used to further explore the possible flocculation mechanism of removal. The zeta potential and flocculation analytical results displayed that the flocculation removal process of coal mine wastewater mainly included hydrophobic effect, adsorption, bridging and charge neutralization, and electric patching when PADD was used. The PADD showed more excellent coal mine wastewater flocculation performance than PAD, commercial cationic polyacrylamide (CPAM) CCPAM and PAM. Thus PADD, with its good flocculation effect on coal mine wastewater under relatively wide pH range, had bright practical application value.