Adsorption of Lead Ions by Linde type F(K) Zeolite

The Test was to examine the adsorption property of Pb(II) irons by Linde type F (K) zeolite. The zeolite was synthesized by fly ash. The adsorbent dosage, pH, reaction temperature and reaction time were investigated. The adsorption isotherm and adsorption kinetics equation were studied. The results showed the adsorbent dosage, pH, reaction temperature and reaction time had significant effects on the adsorption of Pb(II) irons. The removal rate was improved with the increasing of zeolite dosage. The saturated adsorption capacity was decreased gradually. The adsorption of Pb(II) irons tended to saturate when initial pH was 6. With the increasing of temperature, the equilibration time of adsorption was shorter. Langmuir isotherm was more applicable to explain the monolayer adsorption procedure of Pb(II) on Linde type F(K) zeolite. For adsorption kinetics, pseudo-second order model showed better calculation results

High-resolution imaging of ph in alkaline sediments and water based on a new rapid response fluorescent planar optode

A new dual-lumophore optical sensor combined with a robust RGB referencing method was developed for two-dimensional (2D) pH imaging in alkaline sediments and water. The pH sensor film consisted of a proton-permeable polymer (PVC) in which two dyes with different pH sensitivities and emission colors: (1) chloro phenyl imino propenyl aniline (CPIPA) and (2) the coumarin dye Macrolex (R) fluorescence yellow 10 GN (MFY-10 GN) were entrapped. Calibration experiments revealed the typical sigmoid function and temperature dependencies. This sensor featured high sensitivity and fast response over the alkaline working ranges from pH 7.5 to pH 10.5. Cross-sensitivity towards ionic strength (IS) was found to be negligible for freshwater when IS <0.1 M. The sensor had a spatial resolution of approximately 22 mu m and aresponse time of <120 s when going from pH 7.0 to 9.0. The feasibility of the sensor was demonstrated using the pH microelectrode. An example of pH image obtained in the natrual freshwater sediment and water associated with the photosynthesis of Vallisneria spiral species was also presented, suggesting that the sensor held great promise for the field applications

Optimizing Support Locations in the Roof–Column Structural System

The roof–column structural system is utilized for many engineering and architectural applications due to its structural efficiency. However, it typically requires column locations to be predetermined, and involves a tedious trial-and-error adjusting process to fulfil both engineering and architectural requirements. Finding efficient column distributions with the aid of computational methods, such as structural optimization, is an ongoing challenge. Existing methods are limited, with continuum methods involving the generation of undesired complex shapes, and discrete methods involving a time-consuming process for optimizing columns’ spatial order. This paper presents a new optimization method to design the distribution of a given number of vertical supporting columns under a roof structure. A computational algorithm was developed on the basis of the optimality-criterion (OC) method to preserve and removed candidate columns pre-embedded with design requirements. Three substrategies are presented to improve optimizer performance. The effectiveness of the new method was validated with a range of roof–column structural models. Treating column locations as design variables provides opportunities to significantly improve structural performance

Norfloxacin removal efficiency by a carbon filtration column under the influence of nanoplastics: mechanistic analysis and prediction model

Activated carbon is often used in the drinking water advanced treatment process, which has good antibiotic removal capacity. However, the presence of nanoplastics (NPs) as carriers may increase the risk of antibiotic leakage in the carbon filtration column. We designed experiments with the polystyrene nanoplastics (PSNPs) concentration, norfloxacin (NOR) concentration, flow rate, and ionic strength as four orthogonal factors to investigate the effects of each factor on NOR removal by carbon filtration columns. The influence mechanism of PSNPs was inferred by combining with NOR transport curves and characterization analysis, and a prediction model of NOR removal efficiency was established through back-propagation (BP) network. The results showed that the increase of both PSNPs concentration and flow rate decreased the NOR removal efficiency. There was an optimal value of NOR concentration to maximize the NOR removal efficiency, while with increasing ionic strength, the NOR removal efficiency decreased, then increased, and finally decreased again in an inverted ‘N’ pattern. Furthermore, PSNPs can affect NOR removal efficiency via carrier function and aggregation on the activated carbon surface. On the other hand, the relative errors of the predicted and experimental values for two evaluated samples were 3.37 and 6.62%, respectively, indicating a good prediction effect. HIGHLIGHTS Orthogonal experiments were designed to investigate the NOR removal efficiency by a carbon filtration column under different conditions.; The effect of each orthogonal factor on the NOR removal efficiency by a carbon filtration column was discussed and the role played by PSNPs was inferred.; A prediction model for the removal effectiveness of NOR by the carbon filtration column in the presence of PSNPs was developed.

Stimulation of Tetrabromobisphenol A Binding to Soil Humic Substances by Birnessite and the Chemical Structure of the Bound Residues

Studies have shown the main fate of the flame retardant tetrabromobisphenol A (TBBPA) in soils is the formation of bound residues, and mechanisms on it are less-understood. This study investigated the effect of birnessite (δ-MnO₂), a naturally occurring oxidant in soils, on the formation of bound residues. ¹⁴C-labeled TBBPA was used to investigate the pH dependency of TBBPA bound-residue formation to two soil humic acids (HAs), Elliott soil HA and Steinkreuz soil HA, in the presence of δ-MnO₂. The binding of TBBPA and its transformation products to both HAs was markedly increased (3- to 17-fold) at all pH values in the presence of δ-MnO₂. More bound residues were formed with the more aromatic Elliott soil HA than with Steinkreuz soil HA. Gel-permeation chromatography revealed a uniform distribution of the bound residues within Steinkreuz soil HA and a nonuniform distribution within Elliott soil HA. ¹³C NMR spectroscopy of ¹³C-TBBPA residues bound to ¹³C-depleted HA suggested that in the presence of δ-MnO₂, binding occurred via ester and ether and other types of covalent bonds besides HA sequestration. The insights gained in this study contribute to an understanding of the formation of TBBPA bound residues facilitated by δ-MnO₂

Pollution Status and Human Exposure of Decabromodiphenyl Ether (BDE-209) in China

Decabromodiphenyl ether (BDE-209/decaBDE) is a high-production-volume brominated flame retardant in China, where the decaBDE commercial mixture is manufactured in Laizhou Bay, Shandong Province, even after the prohibition of penta- and octaBDE mixtures. The demand for flame retardants produced in China has been increasing in recent years as China not only produces electronic devices but also has numerous electronic waste (e-waste) recycling regions, which receive e-wastes from both domestic and foreign sources. High concentrations of BDE-209 have been observed in biotic and abiotic media in each of the different areas, especially within the decaBDE manufacturers and e-waste recycling areas. BDE-209 has been viewed as toxic and bioaccumulative because it might debrominate to less brominated polybrominated diphenyl ethers (PBDEs) (lower molecular weight and hydrophobicity), which are more readily absorbed by organisms. The highest concentration of PBDEs in dust within urban areas reached 40 236 ng g^–1 in the Pearl River Delta, and BDE-209 contributed the greatest proportion to the total PBDEs (95.1%). Moreover, the maximum hazard quotient was found for toddlers (0.703) for BDE-209, which was close to 1. This suggests that exposure to BDE-209 might lead to increased potential for adverse effects and organ harm (e.g., the lungs) through inhalation, dust ingestion, and dermal absorption, especially for the group of toddlers compared to others. In daily food and human tissues, the amount of BDE-209 was also extensively detected. However, the toxicity and adverse effect of BDE-209 to humans are still not clear; thus, further studies are required to better assess the toxicological effects and exposure scenarios, a more enhanced environmental policy for ecological risks regarding BDE-209 and its debrominated byproducts in China

Phosphite in Sedimentary Interstitial Water of Lake Taihu, a Large Eutrophic Shallow Lake in China

The seasonal occurrence and distribution of phosphite (HPO₃^2‑, P) in sedimentary interstitial water from Lake Taihu was monitored from 2011 to 2012 to better understand its possible link to P cycle in the eutrophic shallow lake. Phosphite concentrations ranged from < MDL to 14.32 ± 0.19 μg P/kg with a mean concentration of 1.58 ± 0.33 μg P/kg, which accounts for 5.51% total soluble P (TSP_s) in surficial sediments (0–20 cm). Spatially, the concentrations of sedimentary phosphite in the lake’s northern areas were relatively higher than those in the southern areas. Higher phosphite concentrations were always observed in seriously polluted sites. Generally, phosphite in the deeper layers (20–40 cm and 40–60 cm) showed minor fluctuations compared to that in the surficial sediments, which may be associated with the frequent exchange at the sediment–water interface. Phosphite concentrations in surficial or core sediments decreased as spring > autumn > summer > winter. Higher phosphite levels occurred in the areas with lower redox (Eh), higher P contents, and particularly when metal bonded with P to form Al–P_s and Ca–P_s. Phosphite may be an important media in the P biogeochemical cycle in Lake Taihu and contribute to its internal P transportation