Development of an Environmentally Friendly Adsorbent for the Removal of Toxic Heavy Metals from Aqueous Solution

An effective adsorbent for the removal of heavy metals was manufactured by immobilization of jujube powder. The adsorptions of Cd, Zn and Cu from aqueous solutions by jujube complex beads (Type 1 and Type 2) were studied in a batch adsorption system. The adsorption data were fitted well with the Langmuir isotherm models. The adsorption capacities (β) for Cd, Zn and Cu were 4.23, 2.93 and 3.64 mg/g in Type 1 and 1.24, 0.70 and 1.35 mg/g in Type 2 beads. The removal efficiencies of the Type 2 beads, with a larger unit surface area, were lower than those of the Type 1 due to part of the casein or cyclic AMP being destroyed during the drying process of the Type 1. These values for Type 1 beads were higher than those of all other adsorbents for each heavy metal. A comparison of the kinetic models on the overall adsorption rate showed that the adsorption system was best described by pseudo-first-order kinetics. The removal efficiencies of Cd, Zn and Cu exhibited similar tendencies to those observed in the equilibrium tests. This indicates that the jujube complex beads developed in this study can be used as promising adsorbents for the removal of heavy metals from wastewater.     

Removal of Phosphate from Aqueous Solution by Functionalized Mesoporous Materials

In the present study, the applications of mesoporous materials based on silica, namely post-synthesized, one-pot synthesized, and pure MCM-41, were investigated for the removal of phosphate from aqueous solution. The mesostructures were confirmed by X-ray diffraction, Brunauer?CEmmett?CTeller, Fourier transform spectroscopy, and transmission electron microscopy. The absorptions of phosphate by the mesoporous adsorbents were examined, with different adsorption models used to describe the equilibrium and kinetic data. The maximum adsorption capacities of the mesostructure adsorbents were found to be 45.162, 40.806, and 31.123 mg g^?C1 for the post-synthesized, one-pot synthesized, and pure MCM-41, respectively. The kinetic data showed that the adsorptions of phosphate onto the post-synthesized and pure MCM-41 followed the pseudo-first-order kinetic model, whereas the one-pot synthesized adsorbent was described by the pseudo-second-order model.     

A Laboratory Column Study on the Biodegradation of Toluene and Methyl tert–Butyl Ether: The Effect of Substrate Interactions

Soil vapor extraction (SVE) is one of the most effective remediation technologies for soil and groundwater contamination. Soil particles can be mobilized by air perturbation during SVE, resulting in the differentiation of porous media, which has not been well addressed. This paper developed a numerical method to study the flow pattern and quantify the change of porous media for the first time. Based on the mass equilibrium and Darcy’s law, a two-phase water–air flow model was constructed with integration of saturation, relative permeability, and capillary pressure during SVE. Relationship between porosity and saturation was deduced and coupled with the two-phase flow model for quantifying change of porous media in real time. Results reveal that both porosity and permeability increase sharply in the early stage of SVE then gradually to a quasi-steady state. These increases in vadose zone tapered off with distance from the SVE screen and the steady period occurred later as well. The influence radius of a single SVE well and the change degree in porosity and permeability of media were proportional to the extraction vacuum and the driving coefficient C, which is more sensitive than extraction vacuum according to the simulation results. Knowledge from this modeling exercise provides a useful tool to estimate the change of remediated zone and assess the environmental risk of remedial activities at real-world contamination sites.     

Photocatalytic Degradation of Chlorophenol Compounds using Poly Aromatic Star Copolymer

This study investigated the encapsulation and photocatalysis of chlorophenol compounds in water using porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer. The chloride ions generated during photocatalytic process were identified and quantified. 2,4,6-Trichlorophenol, pentachlorophenol, and 2,4-dichlorophenol were satisfactorily decomposed in the photoreactor using porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer, with removal efficiencies of 2,454, 498, and 760 mg/g of porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer. The half-life times reached around 30 min, with the exception of that for 2,4-dichlorophenol. The star polymer-impregnated porphyrin is a promising photocatalyst for the removal of chlorophenols.     

Removal of Benzene Using the Characteristics of Block Copolymers for Encapsulation

This study assessed the aqueous benzene removal capacity of a polymeric adsorbent, based on an amphiphilic material, in a batch experiment. Two types of polystyrene-block-poly(N-isopropylacrylamide) have structures containing a hydrophobic core and hydrophilic shell. The encapsulation mechanism of benzene by a polymeric adsorbent was investigated, and found to be attributable to the Van der Waals interactions between the benzene aromatic ring and the hydrophobic core of the adsorbent. The equilibrium data were analyzed using the Langmuir and Freundlich adsorption isotherms, and found to be a good fit to both. The maximum adsorption capacity for benzene by the polymeric adsorbent was found to be 194.53 mg/g. The kinetic data followed a pseudo-first-order kinetic model. Polystyrene-block-poly(N-isopropylacrylamide) showed the potential to be an effective adsorbent for application to wastewater treatment.     

Co-composting of swine mortalities with swine manure and sawdust

The treatment of livestock fatalities caused by epidemic diseases must be timely. Simultaneously, the contaminated excreta and bedding materials must also be treated on site without removal. The composting of manure with bulking materials is widely used on the farm, and the temperature during the composting reaches over 60°C under appropriate conditions of moisture and oxygen, with a suitable carbon to nitrogen ratio. These characteristics of composting can be applied to the degradation of dead livestock. Hence, this study was conducted to evaluate the degradability of mortalities during composting with bulking material comprised of swine manure and sawdust. The laboratory and field studies were conducted using mimic swine mortalities (MSM) and real swine mortalities, respectively. The sawdust to swine manure ratios of 20:80, 40:60, 70:30, and 100:0 were treatments identified as T₁, T₂, T₃, and T₄. In the laboratory study, high degradation of the mortalities (>85%) occurred in all treatments, except the T₁ treatment. The T₂ treatment obtained high degradation at a desirable level. In the field study, the degradation of the soft tissues of the mortalities in the T₂ and T₁ treatments reached 99.7 and 84.5%, respectively. The final C/N ratio of treatment T₂ (17.5) was higher than treatment T₁ (16.8). The addition of swine manure helped to develop relatively rapid temperature homogeneity between the mortality and the bulking materials, and the sawdust to swine manure ratio of 40:60 proved best for swine carcass degradation.