The montmorillonite supported nanozero-valent iron material (MT-NZVI) was synthesized to remove cadmium (Cd). The results showed that the removal efficiency of MT-NZVI on cadmium was much higher than that of montmorillonite (MT), and the removal efficiency of MT-NZVI on cadmium reduced with the increase of the initial concentration and the pH value, but increased with the increase of the dosage.
Chromaticity of cigarette industry wastewater increase when treating by aerobic due to large quantities of lignin, nicotine and carbohydrate. Ozone and advance oxidation are proposed for degradation and decoloration of cigarette wastewater that processed by aerobic. The result shows that ozone process has its advantage of high decoloration rate, simple operation and low operation cost. Optimum parameters of ozone process are ozone dosage of 37.65mg/L, reaction time of 15min, reaction pH of 7.0-9.0. The COD removal rate is 38.3% when the decoloration rate is 57.5%. Operation cost of ozone process is 0.4 yuan/m3.
The Gannan region is the largest navel orange planting area in the world and has the largest production in China. However, about 5 million tons of navel orange waste (NOW) produced annually. NOW has a great environmental risk because of its high content of organic matter and moisture. Anaerobic digestion of NOW with high nitrogen content waste is a promising alternative to treat these wastes. The effect of swine manure (SM), waste active sludge (WAS) as co-substrates and different mixing ratio were examined in three batch-scale studies. In the first investigation, co-digestion of NOW with SM resulted low methane yield and high concentration of VFAs. In the second investigation, NOW was co-digested with WAS, the methane yield was improved by 260% when the mixing ratio of NOW to WAS (VS/VS) was shifted from 1:2 to 2:1. In the third investigation, the co-digestion of NOW with SM and WAS was conducted. Co-digestion of three substrates has higher methane yield than that of previous two studies, with the exception of equal amounts of NOW with co-substrates (mixing ratio of NOW to SM to WAS was 2:1:1). The highest methane yield of all experiments was 0.20 m3 kg-1VS added while the mixing ratio of NOW to SM to WAS was 1:2:1. It seemed to obtain stable digestion performance, the mixing ratio of co-substates to NOW should not be lower than 1:1. WAS was a better co-substrate than SM, as WAS was capable to supply more organic nitrogen to create positive synergistic effects.
Taking the organic modified montmorillonite as a carrier and dispersant, the supported nanoscale zero-valent iron materials with different iron contents were synthesized through the ferrous sulfate (FeSO4) and the sodium borohydride (NaBH4) in it. The structure and morphology of the materials were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). Finally, the performances of the supported nanoscale zero-valent iron were studied by high-performance liquid chromatography to determine the adsorption and degradation of 4-chlorophenol. The results indicate that the supported nanoscale zero-valent iron was well dispersed,different iron dosages imposed a visible effect on the morphology and particle diameter of iron;the degradation of 4-chlorophenol resulted from adsorption and degradation processes. Materials with different iron contents exhibited significantly different performance levels in terms of 4-chlorophenol adsorption and degradation.
The “Twelfth Five-Year” plan of China starts at the emission reduction task in controlling the total amount of ammonia nitrogen. Therefore, the method of how to remove ammonia nitrogen quickly and effectively will be the key point of wastewater treatment. In the current paper, One zeolite synthesized from coal fly ash (P-type zeolite, ZP) was prepared and then modified using lanthanum. The structure of the zeolite was characterized by means of SEM, X-ray, TG-DSC, and the like. The characteristics of ZP and lanthanum-modified ZP (LaZP) in the adsorption and desorption of ammonia nitrogen were simultaneously studied, wherein the results show that ZP and LaZP are featured with obvious crystal characteristics, lots of gap structures, and a strong characteristic peak of P-type zeolite shown in the XRD atlas. For the LaZP, the adsorption equilibrium can be carried out in 30 min. The data for the adsorption dynamics to the ammonia nitrogen are in line with the pseudo-second order kinetics equation, and the adsorption isotherme is well fitted to the Langmuir model. The regeneration test shows that the desorption rate of ammonia nitrogen is proportional to the concentration of NaCl when the pH is about 7. The desorption rate of LaZP to the ammonia nitrogen can reach 90% when the concentration of NaCl is 0.4 mol/l, and the desorption rate of ZP is 70%. Compared with ZP, the desorption speed of the LaZP is quicker, the adsorption equilibrium can be carried out in 6 h, and the adsorption equilibrium of ZP can be slowly carried out in 10 h. Moreover, the adsorption and desorption properties of the LaZP are greatly improved.
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