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Wang, Jingjing; Xiao, Wei; Teng, Hongni; Yin, Huimin; Chen, Xiaoping; Jiang, Xianjing; Huo, Chengqian; Teng, Maohao; Ma, Shuhua; Al-Haimi, Akram Ali Nasser Mansoor
doi: 10.1080/09593330.2018.1556740pmid: 30526390
Cu2O/hollow mesoporous silica (HMS) composite was synthesized using HMS as supporting material by the impregnation method. This composite displayed integrated physicochemical performance of Cu2O and HMS, resulting in low density, large surface area and excellent dispersibility. The synthesized nano-sized composite of Cu2O/HMS demonstrated rapid and effective removal for methylene blue with an efficiency of 99.8% with the reaction time of 5 min. Moreover, the Cu2O/HMS composite exhibited high stability and present no obvious performance degradation after seven cycles. The dye removal efficiency stood up to 89% even after 15 cycles. The improved properties of Cu2O/HMS are possibly the account of the collaborative effect between the mesoporous adsorption with Cu2O photocatalysis.
Huang, Yiyang; Wang, Hui; Huang, Kai; Huang, Donggen; Yin, Shuang; Guo, Qin
doi: 10.1080/09593330.2018.1556741pmid: 30526405
Degradation kinetics and mechanism of 3-Chlorobenzoic acid (3-CBA) in anoxic water environment using graphene/TiO2 (GR/TiO2) as photocatalyst had been investigated. The effects of various parameters such as catalyst dosage, pH, initial concentration, catalyst reuse and dissolved oxygen (DO) on 3-CBA photocatalytic degradation kinetics were studied. The qualitative and quantitative analysis for degradation intermediate products and parent compound were studied by using HPLC, HPLC/MS/MS and IC technologies. The results show that the residual concentration of 3-CBA has a good linear relationship and its correlation coefficient R 2 are all greater than 0.985 by Langmuir–Hinshelwood (L–H) dynamic model under different photocatalytic degradation conditions. Some oxidative degradation products such as 3-chlorophenol, resorcinol, and hydroxyquinol are generated, and some reductive degradation products such as 3-chlorobenzaldehyde, 3-hydroxybenzaldehyde, 3-hydroxybenzyl alcohol, and cyclohexanediol are produced, and part of 3-CBA are mineralized to generate CO2 when DO is in the range of 0.5–1.0 mg/L; When DO is less than 0.28 mg/L, photocatalytic reduction mainly occurs. The results provide a theoretical basis for photocatalytic in situ remediation of pollutants in anoxic water environment.
Chouchane, Habib; Najjari, Afef; Neifar, Mohamed; Cherif, Hanen; Askri, Refka; Naili, Fatma; Ouzari, Hadda Imene; Cherif, Ameur
doi: 10.1080/09593330.2018.1556742pmid: 30517064
The production, characterization and potential application in heavy metals and dyes removal of a novel heteropolysaccharide–protein named, gpHb, produced by an Haloarchaeal strain Halogeometricum borinquense strain A52 were investigated. The highest gpHb yield of 13.96 ± 0.32 g/L was produced under optimized conditions by response surface methodology. We focused on the characteristics and flocculation performance of gpHb. An important attribute of protein with 16 protein types identified that occupied a total content of 50.2% in the gpHb. Additionally, carbohydrate that occupied 30.4% of the total bioflocculant content consisted of three monosaccharides. Fourier transform-infrared spectroscopy indicated the presence of carboxyl, hydroxyl, amine, amide, and sulphate groups. To further study flocculation activities, factors such as bioflocculant dosage, temperature, pH, salinity and cations addition were tested. In comparison to the chemical flocculant polyaluminium chloride, gpHb maintain high activity at large range of salinity and its flocculation activity was higher on both sides of pH 7. Addition of trivalent cation mainly Fe3+ enhances the flocculating rate indicating that the bioflocculant is negatively charged. Its practical applicability was established for heavy metals and dyes removal from saline aqueous solutions. The highest removal efficiency was observed with Cr3+ (91.4%) and Ni2+ (89.60%) and with basic blue 3 (83.8%) and basic red (78.6%). The excellent flocculation activity of gpHb under saline condition suggests its potential industrial utility for treatment of textile and tannery wastewaters.
Almeida, Adelaide; Jóźwiakowski, Krzysztof; Kowalczyk-Juśko, Alina; Bugajski, Piotr; Kurek, Karolina; Carvalho, Fátima; Durao, Anabela; Ribeiro, Carlos; Gajewska, Magdalena
doi: 10.1080/09593330.2018.1557749pmid: 30526391
Silva, R. D. R.; Rodrigues, R. T.; Azevedo, A. C.; Rubio, J.
doi: 10.1080/09593330.2018.1558288pmid: 30556791
This work summarises the results of calcium and magnesium ion removal from raw water feeding an industrial steam generation system. The cations were precipitated with sodium phosphate before separation of the solids by dissolved air flotation, with micro and nanobubbles. Studies were done at bench scale and validated at pilot scale (raw water feed = 1 m3 h−1; air-to-solids ratio = 0.046 mg of air mg−1 of solids; residence time = 11 min). Results indicated that chemical precipitation followed by flotation significantly improved the quality of the boiler water. Best results were obtained after precipitating the cations with 50 mg L−1 of sodium phosphate at pH 11.5 and flotation with a saturation pressure (P sat) of 4 bar, a recycling ratio of 30% and a sodium oleate concentration of 20 mg L−1 as an hydrophobizing reagent. The latter assisted the adhesion of the nanobubbles (100–500 nm) generated at 4 bar with a numeric concentration of about 2.5 × 108 NBs mL−1. At pilot scale, the total hardness in the solution decreased by 80%; the residual calcium and phosphate ion concentrations were 12 and 2 mg L−1 respectively. This cell was designed including lamellae and perforate plate to improve the superficial loading capacity (up to 9 m h−1). The results were explained by chemical and interfacial phenomena and it is believed that this technique has great potential in water softening processes.
Ndiaye, Awa; Andrianisa, Harinaivo A.; Saapi, Sidesse S. Y.; Changotade, Odilon A.; Adugna, Amare T.; Konate, Yacouba; Maiga, Amadou H.
doi: 10.1080/09593330.2018.1561755pmid: 30574834
Vermifiltration technology using Eudrilus Eugeniae could be an alternative low-cost option for the treatment of urban greywater, which is highly polluted with high concentrations of surfactants, sodium and cooking oil. In this study, the effects of these pollutants on performance of a vermifiltration system was tested over a period of 6 to 8 weeks by enriching raw greywater with various concentrations of anionic surfactants (0, 15, 45 and 135 mg/L), sodium (0, 1, 2 and 4 g/L) and refined palm cooking oil (0, 250 and 500 mg/L). The vermifilter system was made of gravel, sand and sawdust layers from the bottom to the top, on which 200 earthworms were added. The greywater used in this study was previously used for dishwashing and laundry by an urban poor household. The greywater quality was compared with the effluent to evaluate the system performance. BOD5, COD, TSS and E. coli removal efficiencies ranged from 93% to 98%, 68% to 93%, 88% to 96% and 1.4-3 ULog, respectively, which are within the range of efficiencies reported in the literature. High proportion of surfactants (95–99%) and oil (84–89%) were removed but sodium was not removed. Instead, an increase in sodium concentrations was observed in the filter over the experimental period. Statistical analysis shows that BOD5, COD, TSS and E. coli removal efficiencies were independent of surfactants, cooking oil and sodium concentrations (p < .05). Thus, short term or accidental exposure of the vermifilter to high concentrations of these three pollutants did not have significant effect on the system performance.
Sengur-Tasdemir, Reyhan; Pekgenc, Enise; Urper-Bayram, Gulsum Melike; Ergon-Can, Tulay; Tutuncu, Havva Esra; Zeytuncu, Bihter; Gul-Karaguler, Nevin; Ates-Genceli, Esra; Koyuncu, Ismail
doi: 10.1080/09593330.2018.1561756pmid: 30574839
Zuo, Zongliang; Yu, Qingbo; Xie, Huaqing; Yang, Fan; Han, Zhicheng; Qin, Qin
doi: 10.1080/09593330.2018.1561757pmid: 30582415
As a renewable resource of reducer, biochar prepared by pine sawdust is proposed for direct reduction of copper slag in this paper. Combined with thermodynamic analysis, effects of reduction time, temperature and CaO addition ratio on solid copper slag reduction characteristics are discussed. The oxides of iron in copper slag are Fe3O4 and 2FeO·SiO2. The reduction processes were carried out step by step for Fe3O4 and 2FeO·SiO2, respectively: Fe3O4 → FeO → Fe and 2FeO·SiO2 → Fe. The porous structure of biochar exhibits higher reduction reactivity and reaction rate than that of coal. CaO reduced the Gibbs free energy of reduction reactions and facilitated the reduction of 2FeO·SiO2 with C and CO. When CaO was added, separation reaction of FeO and SiO2 took place and α-SiO2 and β-SiO2 were produced. When the addition ratio of CaO is above 0.3, CaO·SiO2 and 2CaO·SiO2 are produced. The reduction process of copper slag was established as follows: (a) dehydration and fast pyrolysis; (b) reduction of iron oxides by C and CO; and (c) sweating metallic iron outflows from cracks in pellet. Besides, direct reduction reaction mechanism and transport process of Cu are established based on reduction experiments, XRD and SEM-EDS analysis.
Ramlow, Heloisa; Machado, Ricardo Antonio Francisco; Bierhalz, Andrea Cristiane Krause; Marangoni, Cintia
doi: 10.1080/09593330.2018.1561758pmid: 30569840
The reuse of treated dyeing wastewater has become a viable option to minimizing water scarcity problems and environmental impacts in the textile industry. The potentiality of commercial flat sheet membranes of polytetrafluoroethylene (PTFE) and polypropylene (PP) in direct contact membrane distillation (DCMD) for dye synthetic solution treatment has been explored in this work. DCMD is interesting for the textile industry since a recovery of heat by hot dyeing wastewater for thermal energy is possible. Moreover, DCMD enables water and dye reclamation with possible reuse in the textile process. The commercial availability of membranes may expedite the DCMD commercialization in the textile industry. Experiments were conducted in a laboratory-scale circulating unit with synthetic solutions containing reactive or disperse dye. High mean permeate flux up to 18.8 kg m−2 h−1 with complete colour rejection was obtained. The dyes tested in this study are not able to completely wet the membranes and the increase of the permeate flux when compared to distilled water is attributed to electrostatic interactions between the dyes and the membranes. Moreover, a partial wetting reduced vapour diffusion path and the permeate flux was increased. PP membrane showed higher performance due to higher porosity when compared to the PTFE membrane. In addition, an influence of dye class on permeability was observed. The results were promising when compared to other studies, which used commercial or lab-scale membranes.
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The aim of the study was to evaluate the nitrogen removal and its effects on the plant’s growth and leaves morphology. using two subsurface vertical flow (VF bed), with different depths (0.24 m2 × 0.70 m; 0.24 m2 × 0.35 m) and nitrogen load increments. The VF bed were planted with Vetiveria zizanioides, filled with light expanded clay aggregates (Leca®NR 10/20) and fed in parallel mode with synthetic wastewater. High ammonium nitrogen concentration ([NH4 +–N] from 68 ± 3 to 290 ± 8 mg L−1) was used without toxicity symptoms in plants, although the effects of ammonium nitrogen load were stopped the growth of the plants. Significant differences between ammonium nitrogen removed in each VF bed obtained for total nitrogen (TNinfl.) ≥ 27 ± 0.8 g m−2 d−1. The nitrification was contributed to ammonium nitrogen removal because was found higher values of nitrate and nitrite in the effluent. These values were more higher in VF bed 1 than in the VF bed 2, since ammonium nitrogen removal were also more higher in VF bed 1 than in the VF bed 2. Total nitrogen mass balance was carried out and the results show that the nitrification/denitrification process occurred with nitrogen plants uptake. It was observed that the VF bed depth has an influence on all nitrogen removal processes. As higher the depth root system it is seemed to favour the creation of zones with different oxidations conditions that allow the nitrogen compounds to be removed intensively.
We report on the fabrication of AqpZ immobilized flat sheet membranes. The effects of interfacial polymerization conditions as well as proteoliposome concentration were evaluated. Commercial AqpZ were used as positive control for cloned AqpZ. Specific permeate flux of membranes at higher proteoliposome concentrations increased up to 25 times higher than thin film composite membranes; however; MgSO4 rejection is lowered almost to 1.5%. FTIR and SEM confirm immobilization of proteoliposomes. Thermal analysis showed that increasing proteoliposome concentration has no positive effect on the incorporation of proteoliposomes into polyamide structures. On the contrary, at lower proteoliposome concentrations, incorporation of proteoliposomes was found better. When combined membrane performances were compared in terms of specific permeate flux; MgSO4 and humic rejection and flux recovery after humic acid filtration, the performance of cloned AqpZ incorporated membranes (having 0.1 mg/mL proteoliposome concentration and polyamide formed with 2 min piperazine reaction time) improved 1.7 times regarding TFC membranes. According to the results, increasing proteoliposome concentration did not improve nanofiltration membrane performance. On the contrary, lower proteoliposome concentrations were found to be more effective in increasing membrane performance.