Optimization of antifouling coatings incorporating butenolide, a potent antifouling agent via field and laboratory tests

Rosin-based antifouling paint with the incorporation of butenolide, a promising antifoulant, possesses the potential to deter the settlement of marine organisms on submerged surfaces. With the purpose to extend the antifouling duration, this research investigated the respective contribution of paint ingredients, including butenolide concentrations (5%, 10% and 15%), pigment choices (TiO2, Fe2O3, Cu2O and ZnO) and binder compositions (acrylic copolymer to rosin at 1: 2.5, 1.5: 2 and 2.5: 1), to the field antifouling performance of butenolide. A raft trial was carried out at Yung Shue 0, Hong Kong after the application of antifouling paints on PVC panels. Biofouling dynamics on panel surfaces, such as coverage percentage and biomass accumulation, were monitored until submersion for 6 months to allow for the assessment of antifouling efficiency. Field results showed that butenolide incorporation generally inhibited the settlement of fouling species on the coated panels as demonstrated by the decreased surface coverage and biomass weight. Coatings with 1: 2.5 paints containing 10% butenolide exhibited the best antifouling performance with only 34% of the surface covered by fouling organisms, which mainly consisted of algae and slime. The smallest biomass increase of the fouling community was also observed for 1: 2.5 coatings. An increased proportion of rosin in binder compositions yielded better antifouling performance following the order of 1: 2.5 > 1.5: 2 > 2.5: 1. Laboratory experiments were also conducted to examine the behavior of paint coatings in stirring artificial seawater. Butenolide addition decreased the film hardness and inhibited water uptake, but resulted in weight loss of paint coatings. Along with the gradual release of butenolide, the hardness of paint films increased gradually. Overall, a service life of 6 months, while eliminating the use of heavy metals, highlights the effectiveness of butenolide-incorporated paint formulation, especially 1: 2.5 paint, as an environmentally benign and fouling-resistant candidate for future antifouling application

The Pd-catalyzed hydrodechlorination of chlorophenols in aqueous solutions under mild conditions: A promising approach to practical use in wastewater

Catalytic hydrotreating of chlorophenols was carried out in water with Pd/C at 25 degrees C under atmospheric pressure. 1.0% (w/w) monocholophenols was completely dechlorinated within 60 min. Phenol, cyclohexanone and cyclohexanol were formed. In contrast to the dechlorination of monochlorophenols, the hydrogenation reaction of polychlorinated phenols became difficult and reaction rates were strongly dependent upon the number of the chlorine atoms. The solvent property had a considerably important influence on the dechlorination reaction. Water as a solvent showed more advantages than organic solvents. It was much easier to be hydrodechlorinated for chlorophenols in aqueous solutions. However, the presence of THF, dioxane, DMSO or DMF in water was disadvantageous to the reaction and easily to cause Pd/C deactivation. Additionally, when different halogenated organic compounds were present in aqueous solution, the dehalogenation reaction was the competitive hydrogenation process. (c) 2009 Elsevier B.V. All rights reserved

The permeability effect of microcystin-RR on Escherichia coli and Bacillus subtilis

Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. Most previous work have been done on the toxic effects of microcystins on animals and plants. However, the reports about the effect of microcystins on microbial cells are very limited. In this work, the permeability of MC-RR on the cell outer membrane of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) was discussed. The permeability effect of MC-RR on the cell outer membrane of E. coli and B. subtilis under different concentrations was demonstrated by a rapid and sustained reduction in the A(675) values of lysozyme-treated cells. The decrease of the absorbance values showed a time-and dose-effect. The extravasations of protein and carbonhydrate increased with the increment of the treated-concentration of MC-RR. The results showed that MC-RR could increase the permeability of cell outer membranes of E. coli and B. subtilis. The synergistic effects of MC-RR and lysozyme on bacteria indicated that MC-RR might play an ecological role in bacteria in combination with other substances in some aquatic environments.Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. Most previous work have been done on the toxic effects of microcystins on animals and plants. However, the reports about the effect of microcystins on microbial cells are very limited. In this work, the permeability of MC-RR on the cell outer membrane of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) was discussed. The permeability effect of MC-RR on the cell outer membrane of E. coli and B. subtilis under different concentrations was demonstrated by a rapid and sustained reduction in the A(675) values of lysozyme-treated cells. The decrease of the absorbance values showed a time-and dose-effect. The extravasations of protein and carbonhydrate increased with the increment of the treated-concentration of MC-RR. The results showed that MC-RR could increase the permeability of cell outer membranes of E. coli and B. subtilis. The synergistic effects of MC-RR and lysozyme on bacteria indicated that MC-RR might play an ecological role in bacteria in combination with other substances in some aquatic environments

The influence of ion effects on the Pd-catalyzed hydrodechlorination of 4-chlorophenol in aqueous solutions

The aim of this work was to study the influence of ions on the hydrodechlorination of 4-chlorophenol in water over 5% Pd/C catalyst. It was found that the presence of some ions such as Na(+), K(+), NH(4)(+), Ca(2)(+), Mg(2)(+), Cl , Br ,CO(3)(2-), HCO(3)(-), SO(4)(2-) and NO(3)(-) etc., did not show negative effects on catalyst activity in the hydrogenation process of 4-chlorophenol in aqueous solutions. But, when Fe(2+), Fe(3+), Cu(2+), Zn(2+), Ni(2+) and Pb(2+) etc., were present in water, they could reduce the activity of Pd/C and even led Pd/C to deactivate. (C) 2009 Elsevier B.V. All rights reserved

Studies on remediation of DDT-contaminated soil and dechlorination of DDT

A practical and efficient disposal method for 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT)-contained soil is reported. The treatment process was a combination technique: first to extract DDT in the soil, and then to hydrogenate the extract containing DDT. 4, 4'-DDT was effectively extracted in the soil and hydrodechlorinated in this treatment process. Additionally, solvent media and extracting time for DDT removal were investigated. An efficient heterogeneous catalytic method was also developed by comparing the rates of dechlorination of DDT over two different catalysts in organic-aqueous heterogeneous system. Compared to Raney Ni, Pd/C is a more efficient catalyst in disposing DDT. (C) 2012 Selection and/or peer-review under responsibility of Basel Convention Coordinating Centre for Asia and the Pacific and National Center of Solid Waste Management, Ministry of Environmental Protection of China

The activity and selectivity of catalytic peroxide oxidation of chlorophenols over Cu-Al hydrotalcite/clay composite

Liquid phase catalytic oxidation of chlorophenols (CPs) was carried out over Cu-Al hydrotalcite/clay composite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the catalyst had high catalytic activity, with complete oxidation of 4-CP within 40 min at 40 degrees C. The content and position of chlorine on the aromatic ring had significantly different effects on the oxidation rate of CPs, with the rate sequence of phenol > monochlorophenol (MCP) > dichlorophenol (DCP) > trichlorophenol (TCP), 3-CP > 2-CP > 4-CP. and 3,5-DCP > 3,4-DCP > 2,5-DCP > 2,4-DCP > 2,6-DCP. This was ascribed to the interactions among sigma-electron withdrawing conductive effect, pi-electron donating conjugative effect, and steric hindrance effect of chlorine. It was evidenced that the catalytic peroxide oxidation of CPs in the first step was selective and rate-limiting, where chlorinated 1,4-benzoquinones formed. (C) 2011 Elsevier Inc. All rights reserved.Liquid phase catalytic oxidation of chlorophenols (CPs) was carried out over Cu-Al hydrotalcite/clay composite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the catalyst had high catalytic activity, with complete oxidation of 4-CP within 40 min at 40 degrees C. The content and position of chlorine on the aromatic ring had significantly different effects on the oxidation rate of CPs, with the rate sequence of phenol > monochlorophenol (MCP) > dichlorophenol (DCP) > trichlorophenol (TCP), 3-CP > 2-CP > 4-CP. and 3,5-DCP > 3,4-DCP > 2,5-DCP > 2,4-DCP > 2,6-DCP. This was ascribed to the interactions among sigma-electron withdrawing conductive effect, pi-electron donating conjugative effect, and steric hindrance effect of chlorine. It was evidenced that the catalytic peroxide oxidation of CPs in the first step was selective and rate-limiting, where chlorinated 1,4-benzoquinones formed. (C) 2011 Elsevier Inc. All rights reserved

Catalytic wet peroxide oxidation of phenol over Cu-Ni-Al hydrotalcite

Liquid phase catalytic oxidation of phenol was carried out over Cu-Ni-Al hydrotalcite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the hydrotalcite catalyst had high catalytic activity, where phenol could be completely oxidized by H(2)O(2) into oxalic acid, formic acid and CO(2) within 2 h at 30 degrees C. The catalytic oxidation process was zero-order kinetics with an activation energy of 61.5 kJ mol(-1). A feasible reaction system could be proposed as follows: 0.8g L(-1) of catalyst, n (H(2)O(2))/n (phenol) = 15, temperature of 40 degrees C, 2.66 mM of phenol and time of 2 h. Furthermore, it was found that the presence of inorganic chlorides promoted markedly the oxidation rate of phenol, probably due to the formation of intermediate products containing chlorine such as quinones and/or radicals. (C) 2011 Elsevier B.V. All rights reserved.Liquid phase catalytic oxidation of phenol was carried out over Cu-Ni-Al hydrotalcite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the hydrotalcite catalyst had high catalytic activity, where phenol could be completely oxidized by H2O2 into oxalic acid, formic acid and CO2 within 2 h at 30 degrees C. The catalytic oxidation process was zero-order kinetics with an activation energy of 61.5 kJ mol(-1). A feasible reaction system could be proposed as follows: 0.8g L-1 of catalyst, n (H2O2)/n (phenol) = 15, temperature of 40 degrees C, 2.66 mM of phenol and time of 2 h. Furthermore, it was found that the presence of inorganic chlorides promoted markedly the oxidation rate of phenol, probably due to the formation of intermediate products containing chlorine such as quinones and/or radicals. (C) 2011 Elsevier B.V. All rights reserved