14 documents found, page 1 of 2
Carbon nanotubes as catalysts for wet peroxide oxidation: the effect of surface...
Martin-Martinez, Maria; Machado, Bruno; Serp, Philippe; Morales-Torres, Sergio; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderThree magnetic carbon nanotube (CNT) samples, named A30 (N-doped), E30 (undoped) and E10A20 (selectively N-doped), synthesized by catalytic chemical vapor deposition, were modified by introducing oxygenated surface groups (oxidation with HNO3, samples CNT-N), and by heat treatment at 800 °C for the removal of surface functionalities (samples CNT-HT). Both treatments lead to higher specific surface areas. The ac...
Catalytic wet peroxide oxidation with modified carbon nanotubes
Martin-Martinez, Maria; Machado, Bruno; Serp, Philippe; Morales-Torres, Sergio; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderCatalytic wet peroxide oxidation (CWPO) uses H2O2 as a source of hydroxyl radicals (HO) for the oxidation of organic species. This process is regarded as a potential solution for the treatment of aqueous effluents containing recalcitrant and toxic organic pollutants, difficult to remove by conventional biological processes, mainly if present at high concentrations (1- 10 g L-1) [1]. In a recent study, three ma...
Exploring the activity of chemical-activated carbons synthesized from peach sto...
Martin-Martinez, Maria; Álvarez-Torrellas, Silvia; García, Juan; Silva, Adrián; Faria, Joaquim; Gomes, HelderPeach stones were used as raw material for the synthesis of activated carbons with different properties. Firstly, peach stones were chemically activated using a 12M H3PO4 solution and carbonized under flowing air (400 °C). The obtained activated carbon, named as PS, is characterized by a high surface development (SBET=1262m2 g−1) and acidic character (pHPZC=4.2). A fraction of PS was further carbonized under N2...
Lignin-based activated carbons as metal-free catalysts for the oxidative degrad...
Martin-Martinez, Maria; Barreiro, M.F.; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderA wheat and hemp lignin, obtained from a soda pulping-precipitation process, was carbonized at 800 ◦C under N2 atmosphere. The resulting carbon material was thermally activated under oxidative atmosphere at four different temperatures (150, 200, 300 and 350 ◦C). The materials prepared at higher activation temperatures (300 and 350 ◦C) have proven their potential in the elimination of 4-nitrophenol (4-NP) from a...
Enhancement of p-nitrophenol adsorption capacity throughN2-thermal-based treatm...
Álvarez-Torrellas, Silvia; Martin-Martinez, Maria; Gomes, Helder; Ovejero, Gabriel; García, JuanIn this work several activated carbons showing different textural and chemical properties were obtained by chemical and physical activation methods, using a lignocellulosic material (peach stones) as precursor. The activated carbon resulting from the chemical activation, namely as CAC, revealed the best textural properties (S BET = 1521 m 2 g −1 , pore volume = 0.90 cm 3 g −1 ) and an acidic character. It was f...
Adsorption of Sudan IV from oily wastewater by using modified activated carbon ...
Díaz de Tuesta, Jose Luis; Guliyeva, Rima; Martin-Martinez, Maria; Silva, Adrián; Faria, Joaquim; Gomes, HelderA commercial activated carbon (AC: Norit ROX 0.8, D = 0.8 mm) was modified by chemical and thermal processes, following the procedures described elsewhere [1]. The materials were tested as adsorbents for the removal of a lipophilic pollutant, Sudan IV (S-IV), using a biphasic medium (water/cyclohexane) in order to simulate contaminated petroleum mixtures with water [2]. The AC was modified in successive steps c...
Metal-free catalysts derived from lignin for efficient wet peroxide oxidation
Martin-Martinez, Maria; Barreiro, M.F.; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderIn this work, a wheat and hemp lignin (Sarkanda, Granit S.A.) has been used as raw material for the development of metal-free activated carbons. These materials were tested in the catalytic wet peroxide oxidation (CWPO) of 4-nitrophenol (4-NP; 5 g L-1) during 24 h experiments conducted at relatively mild operating conditions (p = 1 atm, t = 50 °C, pH = 3, catalyst load = 2.5 g L-1 and [H2O2]0 = 17.8 g L-1). Fir...
Surface of carbon nanotubes for wet peroxide oxidation
Martin-Martinez, Maria; Machado, Bruno; Serp, Philippe; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderCatalytic wet peroxide oxidation (CWPO) is regarded as a potential solution for the treatment of aqueous effluents containing recalcitrant and toxic organic pollutants, difficult to remove by conventional biological processes, mainly if present at high concentrations (1-10 g L-1) [1]. In a recent study, three magnetic carbon nanotube (CNT) samples, named E30 (undoped), A30 (completely N-doped) and E10A20 (parti...
Role of nitrogen doping on the performance of carbon nanotube catalysts: a cata...
Martin-Martinez, Maria; Ribeiro, Rui; Machado, Bruno; Serp, Philippe; Morales-Torres, Sergio; Silva, Adrián; Figueiredo, José; Faria, JoaquimFour magnetic carbon nanotube samples (CNTs: undoped, completely N-doped and two selectively N-doped) have been synthesized by chemical vapor deposition. The materials were tested in the catalytic wet peroxide oxidation (CWPO) of highly concentrated 4 nitrophenol solutions (4-NP, 5 g L-1). Relatively mild operating conditions were considered (atmospheric pressure, T = 50 ºC, pH = 3), using a catalyst load of 2....
Lignin-derived carbon materials as catalysts for wet peroxide oxidation
Martin-Martinez, Maria; Barreiro, M.F.; Silva, Adrián; Figueiredo, José; Faria, Joaquim; Gomes, HelderLignin is one of the most abundant organic polymers in the nature, and is obtained in large amounts as a residue in paper and cellulosic bio-ethanol production industries (5-36x108 T/year) [1,2]. A major part of this industrial lignin is incinerated for energy production [3]. Nevertheless, the utilization of lignin as a fuel is not economically rational [3], and the development of alternative uses for lignin ha...