Mohand Benachour

Degradation of the antibiotic chloramphenicol using photolysis and advanced oxidation process with UVC and solar radiation

AbstractIn this work, an aqueous solution of the antibiotic chloramphenicol was treated by photolysis and an advanced oxidation process using hydrogen peroxide combined with UVC and solar radiation. In this system, a reactor containing three UVC lamps (30 W) was used. A factorial plan 22 was designed with the following variables: time and a concentration of hydrogen peroxide and evaluated using the percentage of chloramphenicol degradation as the response. Twelve hours of exhibition to UVC and solar radiation obtained 83 and 21% of chloramphenicol degradation, respectively. When H2O2/UV was used, 98 and 5% of degradation were obtained after one and a half hours of exhibition to UVC and solar radiation with 3 mmol L−1 of hydrogen peroxide. The time-based kinetic constant was calculated as 6.3 × 10−2 min−1 with r2 equal to 0.9878.

Removal of Effluent from Petrochemical Wastewater by Adsorption Using Organoclay

Water contaminated with petroleum derivates is produced in large volumes in many stages of refining oil. This mixture should be treated to separate these derivates from water before it can return to the environment. However, treatment with conventional processes is very often not economically feasible, or do not have the appropriate efficiency with regard to separation, or produce large amounts of mud that also need treatment (Almeida Neto et al., 2006).

Applying Combined Langmuir-Freundlich Model to the Multi-Component Adsorption of BTEX and Phenol on Smectite Clay

Adsorption using clay is increasingly being applied in the secondary treatment of effluents contaminated with organic compounds discharged from oil industries. This study was aimed at applying a combined Langmuir–Freundlich model to describe the multi-component adsorption of organic compounds such as benzene, toluene, ethylbenzene, xylenes and phenol using smectite clay. The results of the study well fitted with the model developed. In addition, the model parameters suggest that maximum adsorption capacities (qm) can be achieved between 2.45 (toluene) and 22.40 mg g−1 (phenol). The equilibrium points for the compounds were achieved in approximately 20–30 minutes.

Heterogeneous photocatalytic degradation of phenol and derivatives by (BiPO4/H2O2/UV and TiO2/H2O2/UV) and the evaluation of plant seed toxicity tests

We examined the photocatalytic degradation of phenol from laboratory samples under UV radiation by using BiPO4/H2O2 and TiO2/H2O2 advanced oxidation systems. Both catalysts prepared were characterized by scanning electron microscopy, Fourier transform infrared and X-ray diffraction. Surface area tests showed about 3.46 and 31.33m2·g−1, respectively, for BiPO4 and TiO2. A central composite design was developed with the following variables--catalyst concentration, time and concentration of hydrogen peroxide--to optimize the degradation process. Removal rates of 99.99% for phenol degradation using BiPO4 and TiO2 were obtained, respectively. For mineralization of organic carbon were obtained 95,56% when using BiPO4 and 63,40% for TiO2, respectively. The lumped kinetic model represented satisfactorily the degradation of phenol process, using BiPO4/H2O2/UV (R2=0.9977) and TiO2/H2O2/UV (R2=0.9701) treatments. The toxicity tests using different seed species showed the benefits of the proposed advanced oxidation process when applied to waste waters containing these pollutants.

Phenolic Wastewaters: Definition, Sources and Treatment Processes

This chapter aims the state of the art concerning the development of advanced oxidation processes (AOPs) for treatment of organic-aqueous effluent for the reuse of liquid water. It presents the major oxidative processes applied for industrial and domestic treatment, where the effluents are often contaminated by phenolic compounds. A special emphasis is given to a relatively new technique called direct contact thermal treatment (DiCTT) that has the advantages of conventional AOP without its inconveniences. The DiCTT process is characterized by the generation of hydroxyl radicals (•OH) by combustion of natural gas, its compact installation and easy operation, being able to be used in offshore oil-exploration platforms, where natural gas is available and the space is reduced. Also, in this chapter, original results on the treatment of the DiCTT technique are presented, which are considered unconventional, by evaluating the oxidation and the conversion of the total organic carbon (TOC) of phenolic compounds at low temperature and atmospheric pressure, with identification and quantification of the intermediate compounds, using high-performance liquid chromatography (HPLC), which may be more toxic than the original pollutants.

Evaluation of the effects of operational parameters in the pretreatment of sugarcane bagasse with diluted sulfuric acid using analysis of variance

ABSTRACT The pretreatment of lignocellulosic residues has been extensively studied as a method to disrupt the cellulose–hemicelluloses–lignin complex in biomass to access the sugars in their respective components. In this work, we carried out a study using sulfuric acid pretreatment of sugarcane bagasse by varying the following operational parameters: solid loading (10–30% of bagasse relative to the volume of the sulfuric acid solution), sulfuric acid concentration (0.5–2.5% relative to the dry mass of bagasse), reaction time (5–25 min), and temperature (135–195°C). The obtained solids from each pretreatment condition were submitted to enzymatic hydrolysis under the same process conditions: 0.232 g of Celluclast 1.5 L and 0.052 g of Novozym 188 per g of pretreated sugarcane bagasse, 72 h of hydrolysis, and 200 rpm of agitation at 50°C. Using central composite rotational design configuration in the experiments and analysis of variance, the results indicate that the conditions that produced larger quantities of glucose by enzymatic hydrolysis (0.35 g glucose/g pulp) with minimum amounts of degradation products were as follows: 20% solids loading, 15 min of reaction time, 1.5% sulfuric acid, and a minimum temperature of reaction of 170°C.