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A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid

100%

Arslan V.

tom Vol. 57, iss. 3

97--111

Clay is widely used in a number of industries due to its special properties like fine particle size, brightness and whiteness, chemical inertness, platy structure, etc. In this study, the general characteristics of clays have been investigated by XRF, XRD, FT-IR, TG-DTA and SEM. The presence of iron as an impurity decreases its commercial value due to giving unwanted colors to clay mineral. Therefore, the dissolution capacity of clay ore was investigated by oxalic acid leaching. Under optimized leaching conditions (0.8 M oxalic acid concentration, 85°C reaction temperature, 1.75 ambient pH, 106+75 µm particle size, 15% w/v solids concentration and 150 min. leaching time) with 250 rpm stirring, 83.90% of Fe2O3 was removed. The amount of iron oxide, the main impurity in the clay, has been reduced from 2.70 to 0.40%. The iron dissolution kinetics was mainly controlled by internal diffusion control of shrinking core model and activation energy, Ea, of 26.29 kJ/mol was obtained for the process. The results also showed that the studied clays have adequate characteristics for ceramics industry, earthenware and porcelain production.

Investigation of the Physico-Chemical Quality of the Wastewater in Fez City (Morocco) Using a Multivariate Statistical Method

84%

El Ouadrhiri F. , Elyemni M. , Adachi A. , Hmamou A. , Bendaoud A. , Chaouch M. , Lahkimi A.

Ecological Engineering & Environmental Technology

2022

tom Vol. 23, iss. 6

15--25

Similar to countries with arid and semi-arid climates, Morocco faces problems of degradation of the quality of its environment and more specifically the quality of groundwater. In this work, we approached the physico-chemical characterization of the raw effluents of three industrial units in Fez city, namely the textile industry (U1), the copperware industry (U2), olive oil industry (U3) chosen for their degree of pollution and their environmental impact,the aim of which is to highlight the degree and nature of the pollution generated by these effluents, and their biodegradability during the winter period January to February of 2018, when the waste water treatment plant (WWTP) is malfunctioning. A set of samplings and measurements of different physico-chemical pollution parameters were carried out such as: temperature, pH, electrical conductivity, turbidity, salinity, chlorides, BOD5, COD, suspended solids (SS), Ca2+, K+, as well as heavy metals. The results show that the U3 effluent is highly loaded in organic matter with high COD (37600 mg O2/L) and BOD5 (13000 mg O2/L), while the U2 effluent contains very high concentrations of heavy metals (Pb, Ni, Zn, Cu, Cd) 91,8, 71, 55,4, 53, 28 mg/L, respectively. on the other hand, the U1 effluent is characterized by high SS contents, and concentrations of Ca2+, K+ exceed Moroccan standards. The COD/BOD5 ratio shows that U1and U2 effluents are difficult to biodegrade even if their organic loads are low. In the light of these results, it is recommended that these discharges be pre-treated before they are discharged into the liquid sewer system.