Currently, biological method has been utilized in the treatment of wastewater -containing synthetic dyes used by textile industries in Iraq. The present work was devoted to study the operating feasibility using reverse osmosis (RO) and nanofiltration (NF) membrane systems as an alternative treatment method of wastewater discharged from Iraqi textile mills. Acid red, reactive black and reactive blue dyes were selected, based on the usage rate in Iraq. Effects of dye concentration, pH of solution, feed temperature, dissolved salts and operating pressure on permeate flux and dye rejection were studied. Results at operating conditions of dye concentration = 65 mg/L, feed temperature = 39°C and pressure = 8 bar showed the final dye removal with RO membrane as 97.2%, 99.58% and 99.9% for acid red, reactive black and reactive blue dyes, respectively. With NF membrane, the final dye removal were as 93.77%, 95.67%, and 97% for red, black and blue dyes, respectively. The presence of salt (particularly NaCl) in the dye solution resulted in a higher color removal with a permeate flux decline. It was confirmed that pH of solution had a positive impact on dye removal while feed temperature showed a different image. A comparison was made between the results of dye removal in biological and membrane methods. The results showed that membrane method had higher removal potential with lower effective cost. The present study indicates that the use of NF membrane in dye removal from the effluent of Iraqi textile mills is promising.

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a b s t r a c tThe present study was aimed at investigating the feasibility of a solar photocatalytic system to degrade toxic materials generated from different activities (e.g., xylene from petroleum refineries, tetracycline from pharmaceuticals factories, and chloropyrifos from constructions and pesticides) using the coupled homogenous-heterogeneous solar photocatalytic process. The system consists of ten Pyrex tubes (25 mm inside diameter and 125 cm long) connected in series and mounted on a parabolic trough collector (PTC) with other associated facilities. Different operating variables were studied to predict the performance of the solar reactor like, pH of solution, loading of heterogeneous catalyst, loading of homogeneous catalyst, H 2 O 2 concentration, and liquid flow rate. The maximum degradations obtained, using coupled heterogeneous-homogeneous solar photocatalytic process, were 100% within 30 min. for tetracycline at (Fe 2+ = 50 mg/l, TiO 2 = 100 mg/l, H 2 O 2 = 200 mg/l, pH = 3 and liquid flow rate = 1000 l/min), 100% for xylene within 30 min at (100mg TiO2/l, 50mg Fe2+/l, 100 mg H 2 O 2 /l, pH = 3 and liquid flow rate = 1000 l/min), and for chlopyrifos, a maximum degradation of 100% was obtained within 1.5 h at (150 mg Fe 2+ /l, 250 mg H 2 O 2 /l , and 400 mg TiO 2 /l, pH = 3 and liquid flow rate = 1000 l/min). Results of this study confirmed the capability of the designed solar system to degrade different types of toxic organics.

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Tetraethyl lead (TEL), which is a common additive to the Iraqi pool gasoline, is usually classified- among the most toxic selective additive even when it is added at low doses (~ 1.5-2.0 %v/v). The present work was devoted to prepare and investigate the effect of phenyl tert-butyl ether as an alternative selective additive to the Iraqi pool gasoline produced in Doura Refinary-Midland Refineries Co. Comparing with other additives-except TEL-, it was found that phenyl tert-butyl ether increased RON of  Doura pool gasoline by (5.7 to 10%) at a dose of 5%v/v and it increased RON by (4.5 to 11.9%) at a dose of 8%v/v. Moreover, it appears to have no adverse human health effects which make the suggested additive promising for increasing the anti-knocking characteristic of Iraqi gasoline.

This work focused on the degradation of toxic organic compounds such as methyl violet dye (MV) in water, using a combined photocatalysis/low pressure reverse osmosis (LPRO) system. The performance of the hybrid system was investigated in terms of the degradation efficiency of MV, COD and membrane separation of TiO2. The aim of the present study was to design a novel solar reactor and analyze its performance for removal of MV from water with titanium dioxide as the photocatalyst. Various operating parameters were studied to investigate the behavior of the designed reactor like initial dye concentration (C = 10-50 mg/L), loading of catalyst (CTiO2 = 200-800 mg/L), suspension flow rate (QL = 0.3-1.5 L/min), pH of suspension (5–10), and H2O2 concentration (CH2O2 = 200-1000 mg/L). The operating parameters were optimized to give higher efficiency to the reactor performance. Optimum parameters of the photocatalysis process were loading of catalyst (400 mg/L), suspension flow rate (0.5 L/min), H2O2 concentration (400 mg/L), and pH = 5. The designed reactor when operating at optimum conditions offered a degradation of MV up to 0.9527 within one hours of operation time, while a conversion of 0.9995 was obtained in three hours. The effluent from the photocatalytic reactor was fed to a LPRO separation system which produced permeate of turbidity value of 0.09 NTU which is closed to that of drinking water (i.e., 0.08 NTU). The product water was analyzed using UV-spectrophotometer and FTIR. The analysis results confirmed that the water from the Hybrid-System could be safely recycled and reuse. It was found that the kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model. A power-law based empirical correlation was developed for the photocatalysis system, related the dye degradation (R) with studied operating conditions.