Advanced Materials Research Vols. 550-553

Abstract: Simultaneous desulfurization and denitrification removes SO₂ and NO_x from flue gas in one unit and only uses one absorbent. Using urea as absorbent removing SO₂ and NO_x in semi-dry spouted bed has the enormous developmental potential and wide foreground for it overcomes two shortages of wet process such as the amount of urea is large and the waste water is difficult to handle. The chemical absorption mechanism and thermodynamics of SO₂ and NO_x with urea were studied, the operating condition optimization of spouted bed was determined through several repeating experiment, the effects of some important operational parameters such as molar ratio of urea and gaseous pollutant, inlet temperature of flue gas and approach to adiabatic saturation temperature on SO₂ and NO_x removal efficiency were analyzed. The results provide a foundation for the commercial scale application of simultaneous desulfurization and denitrification technology.

Abstract: The modified fly ash (MFA) was prepared by calcining raw coal fly (FA) ash with Na₂CO₃ at high temperature. The preparation conditions of MFA and Effects of important parameters such as contact time, adsorbate concentration, pH and temperature on the sorption were researched, respectively. MFA obtained at calcining temperature of 550°C and FA/Na₂CO₃ mass ratio of 12 shows the effective removal for Cd²⁺ from aqueous solution, and the maximum removal was close to 100% with the adsorbent dosage of 10 g/L, initial Cd²⁺ concentration of 200 mg/L at 25°C. The adsorption kinetics of Cd²⁺ on MFA followed the pseudo-second-order model well and adsorption processes might be mainly controlled by intra-particle diffusion. The sorption is favourable at high temperature and the adsorption apparent activation energy was 68.08 kJ/mol which indicates the chemical nature of the adsorption.

Abstract: The inorganic-organic hybrid polymer HAFPAM was characterized by Fourier transform infrared spectroscopy (FTIR) and Elemental analysis. Its application with the synergistic effect of OTAB in coking wastewater regeneration treatment was also investigated. The results showed that PAFC was grafted onto CPAM chains through coordinate bonds due to hydroxyl crosslinking. The CODCr and chroma removal rates can reach 59.09% and 87.5% when the dose of OTAB is 50 mg/L, and _{Subscript text}the effluent can meet the quality standard of reclaimed water. SEM analysis showed OTAB can improve the sedimentation process.

Abstract: The filtration experiments of two PVDF blending membranes were performed. The critical fluxes of PVDF/PMMA and PVDF/TPU blend membranes were measured by the flux-step method. Then tubular membrane module PVDF/PMMA and PVDF/TPU were used to treat alcohol wastewater. The anti-fouling properties of PVDF/TPU membrane module were better than those of PVDF/PMMA membrane module. The critical fluxes of PVDF/PMMA and PVDF/TPU membrane modules were 24 L/(m²∙h) and 22 L/(m²∙h), respectively. In the alcohol wastewater treatment, TMP and SJ of the tested membranes remained stable during this period and membrane module B was more stable than membrane module A. The CODCr removal rates of two membrane modules reached 48% and 58%, respectively. And the UV₂₅₄ removal rates were 18% and 19%, respectively. Both the turbidity removal efficiency were more than 97% and the average effluent values were below 0.10NTU.

Abstract: Based on the summary of biotechnology principles and common processes for the separated desulfurization and denitrogenation in organic wastewater treatment, two novel biotechnologies for simultaneous sulfur and nitrogen removal, which developed from sulfide-dependent denitrification (denitrification with sulfide as electron donor) and sulfate-dependent ANAMMOX (anaerobic ammonium oxidation with sulfate as electron acceptor), were introduced. The reaction mechanism, operating conditions and functional organisms for the new techniques were described. It is considered that the novel process of simultaneous sulfur and nitrogen removal would be of grate benefit to the treatment of wastewater with high sulfate and ammonia in efficiency-improving, energy-saving and resource recovery.

Abstract: The adsorption of Mn²⁺ ion on natural bentonite heated-treated at 110 °C or 200 °C and on acid-treated with H₂SO₄ from aqueous solutions has been investigated under different conditions,such as intial solution pH and initial Mn²⁺ion concentration.The results show that modified bentonite has a better adsorption capability,and the pH value is the main factor affecting adsorption;bentonite modified at higher temperature has the largest adsorption capability.The adsorption process in solution exhibits Langmuir behaviour and ion exchange and surface complex are chief adsorption form.

Abstract: Seawater desalination has long been recognized as an important method for the solution of the world fresh water shortage, especially seawater Reverse Osmosis (SWRO) desalination. Recently the issue is again being raised for the newly developed pretreatment technology using nanofiltration (NF) membrane which has special separation properties owing to the charge characteristics of its surface separation layer. In this study, two kinds of commercial NF membrane have been studied in a pilot UF-NF Integrated Membrane System (IMS). Operating conditions was investigated and the results show that NF can be effectively used for the softening of seawater and provide excellent feed for SWRO.

Abstract: Photocatalytic removal of mercury was studied using TiO₂-modified bamboo charcoal prepared with Sol-Gel method as photocatalyst, and formate as hole scavengers under UV irradiation. In the absence of formate additives, approximately 95% of 30 mg/L Hg(II) ions was found to be removed from the solution by adsorption. Addition of formate resulted in the photoreduction of Hg(II) to its metallic form. The best conditions of Hg(II)-containing wastewater treatment were determined. The results show that the optimum amount of photocatalyst was 4 g/L,the optimum illumination time was 30 min,reached a plateau value at pH 6, the photocatalyst calcinated for 2h at 500°C. and the optimum formate addition amount was found to be 120mg/L, which doubled the adsorption capacity. Accordingly, it is believed that the method developed in this study is effective and practical in industrial wastewater treatment for Hg(II) disposal.

Abstract: An industrial converter slag was treated by a selective reduction-roasting process to recovery cobalt and copper in this study. To maximizing the recovery of cobalt and copper, the major process parameters such as reducing agent, curing agent and roasting temperature were investigated. Under the determined conditions, 95% cobalt and 96% copper can be recovered. According to the mineralogical analysis, it is found that cobalt in the converter slag mainly distributes in the iron-bearing minerals, which migrates with iron during the reduction-roasting process. After the reduction-roasting, most cobalt distributes in the metallic iron in the form of Co-Fe alloy.

Abstract: Commercially available coal-based activated carbon was treated with different concentration of nitric acid. The resultant samples were used to adsorb lead from aqueous solution. N2 adsorption, Boehm titration, point of zero charge (pHPZC) and X-ray photoelectron spectroscopy (XPS) were used to characterize the samples. Acidic pH is favorable for Pb(Ⅱ) adsorption. The acidic groups increase significantly with the increment of the concentration of nitric acid during the treatment. The carboxylic groups of surface carbon play an important role in the adsorption process.