Adsorption of acid and basic dyes by sludge-based activated carbon:Isotherm and kinetic studies

A batch experiment was conducted to investigate the adsorption of an acid dye(Acid Orange 51) and a basic dye(Safranine) from aqueous solutions by the sludge-based activated carbon(SBAC). The results show that the adsorption of Acid Orange 51 decreases at high p H values, whereas the uptake of Safranine is higher in neutral and alkaline solutions than that in acidic conditions. The adsorption time needed for Safranine to reach equilibrium is shorter than that for Acid Orange 51. The uptakes of the dyes both increase with temperature increasing, indicating that the adsorption process of the dyes onto SBAC is endothermic. The equilibrium data of the dyes are both best represented by the Redlich-Peterson model. At 25 °C, the maximum adsorption capacities of SBAC for Acid Orange 51 and Safranine are 248.70 mg/g and 525.84 mg/g, respectively. The Elovich model is found to best describe the adsorption process of both dyes, indicating that the rate-limiting step involves the chemisorption. It can be concluded that SBAC is a promising material for the removal of Acid Orange 51 and Safranine from aqueous solutions.

Removal of lead(II) from aqueous solutions by activated carbon developed from surplus sludge

Activated carbon(AC) was prepared from surplus sludge using chemical activation method with the assistance of ZnCl2. The influences of process parameters on the AC's specific surface area and adsorption capacity for Pb2+ were examined to optimize these parameters. The optimal conditions for the preparation of AC were determined to be activation temperature of 500 °C, activation time of 1 h, impregnation ratio of 1:1(solid-to-liquid volume) with the 30% ZnCl2 solution(mass fraction), giving the BET surface area of 393.85 m2/g and yield of 30.14% with 33.45% ash. Also, the pyrolysis temperature was found to be the most important parameter in chemical activation. FTIR spectra provided the evidence of some surface structures such as C=C and C—O—C. In the adsorption studies, a rise in solution pH led to a significant increase in adsorption capacity when the pH value varied from 3.0 to 7.0, and the optimal pH for removal of Pb2+ was 7.0. It was observed that the pseudo-second-order equation provided better correlation for the adsorption rate than the pseudo-first-order and the Langmuir model fitted better than the Freundlich model for adsorption isotherm. The adsorption capacity of AC to Pb2+ was 11.75 mg/L at solution pH 7.0, the equilibrium time 480 min and 25 °C. Moreover, the adsorption process is endothermic according to the value of enthalpy change.

Effects of chemical modification on physicochemical properties and adsorption behavior of sludge-based activated carbon

This study aimed to explore the adsorption performance of sludge-based activated carbon(SBC)towards dissolved organic matters(DOMs)removal from sewage,and investigated the modification effect of different types of chemicals on the structure of synthesized SBC.Waste activated sludge(WAS)was used as a carbon source,and HCl,HNO 3,and Na OH were used as different types of chemicals to modify the SBC.With the aid of chemical activation,the modified SBC showed higher adsorption performances on DOMs removal with maximum adsorption of 29.05 mg/g and second-order constant(k)of 0.1367(L/mol/sec)due to the surface elution of ash and minerals by chemicals.The surface elemental composition of MSBC suggested that the content of C-C and C-O functional groups on the surface of modified sludge-based activated carbon(MSBC)played an important role on the adsorption capacities of MSBC towards DOMs removal in sewage.Additionally,the residual molecular weight of DOMs in sewage was investigated using a 3-dimension fluorescence excitationemission matrix(3 D-EEM)and high-performance size exclusion chromatography(HP-SEC).Results showed that the chemical modification significantly improved the adsorption capacity of MSBC on humic acids(HA)and aromatic proteins(APN),and both of Na OH-MSBC and HCl-MSBC were effective for a wide range of different AMW DOMs removal from sewage,while the HNO 3-MSBC exhibited poorly on AMW organics of 2,617 Da and 409 Da due to the reducing content of macropore.In brief,this study provides reference values for the impact of the chemicals of the activation stage before the SBCs application.

造纸脱墨废水处理方法的研究

本文采用Fenton试剂氧化处理、声化学氧化法以及活性炭吸附等方法处理脱墨废水,取得了较满意的处理效果。处理出水的CODCr值达到74mg/L,CODCr去除率为95%以上,达到了国家一级排放标准。

KOH活化脱墨污泥基活性炭的制备及表征

以造纸厂脱墨污泥和木粉为原料,采用KOH活化法制备脱墨污泥基活性炭(以下简称"污泥基活性炭"),以碘吸附值为指标,探讨了污泥基活性炭的最佳制备条件;采用X射线衍射(XRD)和扫描电镜(SEM)等对污泥基活性炭的结构进行表征。结果表明,污泥基活性炭的最佳制备条件为:木粉添加量20%、炭碱比1∶1、活化温度675℃、活化时间75 min;该条件下所制备的污泥基活性炭的碘吸附值达623.44 mg/g;XRD分析表明,污泥基活性炭不规则化程度小,保存了原有的纤维结构;SEM分析表明,污泥基活性炭总体呈分散的短小棒状结构,孔呈蜂窝状致密分布,微孔比例达80.3%。将污泥基活性炭用于处理造纸厂碱抽提段漂白废水的效果显著,当添加量为4 g/L时,废水CODCr、色度和浊度的去除率分别达到63.6%、93.6%和91.6%。

磷酸活化脱墨渣制备中孔活性炭研究

以废纸脱墨渣(污泥)为原料,通过磷酸活化法制备中孔活性炭,以碘吸附值和亚甲基蓝吸附值为考察指标,研究了活化时间、活化温度、浸渍比及磷酸浓度等对活性炭吸附性能的影响。得到的最佳制备条件为:活化时间90 min,活化温度450℃,浸渍比1∶3.5,磷酸浓度70%。此条件下脱墨渣活性炭得率为54.57%,得到的脱墨渣活性炭碘吸附值为421.98 mg/g,亚甲基蓝吸附值为10.97 mL/g,比表面积、总孔容和中孔率分别达715.576 m^2/g、0.353 mL/g和97.45%。磷酸活化法制备的脱墨渣活性炭比表面积较大,中孔发达。红外光谱、扫描电镜及X射线衍射表征表明,脱墨渣活性炭表面含有大量羟基等多种官能团;脱墨渣活性炭的晶化程度较大,微晶不规则,孔隙结构稳固。以脱墨渣为原料采用磷酸活化技术可成功制备出中孔活性炭。

薄层高介孔率废纸脱墨污泥基活性炭的制备及其性能表征

本研究以废纸脱墨污泥(DPS)为原料,采用热水和盐酸酸洗两次脱灰、KOH活化、球磨辅助,制备了具有薄层结构且富含介孔的脱墨污泥基活性炭(DPS-AC)。结果表明,DPS-AC制备的最佳工艺条件为:热水预处理和酸洗处理两次脱灰,KOH溶液浓度6.5 mol/L,固液比1∶2,炭化温度750℃,炭化时间90 min,250 r/min间歇式球磨180 min。在此条件下制备的DPS-AC碘吸附量达657.50 mg/g,亚甲基蓝吸附量达230.69 mg/g,比表面积达595.138 m^(2)/g,总孔容达0.646 cm^(3)/g,平均孔径4.339 nm,介孔结构发达。

废纸再生脱墨污泥活性炭对Fe(Ⅲ)离子吸附的研究

探究废纸脱墨污泥基活性炭在Fe(Ⅲ)去除方面的应用可行性。研究结果表明:废纸脱墨污泥基活性炭在活性炭含量为7.5g/l和Fe(Ⅲ)溶液浓度100mg/l,将水溶液pH调到2的条件下吸附3h,对Fe(Ⅲ)的吸附最优。动力学实验结果表明:废纸脱墨污泥活性炭对Fe(Ⅲ)的理论饱和吸附量为40.87mg/g,吸附能力常数为0.029L/g。

磷酸活化法脱墨污泥活性炭的改性研究

以Cr(Ⅵ)离子吸附效果为目标,对磷酸活化法制备的脱墨污泥活性炭进行改性。通过改性效果对比,确定了HNO 3改性方法,并对其改性工艺进行了优化。得到最佳改性条件为:10 mol/L的HNO 3作为改性剂、炭酸比1∶15(m∶V)、改性2.0 h。改性后活性炭用于废水吸附以去除Cr(Ⅵ)离子,在改性活性炭用量为5.00 g/L时,Cr(Ⅵ)离子的去除率和吸附量分别达到83.9%和25.17 mg/g,与未改性活性炭相比,吸附量提高了140.3%。改性活性炭的碘吸附值和亚甲基蓝吸附值分别达到543.92 mg/g和103.5 mg/g,碘吸附值提高了28.9%,而亚甲基蓝吸附值略有降低。N 2吸附-脱附表明,与未改性活性炭相比,HNO 3改性活性炭比表面积从715.576 m^2/g增至1020.161 m^2/g,增大了42.6%;总孔容由0.353 cm^3/g增长到0.608 cm^3/g,提高了72.4%;中孔孔容由0.344 cm^3/g增长到0.393 cm^3/g,增长了14.2%。结果表明,HNO 3改性可大幅提升脱墨污泥活性炭对Cr(Ⅵ)离子吸附性能。

中和-活性炭催化过氧化氢氧化法预处理脱墨废水的实验研究

采用中和-活性炭催化过氧化氢氧化法对旧报纸脱墨废水进行了预处理实验研究。探讨了中和实验、催化实验的各种因素对实验结果的影响,结果表明,20mL的CODcr值为31000mg/L、色度15000倍的脱墨废水,先用稀硫酸进行中和至pH=4,再用质量分数为30%的0.8mLH2O2和0.8g活性炭粉末在pH=3的条件下催化氧化19min,CODcr值降为2300mg/L,COD去除率达90%以上,色度降低为0倍,去除率为100%。