固化微生物处理规模化养猪场废水的试验研究

利用聚乙烯醇、海藻酸钠和活性炭等作为固化载体材料,制备芽孢杆菌为主的固化微生物,用于处理规模化养猪场废水,以废水中COD、氨氮和总磷去除率为指标考察不同曝气方式对固化微生物净化水体的影响。试验结果表明,在常温条件下,固定化微生物投加量10g·L~(-1)、曝气时间6h,间歇式曝气时间比为1∶2时,经过21d的处理,废水COD、氨氮和总磷的去除率分别可达83.1%、88.6%和45%,最终出水COD和氨氮浓度为292.5mg·L~(-1)和77.9mg·L~(-1),符合《畜禽养殖废水排放标准》(GB18596-2001)中COD和氨氮的排放值。     

纳米Fe2O3/Fe3O4光催化法处理造纸废水的研究

以纳米Fe_2O_3/Fe_3O_4为催化剂,用光催化氧化法处理造纸废水。研究结果表明:该催化剂能有效、快速地降低废水中的COD_(Cr),催化剂用量、H_2O_2用量、pH值、反应时间等各因素对处理效果的影响大小依次为:光照时间>H_2O_2用量>催化剂用量>溶液pH值;室温下最佳反应条件为:催化剂用量0.5g·L~(-1)、30%的H_2O_2用量为5‰(V/V)、pH=3.0,300W高压汞灯光照4h,废水的COD_(Cr)值从800 mg·L~(-1)降到48mg·L~(-1),去除率达到94%。实验进一步考察了太阳光照射下催化剂对废水的降解效果,表明太阳光光照下催化剂对废水也有较好的处理效果。Fe_3O_4的存在使催化剂具有一定磁性,可利用磁分离法将催化剂从体系中分离。     

沸石处理模拟生活污水中氨氮效果影响因素分析

为考察投加量、吸附时间、氨氮初始浓度和pH值等因素对污水中氨氮的处理效果影响,采用天然沸石对模拟生活污水中氨氮去除效果进行分析。实验结果表明:模拟生活污水的氨氮浓度条件下,适宜的沸石投加量为4 g/200mL,吸附时间选择3 h较适宜,不同氨氮初始浓度(30～200 mg/L)下,去除率达到了56%～95. 2%。2 h后速率逐渐降低并达到吸附平衡,氨氮的去除率趋于稳定。吸附达到平衡后,随着氨氮初始浓度增加至,去除率呈下降趋势。p H值范围在5～8时,沸石吸附氨氮效果较好。     

Fenton预处理突发苯胺类污染河水试验及现场工程应急处置

针对某化工园区爆炸事故中高苯胺类、高CODCr污染河段水体,提出Fenton氧化法进行预处理,在单因素试验的基础上进行正交试验,研究了初始pH值、(H2O2)/(Fe2+)摩尔比、H2O2与Fe2+投加量及反应时间对受污染水体处理效果的影响。试验结果表明,当反应时间为60min、初始pH值为5、(H2O2)/(Fe2+)摩尔比为8∶1、投加量为(CODCr)/(H2O2)质量比1∶2时,处理效果最佳,出水苯胺类未检出,CODCr可降至119mg/L,去除率达79.6%。根据试验结果指导现场工程应急处置的实施,运行后出水苯胺类浓度可降至0.31～0.77mg/L,CODCr降至235～301mg/L,达到园区原有污水处理系统进水水质要求。     

改性藻类吸附剂去除废水中Cr~(6+)实验研究

研究利用尿素同乙二醛对海藻进行改性制备新型吸附剂吸附废水中的Cr~(6+),结果显示:尿素与乙二醛(40%)的质量比为0.6:1,藻类投加量为2g,初始pH为1,改性时间为4h,改性温度为70℃时;改性后的海藻对Cr~(6+)的吸附效果最好,同时增加的海藻量越多,对重金属的吸附效率越高。讨论了改性工艺的海藻吸附条件,总结了藻类吸附水中六价铬的效果、影响因素,机理以及规律,进一步展望改性藻类在废水处理中对重金属吸附的应用前景。     

生物质灰渣对甲基橙废水的去除性能及机制

为将资源化生物质灰渣用于甲基橙(MO)废水的处理,在明确MO初始浓度、pH值、反应时间和温度影响的基础上,探讨MO去除的潜在机制和效果提升途径。结果表明,MO的去除随MO初始浓度的增加而增加,并在80 mg/L时趋于平衡。pH值为2时有利于吸附的进行,且MO去除在12 h内较为迅速,24 h后趋于平衡。Langmuir模型可较好地模拟生物质灰渣对MO的吸附过程,表明该吸附过程属于单分子层吸附,且对MO的理论最大吸附量为25.2 mg/g。此外,灰渣吸附MO能较好地被二级动力学拟合,说明化学吸附是MO去除的主控机制。FT-IR光谱进一步表明吸附机制主要由静电、表面络合物或沉淀等共同作用。此外,添加H₂O₂(最终质量浓度4%)可使MO的去除率提高67.2%,是提升灰渣对MO去除性能的有效途径。     

铁改性活性炭对水中镉的吸附和再生实验研究

制备了铁改性活性炭,通过快速动态小柱实验研究了活性炭改性前后对镉的吸附性能,同时考察了进水pH、进水流量和初始质量浓度等因素对吸附材料穿透特性的影响,最后对铁改性活性炭再生方法进行了研究.结果表明,铁改性活性炭对镉的吸附量是未改性活性炭的3.7倍,负载的铁氧化物大大提高了改性活性炭对镉的吸附能力,同时铁改性活性炭对镉的吸附受溶液pH、进水流量和初始质量浓度的影响.0.05 mol·L-1的EDTA-2Na溶液能有效再生吸附饱和后的改性活性炭,再生后的改性活性炭可重复使用.     

纳米Fe3O4催化UV-Fenton降解邻苯二酚的效能及自由基的鉴定

采用纳米Fe3O4催化UV-Fenton降解邻苯二酚,考察了溶液的初始pH值、H2O2投加量、催化剂的投加量和反应温度对邻苯二酚配水中COD的去除效果的影响.其结果表明,在邻苯二酚的浓度为100 mg/L、溶液初始pH为7、H2O2投加量为14.75 mmol/L、催化剂的投加量为0.50 g/L、反应温度30℃的条件...     

微波强化光催化处理罗丹明B染料废水

采用微波无极灯强化光催化(MWL/TiO_2)对罗丹明B模拟废水进行处理。初步研究催化剂TiO_2的用量、罗丹明B初始浓度、微波功率、溶解氧、pH、反应温度、外加氧化剂H_2O_2量等因素对罗丹明B降解效果的影响。实验结果表明:最佳催化剂TiO_2的投加量为4g/L;较低pH、高溶解氧浓度、高微波功率、外加氧化剂H_2O_2有利于罗丹明B的降解。与常规光催化相比,微波减弱pH、染料初始浓度对降解效率的影响,同时增强温度对降解效率的影响。     

微生物燃料电池耦合处理重金属-有机废水性能研究

以双室微生物燃料电池(MFC)为研究对象,构建阳极为糖蜜废水、阴极为不同金属离子废水的微生物燃料电池,对其产电性能和去污能力进行测定。结果表明:微生物燃料电池可同时处理有机废水和金属离子废水,其中,Ag~+为阴极液时,其MFC稳定性最好,最高输出电压为198 m V、最大功率密度为23.1 m W/m~2、内阻为500Ω,Cu~(2+)为阴极液时分别为149 m V、13.9 m W/m~2、600Ω,Zn~(2+)为阴极液时分别为16 m V、1.9×10~(-6)m W/m~2、900Ω。阳极化学需氧量(COD)去除率以Ag~+为阴极液时最高,可达72%,Cu~(2+)和Zn~(2+)分别为54%和19.2%。阴极金属离子去除率Ag~+为72%、Cu~(2+)42%、Zn~(2+)19.8%。     

Removal of Cu2+ and Pb2+ in aqueous solutions by fly ash

In this study, the removal of Cu²⁺ and Pb²⁺ ions by precipitation from aqueous solutions by using six fly ashes with different compositions was achieved. The effect of four parameters on the removal of Cu²⁺ and Pb²⁺, which are contact time, fly ash composition, pH of the solution and fly ash concentration, were investigated. The fly ash concentrations required to achieve maximum Cu²⁺ and Pb²⁺ removal were found to vary between 0.2–10 and 0.075–3.5 g/l, respectively. It was also observed that both the Cu²⁺ and Pb²⁺ removal capacities of the fly ashes depend strongly on their CaO content.     

Biosorptive removal of Pband Cd onto novel biosorbent: Defatted Carica papaya seeds

Carica papaya seeds, an agricultural waste in Nigeria, were defatted to obtain defatted C. papaya seed biosorbent. The Fourier Transformed Infrared spectrum of defatted C. papaya seed biosorbent suggests the presence of CO, OH of carboxylic acid, lactonic and amide band functional groups. The adsorption of metal ion onto defatted C. papaya seed biosorbent led to small shifts in the IR bands. The adsorption capacity of defatted C. papaya seed biosorbent was evaluated to be 1666.67 mg/g for Pb²⁺ and 1000.00 mg/g for Cd²⁺. In binary metal ion solution, the defatted C. papaya seeds showed decreased adsorption capacity for either metal ion. The influence of different particle sizes was found to have negative impact on the adsorption capacity of C. papaya seed biosorbent in the removal of Pb²⁺ and Cd²⁺ from aqueous solution. The adsorption of both metal ions was observed to follow the Freudlich model better than the Langmuir model suggesting that the adsorption of both metal ions was on multisites on the defatted C. papaya seed biosorbent. The adsorption was found to be highly feasible, spontaneous and exothermic in nature. Optimization results suggests 5 m³ of 100 mg/L of Pb²⁺ and Cd²⁺ requires 43.3 and 49.2 kg of defatted C. papaya seeds to remove 95% of the metal ions from aqueous solution.     

Screening and optimization of trace elements supplement in sweet sorghum juice for ethanol production

Eight trace elements were screened for increasing efficiency of ethanol yield from sweet sorghum juice using the Plackett-Burman design method. MnCl₂·4H₂O, CoCl₂·6H₂O and biotin was screened as the significant variables which have positive effects on ethanol production from sweet sorghum juice. The values of MnCl₂·4H₂O, CoCl₂·6H₂O and biotin, optimized by Box-Behnken design method, were 7.70 mg L⁻¹, 15.74 mg L⁻¹ and 11.97 mg L⁻¹, respectively. The experimental efficiency of ethanol yield under optimal conditions was 89.30 ± 0.10%, which enhances the efficiency of ethanol yield by 5.63% by the addition of MnCl₂·4H₂O, CoCl₂·6H₂O and biotin. The results from this study have identified optimal conditions as a foundation for pilot scale ethanol production.     

Microstructure evolution of CuInSe2 thin films prepared by single-bath electrodeposition

The composition and the microstructure evolutions of CuInSe₂ thin films under single-bath electrodeposition processes were investigated. It was found that the film composition was mainly determined by the [Se⁴⁺]/[Cu²⁺] ratios in solution, but the film microstructure is strongly dependent on the initial concentrations of Se⁴⁺, Cu²⁺, and In³⁺ precursors. Higher initial concentrations of Cu²⁺ and In³⁺ in solution are beneficial for the fabrication of compact CuInSe₂ thin films with highly crystallized and large grain sized chalcopyrite phase. The microstructure evolution suggests that prior adsorption and reduction of Cu²⁺ ions and the formation of Cu₂Se compound on the substrate can promote the nucleation, growth, and coarsening of CuInSe₂ crystal to form a high quality thin film during the electrodeposition processes.     

Treatment of textile wastewaters by solar-driven advanced oxidation processes

Heterogeneous (TiO₂/UV, TiO₂/H₂O₂/UV) and homogenous (H₂O₂/UV, Fe²⁺/H₂O₂/UV) solar advanced oxidation processes (AOPs) are proposed for the treatment of recalcitrant textile wastewater at pilot-plant scale with compound parabolic collectors (CPCs). The textile wastewater presents a lilac colour, with a maximum absorbance peak at 516 nm, high pH (pH = 11), moderate organic content (DOC = 382 mg C L⁻¹, COD = 1020 mg O₂ L⁻¹) and high conductivity (13.6 mS cm⁻¹), associated with a high concentration of chloride (4.7 g Cl⁻ L⁻¹). The DOC abatement is similar for the H₂O₂/UV and TiO₂/UV processes, corresponding only to 30% and 36% mineralization after 190 kJ_UV L⁻¹. The addition of H₂O₂ to TiO₂/UV system increased the initial degradation rate more than seven times, leading to 90% mineralization after exposure to 100 kJ_UV L⁻¹. All the processes using H₂O₂ contributed to an effective decolourisation, but the most efficient process for decolourisation and mineralization was the solar-photo-Fenton with an optimum catalyst concentration of 100 mg Fe²⁺ L⁻¹, leading to 98% decolourisation and 89% mineralization after 7.2 and 49.1 kJ_UV L⁻¹, respectively. According to the Zahn-Wellens test, the energy dose necessary to achieve a biodegradable effluent after the solar-photo-Fenton process with 100 mg Fe²⁺ L⁻¹ is 12 kJ_UV L⁻¹.     

Highly efficient TiO2 nanotube photocatalyst for simultaneous hydrogen production and copper removal from water

1-D mesoporous TiO₂ nanotube (TNT) with large BET surface area was successfully synthesized by a hydrothermal-calcination process, and employed for simultaneous photocatalytic H₂ production and Cu²⁺ removal from water. Cu²⁺, across a wide concentration range of 8-800 ppm, was removed rapidly from water under irradiation. The removed Cu²⁺ then combined with TNT to produce efficient Cu incorporated TNT (Cu-TNT) photocatalyst for H₂ production. Average H₂ generation rate recorded across a 4 h reaction was between 15.7 and 40.2 mmol h⁻¹ g⁻¹_catalyst, depending on initial Cu²⁺/Ti ratio in solution, which was optimized at 10 atom%. In addition, reduction process of Cu²⁺ was also a critical factor in governing H₂ evolution. In comparison with P25, its large surface area and 1-D tubular structure endowed TNT with higher photocatalytic activity in both Cu²⁺ removal and H₂ production.     

A novel investigation of oil and heavy metal adsorption capacity from as-fabricated adsorbent based on agricultural by-product and porous polymer

Not only marine species, but human and nature environment have been also affected seriously as the marine environment is polluted by oil spill, heavy metal, and others. In this study, a new sorbent fabricated by adding rice straw into polyurethane foams was investigated. Oil types such as crude oil, fuel oil, diesel oil, kerosene and a solution containing Cd²⁺, Cu²⁺ metal ion were used to evaluate the absorption capacity of this new sorbent. The experimental result after 150 minutes showed that, the oil absorption capacity of new sorbent added 25% of rice straw mass and 500 μm of size was highest, correspondingly to 15.086 g/g, 13.964 g/g, 12.226 g/g, 10.746 g/g of crude oil, fuel oil, diesel oil, kerosene, respectively. Moreover, Cd²⁺, Cu²⁺ metal ion absorption capacity was 212.9 mg/l and 193.6 mg/l. Besides, the relationship between contact angles and pore diameters, oil absorption capacity and oil surface tension, SEM were considered.     

Solar-hydrogen production with reduced graphene oxide supported CdxZn1-xS photocatalysts

Reduced graphene oxide (RGO)/Cd_xZn_(1-x)S composites were firstly synthesized by thermal sulfurization method in one pot with elemental sulfur as sulfur source. By using one pot synthesis, Cd_xZn_(1-x)S particles were decorated on the RGO sheets during sulfurization of Cd²⁺ and Zn²⁺ precursors. This synthesis method eased the control of the particle sizes of Cd_xZn_(1-x)S by providing homogenous decoration of RGO with Cd_xZn_(1-x)S particles and increased the strength between RGO sheet and Cd_xZn_(1-x)S particles, which enhanced charge carrier mobility rate. Here, RGO in the composite structure supplied high electron conductivity, high adsorption capacity and extended light absorption ability. Thus, prepared RGO/Cd_xZn_(1-x)S composites enhanced the photocatalytic activity. The crystal systems, lattice parameters, band gaps and surface morphologies of all photocatalysts are characterized to determine the factors that affected the photocatalytic activities of the composites. After that, the photocatalytic activities of prepared photocatalysts were tested by measuring H₂ evolution rates. Among the composites, RGO/Cd_0·7Zn_0·3S structure possessed the highest H₂ production rate (141.6 μmolh⁻¹) and apparent quantum efficiency (19.4%).     

Adsorption of ciprofloxacin pollutants in aqueous solution using modified waste grapefruit peel

ABSTRACT

The feasibility of using discarded solid biomass as modified waste grapefruit peel (MWGP) for the removal of ciprofloxacin (CIP) pollutants from aqueous solution was explored in terms of equilibrium studies, kinetic studies, and adsorption mechanism elucidation. Characterization of MWGP by SEM and FTIR analyses indicate irregular pore structures and carboxylates as the active adsorption sites. Optimum adsorption conditions were determined in terms of pH, Na⁺/Ca²⁺ concentration, adsorbent time, adsorbent dosage, and initial concentration of CIP. Maximum uptake of CIP is 1.71 mmol·g^?1 under optimal experimental conditions. Adsorption data fit the Langmuir isotherm model and the adsorption process follows pseudo-second order kinetics. Mechanistic studies showed that electrostatic, hydrophobic, hydrogen bonding, and π-π interactions are the main driving forces for CIP adsorption on MWGP. These findings suggest that MWGP is a promising adsorbent for the removal of CIP from aqueous solutions.     

Highly efficient visible-light-driven photocatalytic hydrogen production on Cu7S4/Zn0.2Cd0·8S p-n binary heterojunctions

In this work, a series of Zn_xCd_1-xS solid solutions are firstly prepared by a solvothermal process. The optimized composition of Zn_xCd_1-xS solid solution is determined to be Zn_0·2Cd_0.8S. On this basis, the Cu₇S₄/Zn_0·2Cd_0·8S composite photocatalyst with a binary p-n heterojunction has been synthesized by a co-precipitation process followed by a solvothermal method. Owning to the synergistic effect of the heterojunction structure in the interface of Cu₇S₄ (p-type) and Zn_0·2Cd_0·8S (n-type) and the built-in electric field in binary p-n heterojunction, the as-prepared Cu₇S₄/Zn_0·2Cd_0·8S composite photocatalyst exhibits a significantly improved photocatalytic activity toward hydrogen production from water with visible light response, which is approximately 5.0 times and 16.5 times higher than of pristine Zn_0·2Cd_0·8S and CdS, respectively. The possible photocatalytic mechanism has been proposed basing on a series of experimental results. The current work might be valuable inspirations for designing highly efficient heterojunction composite photocatalyst for solar hydrogen evolution.