纳米零价铁颗粒除磷反应机理

从溶液化学与固相表征两方面对纳米零价铁(NZVI)去除水中磷酸根(PO43-)的机理进行初步探究。分别研究不同初始pH值、溶解氧(DO)对NZVI除磷效果的影响,结果表明,酸性环境(pH为3.0~7.0)有利于NZVI除磷,且初始pH值越低,磷去除率越高;好氧环境较厌氧环境更利于磷的去除,DO>8.0 mg/L时对磷酸根的去除率是厌氧条件(DO2等7种不同去除材料中以Ca(OH)2的共沉淀作用去除率最大(99.9%),NZVI次之(87.2%),表明NZVI除磷机理中还存在共沉淀作用。采用多种固相表征手段对NZVI除磷前后进行分析:扫描电子显微镜(SEM)显示反应后出现不规则颗粒;X射线衍射(XRD)表明Fe3(PO4)2是主要反应产物;X射线光电子能谱(XPS)分析未发现磷被还原成低价态。研究表明,NZVI可有效去除水中磷酸根,主要去除机理包括:NZVI对磷酸根的吸附作用、NZVI在水中腐蚀产生的Fe2+离子对磷酸根的化学沉淀作用及铁氢氧化物与磷酸根的共沉淀作用。     

超声对磷酸铵镁结晶特性的影响

利用自制实验装置考察了功率超声对磷酸铵镁(MAP)溶液的结晶介稳区、诱导期、结晶反应速率和晶型等结晶反应特性的影响作用规律。结果表明,对于浓度为4 mmol/L的MAP溶液,分别施加150、250和350 W的功率超声,其达到超饱和状态的临界pH值分别比自然反应条件的临界pH值降低0.14、0.21和0.38,结晶介稳区也随超声功率的增加逐渐变窄;施加150~200 W的功率超声,可将MAP的结晶诱导期从340 s缩短至50~100 s以下,但是继续提高超声功率,结晶诱导期变化不大;超声作用下的MAP结晶反应速率明显加快,随着超声功率的增加,结晶反应速率曲线的缓慢平台期几近消失;扫描电镜观测结果表明,超声作用下MAP结晶产物更加均匀,晶体形貌完整,晶体增长较快。     

废旧磷酸铁锂电池正极材料浸出回收锂工艺

为实现对废旧磷酸铁锂电池的高效资源化回收,提出了一种双氧水氧化—酸浸—浸出液二次浸出的工艺回收正极材料中的Li。通过浸出液二次浸出,选择性地从LiFePO₄/C中浸出Li,既减少了双氧水的用量,又提高了锂离子浸出率。通过扫描电子显微镜 (SEM) 、原子吸收光谱仪 (AAS) 、X-粉末衍射仪 (XRD) 等分析表征手段考察了浸出温度、浸出时间、液固比 (L/S) 、pH以及H₂O₂/Li的摩尔比对Li、Fe、P元素浸出率的影响。结果表明,通过浸出液的二次浸出,Li的浸出率从94.82%上升到99.46%;同时,Fe和P的浸出率分别控制在0.03%和2.3%之内,为后续Fe、P的回收创造了有利条件。所得的Li₂SO₄浸出滤液,经过进一步的除杂和沉锂后得到Li₂CO₃白色粉末;Fe、P以橄榄型无水FePO₄的形式存在于灰色浸出渣中。本研究结果可为废旧磷酸铁锂电池正极材料中锂的工业化回收提供参考。     

表面活性剂SDBS和Tween 80强化过硫酸盐氧化后土壤中石油烃的缺氧生物降解

化学氧化和微生物联合修复是去除土壤中石油烃 (PHC) 的有效技术,但氧化后土壤中残留PHC的生物有效性较低,难以进一步生物降解。向过硫酸盐 (PS) 氧化后的土壤中加入不同质量浓度和质量比的表面活性剂十二烷基苯磺酸钠 (SDBS) 和聚氧乙烯山梨醇酐单油酸酯 (Tween 80) ,探究其对PS氧化后土壤中PHC解吸、土著微生物群落结构和丰度、PHC缺氧降解的影响。结果表明,缺氧条件下PS氧化和微生物联合降解去除了土壤中30.84%的ΣPHC (C₁₀~C₃₀) 。向PS氧化后土壤中加入SDBS和Tween 80能够有效促进PHC解吸,解吸效果随表面活性剂质量浓度和混合体系中Tween 80比例的增加而增加。加入3 000 mg·L⁻¹表面活性剂继续缺氧培养120 d后,氧化后土壤中Firmicutes和Proteobacteria的总数量较对照组减少了2.13~2.58个数量级,抑制了土壤中PHC的缺氧降解。加入800 mg·L⁻¹表面活性剂后,土壤中Firmicutes和Proteobacteria的总数量较对照组增加了0.17~0.81个数量级,促进了PHC的缺氧降解,在SDBS∶Tween 80=1∶3时ΣPHC残留率最低 (较对照组降低了15.80%) 。本研究结果可为深层石油污染土壤的微生物修复提供参考。     

聚乙烯醇包埋水化硅酸钙粉末制备薄片状材料用于处理含磷废水

采用聚乙烯醇（PVA）包埋固定水化硅酸钙（CSH）粉末,硝酸钠作为交联剂,制备片状除磷材料（PVA-CSH）,解决粉状CSH易流失、易堵塞等实用性问题,同时尽量避免对CSH粉末吸附性能的影响。通过SEM和FTIR对材料进行表征,通过批量的静态实验研究材料对含磷废水的吸附行为,通过连续运行实验考察材料的实际应用性能。结果表明,PVA-CSH材料成多孔网状结构,包埋前后CSH基团种类不变;PVA的加入对CSH除磷的吸附速率会有一定的影响,但平衡吸附量基本不受影响,准二级动力学方程可用于描述吸附过程,吸附等温曲线符合Langmuir等温方程;连续柱实验中,同等条件下,CSH及PVA-CSH柱出水磷浓度超出0.5 mg· L-1时,运行时长均为7 d左右,PVA-CSH柱出水COD浓度始终小于10 mg· L-1,NO3--N浓度始终小于2 mg·L-1,PVA-CSH柱出水浊度接近0 NTU显著优于CSH粉末。     

伊乐藻和氮循环菌技术对太湖氮素吸收和反硝化的影响

从太湖梅梁湾采集无扰动泥芯样,分别添加固定化氮循环细菌、水生植物伊乐藻建立室内微宇宙,模拟生态修复,探讨不同修复处理下,硝氮的去除机制.采用15N标记结合同位素配对技术测定了各生态模拟柱中的反硝化速率和植物吸收速率.结果表明,不同处理的实验柱反硝化速率差异明显,同时添加了水生植物和固定化氮循环细菌的实验柱反硝化速率最高,为99.35μmol·(m2·h)-1,植物氮吸收速率为36.55μg·(m2·h)-1.沉水植物伊乐藻在自身吸收氮素的同时也提高了耦合硝化反硝化的作用.与植物吸收相比,反硝化过程是主要的氮去除途径.沉水植物与固定化氮循环菌组合生态修复技术促进了湖泊水体氮素的脱除,起到了净化作用.     

用磷酸铀酰氢（HUP）消除空气中的氚

在常温常压条件下 ,用 4 -7伏的直流电场作用于不同尺寸的磷酸铀酰氢 (HUP)消氚电极 ,在静态和动态情况下 ,考查了它们的消氚特性。对于含 ( 0 51 -1 8 61 )× 1 0 8Bq氚 ,( 30 0 0 -1 2 0 0 0 )× 1 0 - 6 水分的 2 2升空气 ,消氚效率超过 95% ,用液体闪烁计数法 ,测定了消氚后磷酸铀酰氢中氚 ,其中的含量与被试验含氚空气中的氚相一致。     

QA-MCM-41吸附剂脱氮除磷性能

低浓度氮和磷在污水处理中较难去除,排放至水体会造成水体富营养化。以长碳链季铵为功能基团,将其接枝到自制备的介孔材料MCM-41上,成功制得一种吸附容量大且易再生的脱氮除磷吸附剂（QA-MCM-41）。采用SEM、XRD、BET等方法表征了QA-MCM-41微观形貌;研究了氮磷初始浓度、吸附时间及共存离子对QA-MCM-41吸附氮磷效果的影响;采用等温吸附模型、吸附动力学模型、ATR-IR以及XPS等分析手段探究了吸附反应机理。实验结果表明,QA-MCM-41对氮磷的饱和吸附量分别为20.83 mg·g-1和17.67 mg·g-1,SO42-对QA-MCM-41吸附氮磷的效果并未产生显著影响,吸附剂容易再生且重复利用性能较好。吸附动力学模拟及ATR-IR、XPS分析表明,QA-MCM-41对氮磷的吸附均符合以化学吸附为主导的准二级动力学方程,吸附作用主要依靠离子交换。     

DYNAMICS OF ADDED NITRATE AND PHOSPHATE COMPARED IN A NORTHERN CALIFORNIA WOODLAND STREAM1

ABSTRACT: Injections of NO₃ and PO₄ were made during September 1975 into Little Lost Man Creek, a small pristine stream in Redwood National Park, California. Chloride, a conservative constituent, was added in a known ratio to the nutrients. Nutrient loss at a downstream point was calculated using concentration of added Cl as a reference. Nitrate nitrogen (NO₃-N), added for 4 h, reached 920 μg/1 (above 5 μg/1 background) just below the injection point, but increased only to 405 μg/1 at 310 m downstream. The concentration decrease was attributed to dispersion and to uptake by stream biota. Percent of NO₃-N lost decreased with increasing concentration of NO₃-N. Phosphate phosphorus (PO₄-P) was added a week after the NO₃-N for 3 h, causing a concentration increase of 296 μg/1 (above 13 μg/1 background) just below the injection point, of 161 μg/1 at 90 m downstream, and of 98 μg/1 at 310 m. Percent loss of PO₄-P at downstream sites increased with increasing PO₄-P concentration and also for a short period after peak concentration occurred, but then decreased as PO₄-P concentration continued decreasing. Differences in stream response to added NO₃-N and PO₄-P are attributed to differing rates of reaction with biota and differing degrees of interaction with abiotic stream solids.     

RADIUM - 226 IN GROUND WATER OF WEST CENTRAL FLORIDA1

ABSTRACT: Principal U.S. phosphate production is from central Florida where mining, processing, and waste disposal practices intimately associate the industry with water resouces. Available radium-226 data from 1966 and from 1973–1976 in mined and unmined mincralized areas and nonmineralized areas in the primary study area in Polk, Hardee, Hillsborough, Manatee, and De Soto counties were studied using log-normal probability plots and nonparametric statistical tests for significant difference as functions of time, depth, and location. Plots of radium in the water table and Floridan aquifers for mineralized and nonmineralized areas indicate that neither phosphate mineralization nor the industry is a probable factor. For the Lower Floridan aquifer, three separate radium populations are indicated with geometric means of 0.7, 3, and 10 pCi/1. Geometric mean radium-226 content of the water table aquifer is 0.17 pCi/1. Radium in the Floridan aquifer in Manatee and Sarasota Counties is elevated relative to that in the water table and in other areas of Florida. For Sarasota County, geometric mean radium content of the water table is 15 pCi/l versus 7.5 pCi/l in the Floridan. Potential sources include shallow phosphate sediments and monazite sands and possibly crystalline basement rocks or other strata unrelated to phosphatic zones of current economic interest. The existing radium-226 data base is rather marginal in terms of number and spatial distribution of analyses, particularly for the water table and Upper Floridan aquifer. Existing radium data do not substantiate widespread contamination of ground water as a result of the phosphate industry. However, local contamination associated with specific operations has occurred.