Fractal analysis of polyferric chloride-humic acid （PFC-HA） flocs in different topological spaces

The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water with different initial pH (9.00, 7.00, 5.00) and PFC dosages, were calculated by effective density-maximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA flocs, being more than 2.0, calculated by bi-logarithm relation of effective density-maximum diameter and Logan empirical formula at initial pH of 7.00 had 11-13 percentage greater than those at pH 9.00 and 5.00, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.00. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.00 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere vs. logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%--43% difference with their corresponding Df, and they even had different tendency as the change of initial pH values. However, the D2 values of the flocs formed at three different initial pH in HA solution, calculated from the horizontal projected images with magnification about 9, had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.00 and 7.00 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.00 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and some marcopore-size distribution.     

硫酸盐还原菌促进厌氧消化中丙酸转化的研究

由于丙酸积累而造成的酸败问题一直是制约厌氧反应器稳定运行的重要因素之一。试验通过人为添加硫酸盐的方法,研究了硫酸盐还原作用在厌氧过程中对丙酸转化的影响。试验的结果表明,硫酸盐的添加促进了厌氧反应器中丙酸降解的速率,减少了丙酸对产甲烷细菌的抑制作用,从而提高了反应器COD去除率;DGGE图谱显示添加硫酸盐体系中产甲烷菌种群结构发生了变化,优势种群发生了转移。认为硫酸盐还原菌对厌氧反应器中丙酸的降解会产生促进作用,因此可以通过调节硫酸盐还原菌、产酸菌和产甲烷菌之间的协同作用来维持厌氧反应器稳定运行。     

硫酸渣制备高纯度硫酸亚铁

以高铁硫酸渣为原料,采用酸浸-还原-除杂-结晶一重结晶-干燥工艺,合成高纯度硫酸亚铁。通过反应温度、反应时间对硫酸渣中铁的浸出率的影响,以及结晶温度、干燥温度、干燥时间对硫酸亚铁产品纯度的影响做分析实验,得出最佳酸浸条件：硫酸渣与硫酸的固液比为1：3,硫酸质量分数为20％～25％,反应温度为80℃,反应时间为6h,搅拌强度为200r／min;最佳结晶精制条件：结晶溶液pH值为1-3,温度为60℃;除杂最佳条件：pH值约为4．5;冷却结晶温度控制在20℃,结晶干燥过程为30℃,干燥6h。     

水体系中EDTA-Fe(Ⅱ)/Ｋ２Ｓ２Ｏ８降解敌草隆的研究

对水体系中EDTA-Fe(Ⅱ)/K2S2O8降解敌草隆的方法进行了研究.在综合考虑经济性和降解率的前提下,提出了反应的最佳条件:K2S2O8初始浓度为2.0 mmol·L-1, Fe(Ⅱ)初始浓度为1.0 mmol·L-1, EDTA初始浓度为0.5 mmol·L-1,反应时间为300 min, pH=7.0,最终0.1 mmol·L-1,敌草隆降解率可达67.6%.同时,采用分子探针竞争实验鉴定了体系中产生的硫酸根自由基和羟基自由基,并采用LC/MS法鉴定了敌草隆的主要降解产物,从而探讨了敌草隆在EDTA-Fe(Ⅱ)/K2S2O8体系中可能的降解途径.     

SDS、SDBS胶团强化超滤Cu~(2+)的比较

采用模拟含Cu2+废水,以阴离子表面活性剂SDS和SDBS胶团强化超滤分离Cu2+(Cu2+固定为0.6 mmol/L),通过对渗透通量、渗透浓度、去除率、富集率的比较,从而得出SDS、SDBS分离效果的优劣.结果表明,添加SDS的渗透通量始终高于SDBS[其中SDS平均渗透通量为29.92 L.(m2.h)-1,而SDBS只有16.55 L.(m2.h)-1],渗透浓度始终低于SDBS,当渗透液Cu2+浓度接近为0时,SDBS、SDS所需浓度分别为2 mmol/L和6 mmol/L.SDS的Cu2+去除率和平均富集率高于SDBS(SDS平均去除率为85.06%,平均富集率为4.18;SDBS对应值分别为69.05%,4.05).此外,SDS自身的平均富集率也高于SDBS(SDS为3.89,SDBS为3.13).由此可见,SDS比SDBS更适合去除Cu2+.     

强化混凝去除微污染饮用原水中的As(III)

以聚合硫酸铁和聚合氯化铝为混凝剂,采用强化混凝的处理方法,对微污染饮用水原水中微量砷的去除进行了研究.考察了pH值、氧化剂用量、混凝剂投加量、砷初始浓度和原水浊度等因素对砷去除的影响.结果表明,聚合硫酸铁除砷效果好于聚合氯化铝;在pH值为6~8,微污染原水砷浓度为0.1mg/L,聚合硫酸铁投加量为0.078mmol/L时,可使滤后水中砷浓度低于0.01mg/L.     

聚合氯化铁-腐殖酸(PFC-HA)冷冻干燥絮体的表面微观形貌及其孔表面分形特征

采用低温急速冷冻-真空干燥技术制备了不同pH(9.0、7.0、5.0)原水在45.89mg·L-1(以Fe3 计,原水pH=9.0)或28.41mg·L-1(以Fe3 计,原水pH=7.0、5.0)投药量下混凝后形成的PFC-HA絮体的粉末样品,研究了它们的表面微观形貌和孔表面分形特征.SEM图像表明,PFC-HA絮体具有不规则的块、片状形貌,而且在原水pH=9.0或pH=7.0时形成絮体也存在簇状结构.3种样品对N2的吸附-脱附等温线上均存在滞后圈,但样品3的形状不同.它们的吸附量、BJH累积吸附孔体积与脱附平均孔径的大小顺序均为:样品3＞样品2＞样品1,即随原水pH的降低而升高,而且孔尺度分布曲线显示样品3的表面存在大孔.BET比表面积的变化趋势与它们不一致,且样品2的比样品3稍大,样品1的最小.基于分形FHH方程,采用吸附等温线和脱附等温线数据计算出样品1和样品2的孔表面分形维Ds数均在2.94左右,而样品3的均小于2.38.这些Ds值似乎不能完全表示出因孔表面粗糙性而导致的空间填充能力的大小,主要表达了3种样品的中孔甚至大孔的尺度分布引起的不规则性.本试验中采用热力学模型计算出的3个样品Ds值大都超过3,它们已经失去了维数的实际意义;但样品3因其吸附-脱附等温线上的滞后圈接近圆桶式的A类,如果缩小分形标度区间,可以得到与分形FHH方程计算出的Ds接近的值.     

Effect of competing solutes on arsenic（Ⅴ） adsorption using iron and aluminum oxides

The study focused on the effect of several typical competing solutes on removal of arsenic with Fe_2O_3 and AL_2O_3.The test results indicate that chloride,nitrate and sulfate did not have detectable effects,and that selenium(Ⅳ)(Se(Ⅳ))and vanadium(Ⅴ)(V(Ⅴ)) showed slight effects on the adsorption of As(Ⅴ)with Fe_2O_3.The results also showed that adsorption of As(Ⅴ)on AL_2O_3 was not affected by chloride and nitrate anions,but slightly by Se(Ⅳ)and V(Ⅴ)ions.Unlike the adsorption of As(Ⅴ)with Fe_2O_3,that with Fe_2O_3 was affected by the presence of sulfate in water solutions.Both phosphate and silica have significant adverse effects on the adsorption of As(Ⅴ)adsorption with Fe_2O_3 and Al_2O_3.Compared to the other tested anions,phosphate anion was found to be the most prominent solute affecting the As(Ⅴ)adsorption with Fe_2O_3 and Al_2O_3.In general,Fe_2O_3 has a better performance than Al_2O_3 in removal of As(Ⅴ)within a water environment where multi competing solutes are present.     

载铝改性人造沸石对含氟水除氟效果的研究

采用盐酸浸泡活化和硫酸铝溶液浸泡改性的方法对人造沸石进行改性,用模拟高氟水样进行静态及动态除氟实验。动力学研究结果表明:吸附剂吸附速度快,30 min接近吸附平衡,吸附速率可用拟二级动力学方程描述。吸附等温线符合Langmuir方程,饱和吸附量为5.07 mg/g,吸附平衡常数为0.060 2 L/mg。静态实验对浓度...     

铵态氮肥和腐殖酸协同促进孔雀草对土壤中Cd的去除

为了提升孔雀草(Tagetes patula L.)对镉(Cd)污染土壤的修复潜力,通过田间试验,研究铵态氮肥和腐殖酸对孔雀草生长以及土壤中Cd去除的影响.结果表明,氮肥(N)与氮肥和腐殖酸联用处理(NHA)可显著提高孔雀草的生物量;与对照(CK)相比,NHA和N处理下孔雀草地上部生物量分别提高了 2.49倍和1.52倍(肥东土壤),提高了 2.28倍和1.74倍(长丰土壤).在孔雀草生长期间,氮肥和腐殖酸能够降低土壤pH值,尤其是NHA处理;NHA处理较CK处理在肥东和长丰土壤上pH值分别降低了 0.76和0.84个单位;腐殖酸处理(HA)能显著提高肥东与长丰土壤中DOC的含量.NHA和HA处理能显著促进孔雀草根系生长发育,改善孔雀草的根系形态特征.在肥东和长丰土壤中,与CK相比较,NHA处理土壤有效态Cd含量分别增加了 64.1％和53.1％,孔雀草Cd的累积量分别增加了 7.17倍和4.15倍;NHA处理的土壤Cd去除率最高,在肥东和长丰土壤上分别达到17.06％和14.08％.本研究表明在强化孔雀草修复重金属Cd污染土壤方面,铵态氮肥和腐殖酸的联用具有潜在应用前景.