竹材两段挤压浸渍化学机械法制浆废水污染特性比较

本文探讨了不同化学浸渍NaOH总用量下,慈竹和毛竹的化学机械法制浆性能;研究并比较了废水和COD_Cr产生量,探讨了废水的pH值、COD污染负荷、BOD₅、总氮、总磷等关键参数对生化处理的影响;测定了废水固形物的灰分及灰分中主要金属离子的含量,分析了用碱量与制浆得率及废水污染负荷的关系,探讨了废水总有机碳与COD污染负荷的相关性。结果表明,相同浸渍用碱量下,慈竹化机浆强度性能明显高于毛竹化机浆。2种化机浆综合废水产生量6.20~7.73 m³/t,pH值均大于8.5,COD_Cr产生量178.88~410.44 kg/t,用碱量与制浆得率和废水COD_Cr污染负荷相关,废水总有机碳与COD_Cr相关。     

脱油樟木APMP制浆性能研究

分析了蒸汽脱油后樟木片的材性和化学组分,实验室和工厂中试评估了该原料APMP制浆性能并分析了制浆过程中的废水负荷情况,探讨了樟木APMP浆碱性H₂O₂漂白的可漂性能。结果表明,在漂白温度90 ℃、浆浓25%、NaOH用量60 kg/t浆、H₂O₂ 50 kg/t浆条件下,樟木APMP浆的物理强度略低于杨木APMP浆、高于桉木APMP浆,可漂性低于杨木APMP浆和桉木APMP浆,樟木APMP制浆过程废水总COD负荷为杨木、桉木的2倍,当H₂O₂用量70 kg/t浆时,樟木APMP浆白度可达75.0%,得率82.5%。微漂APMP制浆中试结果表明,当H₂O₂用量27 kg/t浆时,樟木APMP浆白度达35.9%。在打浆度44.0 °SR时,纸张抗张指数达28.5 N·m/g,松厚度2.57 cm³/g,可用于配抄中高端包装纸产品。     

麦草烧碱-AQ法浆较佳漂序的选择

本文比较了相同初始卡伯值时烧碱-AQ麦草浆CEH、DQP和D(EOP)D漂白浆与桉木的DQP漂白浆的白度,研究了漂后麦草浆的黏度、打浆性能、纸页的物理强度及废水的污染负荷.结果表明,相同卡伯值时,麦草浆CEH和D(EOP)D漂白浆白度低于DQP漂白浆白度,然而,均为DQP漂白,麦草浆白度低于桉木浆的白度.麦草浆DQP漂白浆表面木素含量也低于CEH漂白浆.麦草浆不同漂序所得浆料黏度的比较表明,相同卡伯值时,CEH漂白浆黏度远低于DQP和D(EOP)D漂白浆的黏度.后续打浆性能、纸页的物理强度及废水的污染负荷的检测结果也表明,DQP和D(EOP)D漂序显著优于CEH.而DQP漂序又优于D(EOP)D漂序,因此,DQP漂序是漂白麦草烧碱-AQ浆的最佳选择.     

ECF漂白废水回用对产污负荷的影响研究

将麦草浆ECF漂白(DQP)中的P段洗涤废水用于D段漂后浆料的洗涤,初步探讨P段洗涤废水回用对漂白废水污染负荷及浆料性能的影响。结果表明,P段洗涤废水回用后,漂后浆料白度升高1~2个百分点,黏度略有下降;不同漂剂用量下,漂白废水COD Cr下降0~2.5 kg/t漂白浆,BOD5下降2.1~2.9 kg/t漂白浆,AOX下降17%~20%,漂白废水产生量减少30%。     

ECF漂白废水回用对产污负荷的影响研究

将麦草浆ECF漂白（DQP）中的P段洗涤废水用于D段漂后浆料的洗涤,初步探讨P段洗涤废水回用对漂白废水污染负荷及浆料性能的影响。结果表明,P段洗涤废水回用后,漂后浆料白度升高1~2个百分点,黏度略有下降;不同漂剂用量下,漂白废水CODCr下降0~2.5 kg/t漂白浆,BOD5下降2.1~2.9 kg/t漂白浆,AOX下降17%~20%,漂白废水产生量减少30%。     

麦草浆ECF漂白废水污染负荷研究

研究麦草碱法浆ECF漂白过程中随着漂剂用量的改变,漂白浆性能及污染负荷的变化情况,并与CEH漂白进行了对比。结果表明:同一H2O2用量条件下(2%),卡伯因子从0.075增加到0.25,纸浆白度显著升高,从75.10%ISO升高到82.34%ISO;CODCr从38.10kg·t-1未漂浆增加到39.91kg·t-1未漂浆;BOD5从8.70kg·t-1未漂浆增加到10.80kg·t-1未漂浆。同一卡伯因子(0.15)条件下,H2O2用量从1.0%增加到3.0%,纸浆白度增加有限,污染负荷却会大幅增加。纸浆如需漂至78%ISO(或80%ISO),且污染负荷维持在一个相对较低水平,卡伯因子不小于0.15(或0.20)。CEH漂白AOX产生量是ECF漂白的7倍。     

低卡伯值硫酸盐竹浆ECF漂白的研究

对卡伯值为11.4的深度脱木素硫酸盐竹浆分别进行了DQP、D0(EOP)D1和CEH 3种不同漂序的漂白。结果表明,在适宜的漂白剂用量下3种漂白竹浆的白度均达到80%,以DQP和D0(EOP)D1为代表的ECF漂白具有很好的白度稳定性。打浆后发现,这3种漂白竹浆的强度性能都较好,其中D0(EOP)D1漂白竹浆的各项强度性能最佳。达到相同的漂终白度80%时,DQP和D0(EOP)D1漂白废水的污染负荷均比CEH漂白废水低得多,其中AOX仅为CEH漂白废水的1/10左右,说明ECF漂白具有更好的环境友好性。综合考虑漂白浆的白度、白度稳定性、强度和对环境的友好性,D0(EOP)D1漂序是硫酸盐竹浆ECF漂白的较佳选择。     

Fenton氧化对制浆废水中难降解有机污染物的去除效果研究

与传统Fenton氧化法相比流化床Fenton氧化法可以有效降低氧化剂的消耗量,同时可以使COD_Cr的去除效率有所提高。由于制浆废水的复杂特性,Fenton氧化反应存在一定的矿化能力极限,处理后废水很难稳定达标。进一步研究确定了最佳反应条件为：H₂O₂用量为1/2Qth、Fe²⁺与H₂O₂摩尔比为1∶5时,一沉池出水进行氧化处理后COD_Cr由1004 mg/L降至235 mg/L,BOD₅/COD_Cr提高到0.59,并通过AOX值和二氯甲烷萃取物GC-MS分析对比,判断废水可生化性显著提高。在此基础上采用流化床Fenton氧化与废水生物处理组合工艺进行处理,可以满足达标排放要求。     

速生红麻纤维形态和制浆造纸性能研究

进行了一种速生红麻(hibiscus canniness L.)的纤维形态和制浆造纸性能的试验研究.该种速生红麻的纤维形态和化学组成表明该红麻适合用作造纸原料;全秆红麻采用烧碱-AQ法制浆可制得卡伯值16左右,得率46%左右的未漂浆,该纸浆有较好的漂白性能,容易用DQP和CEH漂序漂到84%ISO的白度.未漂浆和漂白浆均有较好的强度性能,在相同的打浆度或打浆转数下,DQP漂白浆的强度(尤其是撕裂指数)比CEH漂白浆好得多.     

麦草浆制浆造纸废水难降解有机物成分鉴定

麦草浆制浆造纸废水可生化性差,采用混凝-加核絮凝组合工艺处理后,出水COD_Cr仍偏高,而COD_Cr残留问题一直是困扰制浆造纸企业水处理的难点。为探究其成因,采用气相色谱与质谱联用（GC-MS）全扫描有机物定性分析方法对处理前后的废水进行了分析。结果表明,处理后废水COD_Cr偏高主要是由留在水中未被成功去除的小分子有机物所致,如邻苯二甲酸二异丁酯和邻苯二甲酸单乙基己酯等;通过测定处理前后废水UV254,间接反映出混凝-加核絮凝组合工艺对麦草浆制浆造纸废水中难降解大分子芳烃类有机污染物有较好的去除效果,同时提高了其可生化性。     

水稻中除草剂氯氟吡氧乙酸异辛酯和氰氟草酯的检测方法及其储藏稳定性研究

目的 探究26%氰氟草酯·氯氟吡氧乙酸异辛酯乳油在水稻上的残留行为, 对其储藏稳定性和膳食摄入风险进行评估。方法 待测试样经乙酸乙腈提取, N-丙基乙二胺(primary secondary amine, PSA)、C18和石墨化碳黑(graphitized carbon black, GCB)净化, 再经高效液相色谱-串联质谱法多反应监测模式扫描, 基质匹配标准曲线外标法定量。2018年在9地进行田间残留实验, 并且进行6个月的储藏实验, 获得氯氟吡氧乙酸、氰氟草酯和氰氟草酸在水稻上的残留实验中值、降解率, 对膳食摄入风险进行评估。结果 氯氟吡氧乙酸、氰氟草酯和氰氟草酸在加标浓度为0.05~0.5 mg/kg范围内具有良好的线性关系, 相关系数(r)为0.9984, 3种待测物在水稻中的平均回收率为76.4%~105.0%, 相对标准偏差(relative standard deviation, RSD)为1.2%~8.2%, 定量限为0.05 mg/kg。在6个月储藏实验期间, 3种待测物在稻谷及水稻植株的降解率低于30%。膳食风险评估表明: 普通人群氯氟吡氧乙酸异辛酯、氰氟草酯的国家估计每日摄入量分别为0.0596 mg和0.0120 mg, 膳食摄入风险评估分别为4.73%和1.90%。结论 该检测方法操作简便、前处理速度快、精密度高和灵敏度高, 可以满足对复合农药残留分析检测的要求。氯氟吡氧乙酸、氰氟草酯和氰氟草酸在-20 ℃冰箱6个月储藏稳定, 其在水稻上的残留对消费者不会产生不可接受的风险     

四极杆碰撞反应池-电感耦合等离子体质谱法测定粉条中的铝

目的 建立四级杆碰撞反应池-电感耦合等离子体质谱法(ICP-MS)测定粉条中铝元素的分析检测方法。方法 样品经微波消解后使用电感耦合等离子体质谱仪进行检测,使用内标元素45Sc消除基体干扰和信号漂移,碰撞反应池(KED模式)消除质谱干扰。结果 铝元素校正曲线相关系数为0.999783 ,方法检出限为0.045 mg/kg,相对标准偏差为 0.79 %,加标回收率86.4 %～97.8 %,粉丝粉条中铝成分分析标准物质检测结果在认定值范围内。结论 该方法灵敏度高、准确性高、精密度好,是一种快速、准确的粉条中铝元素含量的检测方法。     

液相色谱-串联质谱法检测蜂蜜中氟苯尼考及其代谢物残留量

目的 建立液相色谱-串联质谱法检测蜂蜜中氟苯尼考及其代谢物残留量的分析方法。方法 样品经氨化乙酸乙酯提取,通过DPC-2固相萃取柱净化,采用Poroshell 120 EC-C18柱分离,以10 mmol/L乙酸铵溶液-乙腈为流动相进行梯度洗脱,电喷雾正/负离子切换,多反应监测模式检测,同位素内标法定量。结果 氟苯尼考在0.2～30 μg/L时具有良好的线性关系,相关系数大于0.999,检出限为0.05 μg/kg,回收率为85.5%~116.3%,相对标准偏差小于10%。氟苯尼考胺在1～30 μg/L时具有良好的线性关系,相关系数大于0.999,检出限为0.3 μg/kg,回收率为85.6%~113.5%,相对标准偏差小于10%。结论 该方法快速、准确、灵敏, 适用于蜂蜜中氟苯尼考及其代谢物残留量的测定。     

氢核磁共振结合支持向量机鉴别蜂蜜植物源

目的建立基于氢核磁共振(1H nuclear magnetic resonance,1H NMR)结合支持向量机分类模型鉴别蜂蜜植物源的方法。方法采集荆条蜜、油菜蜜、洋槐蜜、葵花蜜4种不同植物源的蜂蜜共计122例样品的谱图信息,分全谱(δ0.10~δ9.50)、脂肪区(δ0.10~δ3.00)、糖类化合物区(δ3.00~δ6.00)、芳香区(δ6.00~δ9.50)4个不同积分区间建立分类模型,结合主成分权值系数筛选特征变量,进一步优化判别模型。结果基于主成分权值系数筛选变量范围δ3.40~δ3.90和δ4.60~δ4.70内共计267个积分变量,以该区域积分变量为输入变量建立的支持向量机分类模型,对训练集的判别正确率为97.53%,对测试集的判别正确率为100%。结论通过主成分权值系数能有效筛选特征变量,减少输入变量的同时提高模型稳健性与准确性,基于氢核磁共振结合支持向量机分类模型能有效鉴别不同植物源蜂蜜。     

低聚木糖作为牺牲剂在光催化产氢中的应用

目前光催化产氢的研究主要集中于修饰和改性半导体材料来提高其光催化产氢性能。在光催化分解水产氢过程中需要添加牺牲剂甲醇来消耗掉光生空穴,牺牲剂是影响半导体光催化剂产氢性能的一个重要因素。本研究选择可再生生物质低聚木糖作为牺牲剂,探讨了其光催化产氢性能,并与常用牺牲剂甲醇进行了光催化产氢性能比较。结果表明,未负载贵金属Pt时,半导体材料TiO2和C3N4进行光催化产氢时未检测到氢气。负载质量分数1%的Pt后,半导体材料Pt-TiO2和Pt-C3N4可以作为光催化剂进行产氢,经过24 h的光催化反应,基于催化剂质量,以甲醇为牺牲剂时分别产出4298. 3μmol/g和356. 5μmol/g的氢气,以低聚木糖为牺牲剂时分别产出3054. 5μmol/g和495. 6μmol/g的氢气。低聚木糖可以作为光催化产氢的牺牲剂,尤其用作Pt-C3N4的牺牲剂时,产氢性能优于甲醇。     

Short communication: Investigation of aflatoxin M1 levels in infant follow-on milks and infant formulas sold in the markets of Ankara,Turkey

Aflatoxins are fungal toxins known to be carcinogenic and are classified as food contaminants. This study was performed to investigate aflatoxin (AF) M₁ levels in baby foods sold in Ankara (Turkey) and to evaluate the obtained results according to the Turkish Food Codex (TFC). For this purpose, a total of 84 baby food samples (50 follow-on milks and 34 infant formulas) were obtained from different markets in Ankara and the presence of AFM₁ in the samples was analyzed by ELISA. In 32 (38.1%) of 84 infant food samples, the presence of AFM₁ was detected in concentrations ranging between 0.0055 and 0.0201 µg/kg. The mean level (±standard error) of AFM₁ was found to be 0.0089 ± 0.0006 µg/kg in positive infant follow-on milks. Aflatoxin M₁ was detected in only 1 infant formula sample (2.94%) at a concentration of 0.0061 µg/kg. The extrapolated levels of AFB₁ contamination in feedstuffs were calculated based on levels of AFM₁ in baby food samples. The data estimating AFB₁ contamination in dairy cattle feedstuff indicate that contamination may range from 0.3410 to 1.2580 µg/kg, with the mean level (±standard error) being 0.5499 ± 0.0385 µg/kg, which is lower than the level set by the TFC and European Union regulations (5 µg/kg). According to the obtained results, the levels of AFM₁ in analyzed samples were within the allowed limit (0.025 µg/kg) set in the TFC. Low levels of AFM₁ in infant follow-on milks and infant formula samples obtained during the study do not pose a health risk to infants.     

Degradation of aflatoxin B1 by fungal laccase enzymes

The enzymatic degradation of aflatoxin B₁ (AFB₁) by white rot fungi through laccase production was investigated in different liquid media. A significant (P < 0.0001) correlation was observed between laccase activity and AFB₁ degradation exhibited by representatives of Peniophora and Pleurotus ostreatus cultivated in minimal salts (MSM) (r = 0.93) and mineral salts — malt extract (MSB–MEB) (r = 0.77) liquid media. Peniophora sp. SCC0152 cultured in MSB–MEB liquid medium supplemented with veratryl alcohol and sugarcane bagasse showed high laccase activity (496 U/L), as well as 40.45% AFB₁ degradation as monitored using high performance liquid chromatography. P. ostreatus St2-3 cultivated in MSM liquid medium supplemented with veratryl alcohol resulted in laccase activity of 416.39 U/L and 35.90% degradation of AFB₁. Aflatoxin B₁ was significantly (P < 0.0001) degraded when treated with pure laccase enzyme from Trametes versicolor (1 U/ml, 87.34%) and recombinant laccase produced by Aspergillus niger D15-Lcc2#3 (118 U/L, 55%). Aflatoxin B₁ degradation by laccase enzyme from T. versicolor and recombinant laccase enzyme produced by A. niger D15-Lcc2#3 coincided with significant (P < 0.001) loss of mutagenicity of AFB₁, as evaluated in the Salmonella typhimurium mutagenicity assay. The degradation of AFB₁ by white rot fungi could be an important bio-control measure to reduce the level of this mycotoxin in food commodities.     

Aflatoxins in sunflower seeds and unrefined sunflower oils from Singida,Tanzania

A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B₁ ranging from limit of detection (LOD) to 218 ng g^?1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g^?1 for AFB₁ in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g^?1. Other aflatoxins, except AFG₂, were also detected. For the unrefined sunflower oils, the levels of AFB₁ ranged from LOD to 2.56 ng mL^?1. About 80.9% (17/21) of the analysed oil samples contained AFB₁ of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL^?1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.     

Natural co-occurrence of ochratoxin A,ochratoxin B and aflatoxins in Sicilian red wines

The natural occurrence of ochratoxin A, ochratoxin B, aflatoxin B₁, aflatoxin B₂, aflatoxin G₁ and aflatoxin G₂ (OTA, OTB, AFB₁, AFB₂, AFG₁, AFG₂) in red wines was investigated by HPLC/FLD after immunoaffinity column clean-up in 57 market samples produced in Sicily (Italy). The results showed a very low incidence of these mycotoxins in analysed samples, confirming the high degree of quality and safety of Sicilian red wines. The results indicated 71.9% and 64.9% positive samples for OTA and OTB respectively, with an average level of 0.13 μg l^–1, well below the European maximum permitted levels (MLs). The aflatoxin most frequently detected in the samples was AFG₁, present in 57.9% of samples, while the other aflatoxins were rarely present. Recovery experiments were carried out on eight mycotoxin-free red wines spiked with OTA, OTB, AFB₁, AFB₂, AFG₁ and AFG₂ at two different levels. The limits of detection (LODs) in wines were 0.02 µg l^–1 for OTA, 0.04 µg l^–1 for OTB, 0.03 µg l^–1 for AFG₁, AFG₂ and AFB₂, and 0.05 µg l^–1 for AFB₁. A good correlation was found, with good performances in term of precision for the method.     

Efficacy of Solis, NovasilPlus, and MTB-100 to reduce aflatoxin M1 levels in milk of early to mid lactation dairy cows fed aflatoxin B1

An experiment was conducted to determine the efficacy of 3 adsorbents, Solis (SO; Novus International Inc.), NovasilPlus (NOV; Engelhard Corp.), and MTB-100 (MTB; Alltech), in reducing aflatoxin (AF) M₁ concentrations in milk of dairy cows fed an AF-contaminated diet. Twelve early to mid lactation dairy cows averaging 163 d in milk were used in a 4 × 4 Latin square design with 3 replications. Cows were blocked by parity, body weight, and milk production and were provided ad libitum access to feed and water. Within each replicate, cows were randomly assigned to the 4 dietary treatments for 4 consecutive 7-d periods. Dietary treatments included AF [112 μg of AFB₁/kg of diet dry matter (DM)]; AF + 0.56% SO; AF + 0.56% NOV; and AF + 0.56% MTB. Milk samples were collected on d 6 and 7 of each of the experimental periods. Feed intake, milk production, milk fat percentage, milk protein percentage, and linear somatic cell scores were not affected by dietary treatments and averaged 22.20 kg/d of DM, 33.87 kg/d, 3.78%, 2.95%, and 1.60, respectively, across all treatments. Transfer rates of AF from feed to milk averaged 2.65, 1.48, 1.42, and 2.52% for cows fed AF, AF + SO, AF + NOV, and AF + MTB, respectively. Daily AFM₁ excretion in milk averaged 66, 37, 35, and 63 μg/d for cows fed AF, AF + SO, AF + NOV, and AF + MTB, respectively. The addition of SO and NOV to the AF diet resulted in a significant reduction in milk AFM₁ concentrations (SO, 45%; NOV, 48%) and AFM₁ excretion (SO, 44%; NOV, 46%). In contrast, MTB was not effective in reducing milk AFM₁ concentrations (4%), AFM₁ excretion (5%), or AF transfer from feed to milk (2.52%). Results indicated that SO and NOV at 0.56% of the diet were effective in reducing milk AFM₁ concentrations in cows consuming a total mixed ration containing 112 μg of AFB₁/kg of diet DM.