B. M. Petronio

Adsorption of phenols by papermill sludges

In this paper we studied the sorption capacity of paper mill sludges for phenols. Phenol, 2-chlorophenol (2-CP), 3-chlorophenol 3-CP). 4-chlorophenol (4-CP), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2.4-dichlorophenol (2,4-DCP), 3,4-dichlorophenol (3,4-DCP) 3,5-dichlorophenol (3,5-DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) were chosen for the sorption tests. Kinetic experiments showed that substituted-phenol sorption on papermill sludge was rapid (equilibrium was reached after 3 h); conversely, the time taken by the phenol to reach equilibrium conditions was 260 h. Experimental data showed that particle diffusion was involved in the sorption process but was not the only rate-limiting mechanism; several other mechanisms were involved. The adsorption isotherms showed the following order of retention capacity of papermill sludge: 2-NP = 4-NP < < 2-CP < phenol < 4-CP < or = 3-CP < 2,4 DCP<3,4 DCP=2,4,5 TCP<3,5 DCP. In all cases the experimental data showed a good fit with the Hill equation. which is mathemratically equivalent to the Langmuir-Freundlich model obtained by assuming that the surface is homogeneous, and that the adsorption is a cooperative process influenced by adsorbate-adsorbate interactions.

Metal ion removal from water by sorption on paper mill sludge

Chromatographic columns packed with paper mill sludge are employed for metal ion recovery from water. The breakthrough curves show that cadmium, copper, lead and silver are removed from acid solutions (pH 2, 4); the affinity series is Pb(II)>Cu(II)>Ag(I)>Cd(II). Both the amount of metal retained and the metal-matrix interaction are pH dependent; the sorptive capacity increases with increasing pH. When the metals are present together at the same initial concentrations a competition among the different ions occurs although the affinity order remains unchanged. In metal recovery from the paper mill sludge column, the total amount of the cadmium and copper is displaced by HCl 1.0 M, 65% of the lead by HCl 0.1 M and 75% of the silver by HNO(3) 0.1 M. More than 95% of copper and lead and less than 20% of cadmium were recovered with HCl 0.1 M when the metals were present at the same time.

Paper mill sludge–soil mixture: kinetic and thermodynamic tests of cadmium and lead sorption capability

Abstract Paper mill sludge (characterized by 29.0% of organic substances such as cellulose, lignin and tannins and 71.0% of inorganic substances such as kaolinite and carbonates) was studied in a mixture with soil in order to evaluate its effects on soil capability for retaining heavy metals. Attention was focused on cadmium and lead sorption and two parameters were investigated, the contact time of paper mill sludge–soil mixture and the paper mill sludge–soil ratio in the mixture. Results showed that paper mill sludge and soil interact to form ‘new’ sorbing sites. Taking into account sorption results of lead, the retention of which by soil is substantially increased by sludge addition, can highlight this modification. Also, the amount of sorbed cadmium was increased by sludge addition.

The structural composition of humic compounds as indicator of organic carbon sources.

Various analytical techniques ((13)C-NMR, FTIR, elemental analysis) have been used to study the structures of humic compounds present in the sediments of Martignano lake located 50 km from Roma city (Italy). The total amount of humic compounds present in the upper layer of sediments is practically constant; instead, considering humic (HA) and fulvic acids (FA) separately, it can be noticed that while HA increase remarkably from A(1) to A(3), FA diminish, probably as a result of the continuous transformation of algal debris, present in large amount in A(1), from compounds which are in an early stage of decomposition to more highly degraded organic matter. In deeper layers the percentage both of HA and FA is constant and slightly lower than that found in the upper layer, except for two sampling points. In these stations the amount of both HA and FA are very high and the carbohydrate peak areas of HA and FA increase along with the depth, reflecting the presence of a well localized source of organic carbon or different environmental conditions.

Effects of acid rain on soil humic compounds

The modifications induced by acid rain on the solubility, molecular configuration and molecular weight distribution of humic (HA) and fulvic (FA) acids were studied. A natural soil was subjected to simulated acid rain until a soil pH of 4 was obtained; HA and FA acids were then extracted and characterised. The results obtained were compared both with those of natural soil and with those of a soil subjected to acid rain. Elute analysis indicates the continuous release of soluble organic compounds as a consequence of acid rain simulation, although no relationship was found with the process of soil acidification. The yields of HA and FA show that HA values are the same while FA amount is higher in the natural soil; in acid soils their water solubility increases. The molecular weight distribution shows that HA consist of a mixture of compounds of different molecular weights; they are molecules for the most part larger than 100 kDa and their distribution is not changed by soil acidification. FA can be considered to form a much more homogeneous system; in natural soil, the molecules are larger than 50 kDa, while in acidified soil they are for the most part smaller than 3 kDa.

Soil sorption of heavy metals as influenced by sewage sludge addition

Abstract In this paper it was evaluated how the sorption process of heavy metals (Zn, Cu and Pb) by soil is influenced by the presence of sewage sludge. Results obtained both from sorption experiments and analytical characterization of a sewage sludge estract, showed that confounds of an organic nature deriving from the sludge adsorb on the soil at first, offering new adsorbing sites to heavy metals, increasing the soil sorption ability. However this sorption capacity is inversely related to the amount of metal sorbed, as evidentiated by the Kd graphs, so that only “low metal”; sludges will be able to provide new sorbing sites in addition to the ones supplied by the soil.

Purification of soluble fulvic acid low concentrations by a diafiltration technique

The purification of soluble fulvic acids (FA) based on a diafiltration technique is carried out on antarctic water and snow samples, characterised by low humic compound content (0.1-0.8 mg/l). Results are compared with those of FA purified with the dialysis technique that, together with ion-exchange resins, performs an often used purification process. With the adopted procedure it is possible to minimise the high content of inorganic salts deriving in part from the isolation method XAD-8 adopted, as shown by FTIR, elemental and thermogravimetric analysis.

Characterization of high molecular weightorganic compounds in landfill leachate:humic substances

Abstract We present here some results obtained on the high molecular weight organic fractions dissolved in landfill leachates. These fractions are similar to humic and fulvic acids obtained from soil and marine matrices for some characteristics such as colour, molecular weight range, solubility and for structural features. The characterization of humic substances has been carried out with spectroscopic techniques and thermogravimetric analysis. They have shown the presence of a great amount of functional groups, in particular oxygenated and nitrogenous groups. Elemental analysis has been performed also.

Spatial and Temporal Heavy Metal Concentration (Cu, Pb, Zn, Hg, Fe, Mn, Hg) in Sediments of the Mar Piccolo in Taranto (Ionian Sea, Italy)

The Mar Piccolo (surface area of 20.72 km2) is located in the Northern area of the Taranto town (Ionian Sea, Italy). It is an inner, semi-enclosed basin with lagoon features connected with the Mar Grande through two channels which are very important for water exchange. Mar Piccolo basin is subjected to urbanization, industry, agriculture, aquaculture and commercial fishing. Hence, it is important to have a temporal picture both of heavy metal content and of organic carbon and their distribution (hydrophobic fraction, hydrophilic fraction, humic compounds) to check the progress of pollution in time. Three sediment cores collected on the basis of the pollution sources have been analyzed. Both heavy metal and organic carbon concentrations underline the fact that the anthropogenic input is different in the three sites, and that in time the amount of pollutants coming into the Mar Piccolo have changed in different ways. The high amount of organic hydrophilic compounds present in sediments, both due to the small water depth and to the high accumulation rate, make the sediment site high in oxygen consumption due to a considerable chemical and biochemical transformations of organic matter.

Humic marine matter and insoluble materials in Antarctic snow

Abstract The aim of the present work is to show that the insoluble components of marine origin are always present, together with the soluble ones, in both the coarse fraction and in the fine fraction of the marine aerosol and that they make up a non negligible part of the insoluble material in Antarctic snow. The results obtained show that a large proportion of the insoluble matter present in high altitude Antarctic snow consists of marine organic matter involved in the aerosolization process and that the thermolabile fraction (4000C), largely consisting of fulvic acids, increases with increasing altitude. The effect of distance from the sea coast is harder to demonstrate for particulate fulvic acids at least over the short distances investigated herein (150 km) and owing to the complex orography of the sample areas.