Chlorophenolics from High Molecular Weight Chlorinated Organics Isolated from Bleached Kraft Mill Effluents

Abstract

Extended abiotic incubation and alkaline hydrolysis of chlorinated high molecular weight (HMW) organics (>400D) isolated from bleached kraft mill effluents (BKME) were used to release bound Chlorophenolics. Incubation experiments showed a temperature dependent slow release of 4,5-dichloroguaiacol (4,5-DCG), 3,4,5-trichloroguaiacol (3,4,5-TCG), 4,5,6-trichloroguaiacol (4,5,6-TCC), tetrachloroguaiacol (TeCG), 6-chlorovanillin (6-CVa) and 5,6-dichlorovanillin (5,6-DCVa) from HMW material. Alkaline hydrolysis of HMW with 2 M NaOH at 50 and 100°C released significantly higher concentrations of Chlorophenolics and also 4,6-dichioroguaiacol (4,6-DCG), 3,4-dichloroguaiacol (3,4-DCG) 3,4,5-trichlorocatechol (3A5-TCC) and tetrachlorocatcchol (TeCC) which were not observed during the incubation period. However, chlorocatechols were found to be unstable during alkaline hydrolysis. Chlorophenolic organic carbon partiton coefficients (K oe ) from the solvent extractable (free) and the alkaline hydrolysis released (bound) concentrations were compared to estimated and reported literature values. Measured primary treated effluent KOC values were in agreement with estimated values for 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), pentachlorophenol (PCP), 3,4,5-TCG, 4,5,6-TCG and TeCG but significantly different for 4,5-DCG. Primary and secondary treated effluent chlorophenolic K«c values of 3,4-DCG, 4,5-DCG, 6-CVa, 5,6-DCVa, 2-chlorosyringaldehyde (2-CSAld) and 2,6-dichlorosyringaldehyde (2,6-DCSAld) did not agree with their measured chlorophenolic KOC values. These results suggest that simple hydrophobic interaction does not account for the high concentrations of these Chlorophenolics bound to HMW material.

Reactivity of lignin and problems of its oxidative destruction with peroxy reagents

“…60 ± 62 One of promising approaches to oxidative destruction of residual lignin in industrial pulps during bleaching is the biotechnological method. 63,64 Molecular chlorine is widely employed in the pulp industry for oxidation of lignin during the pulp bleaching, however, its application is accompanied by concomitant formation of a number of toxic aromatic chlorine-containing products, 65,66 including dioxins. 67 The use of sodium hypochlorite for the pulp bleaching is accompanied by the formation of chloroform.…”

Avaliação da biotratabilidade do efluentede branqueamento de polpa celulósicapor processos aeróbios e anaeróbios

“…Observa-se a predominância de compostos de baixa massa molar (<1 kDa) em ambos os efluentes provenientes da planta de branqueamento. Nota-se também maior remoção de tais compostos, o que está de acordo com diversos autores que indicam que fração com massa molar <1 kDa é mais rapidamente degradada quando comparada à fração com massa molar >1 kDa (MARTIN, 1995;SONNENBERG;WIMER;ARD, 1995).…”

Potential for Enhancement of Aerobic Biological Removal of Recalcitrant Organic Matter in Bleached Pulp Mill Effluents

“…Furthermore, some compounds, particularly those containing chlorine (measured by the parameter AOX) are recognizably recalcitrant because they contain chemical structures uncommon in nature, such as the carbon-chlorine bond [17], and their efficient removal depends on sufficient adaptation of the biological solids in the treatment system [15]. Various authors have also observed that high molecular mass (HMM) organic matter in bleaching effluents is more recalcitrant to biological treatment than low molecular mass (LMM) organic matter and that the proportion of HMM organic matter in the effluent may increase after biological treatment [18][19][20]. It has also been shown that the biodegradability of the HMM organic matter depends on the raw material and bleaching sequence used and can be improved by sufficient adaptation of the activated sludge to the particular effluent being treated [15].…”