Dechlorination of Lindane in the Multiphase Catalytic Reduction System with Pd/C, Pt/C and Raney-Ni

Dechlorination of -hexachlorocyclohexane (lindane) is carried out in the multiphase catalytic system, composed by isooctane and aqueous KOH phases, a phase transfer agent (Aliquat 336) and a metal catalyst, e.g. 5% Pd/C, 5% Pt/C, or Raney-Ni. At 50 ◦C and atmospheric pressure the full conversion of lindane to 1,2,4-tricholorobenzene (1,2,4-TCB) is achieved in 5–10 min via the base assisted dehydrochlorination, followed by the metal catalyzed hydrodechlorination with hydrogen to benzene. Aqueous KOH and Aliquat 336 strongly affect the reaction: if present together they co-promote both dehydrochlorination and hydrodechlorination steps; if KOH is absent, the reaction is forced to follow a different catalytic pathway, which involves a removal of a pair of chlorines at every reaction step by zerovalent metal followed by reduction of metal with hydrogen. This is proven by the formation of 3,4,5,6-tetrachlorocyclohex-1-ene and 5,6-dichlorocyclohexa-1,3-diene as intermediates in the reaction over Raney-Ni, and by the absence of TCBs in the reactions on all the catalysts studied. The final yield of benzene via this pathway can be achieved in shorter times than in a system with KOH. The presence of Aliquat 336 in the isooctane-water system produces a 10-fold rate increase, the presence of alkaline water is also important since it avoids catalyst poisoning by neutralizing the hydrochloric acid formed

Waste Aggregates in Asphalt Mixtures

As part of the RILEM Technical Committee TC 279-WMR on valorisation of waste and secondary materials for roads. Task Group 3 used various waste aggregates as a replacement for natural aggregates in asphalt mixtures, namely, construction and demolition waste, recycled concrete aggregates and steel slag. For this interlaboratory exchange program, the mixtures were produced by substituting various amounts of virgin aggregates with the aforementioned waste aggregates in various fractions. The results from eight laboratories were compared to a reference mixture in each laboratory with conventional aggregates. The mechanical performance of these mixtures using such alternative aggregates indicates that bituminous mixtures prepared with the investigated waste aggregates required higher amounts of bitumen but had acceptable volumetric properties. Furthermore, they had better mechanical performance, regardless of the source of recycled aggregates. The results show that such aggregates 76 can be a viable option for use in roads, thereby contributing to the zero-waste society and reducing the use of natural aggregates. However, the adaptation of quality control/acceptance criteria and pavement design as well as the development of specific research aimed at assessing the environmental viability and life cycle sustainability of such materials seem necessary