The present study examined novel wheat straw biochar (WSB) and acid treated wheat straw biochar (AWSB) for cadmium removal from contaminated water. A series of batch and column scale experiments was conducted to evaluate the potential of WSB and AWSB for cadmium removal at different biochar dosage (0.5–8 g/L), initial cadmium concentration (5–100 mg/L), solution pH (2–8) and contact time (5–180 min). Results revealed that cadmium adsorption decreased by increasing biochar dosage from 0.5 to 8 g/L; however, optimum dosage for maximum (99%) removal of cadmium was 2 g/L by WSB and 1 g/L by AWSB. Enhanced cadmium removal potential by AWSB is attributed to increased surface area, microporosity and variation in functional groups. Equilibrium experimental data was well described by Freundlich adsorption isotherm whereas kinetic data were better explained with pseudo-second order model. Both WSB and AWSB have shown good adsorption capacity of 31.65 mg/g and 74.63 mg/g, respectively, that is comparable with other costly adsorbents. Columns packed with WSB and AWSB at laboratory scale have also shown good retention of cadmium with excellent reusability. These findings indicate that WSB especially AWSB could be a promising, cost-effective and environmental friendly strategy for the removal of metals from contaminated water.

Plants under herbivore attack release volatiles that attract natural enemies, and herbivores in turn avoid such plants. Whilst herbivore-induced plant volatile blends appeared to reduce the attractiveness of host plants to herbivores, the volatiles that are key in this process and particularly the way in which deterrence is coded in the olfactory system are largely unknown. Here we demonstrate that herbivore-induced cotton volatiles suppress orientation of the moth Spodoptera littoralis to host plants and mates. We found that (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), an induced volatile, is key in herbivore deterrence: DMNT suppressed plant odour- and pheromone-induced behaviours. We then dissected the neurophysiological basis of this interaction. DMNT-responding glomeruli were also activated by other plant compounds, suggesting that S. littoralis possesses no segregated olfactory circuit dedicated exclusively to DMNT. Instead, DMNT suppressed responses to the main pheromone component, (Z)-9-(E)-11-tetradecenyl acetate, and primarily to (Z)-3-hexenyl acetate, a host plant attractant. Our study shows that olfactory sensory inhibition, which has previously been reported without reference to an animal’s ecology, can be at the core of coding of ecologically relevant odours. As DMNT attracts natural enemies and deters herbivores, it may be useful in the development or enhancement of push-pull strategies for sustainable agriculture.