Tag Archives: lead

Effects of soil contamination could be blunted with nanonutrients

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An October 15, 2024 news item on phys.org highlights research into soil remediation, Note: A link has been removed,

One of the pressing problems that the world faces in the era of climate change is how to grow enough healthy food to meet the increasing global population, even as soil contamination rises. Research recently published in Nature Food by an international team of scientists led by the University of Massachusetts Amherst, Guangdong University of Technology, and Central South University of Forestry and Technology, has shown that nutrients on the nanometer scale can not only blunt some of the worst effects of heavy metal and metalloid contamination, but increase crop yields and nutrient content.

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Caption: Nanomaterials can enter plants through above-ground tissues and root tissues. Soil rhizosphere microorganisms, soil particles, organic matter and rhizosphere deposits can also influence NM uptake in plants. Credit: 10.1038/s43016-024-01063-1 Courtesy of University of Massachusetts Amherst

An October 15, 2024 University of Massachusetts Amherst news release (also on EurekAlert), which originated the news item, describes the problem and the proposed solution, Note: Links have been removed,

“Much of the world’s arable soil is contaminated by heavy metals, like cadmium, lead and mercury, as well as metalloids, like arsenic and selenium,” says Baoshan Xing, University Distinguished Professor and director of the Stockbridge School of Agriculture at UMass Amherst. Xing, who is also the paper’s senior author, notes that such contamination puts severe stress on the ability to grow staple crops, which also affects the nutritional value of the crops that manage to survive. “We need to come up with solutions to reduce the heavy metals that wind up in our food,” says Xing, and one approach that has shown promise is the use of nutrients at nanoscale, or what he calls a “nano-enabled” agriculture.


The bulk fertilizers that you may be more familiar with are made up of large particles, which aren’t as readily absorbed by the crop. This means that farmers need to apply more, which then increases the levels of fertilizer runoff into streams, lakes and the ocean. However, crop nutrients at the nanometer scale can be specifically designed and mixed for particular crops, growing conditions and application methods, and engineered so that the target plant can most efficiently absorb the nutrients into its system, cutting down on the amount of fertilizer needed, keeping costs down and limiting runoff.

Though nanomaterials are already available on the agricultural market and have plenty of peer-reviewed science looking at their effect on the soil and crop growth, Xing and his colleagues’ research is the first comprehensive account of the effectiveness of nanomaterials as a class, with results that offer practical insights to help steer sustainable agriculture and global food safety.

“We collected data from 170 previous publications on the effectiveness of nanoparticles in reducing heavy metal and metalloid uptake,” says Chuanxin Ma, the paper’s co-lead author who completed his doctoral training at UMass Amherst’s Stockbridge School of Agriculture and is now a professor at China’s Guangdong University of Technology. “From those 170 papers, we collected 8,585 experimental observations of how plants respond to nanomaterials.”

The team then conducted a meta-analysis on this enormous trove of data, running it through a series of machine-learning models to quantify the effect of nanomaterials on crop growth and metal and metalloid uptake, before finally testing a flexible quantitative approach, known as the “IVIF-TOPSIS-EW method,” that can illuminate how to choose different types of nanomaterials according to a range of realistic agricultural scenarios.

The results show that nanomaterials are more effective than conventional fertilizers at mitigating the harmful effects of polluted soil (by 38.3%), can enhance crop yields (by 22.8%) and the nutritional value of those crops (by 30%), as well as combat plant stress (by 21.6%) due to metal and metalloid pollution. Nanomaterials also help increase soil enzymes and organic carbon, both of which help drive soil fertility.

“Of course, nanomaterials are not a silver bullet,” explains Xing. “They need to be applied in distinct ways based on the individual crop and soil.” Which is where the team’s IVIF-TOPSIS-EW method comes into play. “Our method can help policy makers choose the best course of action for their particular situation,” says Ma.

Yini Cao from Central South University of Forestry and Technology also contributed greatly to collecting and analyzing the data in this work.

This research was supported by the National Natural Science Foundation of China and the United States National Institute of Food and Agriculture (USDA).

Here’s a link to and a citation for the paper,

Engineered nanomaterials reduce metal(loid) accumulation and enhance staple food production for sustainable agriculture by Yini Cao, Chuanxin Ma, Jason C. White, Yuchi Cao, Fan Zhang, Ran Tong, Hao Yu, Yi Hao, Wende Yan, Melanie Kah & Baoshan Xing. Nature Food volume 5, pages 951–962 (2024) DOI: https://doi.org/10.1038/s43016-024-01063-1 Published: 11 October 2024 Issue Date: November 2024

This paper is behind a paywall.

Wearable solar panels with perovskite

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There was a bit of a flutter online in late July 2014 about solar cell research and perovskite, a material that could replace silicon therefore making solar cells more affordable, which hopefully would lead to greater adoption of the technology. Happily, the publishers of the study seem to have reissued their news release (h/t Aug. 11, 2014 news item on Nanwerk).

From the Wiley online press release Nr. 29/2014,

Textile solar cells are an ideal power source for small electronic devices incorporated into clothing. In the journal Angewandte Chemie, Chinese scientists have now introduced novel solar cells in the form of fibers that can be woven into a textile. The flexible, coaxial cells are based on a perovskite material and carbon nanotubes; they stand out due to their excellent energy conversion efficiency of 3.3 % and their low production cost.

The dilemma for solar cells: they are either inexpensive and inefficient, or they have a reasonable efficiency and are very expensive. One solution may come from solar cells made of perovskite materials, which are less expensive than silicon and do not require any expensive additives. Perovskites are materials with a special crystal structure that is like that of perovskite, a calcium titanate. These structures are often semiconductors and absorb light relatively efficiently. Most importantly, they can move electrons excited by light for long distances within the crystal lattice before they return to their energetic ground state and take up a solid position – a property that is very important in solar cells.

A team led by Hisheng Peng at Fudan University in Shanghai has now developed perovskite solar cells in the form of flexible fibers that can be woven into electronic textiles. Their production process is relatively simple and inexpensive because it uses a solution-based process to build up the layers.

The anode is a fine stainless steel wire coated with a compact n-semiconducting titanium dioxide layer. A layer of porous nanocrystalline titanium dioxide is deposited on top of this. This provides a large surface area for the subsequent deposition of the perovskite material CH3NH3PbI3. This is followed by a layer made of a special organic material. Finally a transparent layer of aligned carbon nanotubes is continuously wound over the whole thing to act as the cathode. The resulting fiber is so fine and flexible that it can be woven into textiles.

The perovskite layer absorbs light, that excites electrons and sets them free, causing a charge separation between the electrons and the formally positively charged “holes” The electrons enter the conducting band of the compact titanium dioxide layer and move to the anode. The “holes” are captured by the organic layer. The large surface area and the high electrical conductivity of the carbon nanotube cathode aid in the rapid conduction of the charges with high photoelectric currents. The fiber solar cell can attain an energy conversion efficiency of 3.3 %, exceeding that of all previous coaxial fiber solar cells made with either dyes or polymers.

Here’s an image used in the press release illustrating the new fiber,

[downloaded from http://www.wiley-vch.de/vch/journals/2002/press/201429press.pdf]

[downloaded from http://www.wiley-vch.de/vch/journals/2002/press/201429press.pdf]

Here’s a link to and a citation for the paper,

Integrating Perovskite Solar Cells into a Flexible Fiber by Longbin Qiu, Jue Deng, Xin Lu, Zhibin Yang, and Prof. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201404973 Article first published online: 22 JUL 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

I found a second item about perovskite and solar cells in a May 16, 2014 article by Vicki Marshall for Chemistry World which discussed some research in the UK (Note: Links have been removed),

A lead-free and non-toxic alternative to current perovskite solar-cell technology has been reported by researchers in the UK: tin halide perovskite solar cells. They are also cheaper to manufacture than the silicon solar cells currently dominating the market.

Nakita Noel, part of Henry Snaith’s research team at the University of Oxford, describes how perovskite materials have caused a bit of a whirlwind since they came out in 2009: ‘Everybody that’s working in the solar community is looking to beat silicon.’ Despite the high efficiency of conventional crystalline silicon solar cells (around 20%), high production and installation costs decrease their economic feasibility and widespread use.

The challenge to find a cheaper alternative led to the development of perovskite-based solar cells, as organic–inorganic metal trihalide perovskites have both abundant and cheap starting materials. However, the presence of lead in some semiconductors could create toxicology issues in the future. As Noel puts it ‘every conference you present at somebody is bound to put up their hand and ask “What about the lead – isn’t this toxic?”’

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Brian Hardin, co-founder of PLANT PV, US, and an expert in new materials for photovoltaic cells, says the study ‘should be considered a seminal work on alternative perovskites and is extremely valuable to the field as they look to better understand how changes in chemistry affect solar cell performance and stability.’

Here’s a link to and a citation for the UK researchers’ paper,

Lead-free organic–inorganic tin halide perovskites for photovoltaic applications by Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir-Abbas Haghighirad, Aditya Sadhana, Giles E. Eperon, Sandeep K. Pathak, Michael B. Johnston, Annamaria Petrozza, Laura M. Herza, and Henry J. Snaith. Energy Environ. Sci., 2014, Advance Article DOI: 10.1039/C4EE01076K First published online 01 May 2014

This article was open access until June 27, 2014 but now it is behind a paywall.

I notice there’s no mention of lead in the materials describing the research paper from the Chinese scientists. Perhaps they were working with lead-free materials.